Well I bought a complete running 1976 400 and I have torn it all down and i'm trying to come up with a good combo to build. My block is a high nickle block whatever that means. Its also a 2 bolt which I hear is actually more desired then the four bolt..just the opposite of what you would think. Im having it bored 30 over this week and Im thinking about having billet 4 bolt splayed main caps added. I was told though that this would actually weaken it like it did on the stock 400 4 bolt main blocks...true or not? I also have a question about rod to cam clearance. I was told to use I-beam rods instead of H-beam rods because I was going to run into a clearance problem with the cam. I was going to use a 6.0" rod but again I was told not to because of the piston pin being in the ring area would be weak and cause ring seal problems..So I need to know whats true and what is not. I plan on running a pair of ported/polished Dart 230cc heads, a Crane #119661 roller cam & about 10.5 to 1 Wiseco forged pistons with a Edelbrock Performer RPM Air Gap intake. My desktop dyno says i'm looking close to 550 HP and 550 TQ at the crank & I may want to spray about 150 shot at times so I need to know this thing is going to stay together. What parts would you use? What works and what doesnt. Will I have a rod/cam clearance issues? Should I use a 5.7" or 6.0" rod? I beam or H beam? To splay or not to splay? What crank will hold together at these power levels? HELP PLEASE!!! Thanks guys!!...joe

Hi Bipolar! I am building up my first 400 right now, so I can't give too much experience to your post, but I will say that if you are planning on 550hp and an occassional shot of nitrous, you may want to seriously consider splaying the caps! Splayed caps are different than a stock 4-bolt in that the outer row of bolts are angled into the block and not tapped straight into it. From what I have learned here on the site recently is that if you are planning on spinning the engine anything over 6krpm, it is good to run with forged components (crank, rods, pistons) for the added stability they give. I went with 5.7" I-beam rods. You can use H-beam rods, but will definately want your machinist to check for clearance. We have some very knowledgeable engine builders around here who will chime in on this I'm sure. Good luck in your build up!
Dano:thumbsup:

I built a 406 for my 67. Its a blast to drive. Runs easy 13.0 1/4 mile times and does world class burnouts on demand. Mine is also a 2 bolt block with dart iron eagle heads ported/polished, XE268 cam and 750 holley on an air gap.

Have you bought anything yet? Just curious but Ill get to some of that later. Anyways, as far as the block goes, it is correct that the 2 bolts are more desireable. And if youve got a high nickel unit(all good things), Im assuming its a 509 casting block(good thing too). Ive never heard anything bad about splayed 4 bolt caps....just good things if done right.

About the rods, I can agree with the 6 inch rod issue, but only to an extent. Its true, with the longer rod, the wristpin is moved up and your running a narrower ring pack. This can be an issue if the machining isnt right(oil control issues can be more prominent than if you were running a less than adequate machined block but with a thicker ring pack). But with a TRUE round bore and good taper, this isnt an issue. Have this thing done right. Get it all squared up good at a shop with good equipment and hopefully they can torque plate hone it(you can get this done at almost any respectable place). Have it sonic checked. Going .030 over is a pretty common amount, but if you can afford to go less, its not a bad idea. Keeping those cylinder walls thick helps. Look for a minimum of .170 or so on the thrust side. Thats what Carl(CNC BLOCKS N/E) likes to see, and he has a pretty good idea of what he is doing!

All in all, 6 inch rods are just fine in a well machined block and have some nice advantages as well over shorter rods(one of the big ones is a lighter rotating assembly due to the lighter pistons used....and thats a good thing). Even though the rod will be longer and heaveir, the shorter piston will still make the whole combo lighter in most cases. Check out the Scat 7/16th capscrew, 6 inch, I beam rods. These are VERY nice for the money. Sure their is better, but for the price, good luck finding another 4340 steel rods that can do the same job significantly(for the price). On piston choice, wiseco makes a nice piece, and the JE/SRP units do real well in these type of applications, as do the Mahle units. All good stuff. If your looking to stiffen things up even moreso, a little bit of hard blok added can help.

On to the motor combo.....I think the DD is a little on the optomistic side for this one. Im not being mean here, so dont take it that way, but a 230 degree roller is mild in a 406. By the time you factor in valve lash, the lobe looks a little smaller yet and if it makes 550 horses, Ill build one tomorrow cause you have found one heck of a "have your cake and eat it too" kinda combo. Id say more like 470 at best if the heads really do the job.

