Hey guys, I have the option to pick up a cast 400 crank for $50, I was thinking about throwin it in my 350 to give me 377, I hear a lot of people running a 377 by using 400 block and 350 crank, is the 377 i could build worth more power than finding a 400 block and a 350 crank and making a 377 that revs higher? or should i find a 400 and build a 406 for the most power? budget is limited but not too tight.
thanks
Adam

your not just going to throw that in there and get 377 ci. Your going to need the right pistons and the potential grinding that comes with it all.

the mains are different sizes, so there is machine work involved.

As well you need to check rod to cam, and rod to block clearances.

Don't think there will be any rod/cam problems b/c he's going to a shorter stroked crank.

Plus, all he has to do is use the right main bearing set that has thick shells and the 350 crank is basically a "drop-in" into the 400 block except you have to check the rear main seal!!

Should make a dandy rpm motor!!

Imho, go for it...

pdq67

Cubic inches rule . . . I personally would just build the 406 and be done with it. Now if there were some reason why you would need to build a really high RPM engine then go for it there are some advantages with the shorter stroke, but not with a $40 cast 350 crank . . .

Build the 406 ;)

More cubes more power for the buck. For some reason these days everyones into "high reving" motors. Buy a Honda if you wanna spin to 8000RPM. Build a 406 if you wanna make awesome HP and tire shredding torque all while keeping your motor's parts intact and out of death-RPM ranges.

Originally posted by Chris88Z:
More cubes more power for the buck. For some reason these days everyones into "high reving" motors. Buy a Honda if you wanna spin to 8000RPM. Build a 406 if you wanna make awesome HP and tire shredding torque all while keeping your motor's parts intact and out of death-RPM ranges. Engines that rev are nothing new, and aren't inspired by "ricers." There are many advantages to building a motor capable of high rpms. Besides, a person only needs enough torque to break the tires loose right...I mean, what else are you gunna do with the extra 100ft/lbs that you cant put to the ground?? imo.

Originally posted by Drag67Camaro:
Hey guys, I have the option to pick up a cast 400 crank for $50, I was thinking about throwin it in my 350 to give me 377 thats what i read, even though most call it a 383 (.030" over) or 385 (.040")

chris88Z, actually these days everyone is into monster cubic inches and torque if i read correctly in every magazine i subscribe to.
Oh yeah and my little 350 spins just a hair under 8,000 RPM's and has no problem doing so, so stick your ricer comment in your ***.

He, He!!

I don't think my old junk 301 ever hit 8,000 rpm b/c my old stock 350's point distributor would float the points even with double springs.. Somewhere around 7,500 or so it seems like??

And I do remember that the double sprung points sure wore the plastic cam follower off real fast!!

I think the kids nowadays are spoiled b/c they don't have to go through the every 10,000 mile re-time along with new plugs and points tune-up like the old motors used to require..

It absolutely amazed me that my 2000 Metro 3-banger corn-popper went right at 99,700 or so miles AND started to miss!! Three new plugs later and she went just fine...

pdq67

Originally posted by Novaguy73:
my little 350 spins just a hair under 8,000 RPM's and has no problem doing so, so stick your ricer comment in your ***. Very eloquently stated, Novadude.

LOL!!

my little 350 spins just a hair under 8,000 RPM's and has no problem doing so, so stick your ricer comment in your ***. What can I say? (laughing my *** off at that one)
I am also one for building small blocks that you can wind to the nines. There just something to be said about hearing those rev's in a mouse motor. And if I want a rice car, i'll let you know!

ROFLMFAO !!!!!

I have spun 300ish, 350ish and 377 cid engines into the 8000+ RPM range.....it religion to me.

What is rice about that ??

And BTW, the 406 is more suited as torque producing engine........more than that of the 377, as it is all about HP.

