C-4 Engine into a C-3
Thread Starter
Instructor
Joined: Jul 2010
Posts: 177
Likes: 0
C-4 Engine into a C-3
I need someones info about how to wire a C-4 engine into a C-3 body and make things work right. I'm not sure how much of the Computer wiring I will need from the c-4 or how to make the fuel flow and the motor to fire properly. If anyone has been through this kind of conversion, please help me. Thanks in advance , Larry
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
I need someones info about how to wire a C-4 engine into a C-3 body and make things work right. I'm not sure how much of the Computer wiring I will need from the c-4 or how to make the fuel flow and the motor to fire properly. If anyone has been through this kind of conversion, please help me. Thanks in advance , Larry
Link=Larrys
Burning Brakes
Joined: Mar 2012
Posts: 871
Likes: 73
From: Memphis Tennessee
It's not as complicated as it may seem. Most of the wiring is self contained in the sense that it only connects between the computer and the engine sensors/actuators. The only splicing needed into you stock wiring is adding a few battery positive and switched ignition to the engine harness and as we'll as adding a circuit for an electric fuel pump.
Racer
Joined: Mar 2012
Posts: 476
Likes: 37
From: Lynnwood WA
I found that going with a new harness was a lot less hassle than messing with a crusty and brittle old one. You may be lucky and have one in good shape, mine was a nightmare of melted wire and poor splices. The custom built stuff made it a lot more plug and play. Also the aftermarket computer came with the VATS removed. Do not forget the VATS! Like Learning Curve says "It's not as complicated as it may seem" The finished product is so nice to live with, that when I went from the C4 L98 motor to a newer one with Vortec heads, I kept the TPI. All I had to do was change the lower manifold. Everything else just swapped over. It really is a nice system.
Last edited by Zorro O; May 4, 2013 at 02:27 AM.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
I went L98 back in '95 when I bought this '72 vert...bolted on the OEM L48 engine, upgraded the engine in '97 to a roller block and aluminum heads....used the serp drive '88-91 vette, with later good compressor and it's a speed density setup....instead of air pump, I have an idler on there....
Thread Starter
Instructor
Joined: Jul 2010
Posts: 177
Likes: 0
Thanks Mrvette,Zorro,& Curve, your input is wonderful and very helpful. I wonder if I will have to put catt's on the exhaust to make the sensors work with the computer?Anyone know of a video of this task ?
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
I being an old ET here from way back, am not scared of wiring, and find the majority of harnesses to be intact and fully functional, just look funky, but mostly the copper and individual coverings are fine.....of course over the years my '72 has been totally reworked in the harness under the dash, in the engine compartment, only thing remotely stock is the harness leading to the back lights....but then again they are not stock either.....there is NOTHING stock about my car, from wheels to roof....but it is all Corvette/Chebby.....
Racer
Joined: Mar 2003
Posts: 448
Likes: 21
From: Klein Texas
I've done several EFI conversions including a couple TPI's. I have one in my '73 Z28.
I've never bothered with the O2. It is there only to make the catalytic converter happy. No catalytic converter, no need for the O2
With a speed density system you only need RPM, coolant sensor, throttle position and MAP to make it run.
I've never bothered with the O2. It is there only to make the catalytic converter happy. No catalytic converter, no need for the O2
With a speed density system you only need RPM, coolant sensor, throttle position and MAP to make it run.
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Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
I've done conversions using the GM wiring harnesses and they've generally been in decent shape and just taken time to remove the excess wiring and make neater. However, a wiring harness is likely best if you're not big on reading schematics to re-work a stock harness. The other big trick is the fuel system. You can stick a inline pump on the fuel line and it will work but every time the pickup is exposed even for a second it will suck air and the engine will stumble. If you search here you'll find some examples of putting an inline pump into the stock tank. It's a bit of fabrication but not too hard.
If you're doing the OD auto too, I would personally do a LT1 and the 4L60e trans. It's so nice to set each shift point curve and the torque converter lockup exactly how you want it to drive.
The O2 or O2's on the older systems pre-95 are to fine tune the AFR. You can run in open loop but why bother when an O2 is so easy to install? Those older systems could care less if there was a catalytic converter on the car or not.
If you're doing the OD auto too, I would personally do a LT1 and the 4L60e trans. It's so nice to set each shift point curve and the torque converter lockup exactly how you want it to drive.
The O2 or O2's on the older systems pre-95 are to fine tune the AFR. You can run in open loop but why bother when an O2 is so easy to install? Those older systems could care less if there was a catalytic converter on the car or not.
Last edited by lionelhutz; May 4, 2013 at 11:44 AM.