Which brings me to my next question. Have you bought heads yet? Dart makes a very nice and durable head(well put together and tough)....but with a lot of the stuff out there now, they just dont hang quite as well in the flow dept. Granted, darts have excellent porting potential(lots of meat to manipulate the casting), but I beleive that you can get excellent results with some of the out of the box, smaller aluminum pieces. For example, the brodix race rite 200cc heads with the CNC chamber option or the AFR 210 heads. Heck, even the 195 AFR heads will ROCK on a 406, but if you are hoping for well over 500 horses, the larger 200-210cc port should help things without having to step up to a gaint, ported 230cc head. Just a thought of course. A good set of hands can make the darts work great. But it sure is nice to make the power with a smaller port/cross section cause that makes for more power everywhere.....not just peak numbers(better low speed power and all).

Back to the solid roller cam...if your gonna use one, make it worth it. I wouldnt go smaller thal a low 240 degree cam. Just for example, those race rites with a sold roller around 243/251 at .050 on a 110 or 108LSA roller should break 500 horsepower(or close to it) and run solid mid 11's in a good car. You could probably stretch more out of it as well(the smaller 230 degree roller would be a great street cam, but would wheeze a bit at higher rpm and have a hard time really going real fast....and I just dont see 550 horses). Or something like the AFR 210 heads with a 247/251 at .050 on a 108 or 110LSA should be worth a little more yet. The darts with a similar setup could work great too....I just think a ported 230cc head is more than necessary and probably wont run much faster(at the expense of low speed torque).

As far as clearancing goes....there are no guarantees no matter what you use. Yer gonna have to clearance something. Those scat rods do have better clearance than stock 400 rods, but that still dont mean that in some situations you wont need a small base circle cam for example. I beam rods are plenty capable though for your motor and can help things.

Lastly, if you go solid roller.....use good lifters. Especially if its a street engine. Lots of lower speed cruising and idling can beat up a solid roller setup. Good lifters with good oiling help a lot. The two most sought after lifters in many cases are the Isky Red Zones and the Crowers with the high pressure pin oiling option. Both of these have pressure oiling to the needles(good stuff). This helps the live better. The iskys usually win cause they are rebuildable, but both are comparable as far as overall durability goes. Eric68 has had great luck with Comp cams super roller lifters, but I havent heard much else about those ones aside from the good things Eric has said. And with the results he has had, they are worth looking into as well.

To much head for that little intake and cam. you will need 30 more degrees of duration and a big single plain to us those heads.. And use a 6" rod. Be sure it is zero decked, keep the cam around 108LCs, lean on the exhaust side. Do this and you can see more like 600HP, if that is too much, use smaller heads and go with your other parts.

Only other thing to really consider, by the time you splay the caps, strap the end caps, fill the deck plugs, etc, etc, etc, all the things that you need to do to make that block live, you could by a new aftermarket block and be done. Been there, done that, never again!

We machine a lot of blocks and on the 400 block have the cylinders sonic tested before anything is done as we have condemed a few of those block due to thin cylinder walls.

We also install a lot of splayed center caps as the caps we put on ore 7.500 wide and the outter bolts are at a 10 degree angle and pull on the pan rails instead of pulling on just the webbing of the block.

A 6 inch rod would be the way to go and Mauhle pistons the wrist pin does ot get into the ring package but we have used many sets or the SRP pistons with no problems.

If this helps a Dart Sportsman block all machined and shipped free in the U.S. for 2395.00

Like I said have the block sonic tested first.

On the rod issue -- thought you would be interested to hear what I recently learned about 6" Scat rods:

The 3/8" capscrew I-beam rod has the least amount of cam/rod clearance out of the three rods I looked at. They have no profile work done to them and weighed in at 649.3 grams.

The 7/16" capscrew I-beam rod has the most amount of clearance out of all the rods I looked at. Probably near an extra 1/4" more than the rod with teh 3/8" bolt. The reason for this is the rods has a lot of profiling work done on the sides and the 7/16" capscrew bolt is only 1.40" long. These rods weigh in at 596 grams -- a full 53 grams lighter than the 3/8" capscrew rod. This adds up to over a POUND LESS rotating weight, especially when you add in the extra amount of material that gets removed from the counter weight.

