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71 Chevelle SS clone - 8.1L Swap
- Thread starter Russell
- Start date
The mid 70's stock 454's I had all had compression around 120-130 psi,I think that is "normal" for the low compression smog motors out at the time..they all ran good and didn't smoke or use oil ..
Sold the 8.1L for more than I paid for it! Win!
Anyways, I've decided to put an Edelbrock Flo Pro 4 setup on it after Christmas and see how it does. If it needs a bunch of hard parts to get the engine to run properly then I will go down that road then. I don't really want to have build a whole new engine just to know what I have though...
Anyways, I've decided to put an Edelbrock Flo Pro 4 setup on it after Christmas and see how it does. If it needs a bunch of hard parts to get the engine to run properly then I will go down that road then. I don't really want to have build a whole new engine just to know what I have though...
Scratch that. Found the reason for the weak vac signal and misfire at idle: cylinder 1 is dead. Plug was wet with gas and it only makes 60 psi. The rest of the cylinders made between 120 and 145 psi. All read differently.
Not sure where the issue is. The intake and exhaust valves all have the same lift amount and I set the lash to make sure (all 16 were good).
Guessing either a burnt / damaged valve or a piston issue.
Either way that means this 454 has to come apart to fix it properly - no amount of EFI smarts are gonna fix this one...
Heavily leaning towards the 8.1L. I found one semi locally for $800 still in the truck running / driving but higher miles at 125k miles / 200k km. It's also an 01 with the older sensors still in it.
There is another really local with 85k miles / 140k km on it out of an 06 but he wants 2k and it doesn't come with with any accessories.
I found a guy who put an 8.1L into a 70 and he said he had to modify the intake manifold to exit straight out forwards vs at an upward angle and replace the oil pan / pickup tube with a shorter aftermarket pan that is commercially available. He also said the #7 spark plug needs a 90 degree boot to clear the steering column and that the power steering pump needs a smaller pulley to clear the steering box.
I have a fabricator local to me who can do the intake mods for me. I can handle the rest on my own.
There are no replacement 454 engines of any desirable miles / build that I'd be interested in, and I am not so keen on a GM crate engine at the moment.
Not sure where the issue is. The intake and exhaust valves all have the same lift amount and I set the lash to make sure (all 16 were good).
Guessing either a burnt / damaged valve or a piston issue.
Either way that means this 454 has to come apart to fix it properly - no amount of EFI smarts are gonna fix this one...
Heavily leaning towards the 8.1L. I found one semi locally for $800 still in the truck running / driving but higher miles at 125k miles / 200k km. It's also an 01 with the older sensors still in it.
There is another really local with 85k miles / 140k km on it out of an 06 but he wants 2k and it doesn't come with with any accessories.
I found a guy who put an 8.1L into a 70 and he said he had to modify the intake manifold to exit straight out forwards vs at an upward angle and replace the oil pan / pickup tube with a shorter aftermarket pan that is commercially available. He also said the #7 spark plug needs a 90 degree boot to clear the steering column and that the power steering pump needs a smaller pulley to clear the steering box.
I have a fabricator local to me who can do the intake mods for me. I can handle the rest on my own.
There are no replacement 454 engines of any desirable miles / build that I'd be interested in, and I am not so keen on a GM crate engine at the moment.
It is very common to have cylinders read differently. The rule to go by is 10% (ish) fluctuation between them is OK. So yes you have a dead hole. Running 8.1 for $800 is not a bad deal. Although for $800 you could fix yours.
beags86
Eastbound and Down
https://www.skipwhiteperformance.co...ck-forged-pistons-scat-crank-rods-20cc_92365/
Here's an 8.1 for you.
Here's an 8.1 for you.
You wanna sell that 454?
beags86
Eastbound and Down
One man's trash, is another man's treasure. I'm expecting a 454 powered Tri-z
Sssshhhhh
keep your 454 . toss a stroker kit in it . add in efi like you were asking about and be done with it .
When stroking a 454 is there any crank to block to cam clearance issues like when stroking a 350 to 383?
not that i recall like hearing with sbc stuff .
I'm excited about an 8.1 swap. Mostly so All you big block purists get your panties in a bunch.
beags86
Eastbound and Down
Has nothing to do with being a purist. Just has to do with what makes the most sense.
Since when does owning and maintaining a 50 year old hot rod make any sense?
Blueprint sells a standard deck stroker short block BBC that comes out at 598 cid. Safe to assume there is enough room in there...
Here's a 598, assembled...
https://blueprintengines.com/produc...e-engine-big-block-gm-style-shortblock-ps5980
beags86
Eastbound and Down
I'm going to be that guy. But if your happy with only 330-350hp that the 8.1 gives you, and you want factory fuel injection/dis, why not just LS swap this? Seems like that's what you need, easy drivability. No hassle on the swap, and almost every LS out there will make 350hp with very minimal mods.
Why would you fight with the hassles of an uncommon 8.1 swap and big block fuel mileage when a LS swap is so easy these days?
Why would you fight with the hassles of an uncommon 8.1 swap and big block fuel mileage when a LS swap is so easy these days?
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One word, torque.
