First post, long time reader. I realize below I will be asking some non carb questions in the carb forum, however most of this is in relation to the TPI to carb swap so I figured I would ask in here.

I will get the vehicle specs out of the way. 87 Iroc 5.7 that was replaced with what I was told is a 1990 5.7 from a GTA. Can't verify this, but not sure it makes a difference outside of a tad more HP. I am swapping the TPI out for a carb setup. I have everything needed to do the swap and I started tear down this evening. As I was sitting here, I started thinking about other upgrades while the top of the engine is apart.

Currently the parts I will be installing are Performer Intake, Carter 750 competition carb, Mallory HEI and Wires, Mallory AFPR and Fuel Gauge, Dougs headers, Dougs Y pipe, cat delete into cat back magnaflow system. This should open this bad boy up as far as breathing goes.

Will I need to, or is it better to, use different spark plugs when switching to carb from TBI? Wasn't sure if I needed a hotter plug going to carb setup.

Timing, does initial timing need to change when running carb as opposed to TPI?

While I have the entire top of the motor apart I thought about cam upgrades. Is there anything in way of an upgrade over stock cam that will compliment the parts listed above? I know I am limited by the stock heads, however I would like to get more power and performance out of the car, and some noticeable lope would be nice too.

I plan on retaining most of the factory harness under the hood just in case the next owner wants to switch back to TPI. Will I be able to use all the current sensors after switching to carb? I know the CEL will come on as I will have unplugged a few connectors for the TPI setup. I'm not worried about this as I can remove the bulb.

I am mainly just wanting to keep all my factory gauges functioning as well as anything else that works off the factory harness. I have read others remove the harness and re-wire things like the Alt, fans and gauges. Is there anything that anyone can think of that will cause an issue if I just pull the harness back out of the way as best as possible after the swap?

Thanks for any answers and pardon me if some of these questions have been asked before. I have about 20 threads up on my screens in reference to the Swap and none cover spark plugs, timing, harness or cam questions in any detail so I figured I would ask. I will continue to search for some answers, and again Thanks in advance for your time.

 

How did you happen to pick that carb?

You will need to set the timing differently than you did for TPI. The best method is to unplug and cap the vacuum advance, then run the RPMs up until the mechanical advance is fully advanced. Set the timing to 34-36 full advance. You will need "timing tape" on the damper to actually read that much advance. Then hook up the vacuum advance and let it do its thing.

Spark plugs can be the same ones as TPI used. Heat range is a function of head cooling characteristics and compression.

I assume you have an automatic transmission, assuming this was a factory 5.7 car. You will need to rig up some sort of torque converter lockup, since the computer will be brain dead after this change. Also, the transmission TV cable (often mistakenly called "kick down cable") needs a specific geometry on the throttle arm to operate correctly. For Edelbrock carbs, there is a "corrector bracket" available to fix that, but I don't know if that bracket will fit a Carter. Should, but I don't know personally if it will.