After giving up on trying to improve my little LO3, I plan on purchasing a shortblock or something of the like within the next few weeks. I was originally planning on using TPI for fuel delivery, but I have decided to go carb. How much work will be involved in changing my once TBI car over to carb? Do all of the gauges have to be changed or can they just be rewired? What about the fuel pump, should i use a mechanical oneor purchase a regulator? How much work is really invovled in this swap? Thanks

 

A few friends and I just did a TPI to Carb swap on my camaro this weekend, the only tricky part was getting the dang fuel preasure regulator to not leak. To get the fuel pump to still work, you have to wire it to an ignition relay instead of leaving it wired up the same, it kept clicking off on us.

As for the actual work, it's basicly taking off the manifold intake and distributor, and putting a new manifold carburetor and distributor on. I got all of the old parts taken off and all of the new parts put on accept for the fuel regulator in one day by myself. I had some help with the wiring, fuel, and carb tuning. all in all, it was pretty simple, but we ran in to problems with my car because of the way it has been wired up, the previous owners did some shoddy wiring.

there are a few tech articles on doing this swap, most of them suggest putting a new fuel pump in rather than going with a fuel preasure regulator, we didn't have time to drop the tank so we put in a regulator. so far it's working just fine.

 

Just did this a few months ago on my wife's 92 RS.

Fuel pressure is handled by a Mallory 3-port regulator which brought the pressure of the stock TBI pump down to a carb-friendly 5 PSI. I had no such problems with the fuel pump turning off. I beleive that having the factory oil pressure sender (located in the block just above the oil filter) is important to making sure the fuel pump continues to run. Also, this sender runs your oil pressure gague on the dash so you'll want it hooked up.

Temp gague sender is located in the driver's side cylinder head between #1 & #3. Put it into the head of your new engine and hook it up so your temp gague continues to work.

The cooling fan switch (just one on a TBI engine) is controlled by the temp switch screwed into the pass. side cylinder head between #6 & #8. You'll want to swap that onto the new engine, too, unless you plan on just wiring the fan to run constantly.

I used an early-style non-computer controlled large cap HEI distributor on my engine and the wiring was pretty straight-forward. Just had to rewire the connector that went to the original remote coil into the appropriate terminals on the side of the HEI (big pink coil wire goes to 12V+, smaller white wire goes to TACH terminal). Works just fine, and yes, my tach still works just like stock.

There are a LOT of unused wires and plugs left over from the original TBI engine, which I haven't cleaned up yet. TPS, IAC, MAP, KS, CTS, EGR, injector plugs, etc, etc, etc.

EVERYTHING works just like stock in my car. The A/C even works! Of course, the check engine light is on, but that's to be expected.

BTW- there are a LOT of ground wires that bolt the backs of the cylinder heads on the original engine. They must ALL be hooked back up if you expect everything to contiue working correctly like mine does. You may wish, however, to extend those wires by a foot or so in order to bolt them on the new motor someplace that's a lot easier to get to and hook them up- like a bolt on the intake manifold instead of back behind the engine.

 

the only thing I would do differently if I had to do it over again would be to use a mechanical fuel pump. I have never had any problems with my Mallory unit and I'm still using the stock TPI pump making ~400 HP at the flywheel. But with a mechanical there is so much less to have to worry about.

Hodge