Well, I've been talking about it for a while now. But I finally got my incometax check and it was friggin HUGE ($4100)! Now it's time to get me some POWER!

I've pretty much descided on what all to use and am looking for some constructive critisism and recommendations, so here goes...

70's model 400 SBC
bored .030" over
nice fresh rebuild
Holley 670 TBI
Single plane intake (not sure which one due to heads, recomendations please)
Vortec heads
Come Cams Xtreme Energy grind 262
Hedman Tork-Step headers
(please recommend a good stall)
TransGo shift kit
3.42 gears and a limited-slip (out of a 4th gen)
sub frame connectors (recommend good company please)
Edelbrock TBI strut tower brace
and prolly some 16" chrome IROC-Z wheels with 235/55's on them to put some power to the ground

Let the recommendations and critisism fly!

 

i'd run more cam and not a single plane intake

 

My 406 came with Vortec heads, Comp Cams 268 XE cam, and an Edelbrock Performer RPM Air Gap intake. The idle is smooth, near stock, and produces great street torque in an 86 T/A. The car is a blast to drive.

 

i'm with ede on the more cam.

but since its TBI i'd stick with the single plane.

 

I'm not downing on anyone who likes TBI, but if you are going to be putting that kind of money in a engine, why don't you convert to carb, so you can have, in my eyes, many more tuning options at a reasonably less cost than with TBI and the chip burning. I have helped guys with TBI build ups and they never seem to make the power compared to the price and parts in them. Especially with any type of heavy breathing 400, I wouldn't expect much rpm capablity. Those TBI's just don't seem to breath all that well. Just some food for thought. Before you commit to TBI, I would just look at carbs, I think its the way to go, other than super expensive EFI. Of course thats just my opinion and experience. And you know what they say about opinions, they're like ___holes, everyone has them. Good luck with the buildup, I think you will be happy with the 400, I know I like mine.

 

Get the upgraded Vortecs from Scoggin Dickey (for more lift) or get the ones you buy modded. Then run at least the XE268 prefferably with 1.6 rockers. I run the 262 in my 350 and it is great, but for a 400 it's too conservative IMO, you'd be leaving power on the table for no good reason. The 268 would still idle and drive great in a 400, in fact the next cam up (274?) probably wouldn't be a bad choice at all either.. Can't comment on the TBI stuff, no first hand knowledge there but a carb setup sure seems like it would be easier to get running and will make max power... Can the 670 TBI support the 425+ hp this setup is going to make??

 

I'm building one now. Comp cams XE 274H. But I'm using Dart Iron Eagles 72cc w/200cc intake runner,2.05 intake, 1.6 exhaust heads instead, RPM Air Gap, and Demon 750 DP carb.

We figure (the engine builder and I) to get closer to 450+ HP at the fly at the dyno hopefully. Is the TBI 670 cfm's?? If so, it's too small. You want it to breath....ditch the TBI thing..

 

Well, I want to keep the motor at bay, near 375hp max, cuz I don't have the $ to upgrade the rest of my drivetrain just yet.

All the ECM/Chip tuning is gonna be done by Craig Moates so I'm assuming he'll be able to squeeze the 375hp I seak out of the the TBI setup safely.

And as far as the cam, I figured the 262 would be perfect for 350-375hp and make some awesome streetable torque.

Anyone have any recommendations on what size stall to run? And can anyone link me, or give me a part # to a signle plane intake that'll work with the vortec heads?

 

ttt.

 

OK, I'll accept the TBI thing...for now. Not having the drivtrain ready is a valid point also. Mines not ready for it either.

But upgrade each one once. Keeping the motor "at bay" now, just tells me that you may upgrade in the future. That'll cost extra $$$ on top of what you're putting in it now. I think the heads will flow fine, I'd get the Vortec RPM Air Gap intake, bigger cam also. Comp recommended the XE274 for mine when I called them.

It's still streetable on a 400, and will have enough vacuum for power brakes etc...street/strip cam. You didn't mention pistons...IIRC the Vortecs are 64cc chambers. You may want a dished piston to keep compression no higher than 9.5:1.....they detonate easier than 383's.

Just some "constructive" critizism....

 

Well, from what I've read, the stock CR on the 400's was something like 10.2:1. I may have been tripping, but I could swear that it had a rediculous CR for a stock motor with cast heads.

I'm gonna shoot for something like a 9.8:1 CR for this 400. Is that too high, would 9.5:1 be better?

I'm gonna go ahead and get the "upgraded" vortecs from sdpc2000.com and maybe go with the XE268 or even the XE274. I just don't wanna put my drivetrain in too much jeapordy and from what all I've read on this site, 375hp is about the maximum attainable HP with the holley TBI and ALOT of expert chip tuning (which I have covered )

Edit: when I order the rebuild kit, i'll tell them what size heads i plan to use and find out which kit/pistons will keep me in the right CR range

 

Yeah, I just went and looked, http://store.summitracing.com/partde...2DMHP138%2D300 , and the lowest CR kit they sell is 10.14:1 from summit.

 

ttt.

 

Try this link here for stock compression ratio on a 400:

http://www.carcraft.com/techarticles/1001/index.html

It was a smog era engine, so compressoin was lower tham 10:1.... I wanted to go up to 10.5:1 on my 400, but the builder talked me out of it due to detonation problems. But - I'm using iron heads. I think you'd get away with a higher compression with aluminum heads.

Here's another 400 buildup using Vortec heads....hope this helps!!

http://www.chevyhiperformance.com/te.../148_0306_406/



EDIT: Sorry I can't recommend a torque convertor....it's a non-factor for me since I have a T-5.

 

In reference to the high comp ratios back in the early 70's, don't forget about the leaded fuel they were able to run. The lead allowed the use of high compression ratios without preignition and detenation. That's how they were able to run 11 to 1 in a pump gas street engine without extreme radical cams and such. So when you see those compression ratios back in the 60's and 70's don't base your comp ratios off them.

I use a Coan convertor, somthing around a 2800 to 3000 stall would probably suit you well. It will depend on the cam you use, but I think either cam you specified would be a good match with something around 2800.

http://www.coanracing.com/Converters/ConvMain.asp