VIN666

Hi guys.

I'm a V8 noob and I have a bunch of questions.
Yes, I did use the search function and I also contacted a couple of users directly.
Unfortunately without any success.

So, first I'd like to do some research using this thread, and later this year or spring next year this might become my swap thread with lots of infos and pics.

- will a sbc 400 bolt up to my car and my 4+3 tranny?
- will a 750 holley with a regular intake fit under my hood?
- how hard will it be to get rid of all the cross fire's electronics?
- will my dash still work (digital)?
- what exhaust shall I use? I want to get rid of all emission BS...
I have seen real cheap dual exhausts without any mufflers or cats that bolt up to the stock manifolds. Can I combine that with shorty headers and a 400 sbc?

Alright, that's all for now.
I hope to receive a lot of feedback.

-Tom

Demonic85

1. yes
2. depends on the height of the intake, a low rise will work and you will most likely need a drop base air filter.
3. i would just unplug what you dont need and tie it down somewhere.
4. for the most part they will, like speed and tach.
5. what kind of emissions laws do you have? that will answer your question. LT headers, dual exhaust with an X pipe, and good mufflers make the perfect setup IMO.
6. shorty headers are better than the stock manifolds but long tube headers are worth it.

VIN666

Thanks a lot.

So in other words: a rather easy swap, right?
As far as emission laws go, well I don't know to be honest.
It needs to pass inspection. But being a 84 there's no emissions.
Still, if the car was equipped with cats it technically must have cats...
But first of it depends a lot on the shop you go to, and second there are exhaust systems with high flow cats. We'll see.

Oh, I almost forgot:
How am I going to solve the fuel pump issue?
The 400 has a mechnanical one, the vette an electrical (afaik).
Can I let the motor suck gas through the stock pump using it's mechanical pump, or wont that work?

Thanks for all the great info again!

Deakins

Just put an adjustable regulator in line and block off the mechanical fuel pump boss. That way you can still use the pump and have the pressure you need. I have done this swap in a TPI car so if you want to contact me directly you can. Hope this helps.

Iroc57

Worry about those details when you are closer. You will regulate the pressure from your in tank pump.

qws

How does the in tank pump exactly regulate the pressure?
So your saying you don't need a regulator?

Iroc57

No...sorry

When I said you regulate it I meant with a regulator. I use the Mallory 4309 if I remember correctly. It is a return style so I dial in exactly what I need at the carb and the rest just circulates. I think that I paid $75 for it new.

VIN666

Thanks guys.

The reason I'm asking all this even though I'm far from doing it, is that I want the swap to run smooth and get ALL parts up front.
The more I can sort out before the swap, the quicker it will be.

The guy selling me the motor was not sure if the stock pump will be able to take the abuse of running against a regulator. That's why I asked.

So to sum up:
- I'll need the motor carb to pan
- this exhaust system (http://www.corvettecentralexhaust.co...mance_dual.php) the smooth flow one
- these "mufflers": http://www.parts123.com/parts123/yb.dll?parta~partsort
- a manual 400 flywheel
- a decent clutch
- a fuel pressure regulator (incl. return line ???)
- an aluminum radiator
- dual electric fans

Anything else?


@deakins: Tthanks, you'll hear from me!

Deakins

Yeah I always recommend running a return style regulator that hooks into the return line; this really saves the pump from dead-heading into the regulator all the time.

gman1984

I am doing the same dumping the cross fire for a carb, is there anything that has to be done for an automatic transmision?

rodj

You need some means of engaging the TCC,
either a manual switch or a rework of the switches in the trans so TCC automatically engages when trans shifts into 4th

93 ragtop

I may be wrong on this, but are you all sure the 400 sbc will work with the 4+3 flywheel? The 400 is external balance and the orig. setup was internal balance. Also, wont the frame section where the harmonic balancer sets, need to be clearanced for the bigger balancer on the 400?
Again, I may be wrong, just asking.

bjankuski

You are correct, in stock form this will cause issues. You can either have the engine internally balanced and then use neutral balanced components or you can buy a seperate bolt in external balancer for the rear flywheel and a smaller diameter aftermarket external balancer for the front.

The Green Rocket

I don't know what power level and driving you are planning on - but the 4+3 is not really setup for any kind of powerhouse 400 engine. When you lay the computer/Crossfire injection wiring harness off to the side be sure to bag it and seal it to keep the connectors clean in case you ever go back to the Crossfire.

As I recall, the fuel pump for an '84 Crossfire injection is not high pressure like the '85 and up C4's. See if you can find out what its pressure is - you may be able to run it as is without a regulator or return line.

When you build your 400 engine do it as an internally balanced engine - this will give you more choices for the flywheel and crankshaft damper.

Thomas

gman1984

Thanks for the advice i now have some more research to do. Thank you

JLeatherman

I have a 400 crank in my 84 car with a carb now (well, aftermarket 3.75" crank, but it's still externally balanced). The flywheel isn't the problem, several places make an externally balanced 153 tooth flywheel or flexplate. The harmonic balancer is trickier. I bought mine from a place in Louisiana I think. It's gotta be a small external-balancer. The stock 400 balancer, and most aftermarket external-balance balancers will hit the vette crossmember. Someone else on the forum told me about the place and I had it matched to the crank/flywheel at a local machine shop.

Stock crossfire pump is 15psi which is still too much for a carb. I carb'd my '84 and run a Mallory 4307M return-style regulator. Works great, 6psi at all times.

LD85

You can have the crank neutral front balance and external balance rear,

or complete internal balance front and rear

or external front and rear.

I have had all 3 mentioned above.

my recommendation is neutral front and rear

the 4+3 FW is OK and cheaper in neutral balance than the external 153 tooth balance.

qws

CFI fuel pressure is regulated in the rear TB unit through a regulator. 9-13 psi. The pump however can give you almost 15 psi.
You will need to get a aftermarkert regulator for the carb

VIN666

Wow, it's been ages :P

Current status: Drove car out of barn (where swap was performed) onto trailer and off the trainer into my garage.
So it "runs".

It's been in this state for all of 2010. Didn't touch it, too many other projects.
SRT and Ninja took up all my time. Those are done though, so the Vette is next.

Here's what my setup consists off right now:
-I used a balance spacer that gets bolted between the stock flywheel and the crank.
-We convinced the front frame to accept the 400s front balancer.
-We convinced the front frame to clear my mechanical fuel pump.
-I pulled the electric fuel pump's fuse and use the mechanical one.

Is this going to work? I'll find out shortly LOL

Next steps:
Finish wiring and clean up all the crossfire crap.
Buy and hook up exhaust (true duals, straight pipe).
Hack up hood to accommodate the 400 with carb and filter.
Hood won't even close with the filter off btw


Just wanting to let you know that this isn't another one of those projects that never happened :P

It just get set aside for a season

Keystring

Don't know why you went with a mechanical pump instead of a regulator and just used the in-tank one.

But, anyway..

Personally, I would remove the pump from the tank and install a pickup tube and filter . I'm not sure how well you are going to suck the fuel past the pump once you start opening her up on the road or track.

BTW.

My Vette is 'carbed' and I use an underhood regulator and the in-tank pump.

Works great! (I do have to change those hoses though)