ping. cam to small??
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ping. cam to small??
Hey guys finally got my 390 together after a while it waiting aaaaand it pings. Even a little while idling in gear and cruising!! I've put premium in it to no avail and I've retarded the timing to where it barely runs and it pings worse!!!! Previous owner rebuilt bottom half and I drove it for 2 months with no problems. It didn't have hardened valve seats so I pulled the heads and had those done and put her back together. That's it!!! The pistons aren't in the hole like they used to be they are flush with the deck at tdc by my eyeball so I know it's higher comp than stock. Do I just need more cam??? That's stock too. Has 4bbl and headers and runs like a raped ape but I've only ran it once cause of the ping!
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Join Date: Aug 2003
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I'd do a compression test and see how high it is for one thing.
If to high look for higher octane grade of gas or booster.
Check your vacuum advance that it's working an not leaking.
The 360 pistons have the long skirts versus the 390 ones.
May be your 390 engine is from a car as they have less deck height
putting the piston closer to the deck.
What's the casting #'s on the heads an block by rear of alternator?
Orich
If to high look for higher octane grade of gas or booster.
Check your vacuum advance that it's working an not leaking.
The 360 pistons have the long skirts versus the 390 ones.
May be your 390 engine is from a car as they have less deck height
putting the piston closer to the deck.
What's the casting #'s on the heads an block by rear of alternator?
Orich
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The c8ae-h heads are from a car, mostly small cc chambers.
My first 390 was a from a 1967 wagon heads c7ae that compression was around 9.4
76 cc chambers.
My 2th 390 block D4TE with 68 fairlane heads cast# c8ae-h that I pulled off the car.
Truck heads should have a like a T=truck in it. The A=auto
I had to use the Highest octane gas and back my timing to TDC-2* with out it pinging
with having my cab over camper on and near sea level.
Now running 8.3 ratio with 76cc c8ae heads with a 428 crank and I can now run regular gas if needed when price goes to high.
Orich
My first 390 was a from a 1967 wagon heads c7ae that compression was around 9.4
76 cc chambers.
My 2th 390 block D4TE with 68 fairlane heads cast# c8ae-h that I pulled off the car.
Truck heads should have a like a T=truck in it. The A=auto
I had to use the Highest octane gas and back my timing to TDC-2* with out it pinging
with having my cab over camper on and near sea level.
Now running 8.3 ratio with 76cc c8ae heads with a 428 crank and I can now run regular gas if needed when price goes to high.
Orich
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You can also cup your hand over the carb as it's idling and if engine speeds up in rpm then changes are your running lean. Also having headers leans your over all gas/air mixture stock Holley's carbs for a fe run around #64-66 main jets.
I'm sure if it's been pinging your spark plugs will be white with little gray beads of molten metal specks from the top of your pistons if you run it long enough to start any damage.
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Orich
I'm sure if it's been pinging your spark plugs will be white with little gray beads of molten metal specks from the top of your pistons if you run it long enough to start any damage.
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Orich
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