Jump to content
HybridZ

Chevy 302 build for my z32 w/th400


Recommended Posts

  • Replies 59
  • Created
  • Last Reply

Top Posters In This Topic

read these

 

http://www.rbracing-rsr.com/runnertorquecalc.html

 

http://forum.grumpysperformance.com/viewtopic.php?f=69&t=1040&p=1943#p1943

 

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=796

 

http://forum.grumpysperformance.com/viewtopic.php?f=52&t=322

 

on a 302 designed to run at 4500rpm-7800rpm,with a cam like your going to be using to maximize the peak hp, youll want a larger head port than most people will suggest, because your trying to make 450-500 plus hp,and because , you can basically forget about maximizing low rpm torque, use the calculators, but a head like an AFR or brodix 195cc-200cc, or larger vortec heads will be the minimum required,if you truelly want to maximize the hp without getting insane prices like the 18 degree heads, or 2.2 heads, yes I know that the COST keeps increasing and you can use the standard vortec or ported fuelie heads,yes you can get good results, but the better heads do have advantages, its always a compromise, and you have to make choices

 

example

 

http://www.airflowresearch.com/index.php?cPath=24_29

 

http://www.jegs.com/i/Brodix/158/1021001/10002/-1?parentProductId=760699

 

as you can see in this chart most of the stock heads don,t flow as well as the AFR 195cc heads and there ARE better flowing heads

image17of.png

 

 

you might want to read this also

 

http://www.chevyhiperformance.com/techarticles/148_0506_gm_bow_tie_vortec_small_block_engine/index.html

Edited by grumpyvette
Link to comment
Share on other sites

Thanks guys, what about heads?

Those Dart heads you were looking at are pretty nice. AFR's are king of the hill but are alittle more money. You may want to run a stud girdle with whatever heads you buy as it really helps. Make sure whatever head your running you use the bigger 7/16" studs rather than the 3/8". There is really no comparison between aftermarket heads an production heads for obvious reasons. Hands down the aftermarket serious contenders will outshine anything GM has ever made or will probably ever make. Why don't you call Dart, Brodix and AFR and see what the experts recommend for you particular combination. It would be interesting to see what they all have to say.

Link to comment
Share on other sites

I agree that the AFR are the best bang for your buck. My 210's I bought with AFR scorpion roller rockers 1.6 and stud girdle on 7/16 studs have no apparent float at 7800 rpm. I would have loved to afforded a T&D or jesel. AFR also sells matched intakes..IMO a matched topend combo from one company is your best bet unless you choose a crappy company of course.. Good luck on your 302 I understand what you want and why. Hell, I should built a Camaro drag car That I could fit in easily,find bolt on parts cheap and been like everyone else.....but no, I am a hybrid Z kind of guy.

Link to comment
Share on other sites

Thanks guys. and thanks for the support GRUMPZ

Vette, That build you posted at the bottom is nuts. Its one of those "if i was a millionaire, i would" builds. haha. I sent a message to the guy on ebay that builds those heads and asked him if he could build a set of dart 200cc for me with all the bells and whistles of the 230s he advertises. He hasn't got back to me yet, but i'll let you know when i do.

On a different note, my race buddy justin who races dirt track late model told me not to get my block decked yet. He said this has never happened to him but he has heard of it happening. He said they always bring in their whole rotating assembly installed into the block so that measurements can be taken instead of just going on calculations on paper alone. He said there has been times some pistons are at perfect 0 and the one at the opposite end will be 3 thousanths off. :(

So this way would ensure that all get decked to perfect 0. Anybody else ever experienced this?

Link to comment
Share on other sites

The deck should be squared parallel and perpendicular to the crank. If any of the pistons are that much off, get some more pistons, or match up pistons on the long side with rods on the short side to even them out. Even the crank throws can be off a little. Realistically, a thou or two variance in deck height isn't a big deal.

 

jt

Link to comment
Share on other sites

The deck should be squared parallel and perpendicular to the crank. If any of the pistons are that much off, get some more pistons, or match up pistons on the long side with rods on the short side to even them out. Even the crank throws can be off a little. Realistically, a thou or two variance in deck height isn't a big deal.

 

jt

 

I agree! Back in the day we used to measure stock rods for length and yes there was some variance. There is also some variance in cheap pistons, but mostly stock type or claimer pistons. Ones like JE, Lunati, Manley, Ross, Diamond, BRC, etc, etc. are spot on. Crank throws can be off on stock cranks but rarely on aftermarket and when they grind the crank the throws should be all the same. In the old days, they called it "Crank Indexing", which meant that all throws were exactly 90 degrees apart and all throws equal distance from the centerline on manufacturers spec.

