I'm currently running a 427, and probably will for awhile to come. But I'm in the very early planning stages of the next build.
Right now, I'm running a fairly low RPM build. I haven't dynoed it, but I'm sure the peak probably comes in a little before 6000 RPM. For budgetary reasons, I'd like to keep the same block and utilize more stroke - I'm thinking I'll go with a 496. I'd like to also keep the RPMs down to no higher than 6500, I think. So basically, I'd like to go with something similar, with more inches.
Now, my current combo is down in my sig, and I'll be looking to recycle some parts if possible. Is it realistic to run those heads and intake on a stroker motor in that same RPM band, or will it need more flow than those pieces can provide? Also, I believe the motor's overcarbed right now - would that 830 be enough to feed a moderate 496?
Would it be advisable to run a hydraulic roller in that particular application? I'm thinking I don't want to go any higher than about 10.5:1 (I'd like to stick to 91 octane).

The bottom line is, I'd like to get the car coaxed as deep into the 11's as I can. Am I thinking along the correct lines here? For reference, my current combo has been good for a best of 13.28 @ 109 MPH. Obviously, traction is a more immediate issue than the next motor. But I'll figure that out separately.

Thanks for any input on all this wishful thinking!

Why do you think you are overcarbed now?
830 is a good carb, I've got one I'm going to try this year.
It idled my zz4 350 sweet as could be, and it didn't bog or hesitate when I razzed the throttle

I think your headed in the right direction here. I also think you can re-use a lot. The heads are older, early 70's oval deals. Supposed to have 113CC chambers, but that could vary a bit as the big chevy heads often did a little. It may be a hair larger, but measure to be sure so you get the right pistons. Any of the ovals from them days had potential, so a little work and they should be useable. Large valves and good bowl work will be nice(unshroud the chamber if you go with larger valves). If you cant do all that...Id prefer bowl work over just valves. Just use stock size valves with a good valve job and the bowl work for good results. But if you can help it.....valves and bowl work and unshroud them chambers.

Your intake is PLENTY fine. I can tell you about some 10.50 ET cars using the performer rpm on all motor 489-505 combos. One of the cars actually slowed down swapping to a vic junior single plane. MPH picked up a little with the vic, but the damage done at the 60 foot and first half of the track was too much to overcome even with a little extra MPH......so the car found a couple MPH, but it ET'd slower with the vic. He went back to the RPM and still uses it running in the 10.40's. You will be fine with it.

The carb definitely wont be too big. If anything....too small. Maybe just right depending on the final combo, but definitely not too big.

For a cam, maybe its just me but I dont like hydro rollers in the big chevy. The valvetrain is heavier to begin with, plus with the extra inches, it needs more cam to rev any degree, so that means more spring too. With the heavier spring, heavier valvetrain, and heavier valves, it definitely takes a bigger dollar, more precise valvetrain to get a hydro roller big chevy to rev as opposed to the small block. If you really wanna do it......use lightweight EVERYTHING in the valvetrain and still dont spec out a cam that needs to rev over 6000rpm to make its power unless your really confident that youve got the lightest strongest stuff, and you are confident that the geometry in the valvetrain is as good as it could be. Otherwise, rev in moderation with the hydro roller.

Id prefer a solid flat tappet myself like this one http://www.holley.com/402A3LUN.asp

Its designed by Harold Brookshire formerly of comp(years back) and ultradyne. This cam he has reground/refined a couple times over the years. Ultradyne sold a version made by Harold, and this particular one was the most popular sellers especially for small blocks. It will definitely hold its own in a big block too. The one that sold the best for the big chevy is larger though and usually ended up in 10 second cars. I think its a tad large for the setup as is.....but maybe youd grow into it later!

Just in case you wanna peak at it, here it is. http://www.holley.com/402A6LUN.asp.

This cam(and its variants from Ultradyne) have ended up in many a big block with lots of success.....but like I said, I think its more potent than you need right now. I like the other one better.

If you like something in between the two....peak at http://www.holley.com/402A4LUN.asp. Also would do real well in almost 500 inches.

The only worry I have is the converter. If it already flashes 4200 revs....another 60 plus cubes and lots more grunt just may wreak havoc on the converter! Id consider a tight 10 inch ATI that flashes no more than 4000 revs. 11.50's ought to be easy with pratice and trial and error.

Thanks, Greg. I like that middle cam particularly. As for the converter, I actually think I'm going to swap mine out this summer. I've got a vibration while accelerating in gear, and I'm suspicious the converter's the cause. It also has more slippage than I'd like (it's very loose for its size). So I think I'm actually going to back off on the converter some. Maybe down in the 3's somewhere.
The heads already have the bigger valves in them. They were ported, but I'm not sure about the bowl work or the amount of unshrouding done. I'll have to look closer when I get to where I'm going to disassemble the current motor.
My first step is to try to get traction under control and see exactly what I can get out of the current motor, so I have a reliable baseline. I think I can probably get at least mid 12s out of it with enough tuning on the chassis. The first time I need to tear down the bottom end on the motor, though, that reciprocating assembly's going out the door!

First off, I'd baseline it now using no more than a cheap set of tuned slapper-bars and a pair of real slicks!

275 to 295 jobbers if the bigger will fit??

