383 Rebuild
Thread Starter
Staging Lane
Joined: Aug 2009
Posts: 75
Likes: 0
From: everett, wa
383 Rebuild So whilst tearing my car down for my 24x conversion i decided to dig into the motor to get to the bottom of my intermittent low/no oil pressure issue. This is what i found:
So It's going in for a rebuild but that's where i need help. I'm guessing bearings are toast, Cam needs replacing and crank needs resurfacing. There was only one slight nick i could catch in the crank with my fingernail the rest just is no longer shiny or polished.
The plan then is to have the pistons replaced with something that will bring the compression back up to where it should be(currently sits at 9:1 shooting for 11.5:1?) new rings, bearings, cam, rotating assembly rebalanced, heads cleaned and flow tested to spec cam etc.
Any recommendations on a good piston that won't break the bank and an idea on costs for the machine shop?
Sorry for all the questions this is my first rebuild and i don't wanna get stuck halfway thru with a sweet looking boat anchor
So It's going in for a rebuild but that's where i need help. I'm guessing bearings are toast, Cam needs replacing and crank needs resurfacing. There was only one slight nick i could catch in the crank with my fingernail the rest just is no longer shiny or polished.
The plan then is to have the pistons replaced with something that will bring the compression back up to where it should be(currently sits at 9:1 shooting for 11.5:1?) new rings, bearings, cam, rotating assembly rebalanced, heads cleaned and flow tested to spec cam etc.
Any recommendations on a good piston that won't break the bank and an idea on costs for the machine shop?
Sorry for all the questions this is my first rebuild and i don't wanna get stuck halfway thru with a sweet looking boat anchor
Honestly If I were buying pistons I wouldn't buy anything less than Mahle PowerPak. Just get the flatop to fit your bore/stroke/rod combo.
If this is your first rebuild does that mean you bought the car with the 383?
The cam damage is likely from massive valve float, the lifter gets throuwn and comes down hard and can chip the cam, once chipped past the hardened surface the lifter start cutting in.
Meaning the springs were either left in way too long or the cam, the springs were wrong in the first place or the cam was just inappropriately spec'd in the first place. There was a very popular vendor who lost popularity because he was selling a lot of valvetrains that self destructed in 2-3000miles.
Any details on what the crank is?
If this is your first rebuild does that mean you bought the car with the 383?
The cam damage is likely from massive valve float, the lifter gets throuwn and comes down hard and can chip the cam, once chipped past the hardened surface the lifter start cutting in.
Meaning the springs were either left in way too long or the cam, the springs were wrong in the first place or the cam was just inappropriately spec'd in the first place. There was a very popular vendor who lost popularity because he was selling a lot of valvetrains that self destructed in 2-3000miles.
Any details on what the crank is?
Thread Starter
Staging Lane
Joined: Aug 2009
Posts: 75
Likes: 0
From: everett, wa
Honestly If I were buying pistons I wouldn't buy anything less than Mahle PowerPak. Just get the flatop to fit your bore/stroke/rod combo.
If this is your first rebuild does that mean you bought the car with the 383?
The cam damage is likely from massive valve float, the lifter gets throuwn and comes down hard and can chip the cam, once chipped past the hardened surface the lifter start cutting in.
Meaning the springs were either left in way too long or the cam, the springs were wrong in the first place or the cam was just inappropriately spec'd in the first place. There was a very popular vendor who lost popularity because he was selling a lot of valvetrains that self destructed in 2-3000miles.
Any details on what the crank is?
If this is your first rebuild does that mean you bought the car with the 383?
The cam damage is likely from massive valve float, the lifter gets throuwn and comes down hard and can chip the cam, once chipped past the hardened surface the lifter start cutting in.
Meaning the springs were either left in way too long or the cam, the springs were wrong in the first place or the cam was just inappropriately spec'd in the first place. There was a very popular vendor who lost popularity because he was selling a lot of valvetrains that self destructed in 2-3000miles.
Any details on what the crank is?
I had been looking at the Mahle power pack as well as some either nice options like JE or SRP. Also will probably just bite the bullet and get an entire valvetrain set up from AI and be done with it. I just wanna have my ducks in a row before i go to the machine shop so they don't pull the wool over my eyes.
As far as oiling symptoms it had abnormally high pressure(like needle pegged full) all the time unless i did a WOT pull or ran on the freeway for an extended period. Then it would dip down to 10 or les PSI for a second or two then right back up. Eventually i started running a half a quart or so over filled which helped a ton but still happened every once in a while.
Staging Lane
Joined: Jul 2012
Posts: 81
Likes: 1
From: Detroit Metro Area
Weird! (not meaning to derail) I was just curious because I have an odd oiling issue on my freshly build 383 that only recently started to occur after 4,500 miles... I haven't gone to the extent of pulling the engine apart as I haven't been driving it much, if at all. Basically if I go over 4,500 RPMs at WOT when the oil is hot it drops from 60psi down to 50 psi and holds, pretty weird. It's going to be taken apart soon and I just hope it's not torn up like yours, I would be sad face.