 

Just brings things to attention that your machine shop is or should be a big decision making process. There are stock machine shops, bad machine shops, good machine shops and truly great machine shops. Just keep in mind that people can and do make mistakes, even the best.

Link to comment
Share on other sites

I built a basically stock 9.7:1 331 SBC with 461 double hump heads (bowl ported) and a Comp Cams 270 Magnum solid flat tappet cam for my first V8Z buildup. It was a fun engine. Loved to rev, sounded good, etc. But riding in Z's with 383s killed that for me.

 

The next build was a 407ci SBC, with barely streetable solid roller cam and Canfield 215cc heads. Still running a dual plane (Performance Parts Crosswind - like the Air Gap RRM). Likely around 490hp/510lbft according to Desktop Dyno 2000. No Idea what a 1/4 mile run will be, but it will stay right with a Ford GT from a 15mph roll until I lift at 145 (did that a few times on the back straight at VIR, 2 days after I installed the engine).

 

It's an entirely different world. Torque is too much for the tires, even at 70mph when I am turning more than 3500rpm and hammer it. It's now scary fast to most people, and there's no desire for more really, since it can't hook up what it has now. I doubt you could convince me to go back to a 327, much less a 302. Now a 377 - that sounds like a plan....hmm...new pistons, 6.??" rods, 3.5" crank.... Never mind - only if I break this 407!

 

The 302 would be cool to listen to though, and the top end would be very fun. I'd run something like 4.56:1 gears though, and a manual transmission.

 

Notice that the video of the 302 on the dyno had the thing idling at about 1900 rpm. I'd get used to that. Hence the 4.56:1 gear choice. Even that light little car is going to need that ratio to make it at all livable on the street. I'd be looking for used heads from a circletrack team, with shaft-mounted rockers and some nice valvesprings/retainers/etc. to keep the valves doing what you want them to do, etc. Maybe some 18 or 15 degree heads, since that's what many of them run. It's only money!

 

Sounds like fun!

Edited by pparaska
heh - I see I'm 12 posts from 5000 when I wrote this!
Link to comment
Share on other sites

I built a basically stock 9.7:1 331 SBC with 461 double hump heads (bowl ported) and a Comp Cams 270 Magnum solid flat tappet cam for my first V8Z buildup. It was a fun engine. Loved to rev, sounded good, etc. But riding in Z's with 383s killed that for me.

 

The next build was a 407ci SBC, with barely streetable solid roller cam and Canfield 215cc heads. Still running a dual plane (Performance Parts Crosswind - like the Air Gap RRM). Likely around 490hp/510lbft according to Desktop Dyno 2000. No Idea what a 1/4 mile run will be, but it will stay right with a Ford GT from a 15mph roll until I lift at 145 (did that a few times on the back straight at VIR, 2 days after I installed the engine).

 

It's an entirely different world. Torque is too much for the tires, even at 70mph when I am turning more than 3500rpm and hammer it. It's now scary fast to most people, and there's no desire for more really, since it can't hook up what it has now. I doubt you could convince me to go back to a 327, much less a 302. Now a 377 - that sounds like a plan....hmm...new pistons, 6.??" rods, 3.5" crank.... Never mind - only if I break this 407!

 

The 302 would be cool to listen to though, and the top end would be very fun. I'd run something like 4.56:1 gears though, and a manual transmission.

 

Notice that the video of the 302 on the dyno had the thing idling at about 1900 rpm. I'd get used to that. Hence the 4.56:1 gear choice. Even that light little car is going to need that ratio to make it at all livable on the street. I'd be looking for used heads from a circletrack team, with shaft-mounted rockers and some nice valvesprings/retainers/etc. to keep the valves doing what you want them to do, etc. Maybe some 18 or 15 degree heads, since that's what many of them run. It's only money!

 

Sounds like fun!

 

 

That cam sounds like something I might be interested in.

Your comment on your 407 about traction is one of the main reasons for my thoughts on my 302. I guess what it comes down to is, I'd rather slip the clutch, than have the tires slip.

I maybe making a mistake, and will learn from it. BUT at the same time, I will have a blast with this setup.

If it dosnt work out, or is as terrible as people preach it to be, i have a 406 with twisted wedge trick flow heads I can slide in there.

 

I dont have 4.56's. Even with overdrive the short tire of a Z car would make highway speed require waaay to much RPM for me. I have 3.90's

Link to comment
Share on other sites

That cam sounds like something I might be interested in.

Your comment on your 407 about traction is one of the main reasons for my thoughts on my 302. I guess what it comes down to is, I'd rather slip the clutch, than have the tires slip.