The H-beam rod has a better profile around the rod bolt threaded end than the 3/8" capscrew rod, but not as much clearance as the 7/16" capscrew rod. I haven't weighed them yet so I cannot say what the weight is. The appear to be "in the middle" for cam to rod clearance.

Bottom line. If you want lots of cam-rod clearance for a big stroker motor go with the Scat 6" rod with the 7/16" bolt. They are only about $50 more than the 3/8" bolt version but are way better.

I agree with Eric on the rod issue. The Scat I beams with the 7/16 cap screw are the way to go. They give you the most clearance and are very strong. I was very impressed with the quality of the rods as well. The measured ID of the big ends were damn near identical on my entire set.

Doc

Eric have you seen a set of 5.7 I-Beam Scat rods are the profiles the same as the 6" rods?In Competition Products the 3/8 rods are $289.95 a set and the 7/16 sre $.299.95.

hey bipolar, what is the main purpose of the car this 400 is going in? what rpm range are you wanting to make big power in? i recently tried having a good core 400 block built w/ an all forged eagle rotating assy. & it was cheaper to buy an assembled short block with all eagle 4340 stuff, je pistons, & a dart block. if you go with the splayed caps, plan on about $6-800 for the caps & machining for them. definately have the block sonic checked first!!!

As far as machinist go I suggest finding a good one with not only a lot of experience but having the correct equipment for the job. I chose my machinists based upon recommendations, the fact that he owned his own dyno, and had a flow bench, as well as CNC mills and lathes with years of experience in set-up. A machinist with this kind of experience is often referred to as a tool and die maker. It also helps to walk into the office and see this:

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02647.jpg

I also have a 509 block but mine isn't the high nickel content block which makes it much tougher. You can tell because it says 10 in the front timing cover valley instead of 20.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02678.jpg

I chose to go with the four bolt main conversion because I was planing on more than the 450 horse design limit of the block. I was going to go with the full conversion of front and rear steel main caps but Milodon couldn't deliver them for another eight weeks so I went without them. It really doesn't add that much in terms of strength. I just wanted to have all the caps of the same material so their coefficient of expansion would be the same.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02683.jpg

I bolted the whole thing together with ARP studs and bolts.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02845.jpg

I chose to use Eagle products and bought a complete forged lightened rotating assembly already balanced. I spent about ten grand altogether on parts which I kept in my bedroom as I saved up enough to get everything together.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02684.jpg

Anyway I opted for the six inch H-beam rod which puts the piston pin in the oil ring, but because the J&E Sportsman forged pistons come with rails there isn't a problem. Here you see can also see the added cross section (meat) of the H-beam rod.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02813.jpg

I also used Total Seal™ Gapless second rings with a Perfect Circle moly filled top ring which were file fitted to the bore.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02816.jpg

You must have 0.050 inch clearance at the oil pan rails as well as at the bottom of the cylinders. You want a minimum of 0.030 inch clearance as it clears the lobes of the cam. Here the rod bolts hit the block.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02758.jpg

You must grind the block for the bottom end clearance.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02769.jpg

To clear the cam you must grind on the rod and rod bolt. Because I used H-beam rods they were already clearanced for up to a 4.00" stroke with the rod bolt head sunk an additional 0.100" into the rod for the cam clearance. I still checked using a copper wire gauge. (A better Idea I heard on this site is to use a plastic tie strap of the desired thickness).

I chose Edelbrock Victor Juniors for my heads though AFR 195's were my second choice. I was thinking I would probably be spending more time against the rev limiter than most normal people but that is just my style of driving.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02849.jpg

I used a CompCams hydraulic roller conversion for my early model block ('78) and an Extreme Energy hydraulic roller cam with 224°/230° duration @ 0.050 .502"/.510" lift and a 110° LCA which is a mild grind for street driving. I also used Magnum chromemoly pushrods 5/16th x 7.300" (0.500" shorter) and ProMagnum chromemoly roller rocker arms and opted for the polylocks 0.3" shorter than normal (4600-16) to fit them under my cast covers.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02821.jpg

I went with a Holley Street HP 750 cfm vacuum secondary (0-82750) carburetor though I thought about going bigger.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02818.jpg

I went through nine test assemblies on the engine to get everything to spec (blueprinted) and with this combo it dynoed out on the fourth pull at 527 hp @5800 and 527 torque @4600 which I took as sign to say we were done, and throw it in the car. It was set up to run up to a 250 hit of nitrous (ring and piston clearances) and with the parts I have I feel confident it will stay together.


