A year ago I had the motor in my 93 Vette rebuilt. I've put maybe 4000miles on it since (been working on appearance, since I saved this car from a sunbaked un-cared for doom.)

I've noticed that the car is a bit lacking in get-up-and-go. I'm not entirely sure why this might be as I'm not a mechanic but an interior/detail guy.

We pulled the original motor out and cleaned it up (headjob, new manifold); upgraded the major components (new cams, pistons, rotating assembly, roller rockers, lifters); put some new parts throughout the engine bay: Hooker SuperComps, SLP cold-air, new radiator, water pump, oil filter, spark plugs, wires, fuel injectors, other busted hoses and things, thermostat, adjustable fuel regulator. Had the tranny rebuilt (4sp Auto). The exhaust is a rustic Flowmaster with cutouts that I will toss when I can afford it.

Okay. We had a hi-output fuel pump installed but managed to ruin it when my friend forgot to disable the one in the tank, so I'm running the stock pump. Still have stock throttle body. I have yet to purchase a lot of other engine components, ie maf, o2, throttle cable, pullies, that most likely have wear and tear (this car was wrecked a few times in its poor life).

Okay, so originally I thought that the car's lethargic performance might be due to a fuel problem i.e. running too rich at low RPM. But I'm sure that it cannot be that easy.

I have seen that there are some very, very brilliant people on this forum, so I hope I've provided enough to get some ideas. (I don't know all of the EXACT engine specs off the top of my head. I have them written down somewhere here

Thanks for any suggestions!

 

can you describe any specific symptoms? (hesitation, back firing, hard starting, etc.). did you cover the basics? (clogged air filter, clogged fuel filter, etc.).

 

Initially when testing the car it was bucking at about 3,000 RPM and this would continue up through the range. We resolved this by removing the ruined hi-output pump.

The only way I can describe it right now is lethargic. I was driving on the Freeway a few weeks ago when a Lotus Elise sailed past; I wanted to catch up for a better look so I stomped on it. The acceleration scared the hell out of me, gave me a pit in my stomach.

However, from a dead stop the acceleration feels barely equivelant to a stock 93. This is led me to the fuel pressure/mixture idea.

The air filters do need a good cleaning, tho they are not up to K&N's you need to clean these now or die par.

 

if you are getting the power you expect at higher speeds, but not from a dead stop, it may be something as simple as a timing adjustment (it might need to be advanced at bit). does it idle properly?

 

It idle's pretty well, kind of lopes, but it doesn't severely stutter or fluxuate (its hard to tell with those cutouts open, as they cause so much extra noise and vibration). I believe that the chip has it idling around 900 give or take.

 

Are you saying that you're experiencing a noticeable decrease in off-the-line acceleration over time?

what is "die par"?

Larry
code5coupe

 

Afer driving the car for a while after the rebuild I decided to see how it accelerated when pushed. That is when I noticed the bucking problem, which was resolved by taking out the two messed up pumps and putting a new stock one in.

Since then the car's off the line acceleration simply has felt flat. Upper end stuff feels fine, it climbs through the three digits like a second hand.

"die" par. sorry, sometimes i'm a bit eccentric when I complain. I just meant that the filters aren't at the "these MUST be cleaned" level.

 

It sounds like the car has not had acceptable acceleration after the rebuild.

You said that you upgraded with "new cams". Certain cams will kill your lowend power while giving you more on the top end.
Perhaps that's the case here.
What cam did you put in the engine?


Larry
code5coupe

 

We went with a Comp Cams Xtreme energy cam.

 

This is why you don't start a project when you're 18 and pick it up again at 21 having not thought about it for a year.