Well while poking around thease boards I got a crack head idea...

I want to put a 400 SBC in my car. That is pretty standard but I want to use ALL of my stock LG4 manifolds and CCC setup.

Pretty much I want 400+ cubic inches that looks like a stock lg4. I am pretty sure that a modified q-jet will flow plenty of air for an underbuilt 400 the only thing I am really worried about is the exhaust manifolds. Is it possible to get them to flow in any way acceptable for 400 cubes? I am not adverse to getting a custom y-pipe made but Headers look too "distinguishable". Are there any exh. manifolds that flow better than 87 lg4s or were they all the same?

Also am I going to have trouble getting a t-5 bolted to a 400 - more spefically can i use a stock flywheel or do I need to get an aftermarket peice?

 

L69 and LB9/L98 manifolds flow better than LG4. They have a bigger opening, and require a bigger y-pipe.

A much better bet would be to go with Hooker 2055 headers (come with a great y-pipe), and add '86-'90 TPI single-cat application direct-fit cat and cat-back. It is all emissions-legal (may have to modify the A.I.R. to the driver's side slightly). Your 400 wouldn't be "distinguishable" from my 305, so what's the issue there?

I haven't seen anything lately, but I believe some time in the past an externally balanced, two-piece rear main, 153-tooth flywheel was discussed on the Tranny forum. It would be an aftermarket piece, but the cost wasn't that bad. I've also seen bolt-on balance weights, but not sure if they would work for a manual tranny.

 

I found a flywheel for a 400 in a truck with a stick. I am not sure about the tooth count (it might be 168). Would that work for a t-5?

 

The T-5 won't care; but it won't fit the chassis.

As was said above, if you change any one thing, make it the exhaust. The LG4 exhaust is one of the main reasons you're wanting to swap in a 400 in the first place, because it's the most influential thing in making the LG4 so gutless. You'll have a really gutless 400 with that drinking-straw POS setup choking it.

 

Actually I want a 400 for the same reason I want twin turbos - Tim allen syndrome. Adding cubes seems to me to be the most cost effective way of breaking parts. I have done more reasearch and the only question I have left is what kind of fylwheel am I gonna need?

 

With the LG4 exhaust, you won't break much of anything; it won't run at all past 4000 RPM or so. It'll be like driving a tractor.

When I put a 400 in my car, I used a stock 82-85 305 flywheel, and sent it out to the balance shop and had it "unbalanced" to the stock 400 balance spec. I drilled the missing starter bolt hole, wihtout which it is impossible to bolt up a starter. Your block might have that hole but probably not.

 

400's need to breathe a lot of air, and the stock LG4 induction and exhaust system will not work. You will need at least an air cleaner from an L69 car with the two snorkels. On the exhaust side there's no other option but headers. Remember flow = power and without any flow you will have a barely running slow 400. That's the same way the came out of the factory, choked up, and they only made like 170hp which is only a small improvment over the power your LG4 puts out for a whole lot of wasted money.

 

lol, that would be a pig.

the induction and exhaust is nowhere NEAR enough for even a bone stock 305.

so why would you choke a 400 with junk parts?

adam

 

The whole Idea was to have an underbuilt 400 so as not to break the rest of the car so that when the rest of the car can handle the rest of the power the potential would be there. Not to mention that whuppin of ppl with what looks like a stock 305 would be cool.

 

I don't think so...

It costs alot more to build something twice, than to get it the way you want it the first time.

The smarter path would be to work on what would be inadequate or you think you'd tear up first, if you have a clear idea of what that would be; then put the motor in later. You'll get to your ultimate goal (a fast but reliable car) much faster and cheaper that way.

 

I have pretty much figured that much out by this point. I think the 305 is gonna hafta say at least for a little longer.