Larger Dave

Larger Dave,

What are you putting that engine in? A late 80's impala? Just curious.

Put it in my '89 Caprice (wife's old cop car). Have a 582 in my '85 Impala. Hope to get the '85 painted with '89 front and rear trim to look identical, so that as I cruise around with the SBC I can "Go home and get my slicks" (and the '85 BBC).

Put it in my '89 Caprice (wife's old cop car). Have a 582 in my '85 Impala. Hope to get the '85 painted with '89 front and rear trim to look identical, so that as I cruise around with the SBC I can "Go home and get my slicks" (and the '85 BBC).


Sounds fun...definitely have you a couple SS Impalas even though GM didn't make'm that way. I'd love to see the look on the unsuspecting mustang driver's face, hehehe

I have engine close to yours 406 240 duration 525 life 6 inch rods 780 holley dart 200 hundred CC heads FOR 9.6 compression dart intake balanced gasket ported the set up runs smooth i think you love it did you have a dyno run with out nitrous, i like H P guess i dont want dyno the engine thanks
River

527 was motor alone, and I'm running 10.9:1 compression (angle cut head a little). I built motor with three piece timing cover to be able to swap cams in driveway at a moments notice. NOS was built into clearances in ring end gap and piston to wall fit, not as in some under manifold installation (though I'm not above such things as Smokey Yunick is one of my hero's da Grump is da other).

Sorry didn't mean to hijack your post
Larger Dave

You may have to clearance the block if you are going to use 6" rods, H beem or I beem. It is not a big deal though, core shift plays a big part in where the rod bolts are going to make contact with the block. I use a small base circle cam solid roller AFR 210 heads Eagle 4340 crank and eagle 6" h beam rods Vic Jr intake AND A BG Claw 750 dp. Wisco pro tru flat top pistons, your machinest will wine about them because the triple pin retainers are a pain in the arse to install but a great deal for the money. Those guys are right about the solid roller lifter issue, buy a quality lifter set up, I just installed a set of Crowers in mine. We will be trying to get my car into the tens this year
http://i33.photobucket.com/albums/d84/lowcamaro/DSC00084.jpg
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Bipolar, there's some great stuff here, maybe we can both learn something. With what little I know I wouls agree with "Larger Dave" about finding a good machinists and with "Greg" about the cam. I'm having a new engine built and like "Larger Dave" I went with Eagle Racing Products as well. After talking with my builder he convinced me of the old saying "there's no replacement for displacement" so rather than go with a BB, and rework the front end of my 68 Camaro, I went with a new Dart "LIL M" block, an all forged and balanced Eagle 415 rotating assembly. And like Greg said, I went with the AFR 210 race ready heads. Greg also mentioned a larger cam, I went with a Comp Cam Extreme Energy XR294HR roller cam, Comp Cams Hi energy roller lifters, and Comp Cams High Tech 1.6 roller rockers. I'm using an Edelbrock Air Gap RPM intake with a Holley 750 hp. My cam is about 242/248 @ .05 with a .540/.562lift (not counting the additional lift with the 1.6 rockers) and a 110 LSA. Like you I'm hoping for about 550-580 at the flywheel, but after reading all this maybe I'm nuts. My builder seems to think we'll hit somewhere in that range. He, like me, is in his 50's and still racing dragsters and has been building engines here in the pacific Northwest as long as I can remember. I'm not looking to race this thing every weekend but I don't want to back down from anyone on a Fri or Sat. Go ahead, you can say what you thinking..............what an "old" fool, and your right (I am old). Good luck Bipolar on your build, and most of all research what your doing and have fun with it.

As far as your motor making 550 ish horsepower with your setup, its not unheard of! Basically, when I quote numbers, I like to be on the optomistic side. Mainly because you are depending on the dyno, the operator, the conditions, and the tuneup to all be in your favor. In some situations, a motor like yours might only show 500 ish...but in others, it might show a good deal more. However, your better off expecting less(something thats plenty beleivable)...that way if you hit it, your not dissapointed....and if you get more....even better yet. In most situations, a motor like yours(or something similar to what I was talkin about) should show numbers around 500. But if you really work on it and the dyno is run well and everything is controlled well....you could see more for sure. I just would never expect 550 NA horsepower out of a 230 degree roller. That would just be too easy hehe. And like I said....if it were to make that much power with the small cam...I really would find a way to build it tomorrow cause once again, its just too easy(and I like that)!

