84 engine swap
Melting Slicks
Joined: Jan 2008
Posts: 2,054
Likes: 120
From: AZ
My car has a late 70's truck block, built, under a TPI. The mods are rather extensive but a custom chip in a GM ECM works very well. You'll need all the sensors and as Kev said, similar specs to the L83 so the ECM isn't too confused about how much fuel to add, when.
Not a pro at this, just relating my situation.
Not a pro at this, just relating my situation.
Thread Starter
Advanced
Joined: May 2014
Posts: 55
Likes: 0
From: Indianapolis Indiana
Its my daily driver and so i can just pull one out and put the other in, i was going to build it to specs but was going to do the performance upgrades done to it so it will still respond to the ecm
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
In that case I would look at what some else had done successfully and mirror it. Performance mods will require a custom or "tuned" chip for ecm. Cross-fire wasn't very popular to mod so a fair amount were "carbed" as a result. In any case do your homework first. Trial and error gets very expensive quick
Pro
Joined: Jan 2003
Posts: 706
Likes: 47
From: Denver Colorado
If you build your engine as a mild driver without a radical cam and with low compression, say 9 to1 or so and use all the stock '84 sensors you should be fine with the Cross-Fire setup. I built up an L83 with aluminum L98 heads and a well-ported stock Cross-Fire intake and had no issues with a stock chip. I did increase fuel pressure to 13 psi to eliminate an off-idle bog. My compression was above 10 to 1 BUT, I'm also above 6,000 feet altitude, so don't go with flat top pistons if you use the later heads!
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
The Fan switch screws into one of the pipe threaded holes in the cylinder head. Not sure which head, but I THINK it's the passenger's side as well.
Swap should work w/no issues. Only functional diff between the two engines is that the '84 has forged 9:1 pistons, the '77 likely has cast w/lower compression.
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
Tom's got it right. The switch for the fan relay screws into the threaded port in the passenger side (in U.S.A.) head between cyl. 6 and 8. My question would be the cam specs. I can't believe the '77 cam would be the same as the '82-'84 CrossFire cam. They are both flat tappet cams, but 5 years difference, and carb to EFI, there's no reason to expect them to be the same!
Thread Starter
Advanced
Joined: May 2014
Posts: 55
Likes: 0
From: Indianapolis Indiana
So if i change the pistons i should achieve same compression? I was going to go with renegade manifold 180cc heads with 2.02 intake and 1.60 exhaust, going with crane 2040 powermax cam, 1.6 rocker arms. I was just gonna build the engine thats in the vette right now but its my daily so thats why i want to build a different engine tha would work for the car that way i can minimize the down time of the car
Melting Slicks
Joined: Jun 1999
Posts: 2,931
Likes: 127
From: Ashland Alabama
Any small block from 1985 on back will work fine with the crossfire setup your wanting to do. Ive got an 81 350 that's been carbed, tbi, and tpi before. No mods required between each setup on that same motor other than changing the intake manifold motor wise.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Cam and compression may be different, but not enough to matter in a meaningful way, IMO. Now, if you're going to do a Renegade, cam, rockers, you'll MAY need a tune...depending on what your criteria is, and what is acceptable to you.
And if you're going w/a bigger cam, more compression would be helpful to low end tq.
Melting Slicks
Joined: Jun 1999
Posts: 2,931
Likes: 127
From: Ashland Alabama
Also when doing a cam think what your really going to do with the car. If you want grunt and a real nice push when taking off and just a generally fun motor not really racing people just cruising get what is referred to as an rv or truck cam profile. Lots more usable torque down low. Ive run both in the same motor in my trans am. The "race" cam was faster actually racing the thing but mpg and shear pleasure driving the car was with the rv/truck cam.