The previous owner of my car took the original 1987 2.8 L engine out of my car and dropped a 1987 5.7 L IROC engine in it. My concern is that they did not change the rear end gearing. I am assuming that the v6 would have a different rear end gear set than the v8. Could having the wrong gears be messing up my engine's power or causing it to run at higher RPMs?

I noticed that my car really gets a power boost once it hits 4400 RPMs and there is a noticable increase in acceleration speed once above that RPM. Is this just the power curve of my engine or could it be caused by the rear end gears?

Thanks

 

a v6 car prolly had 3.42 gears(mine did) where most v8 had 2.73s to 2.77s or something like that

 

Ah, so they do have a different setup. Would running the v6 gears on my 350 cause any problems or limit power?

Thanks for the info

 

uh, no. The steeper gears are a good thing.
Something is wrong with your engine, typically that engine will be running out of power at that RPM. It should be STRONG in the 2500-4500RPM range though.

 

Thats not good, do you have any idea what could cause that to happen, transmission maybe? Just someplace to start will help.

Thanks

 

If someone does an engine swap then sells the car, typically they screwed something up and don't know how to fix it.

What induction is on the engine? Carb or did they keep FI? Does the check engine light work or was it disconnected? Throws any codes?

Since it's a cobbled together setup with a lot of unknowns it's really hard to find a starting point.
I doubt it's the tranny, but i'm not sure exactly what the problem is. Try describing it better? At WOT or at partial throttle? any other problems, bogs? Does it ever stall? etc?

 

Well, the previous owner did the engine swap a long time before he sold it to me (months or years I believe).

It is a 5.7 Liter TPI engine from an 87 IROC-Z. Check engine light works and was previously throwing out a code 34 (MAF senor), but I replaced that and the light has not been on since. I noticed the power jump after 4400 RPMs when the car was running with wide open throttle.

The car seems to lack power from 15-35 MPH. I put the pedal on the floor and wait to feel the acceleration, but nothing happens until I get up around 4400 RPMs, and then I start feeling it accelerating a lot faster. When I am going about 40 and I floor it, the car jumps and accelerates great.

Hope the info helps with getting a starting point

 

when was the last time you did a tune up on it? (cap, rotor, plugs, wires, o2 sensor)

 

I have had it since June 2007 and I have only changed the fluids (oil, radiator, transmission). I was going to change the plugs and found that they are really hard to get to so I decided to hold off until I pull the engine out which I will be doing in a week or so. I am planning on putting in a new oil pan, spark plug wires, spark plugs, and possibly front seal while the engine is out.

I am still kind of new with this stuff, what is the cap and rotor?

Thanks again

 

ekkk......if you havent had distributor 101 i wouldnt suggest you pulling the motor out...........sounds like you could need a fuel filter to me

 

I just didn't put together that he was talking about the distributor cap and rotor, still not the quickest with terms. I am taking pictures to document where everything goes and been reading up on it. I won't be doing it alone, my dad is going to be helping me and he has done a lot of motor pulls and replacements.

I purchased a fuel filter when I got the car but never put it on because I couldn't find it at first and then forgot about it. I'll definitely be replacing it soon.

Thanks for the info