400's get a bad rap. I know guys who run stock 400 (.030 over 406's) with GOBS AND GOBS of nitrous on bone stock factory original 70's nodular iron cranks...... they're in no way weak...

However, if you're gonna use a Gen1 SBC block, why bother with LT4 heads at all??... You have a wide variety of cylinder head choices for much less money.... What about some PnP Dart heads or something?

I thin you can then adapt an LT1 or LT4 intake (depends on which one lines up properly with the intake ports), or even use a TPIS mini-ram or superram intake and stock wiring harness.

The only "problem" I don't know how to fix would be getting the "low res" opti pulse into the computer in the absence of an opti....

If someone can explain that to me, I would consider doing a Gen1 SBC in the car rather than an LT1.

-Michael

 

Hmmm, the opti spark would be a problem. Does F.A.S.T. depend on that with their LT1/LT4 harness?

What heads can you guys think of that will flow better than the outlined LT4's in my link? Remember too, they also have to be smog legal heads.

I just figured by buying an LT4 donor motor for the intake, fuel rails, etc, I would have the LT4 already so why not work with them. Since the opti spark now seems to be a problem, I'll either have to use and aftermaket computer and harness or my factory TPI harness with a custom chip.

 

Thats what I meant. LTx heads won't just bolt on to any SBC, for the cost and pain of converting you're much better off going with aftermarket heads, and if you like the intake style, TPIS offers a miniram intake which looks the same but has the provisions for coolant and a distributor hole already in the back of the manifold. If you're really set on the LT1 intake though, check out www.LT1intake.com.

 

A TPIS Miniram is $900 and the fuel rail kit is $350.

Also it has no cold start injector and egr valve. You need the egr to pass smog here in CA.

 

Crossover coolant passages might be a problem if you use a LTx intake with gen 1 heads. You might be able to fix this though. I would just reccomend doing the 400 with a miniram and accel DFI or something of that nature.

 

Why not just build up the LT4? Sounds like you REALLY want to waste alot of money. I guess it's your project, do whatever you want.

 

Well right now I'm researching a Miniram with some AFR 195's on the 400ci SBC...

 

Just FYI, you need EGR to pass smog and the miniram doesn't have provisons for EGR, which you already know. Yes, the LT1/4 manifold has provisions for EGR, but you won't be able to put and EGR valve back there if you have a conventional distributor.

 

As far as the opti, you won't even need that if you run a crank trigger system. It locks out the distributor and uses a crank sensor for the timing. Look into the current issue of GMHTP and try to get ahold of the guy that put a distributor on his LT1 and see if you can't run something similar.

 

Yeah it looks like I'm kinda screwed out of doing any kind of low profile intake to clear my STB and still pass smog.

 

Like these guys.. so many choices for SBC stuff, it almost seems silly to spend the money on converting LTx stuff to it. If it's the manifold you want, you can make that work by itself obviously, but in the end I think you'll have a good bit of $ in it. Even if I already had LT4 heads, I'd probably sell them and take advantage of the nearly endless SBC choices.

Got your mail btw, but cant send w/o being on the RR network til I get back in town.

 

Have you considered just getting a blown/heads/cam 383 setup? There is a guy in CA passing smog, with a 9 second pig heavy, TH400 LT1. Blown of course.