I maybe making a mistake, and will learn from it. BUT at the same time, I will have a blast with this setup.

If it dosnt work out, or is as terrible as people preach it to be, i have a 406 with twisted wedge trick flow heads I can slide in there.

 

I dont have 4.56's. Even with overdrive the short tire of a Z car would make highway speed require waaay to much RPM for me. I have 3.90's

 

Well, I have 6 year old Toyo RA-1's on the rear, 255/40-17. They are pretty hard now. I'm probably going with some Dunlop Direzza Z1 Star Spec's next. My point is that my tires are hard and don't grip that great, so this issue of traction is hopefully temporary.

 

I'm not saying it will be a mistake to do the 302 - I think it will be fun. The 3.90s may be fine (I'm running 3.70s). But you are going to need limited slip!!! A Turbo 400 has a lower first gear than the Turbo 350. That should help. An overdrive of some type would be a good idea. A gear vendor's unit on the TH400, or a T56 instead.

 

Sounds like fun!

Link to comment
Share on other sites

Hey guys, get ready for a bad update. My wife and i have run into some bad bills. My wife has a cadillac cts, that is kind of becoming a lemon. i told her its time to sell it, cuz she can't even drive it in nebraska winters anyway. she loves her cts like i lover my z. she said she would only sell it if i sold my z. so i need your opinions guys. what should i do? should i keep throwing 2-3000 at her car almost every year, or should i bite the bullet and sell my first love. i have almost had to sell it before for the same reason. if i sell my z im still going to build the 302. i know i won't have a car for it, but i know eventually i will. I have a crappy s13 i could throw it in. i just don't know. I hate her car so much that i actually want to sell mine just to never see it again. I keep telling her for that ammount of money we pay in repairs each year, we could easily have a brand new car.

Link to comment
Share on other sites

How old is the CTS, and how many miles? If it is relatively new, then a $3000/year maintenance bill seems justified, since the depreciation hit upon selling it would be staggering. If it's, say, 7 years old - then perhaps it is better to cut one's losses and sell.

 

I can personally attest to the transformation of Pete's car in going from 327 to 406. I'm not a skilled driver and relied on Pete's demonstration to appreciate the car when it was a 327, as my attempts to drive it were rather disappointing. But when I drove the 406 version last year, it was deeply pleasurable! It is a wonderful sensation to be able to light up the rear tires at will, especially if a downshift is not required. In controlled racing circumstances of course one should worry about gearing, tire diameter, the torque curve and so forth. But in a casual street situation, the sheer wanton excess of torque is just too good to forego, for any benefit of high-rpm horsepower maximization. If anything, I would have preferred a tamer carb, and a shorter-duration cam with less overlap.

 

Poor traction is a good problem to have. I'd much rather worry about tires and suspension tuning, than about finesse of clutch technique, gearing, tuning, and peaky torque curve.

Link to comment
Share on other sites

Hey guys, get ready for a bad update. My wife and i have run into some bad bills. My wife has a cadillac cts, that is kind of becoming a lemon. i told her its time to sell it, cuz she can't even drive it in nebraska winters anyway. she loves her cts like i lover my z. she said she would only sell it if i sold my z. so i need your opinions guys. what should i do? should i keep throwing 2-3000 at her car almost every year, or should i bite the bullet and sell my first love. i have almost had to sell it before for the same reason. if i sell my z im still going to build the 302. i know i won't have a car for it, but i know eventually i will. I have a crappy s13 i could throw it in. i just don't know. I hate her car so much that i actually want to sell mine just to never see it again. I keep telling her for that ammount of money we pay in repairs each year, we could easily have a brand new car.

 

That sounds kinda petty. I'll only sell my car, if sell yours... Give me a break. You shouldnt be punished because of her poor car purchase.

My girl owns an '06 CTS, no problems yet :-|

Link to comment
Share on other sites

Hers is an 03, has 227,xxx it had quite a few when she bought it. now it seems like everything is breaking, or going out on it. i have done what i can on it that i could actually fix myself. i told her i hope the motor just blows and if she really wants to keep it there is a small block chevy in the shop that could go in it that i could work on all day long.

Link to comment
Share on other sites

Her car is DONE. It's used up. She can get a newer one that she'll love even more.

Her car is a transportation appliance that is used up and easily replaced with one like it but in better condition

 

Yours is hard to find, you have a personal attachment to it. Finding another is not as easy. Yours is probably worth next to nothing - so getting rid of it is not so smart.

 

You would not believe the heart-felt advice I typed out and deleted....:fmad:

 

(9 posts away from 5000 as I write this.)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...