Be careful when you say everyone. I see the huge advantages of 427, 406, 421 sbc motors and will build one myself eventually. But like a moth on a yard light I'm drawn back to the short stroke high winding stuff. It's a whole lot of fun with 4.56 or 4.88 gears and like someone already pointed out unless you're tubbing it out there is only so much torque you can use off the line. These are the motors I grew up on and still like them today, even though like Nova pointed out all the mags are pushing stroker motors, and for a good reason.

It's still fun to push the short stroke stuff, although I haven't had a lot of sucess taking 3.48 stroke motors upstairs, the 3.25 and 3.00 stroke stuff has never come apart on me....yet.

What I find funny is that a sb400 is "designated" as a low rpm torque engine and a bb427 as a high rpm engine even though it has the same stroke and a much heavier rotating assembly.

A sb400 can rev high with the right combination of parts, just like most engines.

Right on Lonnie
There are some fast pumpgas 406s out there that turn 7000 all the time, not that its high, but its no 5500rpm truck motor. It is still a large bore motor, even if the stroke aint that short.
I will say that its nice to have the extra cubes on the street, if built right you can keep the gear and stall conservative so its more streetable, and still go fast.

Originally posted by Novaguy73:
chris88Z, actually these days everyone is into monster cubic inches and torque if i read correctly in every magazine i subscribe to.
Oh yeah and my little 350 spins just a hair under 8,000 RPM's and has no problem doing so, so stick your ricer comment in your ***. When the crap did I EVER say anything about rice or "ricers"? Its stupid for this guy to build a "9000RPM" motor when he even thinks about mentioning a stock cheapo cast crank. Hey if you wanna build a high reving motor have fun, nothing wrong with that but when you take into the consideration of all the beefed up internal and valvetrain parts you need to do it safely you might as well throw the word "budget" out the window. For example (keyword: example) why build a 500HP 377 that you spin to 8000+RPM when you could build a 500HP 406 that you spin to 6200RPM? You'll go much easier on parts, you won't have to beef every little thing up, you'll be more streetable, motor will probably last longer, and it'd just be a better overall motor for the buck - Especially in a somewhat heavy car like the typical f-body.

So, wanna build a high reving motor I have NO problem with that ...nothing "ricer" about it, but in a case like this, in my opinion, its not the logical thing to do.

Thanks for all the replies guys!
I am leaning towards the 406 build because if i was too build the 377 i would get new heads/pistons/carb and everything anyways. I just bought a converter from a guy that stalled at 3800 behind a mild 454, another guy wants to sell me his complete 400 but it spun a bearing, i gotta ask him a price on it, but i was hoping to find a 2 bolt block, get a rotating assembly, some canfield? heads, keep my RPM intake, and get a larger carb (600 now), as for a cam, throw me your suggestions!
Thanks again guys
Adam

"Buy a Honda if you want to spin 8,000 RPM's" I believe is the quote. Maybe you need to look back. And last i checked a Honda is a ricer, so leave your words where they fell partner.
Oh and hes not even talking about the short stroke 377. Hes talking about the 3.75 stroke in an un-bored 350

[ 06-19-2004, 08:28 AM: Message edited by: Novaguy73 ]

Originally posted by Novaguy73:

Oh and hes not even talking about the short stroke 377. Hes talking about the 3.75 stroke in an un-bored 350 thank you, I knew i wasnt reading it wrong!

You guy's do realize that the '65 and '66, 365hp,(carb'ed) and 375hp,(FI)/327 motors as well as the '67, 302, Z- motor used the 11/32" rod bolt rods and small journal cranks AND ran just fine!!

My long gone crippled Buddy's 375hp/327 FI motor that was no more then cammmed up would go above 8,000 easy b/c that's how high it was when my other Buddy that was riding shotgun for him to shift it said it was when all h-ll blew outta the clutch, pressure plate, bell housing and fltywheel when it was shifted from first to second gear the night I pulled him home using a rope!!!

A short-stroke SB running 7,000rpm through glasspacks marching down the road is music to my ears to this day!!!

AND even prettier with the 2-1/2" plumbing pipe nipple dumps opened!!

pdq67

pdq even better with just the headers! I'm with you on this one.

