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71 Chevelle SS clone - 8.1L Swap
- Thread starter Russell
- Start date
Read his last post lol. 8.1L is out. 454 is moving on up to the east side.
beags86
Eastbound and Down
This 8.1 yeah, but I didn't know if he was thinking about another one
OK, I'll buy it for $01,500 ..........Deal, D - U - N dun.
I see the 8.1 is likely out anyway, but here is my take...
If you are the type to leave the engine stock and want the modern EFI without touching the engine itself, then go with the 8.1 even it if doesn't really match the car. Keep in mind, brackets, belts, header location, carb height, valve cover height, etc will all be different for a tall deck.
If you are the type that likes to change cams, intake, (especially heads), etc, then the Mark IV block has a LOT more economical options, and a lot more potential.
After noticing you already talked about taking the pistons out, I would say the old Mark IV is more for you because parts will be a lot less expensive with more options. BTW, Zim is right, it isn't possible to take them out the bottom on a BBC, the bores are staggered over the main cap girdle area and it physically won't come out, even if you could somehow get the rings back in the bore.
Sweet car by the way!
Found the reason for the engine seizure. Cylinder 7 and 8 rod bearings are toast. Looks like they got nice and warm! I'm going to throw this engine in the corner for now. Maybe build a Rylar 540 stroke beast someday for the fun of it when I am rich and famous lol
I didn't have time to dig into the 454 tonight, but I did finally get all my regular maintenance done on the whole fleet. Tomorrow I plan to drop the fuel tank out of the caddy and get the sending unit fixed up. I also want to try to get the drag link lengthened up a bit to center the steering wheel. If there is still time left over, then I will put the Chevelle back into the shop and start messing with the engine a bit more to ID it.
No further news on the sniper setup. Dude isn't overly good at communication and can't seem to answer basic questions about it.
I didn't have time to dig into the 454 tonight, but I did finally get all my regular maintenance done on the whole fleet. Tomorrow I plan to drop the fuel tank out of the caddy and get the sending unit fixed up. I also want to try to get the drag link lengthened up a bit to center the steering wheel. If there is still time left over, then I will put the Chevelle back into the shop and start messing with the engine a bit more to ID it.
No further news on the sniper setup. Dude isn't overly good at communication and can't seem to answer basic questions about it.
Pull the number on the 454 yet ?
Nope. This past week was all about getting vehicle maintenance done. My wife and kid were out of town for the week, so I busted butt getting winter tires on, oil and filters changed and fixing up a Tahoe I bought recently to use as a winter beater (09 Tahoe Hybrid - Cause it'll be funny to turn it into a solid axle wheeler someday haha). I did put Myrtle in the shop and got the fuel sending unit fixed up and the gauge calibration sorted out. No more sticky float causing me to run out of diesel, hopefully!
With that done, Myrtle is back outside in the snow storm and the Chevelle is inside. When I have some time, I plan to pull the valve covers off to check the valve lash / lift and ID the heads. Then I can do a leak down test and see if it has a blown gasket somewhere causing issues. I can also do a compression test and see if all the cylinders are even and making a decent amount of pressure. I can also figure out what it has for an intake on it. I may pull the carb off and tear it down to see if I can't find anything obviously wrong there as well. The engine only draws about 4"hg of vacuum and has a pretty good misfire at idle. The choke seems to be working okay, but it won't stay idling without feathering the throttle unless the idle is set way high and it gets into the jets vs the idle circuits. Once it gets moving and is above 3000 rpm the engine does pull a bit better, but not enough to spin the tires from a rolling start.
I am super torn on what to do with this thing. I found a GM performance serp belt drive in new condition with a CS-130 alt and power steering pump, AC delete and all belts / pulleys / tensioner and hardware for $500 locally. The Holley EFI setup is going to be just over $2500 all in which puts me at close to $3000. I found a low miles 8.1L locally that I can hear running for $1500 as well. An in-tank fuel pump with regulator and hydramat is around $500, plus an easy $1000 for the install puts me as a similar price for fixing the 454 up at about $3000. If the 454 needs hard parts beyond the EFI setup, it'll cost more than the 8.1L.
I should say, the cost is not the end-all be all for me. I've got some money put aside for fixing the car up for next summer, but my budget is not unlimited. I just want to make sure I am happy with whatever I wind up with and keep costs down as best as I can.
I know I would personally be happy with either engine as long as it starts and runs reliably and has top notch driveability.
With that done, Myrtle is back outside in the snow storm and the Chevelle is inside. When I have some time, I plan to pull the valve covers off to check the valve lash / lift and ID the heads. Then I can do a leak down test and see if it has a blown gasket somewhere causing issues. I can also do a compression test and see if all the cylinders are even and making a decent amount of pressure. I can also figure out what it has for an intake on it. I may pull the carb off and tear it down to see if I can't find anything obviously wrong there as well. The engine only draws about 4"hg of vacuum and has a pretty good misfire at idle. The choke seems to be working okay, but it won't stay idling without feathering the throttle unless the idle is set way high and it gets into the jets vs the idle circuits. Once it gets moving and is above 3000 rpm the engine does pull a bit better, but not enough to spin the tires from a rolling start.
I am super torn on what to do with this thing. I found a GM performance serp belt drive in new condition with a CS-130 alt and power steering pump, AC delete and all belts / pulleys / tensioner and hardware for $500 locally. The Holley EFI setup is going to be just over $2500 all in which puts me at close to $3000. I found a low miles 8.1L locally that I can hear running for $1500 as well. An in-tank fuel pump with regulator and hydramat is around $500, plus an easy $1000 for the install puts me as a similar price for fixing the 454 up at about $3000. If the 454 needs hard parts beyond the EFI setup, it'll cost more than the 8.1L.
