Caprice police car engine compatability in manual GMT400

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5speed91

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Its been a few years since I've been here. I sold my truck a while back to buy a new 2014 Chevy Caprice with the 6.0L and found I could not live without a truck. Luckily the guy I sold it to didn't need it anymore so I was able to buy my same truck back and thanks to my wife, still keep the LS powered 2014 Caprice! Its a 1991 C1500 with the LO3 engine and 5LM60 manual trans.

Question is, I have acquired a 1993 Caprice police version LO5 engine with 134,000 miles and want to swap it into my truck to replace the weak LO3 engine. I know the intake manifold is a little different, the exhaust manifolds need to be swapped over along with the accessory brackets. So are there any other differences these engines have being destined to go in an automatic vs manual equipped vehicle such as different crankshaft hubs or the like. IE will my clutch, input shaft, pilot bearing etc work on an LO5 that originally was mated to a 4L60? Also, I have seen that for unknown reasons, the LO5 in a police car seems to be unique in that they have a different part number and flow rating for the fuel injectors compared to other LO5 applications. I'm not sure why this is but if I have to run the Caprice Computer will there be issues with my truck not having an automatic trans?

FYI - unlike the trucks, 1993 Caprice did not use a computer controlled trans. Only has electric speedo sensor and lock up torque converter. 1994 with the LT1 was the first year of the 4L60E in the CAPRICE.

The 1993 Caprice police LO5 was one of the more powerful TBI engines with a rating of 205 or 210 HP depending on the source but everything I have seen says this is not a result of the higher flow injectors but improvements made to the vehicle's crossoverpipe and cataletic converter.

Last question, as another option, could I reuse my OEM LO3 computer and replace the PROM with that from a LO5 or do I need the entire LO5 ECM?

Thanks.
 

Badass69

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Way back like 20 years ago I had the 9C1 Caprice injectors in the tbi on my L05 in my truck. It ran well just with the base timing bumped and playing with an adjustable regulator but it would have been better tuned. The bottom end of that Caprice is just the L98 from the TPI Camaro... same cam and all. Then it just had 193 heads stuck on it. Bolt your flywheel on and as the 305 and 350 flex plates and flywheels interchange.

You would just need a prom from an L05 for the swap but to optimize it all you could get one custom burned.... there is probably a couple people left still doing it lol.

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5speed91

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Way back like 20 years ago I had the 9C1 Caprice injectors in the tbi on my L05 in my truck. It ran well just with the base timing bumped and playing with an adjustable regulator but it would have been better tuned. The bottom end of that Caprice is just the L98 from the TPI Camaro... same cam and all. Then it just had 193 heads stuck on it. Bolt your flywheel on and as the 305 and 350 flex plates and flywheels interchange.

You would just need a prom from an L05 for the swap but to optimize it all you could get one custom burned.... there is probably a couple people left still doing it lol.

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Thanks so much! I have the ECM from the 1993 Caprice. Question is, if I use it (assuming they are the same connectors between 1991-1993, will it throw some kind of trouble code due there being no input from the locking torque converter clutch that the original vehicle would have had?
 

5speed91

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That caprice motor should have a roller cam too

I keep seeing this on multiple forums. And I thought I knew so much about GM. Are you implying that all TBI truck engines do not have roller lifters? I feel embarrassed to raise the question over 20 years since the last TBI engine was sold in a vehicle but this intrigues me. I did replace the intake manifold gaskets last year on my LO3 equipped truck which did in fact have flat tappet lifters. I incorrectly assumed this was wrong and chalked it up to the truck having a reman engine installed by the previous owner. (I know, who is the world would replace a failed 305 with another 305? He was not in the know. Anyway now that I see this over and over in various forums, I cant believe I did not know this. All of my Caprices I had back in the day that were from the late 1980s (non police cars and police cars, 305s and 350s, 4bbl or TBI all had roller cams. In fact, I thought all 1987 up Gen I Chevy Small blocks were roller cam that had the center bolt valve covers. Learn something new all the time.
 

Jorge6.5

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From what I gathered, all the gm cars with small blocks from 87 up had roller cams but the trucks only got the flat tappets. The truck motors should still have the holes to accept the hardware related to the roller cam setup.
 

5speed91

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From what I gathered, all the gm cars with small blocks from 87 up had roller cams but the trucks only got the flat tappets. The truck motors should still have the holes to accept the hardware related to the roller cam setup.
So strange and I wonder why they did this? What advantage to flat tappet? Also are people having failure issues with these flat tappet engines related to the 2003 ear zinc depletion from most popular oil brands? These cams may not be high performance enough but a lot of people myself included have had cam failure issues in 1960 and 1970s flat tappet engines after the zinc levels were quietly dropped from the oils courtesy of the EPA without much in the way of informing consumers.
 

Badass69

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The Caprice is roller. .. L98 cams were roller lol. All passenger car engines were roller but the only Tbi engine in trucks through 1995 that came roller equipped for all intents were the 4.3. There may be some obscure odd ball van or something retarded that is roller earlier but who cares lol.

About half of the tbi truck castings for 350's were 1 piece blocks not even provisioned for a roller cam... my old 92 I mentioned earlier was one of those. So no... not all 1 piece blocks even can accept factory roller hardware.

As far as plopping the caprice prom in the truck ecm maybe... if the two computers themselves are the same part number.

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5speed91

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Thanks everyone for the good info. I guess I will just try the Caprice ECM since it is matched to the engine already and if that does not work then the Caprice PROM into the truck ECM and see what happens. I'm thinking even though the Caprice has a non computer controlled trans that the TCC is still monitored by the ECM and may cause a code, but we will see.
 
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