Like someone already pointed out it doesn't make sense to build the little motor to run high rpm when you can build the bigger cid cheaper and with less expensive parts to run quicker (in some cases) and it'll certainly outlive the high winding mill. But if we did what made sense none of us would be dumping 20K into a first gen Camaro. It's all what you are passionate about.

Besides when you do the math it adds up:

Set of ARP SJ Pro-series rod bolts.......$65
Fresh Forged #4577 327 SJ Crank..........$100
140 off road cam and solid lifters.......$200
Used Forged TRW 12.15:1 pistons..........$250

The look on the guy face with 100-150 more cubes in your rear view mirror................Priceless

Ditto SY1!!!

pdq67

Originally posted by Chris88Z:
Especially in a somewhat heavy car like the typical f-body. Typical, meaning a typical second, third or fourth gen.....right? Cuz I know you're not going anywhere with that one.

OK, well lets clear this up. What exactly are your build options?

I found your first post confusing and thought you were trying to say that you were considering de-stroking a 400 . . .

If you can get a good 400 core I'd build a 406. More usuable power IMO.

If you are considering building a 377 with a 400 block and a used stock cast 350 crank don't bother -- a stock cast 350 crank isn't something that I'd trust at high RPMs where a destroked 400 really shines.

If you have a 350 block and can get a cast 400 crank then go for it, a 383 is what you would have and it will run quite well . . . almost as well as a 406 ;) You just have to have the 400 crank's main journal turned down to the 350 main size, its probably not much more money to start with a new cast aftermarket crank.

PS. A spun rod or main can usually be fixed, but it costs money . . . just make sure the block is worth it before you commit to a project that starts with a hurt block.

Eric I think he's talking about building a 383, but got confused and called it a 377. He seems to know what makes a 377 though. Aren't all GM 400 cranks cast?

Well I always said I never want to get so old I quit learning anything new. So today I picked up a copy of "How to Build Big-Inch Chevy Small Blocks" and I'm gonna read it. I had already been kicking around a 400 block short stroke motor, so as long as I'm using the 4.125 block I might as well take a serious look at all my options. Some of the dyno results they have for the different combos are pretty exciting. Of the 3 different 383 motors they tested the top dog was a 13:1 mechanical roller motor with AFR 220 heads rated 622 hp @ 7200 rpm and 475 lbs of torque @ 6100. There is also a 10.4:1 mechanical roller Dart Iron Eagle headed 383 rated 530 hp @ 5900 and 506 lbs of torque @ 4900. Anther 383 had 10:1280 hyd roller AFR 210 on 91 pump gas made 474 hp @ 5400 and 486 ft lbs @ 4600. The 406 made similar numbers. Some pretty serious numbers.

They also compare a 377 and a 420 that are built similarly. The 377 at the strip would easily have it's way with the 420, but in a street car with less gearing the 420 has so much more torque and a much wider curve it is the obvious engine for the street. They also discuss it isn't hard to build a 700 hp normal aspirated 302, but add it'll have to spin over 8000 to make the power, be dead below 4,000 and have a very, very narrow curve, probably 6,800-7,800.

None of this is news to most of us, since it reinforces what most have been saying about long and short stroke motors. But I admit I'm surprised at how high some of these long strokes seem to wind and make power up high as well as tons of torque down low. Obviously it's much easier to get the performance you're looking for from a long stroke motor, but the short stroke can be pretty fun too, expensive to live in the high rpm range, but fun.

how cool would that be to kick EVERYONES *** with a 302 though....eh???? Youde have to run a 5.XX gear and a 5 speed jerico to make it work but boy it would be cool.
So the 377 would have its way with the 420 on the strip huh?

Thanks,
I have a 350 block, i could get a 400 crank, im gonna forget about the 377 by making a 400 block with 350 crank, if i kept my 350 std bore and put in a 400 crank, it would be a 377 right? I think if i can find a 400 block ill just build a 406, with a holley 750, 3500ish stall, RPM intake, canfield 197cc heads and about 10.7 CR what cam should i look at? rear is gonna get a 4.10 next week
thanks

Novaguy I'm not so sure, but the author of this book seems to think so. I think his point is the motors each have a different ideal application.