I should say, the cost is not the end-all be all for me. I've got some money put aside for fixing the car up for next summer, but my budget is not unlimited. I just want to make sure I am happy with whatever I wind up with and keep costs down as best as I can.
I know I would personally be happy with either engine as long as it starts and runs reliably and has top notch driveability.
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Which one will accept forced induction better ? should be the question ........
After a few tests and diagnostics on the 454 you will have the answer to the debate.
Good luck! I’m kinda hoping the current BB will make the cut!?
Well, I woke up with a sore throat today and took the day off work. Definitely coming down with a cold 
Still took some time to go out to the shop and try to ID this engine. It's a 361959 casting which my research tells me is a 1970-1976 454. I wasn't able to make out the date code on the engine or find the P for passenger car due to an oil leak from the valve cover. The heads are 6272292 which are oval port heads. They are date coded as being cast in 72. The suffix code on the front is super hard to make out but looks like C9(P or F?) 1(4?)0992. That suffix code didn't really pull much up when I searched for it. I think I can presume this is a car 454, but I'm not sure what vehicle it is out of or what kind of power it made originally.
Still took some time to go out to the shop and try to ID this engine. It's a 361959 casting which my research tells me is a 1970-1976 454. I wasn't able to make out the date code on the engine or find the P for passenger car due to an oil leak from the valve cover. The heads are 6272292 which are oval port heads. They are date coded as being cast in 72. The suffix code on the front is super hard to make out but looks like C9(P or F?) 1(4?)0992. That suffix code didn't really pull much up when I searched for it. I think I can presume this is a car 454, but I'm not sure what vehicle it is out of or what kind of power it made originally.
Looks like it is a generic 454. Low compression from the factory, would take some boost ........ 
Nice intake though
Nice intake though
That ID number on the block in front of the passenger side head might be the "partial VIN" number they stamped before the actual engine ID code..a 1970-76 car 454 would have a three digit code with a "C" at the beginning,and "T" for a truck engine..
It may be a marine block,those have some different stampings than a car or truck block...
I've seen a few BBC with the engine code located above the timing cover too,but I think those were tall deck ones like a 366 or 427 C-60 or bus engine..
This site has a lot of engine codes listed for marine,car & truck 454's.
Some with "CPJ" are 1971 Chevelle 454 LS6's !..hope its one of those!
Chevy Camaro Big Block Engine Suffix Codes
It may be a marine block,those have some different stampings than a car or truck block...
I've seen a few BBC with the engine code located above the timing cover too,but I think those were tall deck ones like a 366 or 427 C-60 or bus engine..
This site has a lot of engine codes listed for marine,car & truck 454's.
Some with "CPJ" are 1971 Chevelle 454 LS6's !..hope its one of those!
Chevy Camaro Big Block Engine Suffix Codes
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The LS6 has aluminum heads. Not likely going to be one of those engines haha! I'll dig into it more later and get the back end cleaned up to find more info.
Right now the plan is to go with a Holley Sniper EFI setup on this engine and see how it behaves. I've decided not to go with an 8.1L at all.
Right now the plan is to go with a Holley Sniper EFI setup on this engine and see how it behaves. I've decided not to go with an 8.1L at all.
LS6 is iron, LS7 is aluminum. I'd go with the 454. It will drop in zero issues, can be built to make more power than the 496. Last one I built was lil over $2500 to build, including assembly. Got lucky on the heads, they were already done.
Yeah I vote to fix/build the current 454. Heck you could even stroke it to a 496 and just call it an 8.1L swap. A guy here a few hrs from me was selling a running 454 long block out of an '81 C30 that I really wanted to buy so I could build a motor for my C30 without pulling the current one. He was only asking like $350. Oh well other things come first. Either way you end up going the car is gonna be sweet!
The numbers sounds like what an original early 70's SS Chevelle big block would have come with to me. does the engine look like i was ever rebuilt before? I had a 1970 SS 396 (402) Chevelle I bought when I was a senior in High School for $800. The engine had been rebuilt before I bought it, but after a couple of years the engine needed rebuilding again, and since it had already been rebuilt once it was clapped out. I went to a junk yard, and bought a 396 out of a 1968 station wagon that had never been rebuilt before, and rebuilt that one into a 402 Big Block. Back in those days big blocks where easy to find in junk yards.
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Just for curiosity’s sake, what made you push in favor of the 454 over the 8.1?
The biggest reason for going with the 454 vs an 8.1L is clearance concerns. When I was looking at other installations of 8.1L engines into these cars, folks were having issues with hood and oil pan clearances. The 454 may run good with the EFI swapped onto it. $500 for a serpentine belt drive is a solid deal as well. If it needs a camshaft swap later on down the road, I suppose that won't be the end of the world.
I do not think this engine has been rebuilt. Re-painted, new cam, headers and intake - Yes. I would expect the numbers on the head surface to have been milled off if the engine was overhauled at some point. I can't imagine someone having the block bored out and having taken the heads off without re-surfacing the mating surfaces which would definitely have wiped out the suffix codes.
I do not think this engine has been rebuilt. Re-painted, new cam, headers and intake - Yes. I would expect the numbers on the head surface to have been milled off if the engine was overhauled at some point. I can't imagine someone having the block bored out and having taken the heads off without re-surfacing the mating surfaces which would definitely have wiped out the suffix codes.
You could just take the 454 out, and do a re-seal, ball hone, re-paint, and re-ring job on it. Freshen up the heads, and change the cam to something that goes with what ever gears and tires you have.
Throw that edelbrock in the garb and bolt on a qjet or Holley and run it