WoW guys, I don't know what to say. Let me start with THANKS! There is a whole lot of info here that is really going to help me and I greatly appreciate it! I am having all my machine work and some assembly work done here locally by Larry Woodruff of Woodruff Racing Engines. He is the guy you go to if your serious about your motor. He has been building racing engines for over 30 years and has good knowledge and equipment. Im sure he could have answered my questions about my rod clearance issues and will be able to help find a good combo, but I wanted to find out as much as I could before I even took it to him. The block will be dropped off tomorrow for the cleaning, checking, machining, and prep work to begin. Im sure he will give me some good info and suggestions too. I'll be taking notes.:) I hope the block checks out good. I'll keep you informed. Thanks again!!

Im building one of these and am considering a 3.875 crank...
Anyways, I have a question for this thread and anyone able to respond:
Is there any WINDAGE issues involved in these 400's, with or without a stroker crank?
If so, what pans, windage trays, etc are considered and/or used?
Thanx!

I don't think there is anything special with a 400 based stroker motor in regards to windage. Windage in general is lost HP, and a windage tray will help reduce it. In addition I like to use the Moroso oil pump baffle (the one that goes in the back of the pan between the oil pump and rear main cap) to reduce the amount of oil that sloshes up into the crank during hard acceleration.

I am using a CV products 1080 oil pan. It was recomended to me by Carl C -- its a good pan at an affordable price.

Here's a unit with all the listed parts included. Made 580 HP and 523 Torque. Runs around town here on 93 from the local station and will be raced on 100 unleaded. I had posted this a few weeks ago. Thanks, Gary in N.Y.

(Quote)
Block=Dart SB (Steel-Caps), 9.025" decks, block-plated +.030" (4.155"), Dart supplied main bolts.
Crankshaft=Eagle #435037505700 (4340 Internal-Balance)
Pistons=Ross #95465, Flat-tops, 1.268" C.H.
Rods=Eagle #CRS5850B3D
Rings=Speed-Pro #R9346+35 (Gapped @ .018" Tops, .014" Second, and Low-Tension Oils)
Cam=Blue-Racer #WG5008MR (Mechanical Roller -Lash .022"/.024")
Lifters=Comp Cams 818-16
Damper=BHJ #CH-IBS-7
Oil Pan=Customer Supplied #N.A. No windage trays installed. (Kick-out pan with 1 baffle with trap door).
Timing Chain=Wolverine #TC499S (Nylon timing set machined for roller button)
Cylinder Heads=Pro-Topline 23 Degree, 2.080's, 1.600's, 235 CC runners, fully ported in house.
Valves=Ferrea’s #N.A. (Intake and Exhaust)
Springs/Retainers= Comp Cams #N.A. (Titanium Retainers).
Head Gaskets=Corteco (Detroit Gasket) #55431HG (.038" composition).
Fasteners=ARP # 134-4001 (Stud Kit)
Rocker Arms=Blue-Racer (8)#WG6004 (1.6-Intakes) - (8)#WG6002 (1.5-Exhausts).
Pushrods=Comp Cams #7993-16 (5/16”)
Stud Girdle=Comp Cams #4009
Intake/Carb=Edelbrock #2970 (Super-Victor) / Holley 8896-1(4500 CFM)
Compression ratio is "dead-on" @ 10.95 and runs with no problems on 93 Octane @ 34 Degrees total timing. I will add here however, we did the initial test using 110 because it was in the fuel cell. We ran it out and tested on 93.
Final numbers=580 HP @ 6400 RPM and 523 Ft.Lbs. @ 5500 RPM. You have to remember this is numbers we delivered the unit at on the weekend. We do have them slightly higher from some more of our own tests, but gave it to the customer at the posted numbers. This one will be returned in 1 year to be converted to a "Blown" alcohol unit with only a cam change, the C.R. will remain constant with the blower. Thanks, Gary in N.Y.
P.S. There are not really any “high-end” parts in this unit except for the “Dart” block. This one also has a $15.00 "nylon" timing chain setup listed above, which we figure was worth some additional "upstairs" H.P. We use these on a number of mechanical roller, street units, to keep the engine/driveline vibrations from getting up to the cam/lifter area, as opposed to a "Jesel" belt setup. It goes to show the power you can achieve without those “exotic” components. Please note both the ring gaps and the quench in particular, as these are the 2 main reasons for this post. (End Quote)