The 377 they tested peak hp 589 @6400 and peak tq 516 @5200. The 420 peak hp 524 @6000 and peak tq 519 @4500. The 377 had Victor Jr aluminum heads, Isky mech roller 264/272 @ .050, Victor Jr intake and BG 750 annualar carb. The 420 had Airflow 195cc heads, Comp cams 236/244 @ .050 mech roller, Victor Jr intake, Holley Hp series 750 carb. Headers used were 1 7/8 with Flowmaster 2 1/2 inch exhaust. Here's what they wrote about the test results:

"Unquestionably the 377 engine makes a ton more horsepower, with 589 vs the larger engine's 524, an advantage for the 377 of 65 hp. But looking at the torque curves the large 420 makes much more torque, out producing the 377 by 45 ft-lb at 4,500 rpm and perhaps as much as 100 ft-lb at 4,000 rpm. By 5,000 rpm the 377 has assumed command, delivering more horsepower from this point on up. If each engine were optimized for drag racing, the more powerful 377 would easily out-accelerate the larger 420. But compromise the gear ratio and transmission selection for street car use and the stronger torque curve of the larger 420 would create a much better acceleration rate given a less-than-optimal rear gear ratio".

So it's just like you said in your post. Run 5xx gears and you can run the shorter stroke motors against the big boys. by the way the 302 can take down it's share of much larger displacement motors, but it depends on the level those motors are built and how well the cars are set up with gearing ect. The trick to running the 302 is build the hell out of it, gear the hell out of it and have fun. Now if you find yourself lined up against someone who has done the same to their BBC or large SBC you're not gonna win that battle.

[ 06-22-2004, 06:42 PM: Message edited by: SY1 ]

Intersting debate . . . I guess it kind of goes back to the TQ vs HP arguement . . . and you are right, you CAN make up for TQ with converter and gearing to a point -- but you can always add more gear and converter to the big stroke engine too. :D

A couple things I've found interesting -- in the Engine Masters Challenge I noticed that there seemed to be a trend towards smaller bore/long stroke engines. Now you would think that the smaller bore would cause shrouding and limit head flow, but there was some discussion about how a smaller bore actually creates a faster burn (less distance for the flame front to travel) and as a result generates less reverse TQ with less ignition advance. Aparently, since these engines were making best power with less ignition advance anyway, they could up the compression and still get away with pump gas. Maybe these results and strategies were driven somewhat by the rules, but they were interesting none-the-less.

The same theory also seems to be backed up by the OEMs making little 4 valve engines with hemisherical chambers, small bores, and relatively long strokes . . . and the Big Boys at the track having such success with the 632" BBC. I think as long as there is enough cyl head flow to support the extra inches the big inch motors will rule.

IMO I think the bore/stroke relationship comes down to whether an engine is short on cylinder head flow or has excess flow available. In other words, if an engine is limited by head flow I think that the larger bore shorter stroke combo would probably make more HP per cid. On the other hand, if the engine has excess flow it can put the extra stroke to work and make more power . . . as long as rod/stroke ratio is acceptable and there is nothing weird going on with sideloading, etc.

Don't get me wrong, I'm not saying that big bore short stroke motors are bad . . . but if I were building an engine for the strip (ie: a dedicated race car) I would go for max cubic inches as long as bottom end dimensions could be built to be reliable, there was no displacement limit in my class, and cylinder head flow could support the displacement/RPM.

Now if there was a size limit in a particular class things would get interesting. If fuel octane is limited (like Engine Masters) maybe the combustion chamber size & shape becomes more important than flat out flow. BUT if fuel isn't limited, only limited displacement, it seems that high compression, high RPM, and head flow would be the name of the game. I've always liked the idea of a 4.155" bore x 3.25" stroke 353" SBC myself or even a 4.5" bore x 3.766" BBC with some killer heads.