Sounds like you got a decent deal on the car though!
Sounds like you got a decent deal on the car though!
That wasn't a stock cam but that doesn't really matter other than apparently someone put a very nice crank in an otherwise POS engine.
How are the heads? If someone put a cam so small the tuner said it could have been stock then the heads probably weren't done right either. Probably a "no replacement for displacement" mentality without the understanding displacement needs to be FED.
How are the heads? If someone put a cam so small the tuner said it could have been stock then the heads probably weren't done right either. Probably a "no replacement for displacement" mentality without the understanding displacement needs to be FED.
Thread Starter
Staging Lane
Joined: Aug 2009
Posts: 75
Likes: 0
From: everett, wa
That wasn't a stock cam but that doesn't really matter other than apparently someone put a very nice crank in an otherwise POS engine.
How are the heads? If someone put a cam so small the tuner said it could have been stock then the heads probably weren't done right either. Probably a "no replacement for displacement" mentality without the understanding displacement needs to be FED.
How are the heads? If someone put a cam so small the tuner said it could have been stock then the heads probably weren't done right either. Probably a "no replacement for displacement" mentality without the understanding displacement needs to be FED.
Any idea on basic machine shop costs for labor? More just looking for a ballpark of should i be saving up 1000$ for it or wayyyyy more?
Thanks for all the help capricemgr
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I haven't built an engine yet so I am taking a bit of a shot in the dark and it will vary by location but the crank cleanup is probably going to be $150, $250 for the rebalance, $60 for cam bearing install, also going to need at least a hone if not a full bore to the next size, get it checked out before ordering pistons. Rods will need to be checked for roundness on the big end.
I would set aside a full $1000 for the machineshop I don't think it will be that much unless they say the mains need work and the rods need resizing if both then I could see going over $1000 even.
The heads probably are not 64cc that would be rather big for an aluminum LT1 head, Generally they are 56-58ish stock depending who you ask and I know one vendor recently added an CNC option to make them as large as 61cc.
If they are 2.02/1.60 valves I would take that as a bad sign, to make those sizes work right the seats need to be replaced at substantial extra cost without any real return, 2.00/1.56 valves have taken this casting into the 9s NA. Maybe they were just larger valves and 2.02/1.6 was just repeated as an assumption?
I would set aside a full $1000 for the machineshop I don't think it will be that much unless they say the mains need work and the rods need resizing if both then I could see going over $1000 even.
The heads probably are not 64cc that would be rather big for an aluminum LT1 head, Generally they are 56-58ish stock depending who you ask and I know one vendor recently added an CNC option to make them as large as 61cc.
If they are 2.02/1.60 valves I would take that as a bad sign, to make those sizes work right the seats need to be replaced at substantial extra cost without any real return, 2.00/1.56 valves have taken this casting into the 9s NA. Maybe they were just larger valves and 2.02/1.6 was just repeated as an assumption?
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Staging Lane
Joined: Aug 2009
Posts: 75
Likes: 0
From: everett, wa
I haven't built an engine yet so I am taking a bit of a shot in the dark and it will vary by location but the crank cleanup is probably going to be $150, $250 for the rebalance, $60 for cam bearing install, also going to need at least a hone if not a full bore to the next size, get it checked out before ordering pistons. Rods will need to be checked for roundness on the big end.
I would set aside a full $1000 for the machineshop I don't think it will be that much unless they say the mains need work and the rods need resizing if both then I could see going over $1000 even.
The heads probably are not 64cc that would be rather big for an aluminum LT1 head, Generally they are 56-58ish stock depending who you ask and I know one vendor recently added an CNC option to make them as large as 61cc.
If they are 2.02/1.60 valves I would take that as a bad sign, to make those sizes work right the seats need to be replaced at substantial extra cost without any real return, 2.00/1.56 valves have taken this casting into the 9s NA. Maybe they were just larger valves and 2.02/1.6 was just repeated as an assumption?
I would set aside a full $1000 for the machineshop I don't think it will be that much unless they say the mains need work and the rods need resizing if both then I could see going over $1000 even.
The heads probably are not 64cc that would be rather big for an aluminum LT1 head, Generally they are 56-58ish stock depending who you ask and I know one vendor recently added an CNC option to make them as large as 61cc.
If they are 2.02/1.60 valves I would take that as a bad sign, to make those sizes work right the seats need to be replaced at substantial extra cost without any real return, 2.00/1.56 valves have taken this casting into the 9s NA. Maybe they were just larger valves and 2.02/1.6 was just repeated as an assumption?
That's good info on when to order pistons/extra parts as well. i didn't know if i showed up with all the goodies and the shortblock or if i ordered after they check over the motor.