P.S. You can see from the photos this unit required a 4500 holley and will need 2.000" primaries. The headers on the unit in the photo have been replaced with the 2.000" ones as of 3 weeks ago. The ones in the photo are 1.750's. When we dynoed the unit we were down some 50 HP with the 850 carb AND 1.750" pipes. The El Camino it's in is a real "sleeper".

http://i16.photobucket.com/albums/b28/GOSFAST/PES%20Engines/th_P1010555.jpg (http://i16.photobucket.com/albums/b28/GOSFAST/PES%20Engines/P1010555.jpg)
http://i16.photobucket.com/albums/b28/GOSFAST/PES%20Engines/th_P1010571.jpg (http://i16.photobucket.com/albums/b28/GOSFAST/PES%20Engines/P1010571.jpg)
http://i16.photobucket.com/albums/b28/GOSFAST/PES%20Engines/th_P1010553.jpg (http://i16.photobucket.com/albums/b28/GOSFAST/PES%20Engines/P1010553.jpg)

Windage control is only important above 4500 RPM. The higher you twist it the less power you loose to parasitic drag with some kind of oil control scheme.

I used Moroso oil control parts (except the wiper which was paper thin once it cleared the wider four bolt conversion) with my 3.75" stroke 406. Here you can see the baffle bolted beneath the oil pump.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02835.jpg

Here you can see that there isn't much room to clear rod bolts and windage tray. I had to slot the windage tray to clear bolts.

http://photobucket.com/albums/f63/3454545/?action=view&current=DSC02838.jpg


Larger Dave

action=view&current=DSC02835.jpg[/url]

Here you can see that there isn't much room to clear rod bolts and windage tray. I had to slot the windage tray to clear bolts.




Larger Dave

So you didnt have to clear the pan rail or much of the windage tray with that crank/rod set-up?
Was difficult to see your clearancing on the windage tray but that's ok!
I want to use the 1/8" bigger crank but I might need more clearancing with that.

BiPolar...what have you done since this post?

So you didnt have to clear the pan rail or much of the windage tray with that crank/rod set-up?
Was difficult to see your clearancing on the windage tray but that's ok!
I want to use the 1/8" bigger crank but I might need more clearancing with that.

BiPolar...what have you done since this post?

Clearance is really effected by your choice of connecting rods. As I said before, out of the Scat rods, the 7/16" capscrew (I - Beam) rod has the most clearance. By far.

"And now for something completely different!"

This is a great thread. I'm finding it very interesting to see what combination of heads/cam/intake etc people are combining to make their target power with these 400's. Since most of this is targeted at absolute power, I'll throw my 415ci stroker into the mix to add a little color to the budget builder.

I purchased the Speed-o-motive 415ci kit a while back and built the engine for towing (small valves, economy cam, 9.5:1 compression on iron heads). It completely surpassed my performance expectations pushing a 6800lb truck reliably with the feel of a big block. On trips it would regularly get 15-17 mpg on a Q-jet.

http://www.speedomotive.com/500_hp_maxi_mouse.htm

I sold the truck but kept the engine in hopes of taking the opposite approach and looking for more aggressive power under half the weight (the 68 Camaro). I have the engine bagged up from getting completely reworked at the machine shop and now I'm in the expensive phase of buying parts like it sounds most of the people on this thread are trying to do.

My original build on this engine was for towing (under 6000 rpm), so I opted for the cast rotating assembly with some additional preparation to keep the cost down. Since I'm leveraging the same rotating assembly for this build it makes matching the rest of the components to the 6000 rpm limit, 10:1 compression (california 91 octane) all the more essential to make the most over the entire band. But, the displacement of a 400 and its intended use puts the build in an interesting dilemma as its sits right in the cross-over of parts selection to a more radical and higher revving engine. I feel I’m right on the cusp of leveraging a more aggressive open plenum manifold and larger runner heads but need to be careful not to loose too much velocity on the bottom side. Also, running a hydraulic roller cam with the peak rpm in mind leaves me with only a few options (approx. 230 to 236 duration & .510 to .560 lift , 110 lsa)

I think a lot of people building a budget 400 are going to run into these same dilema’s (being at the top of the small block line) so I thought I’d throw that out there with some random thoughts below and see what kind of feedback I get. There is a lot more to building a successful power plant than what is listed, but these seem to be the pain points with the 400 block under 6000 rpm. Thoughts?