Sorry to ramble . . .

Another interesting point about that comparison is that the combos are completely different. Different heads, the 377 has WAAAAY more cam, etc.

I would love to see an exact comparison with the only difference being bore and stroke.

You can get a feel for this by running D2K's engine simulations for a 302, 307 and a 305 by setting everything except the engine sizes constant.

Then do nothing but play with cam spec's to see what happens b/c stroke has more to do with how an engine combination uses, (for a better word), stroke increases or decreases.

Just be sure and use the same spec's for the cams that you run through everything and then change cam spec's after running each one through the three motors..

It's interesting to say the least.

I did this early on trying to learn about all this stuff and finally figured out that grunt is where it is at.. BUT only for a street motor!!

Just take all this with a grain of salt b/c it is still just sim. program stuff AND you can't drive a computer !!

As for smaller bores and longer stroked motors being more eff. up to a point, it is true as long as the rod/stroke ratio is OK!!

Take a historical look at the old English sports car motors b/c they had small bore, long stroke motors in them b/c of tax purposes if not mistaken. AND the heads tended to have what can be called vertical ports moreso then "J" shaped ports so that the f/a mixture could get as good a shot at the small cylinders as possible. That and circumferenital piston quench stuff helped too..

This stuff is fascinating to say the least when you really start digging into it.. Kinda like the Fueling BB torque heads sorta stuff......

pdq67

PDQ
Not to discredit you, but there are things that a "cheap" computer sim just
doesnt take into consideration. The big/bore short/stroke motor will have some
advantages like: heads will flow 10-15cfm more on a bigger bore, theres less
frictional loss in the piston skirt, rod ratio diff and so on.... and I dont think the
the dyno sim considers these and other aspects, so the real world results
will be different.

I know that, that's why I say it is just sim. stuff..

Rather look at the trends in power curve movement and such!! As well as total area under the curves, not for actual values but how they change with changes made between the different bore/stroke motor combinations when you hold cubic inches constant!!

You can also look at Pat K's DCRC site and play with this stuff too as well as intake valve closing point and CR. changes.. BUT still hold cubic inches constant!! AND then vary rod length....

pdq67

Some real good points made here. Greg's right the 377 is obviously set up with an unfair advantage, but that's only more of a tribute to the tremendous torque advantage the 420 has when you gear the two motors with more streetable gearing and the 420 runs away from the 377.

Eric I've always felt if I was limited in class to a 355 cid motor I'd definitely build the 353 with the 327 crank and 400 block. Partially because I've been real rough on 350 bottom ends.

I think we agree it comes down to what you want to do with the car and what you're willing to put up with if it is a dual purpose car, because those are all about compromise. A good example of this was when I was first married I had a 70 SS 396 Chevelle with a Th400 and 3.31 gears. Great car, lots of torque and my wife loved driving it (she had a 72Z28 when we dated and had owned other 2nd gen 4 speed Camaros with mild 350s). I sold it and replaced it with a 68Z 302, 4.11 gears, 140 off road cam, manual steering. She couldn't wait to drive the car. She went next door turned around and said "I'll never ask to do that again, it's too much work!". That car was a hand full to drive on the street, but that's one of the things I liked about it. The Chevelle was a lot more street friendly and a much better ride than any first gen I've ever owned. Both cars ran about the same, with a slight edge to the Camaro. I never got the 4.11 gear set into the Chevelle before I sold it, but it did have quite a bit of other modifications, more cam, better Holley carb, better heads, headers. It's just about what are you willing to compromise. Had the Camaro had more gear, or less cam, and power steering she'd have loved it. But I would not have enjoyed it as much myself.

Sorry, I closed out too quick!!

I look at Pats DCRC program by running intake closing points through it and then back track using a CR program like Ross Racing Pistons has to set quench and head chamber size, then plug all this into D2K and run a bunch of sim's and watch what happens...

