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So the car I just got appears to have been given a heart transplant.
The block that's in it is from a 1974 Chevy Police car and is listed as only having 235 HP.
Short of putting it on a dyno is there a way to estimate the HP it's putting out in the Vette?
Is that listing most likely based on how they measured HP that year and in so doing skewed it down from the numbers released for 1971?
Would extra emissions from 1974 that would not be on the 1971 car make a difference as well?
I bought a car that was advertised as having a 360 HP LT5 engine, not a 235HP parts unknown engine. I know I'm at fault for not checking all this before purchase but it was a slightly long distance sale and I don't know what I'm doing yet.
Flame suit on.
Also, wouldn't it be a bit disingenuous to have an NCRS sticker on the windshield with that motor in it?
Last edited by tknospdr; Dec 3, 2020 at 12:33 PM.
Reason: Added another thought...
How did you determine it is a 1974 Police Car engine?
You can guess on power but without knowing what is in the engine then no....you cannot tell for sure.
How did you determine it is a 1974 Police Car engine?
You can guess on power but without knowing what is in the engine then no....you cannot tell for sure.
Here's one pic, where do I find the other # you're asking for?
Drivers bellhousing pad in the back...7 digit raised cast number. The date code should be there too.
Clean the rest of the front pad off and see if it matches your VIN. Hard to see.
Ok so more than likely it sounds like you aren’t going to have a numbers matching car.
On the plus side, even if your motor is stock, it’s probably not far off from a stock ls5 in performance.
I can’t find any info as to why the Ls4 in the corvette is 270 hp vs 235 in other 1974 models. The most obvious is the single exhaust and log manifolds vs dual and corvette manifolds on the vette.
Can’t find any info on whether or not the cam specs are any different in the various ls4 models vs the corvette, but the corvette cam isn’t that wild, so I can’t imagine it’s much worse, if at all different.
The ls5 is 360 gross hp net in 1971, and basically the same motor in 1972 produced 270 net. The Ls4 that follows in 73 and 74 makes the same 275/270 net horse as the 72 model.
if performance is your concern, a set of headers, cam, and intake will make it way out run a stock LS5.
Are the last three letters on that block pad "CWM"? If so, that's an LT4 454 engine from a 1973 or 1974 Corvette 4-speed. 275 hp (in 1973), and unlikely to be from a cop-car.
Last edited by Bikespace; Dec 3, 2020 at 04:32 PM.
Ok so more than likely it sounds like you aren’t going to have a numbers matching car.
On the plus side, even if your motor is stock, it’s probably not far off from a stock ls5 in performance.
I can’t find any info as to why the Ls4 in the corvette is 270 hp vs 235 in other 1974 models. The most obvious is the single exhaust and log manifolds vs dual and corvette manifolds on the vette.
Can’t find any info on whether or not the cam specs are any different in the various ls4 models vs the corvette, but the corvette cam isn’t that wild, so I can’t imagine it’s much worse, if at all different.
The ls5 is 360 gross hp net in 1971, and basically the same motor in 1972 produced 270 net. The Ls4 that follows in 73 and 74 makes the same 275/270 net horse as the 72 model.
if performance is your concern, a set of headers, cam, and intake will make it way out run a stock LS5.
If so, that's great news. I do want to put headers on it, after I fix the other more pressing issues like leaking master cylinder, rear main seals, etc.
Originally Posted by '73and'75
Am I missing something here? Block stamp from the OP picture is "T0220 CWM"
T0220 = Tonowanda built engine, February 20 CWM = 1974 LS4, manual transmission
As others have said, please post a pic of the VIN derivative stamp from the pad.
I thought it was CWM at first too. Someone else said it looked more like a U to them so I was bowing to a more experienced eye.
CWM pulls up as 1973 corvette for me but either way that's better news.
I'm posting from work right now so I can't take another picture currently. I already had that first one.
Not sure exactly where to find it even with the helpful description, but I'll keep looking.
I will answer your last question. A NCRS sticker has nothing to do with the car. Has to do with the owner who put it there. Might have been a NCRS member or an owner got hold of a sticker and put it in the window.
Alright, it's pretty clear that it's CWU, so we're back to a non-vette engine...
And the rest looks like 14J122866, but I don't know what that means.
Drivers bellhousing pad in the back...7 digit raised cast number. The date code should be there too.
Is that accessible from the engine bay, or under the car? If someone could post a pic to point me in the right direction I'm happy to wiggle around in there till I find mine.
Alright, it's pretty clear that it's CWU, so we're back to a non-vette engine...
And the rest looks like 14J122866.....
that’s the VIN derivative of the car it came out of. I’m going to go out on a limb here, but the last 6 digits are not the same as the VIN number of your car?
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