Edelbrock RPM Air Gap Intake (tuned for 175cc runner heads?)
Victor Jr. (expecting higher than 6000 rpm, suffers below 3000?)

195cc AFR 2.02/ 1.94 (more suitable for the Air-Gap?)
210 cc AFR 2.02/ 1.94 (overkill for peak rpm of 6000?)

For those who cut their teeth on small cube high reving small blocks there is a potential fly in the ointment, as it were, on cams. The bigger the engine the more cam you need. My 236° duration at 0.050 lift was chosen to keep my wife happy. She hates my lumpy, rough idling big block cars (which are pretty radical). I'd built this motor with her driving it occasionally in mind (I can always push the button on the 250 shot giggle gas if I need a thrill). So if you're used to a 327, you might want to drop down a line or two for the same "feel" in a 400+ small block.

Happy motoring


Larger Dave

I agree with Dave. The exact same cam I have in my 410 went to 6800-7000 in my old 388. It seems to be happy getting shifted right at 6500-6600 in my new 410. I still have a little tuning yet to do with the 410 though and the 750 carb may be a tad on the small side.

Anyone have any ideas about oil pump clearance with the 6" 7/16 rod? Does the capscrew head get close to the pump?

I am contemplating a stroker build on a Chevy II with a front sump pan, and the unique oil pump required can get a little close to the reciprocation assembly on long stroke engines.

you know they still make small base circle cams lol:clonk:then you wont have to worry about rod to cam clearance and i agree that you need more cam but not much more if heads flow correctly

Well here is my 2 cents worth.

If this is a street engine that plays on the weekends, I would run 5.7 rods and use a small base circle cam such as NER suggested. There is a very good selection of pistons for the 5.7 rod in a 400/406/408.

Crane makes some pretty sweet hyd rollers that are ground on billet cores with cast iron distributor gears and have .860/.900 base circles like the HR-306-2S-10 (part # 119651) that is a 240/248 and .558/.558 and 110 lobe separaton. This cam will clear stroker rods in a 400 small block. This is a healthy cam and is capable of 500 HP in a 400 small block with the right combo.

I am not real keen on the idea of spending money for the splayed caps. I would run ARP studs on the mains and keep them a 2-bolts.

JMO

Good Luck on your build. :D

GOSFAST
Here's a unit with all the listed parts included. Made 580 HP and 523 Torque. Runs around town here on 93 from the local station and will be raced on 100 unleaded. I had posted this a few weeks ago. Thanks, Gary in N.Y.


Gary,

That is a sweet looking small block, good job! :thumbsup:

I opted for the splayed caps because the engine was built for 520HP on motor alone with an additional 250 horse shot of nitrous waiting in the wings. Neither I nor my machinist were comfortable with 770 horses beating on a two bolt main even if they are held together with ARP studs; the webbing won't hold that much concentrated force. I wanted to spread the force out to the rest of the block.

The only reason I didn't go with a Dart block was because I was supposed to being doing a simple rebuild of the 305 engine, and my wife now knows the difference between a big block and a small block. I had previously slipped a ZZ502 past her last time replaced my Impala's 305 with a stone stock Chevrolet replacement motor. (the sacrifices and compromises I have to make to maintain marital bliss; well I'm sure you guys no what I'm talking about :rolleyes: )


Larger Dave

Larger Dave,

Isn't it funny how things turn out. A 305 became a 400 with a 250 shot! LOL

:clonk:

That seems to happen every time I pick up a wrench, if the wife will let me any where near a credit card. I think Tim Allen may have met me at a car show and copied my schtick.


Larger Dave

keep that sucker cool. .030 is the most yo want to go.they do get hot fast. try to buy a water bypass kit. it connects the rear of the heads and leads to your water neck, increasing the waterflow. 500 hp. is a lot of stress on that block. make sure it is perfectly balanced. if all els fails try a bb. more hp. less stress.