I know everything is sim's but it sure beats me using my old slide-rule like I did back in School years ago...

BUT the truth is in time slips!! A bunch of time slips like Ed always says!!!
pdq67

Not to beat a dead horse here but I was scowering the magazine archives looking for an article related to a question on another topic and ran across an old 377 vs. 383 shootout. Both engines were identically prepared with compression, heads (TFS), cam (Comp HR 280R 242/248,.570/.576) intake, etc.

The dyno curves were very close. The 377 peaked at 454HP/450 TQ. The 383 peaked at 450/458. Average torque below 5000 RPM was 434 for the 377 and 447 for the 383. Average HP above 5000 was 443 for the 377 and 437 for the 383.

Their drag sim program estimated 11.69@117.6 for the 377 and 11.64@117.5 for the 383.

Greg, I remember reading that now that you mention it . . . it was an interesting piece.

The thing about those two engines is that you could gear the 383 motor with say a 3.90 gear set and the 377 with a 4.10 gear set and probably run exactly the same ET with both.

SY1 said it well IMO -- the high winder may be more fun for some and the TQ beast more fun for others . . . either way they can run the same times -- as the old cliche' goes, "there's more than one way to skin a cat."

Good job Greg, now wer're finally comparing apples with apples. That's interesting how close the two motors come out on the numbers. Like Eric said looks like it comes down to what motor you really want to build, seems they'd both be great. I bet a lot of guys make their decision based on what pieces they've got on hand already.

It's just about where you want your power peaks to be in the curves b/c indentical motors but with different bores and strokes will make the same power but their peak power numbers will be separated by the distance between where they lie on the rpm scale! AND this is with optimal cams in each one!!

Imho..

I ran a really long stroked/real small bored motor through D2K and compared it to one that was the same size, but opposite with respect to it having a great big bore but really short stroke AND they produced the same power!! So go figure..

Of course the nit-picking details like port size, valve size, shrouding, cam LCA's and ICA's , etc..., will skew one from the other UNLESS each one is optimized to each's combination and then it will still turn out the same. EXCEPT as you go up the rpm, natural running friction motor eff. will start to rear it's ugly head with respect to the long stroked motor NOT running as well as the short stroked motor at max. rpm... (I.e., cylinder wall/piston ring side-loading friction and such crap show up b/c the longer stroked motor is sliding it's pistons a longer distance then the short stroked motor is)......

AND then drop each one in the same car and optimize the car for each one AND I bet it will still turn out this way like SY1 says.....

pdq67

Not to stir the pot, but 8-9000rpm smallblocks... NASCAR, 750ish HP?

Yes, I saw that article too and wondered just how the NASCAR boys got 700hp out of a SB motor??

Probably nothing stock in it and probably sure not streetable, imho..

BTW, the car is neat, but I still like my car just restified and not all flaired up but that's just me.. I'm an old-fashioned kinda guy...

Tito Jones has a very fine looking pic of the car he's putting together over at Pro-Touring's site that is sorta in a way like it!!! Please check it out..

pdq67

Im a firm believer that if you want to get the most out of a motor you have to build it for what it is. Your not going to make a low end torque monster out of a 302/327/350 and your not going to make a 9,000 RPM motor out of a long stroke anything. If you want to make a shorter stroke motor go, be ready to wind it and gear it. If you want to make a shorter stroke motor go do the opposite. Its like trying to compare apples to oranges. What works for a 472 CI small block isnt going to work for a 302. And vice versa. So to try to compare them in an identical buildup is silly. If you want to compare them, have the same motor builder do an all out, balls to the wall, comparo. Build both the right way and go for all out power on pump gas, thats the only restriction. Then run them in the same middle weight car on pump 91 octane. Gear according to the motor and make all conditions optimal for THAT motor, run until you get the best times you can. Dont make conditions favor either motor but change according to what the motor likes. Either the 377 would be a slug off the line or the 383 would run out of RPMs with the gearing so that obviously couldnt stay the same. Thats the only way to detirmine anything.