I say this b/c I have a feeling there's more than low 13's in her!!

pdq67

500 cubes is the practical upper limit for oval port heads and the bare minimum for rectangular port heads. I think 2.25" or 2.30" intakes with 1.88" exhaust valves are ideal. I also recommend 11/32" stems help lighten the load, titanium retainers help more.

Pocket porting the bowls is critical on all heads. Everything Dave Vizard said in his book about porting small block heads applies to the big block head (except were to grind specifically obviously). So you want to improve low to mid range lift flow and unshroud the valves in the chamber. I would rather have a larger chamber with free flowing heads than higher compression (you can always get a bigger dome on the piston).

As a motor increases in displacement you will need more cam. If you are going to go with a hydraulic roller so be sure to get a billet core with a press on cast iron distributor gear as you will need to run more spring pressure to control the valves than a cast core will accept. Once you have a billet core cam, you can run a rev kit to control the added mass of the tappet. I run a three piece timing cover because I like to be able change cam grinds often in the search for the perfect cam and I am never satisfied. It could be worth the expense in saved aggravation later. Since I can not make up my mind with any one set of specs on a cam I won’t offer any advise there.


Larger Dave

Grag, great to hear from you, you haven't been around much lately. Your knowledge and no-nonsense approach are, as always, of great value!!!

Thanks "JamM" lol, glad to be back(see your above post, just "ribbing" you a tad.

I wanted to elaborate on one or two things from my previous post. Number one is the intake. I just wanted to make sure that I did not come across as sounding like EVERY engine going 10.5's or slower will benefit with an RPM over a vic. Although the one example I gave did like the RPM better, once again, not every single combo will.

The important part I really wanted to stress is that this intake is very capable. So you can very well acheive your goals of deep in the 11's with the RPM. Even if a vic would potentially be faster on your engine(maybe...it could happen), the rpm isnt a limiting factor so you can save your money there hehe.

Also, didnt even notice the MPH, but yeah....109 is flying pretty good. Capable of waay more than mid to low 13's. That indeed is where Id spend money first.

Although the converter might be loose for the current setup, and who knows maybe have something to do with the vibration.....the current on at least works in order for you to be making that kind of mph out of a combo thats not super rad. Its definitely staying pretty tight at the big end!

Id do the traction deal right now cause it ought to be way in the 12's with good hook as is.

Next note...I just re-read your combo specs and noticed that the thing already got 2.19 valves. I automatically assumed we were dealing with smaller, stock valves, but apparently not hehe! If you want to stick with the 2.19's and just do some good headwork, that setup would be capable of well into the 11's without spending any more money on any larger of a valve. If you wanna go all the way with larger valves, thats up to you. Done right...it just increases potential. But as is, it can be run into the 11's with 2.19's.

Thanks again, guys! I'm getting good information here.
I do have a used pair of drag radials on a set of rims that stick out past the lip on the quarters, and I might try those.
I have 3-way adjustable shocks on the front of the car - does anyone have any advice on where to set those for best hook (90/10, I'm guessing?)?

For what you want, go with a hyd roller. You`re a perfect candidate for one if the funds allow.

All this talk about big blocks not being able to rev with hyd rollers :rolleyes: it never seems to go away.

If you`re looking for a 6500 rpm limit get a UDHarold design HYD roller in the 250-255 @ .050 range with .600-.650 lift it will CRUSH any of the solid cams mentioned above.
Of course the converter needs to be right too.

The 830 annular Holley is one of my absolute favorite carbs but it`s WAY too small for a 496" motor.
A 1000 HP would be about spot on. A 4781 850 would do well too though.

I've heard of the UDHarold cam design in a few different spots on this board now. To what exactly does that refer? I've gotta plead ignorance.

UDHarold is Harold Brookshire. He is a very well known, renowned designer, and he designed them camshafts I linked to above.

He also worked for comp in the 70's and designed some cams for them that are still around today(like the high energy series). Also designed for ultradyne for a while(hence where UDHarold came from...ultradyne Harold). Then went with lunati for a brief period and designed a lot of lunati's new catalog cams including the voodoo camshafts, and now he is off again doin his own thing.

Harold has always made good products, and he has a variety of wins in various different motorsports over the years, so yeah, he has worked for a few of the major cam companies and he does good stuff. The reason why Im most impressed with his products though is because of Harold himself. He is a stand up guy that puts a lot of time into helping others out. He drops in and out of all the message boards online helping when he can, which is a lot more than I can say about others as "high up on the pole" as Harold.

Dont get me wrong, there are a TON of super sharp guys online everywhere. So, no credit taken from any of these guys that put in the time. You just dont see a lot of the "higher up" sorta "celebrity type" guys in motorsports putting the kinda time into helping us small time folk. But Harold puts a lot in all over. I have no clue who does the cams for comp cams nowadays. He knows what he is doin obviously...I just dont know who he is if you know what Im sayin. Thats why I support Harold more than anything. His stuff is at the major companies, so its quality will be as good as anything else, but he will give you his phone number and tell you to call him up and chat with him about cam selection. I respect that.

Wow. I agree, that's really cool. I'm impressed!

What BigRed said...
but with that cam it aint gonna run no 11s now is it;)

10's are OK too.
;)

What BigRed said...
but with that cam it aint gonna run no 11s now is it;)

oops...my bad, sorry :)