302 flywheel balance??
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Hotshot
Joined: Jul 2005
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302 flywheel balance??
the kids bought an old 302 mid 1980s that they were told "ran good". they put in a mild cam and new lifters, bought an aftermarket flywheel, bolted it to a 5 speed manual in a 1996 for 1/2 ton 150.
truck starts, and will idle, but not good, has a bad vibration. vibration is noticable from 1000- 3000 rmp, but dont appear to get worse as high speed, maybe even slightly better. other problem is the truck is gut less. will hardly pulll away from a stop sign.
they swear they got the cam in correct, but im not sure. ready to pull the valve cover tonight and see vale open and close positions relative to crank TDC. i am also wondering, is the motor balanced internal or external on the fly wheel? main problme is i dont know if the motor really "ran well" when they purchased it.
I have checked the igniition timing, checked the carburetor and gas flow, no ready for compression test, valve timing, and question if the vibration could be valve timing or internal, or could it be flywheel??
truck starts, and will idle, but not good, has a bad vibration. vibration is noticable from 1000- 3000 rmp, but dont appear to get worse as high speed, maybe even slightly better. other problem is the truck is gut less. will hardly pulll away from a stop sign.
they swear they got the cam in correct, but im not sure. ready to pull the valve cover tonight and see vale open and close positions relative to crank TDC. i am also wondering, is the motor balanced internal or external on the fly wheel? main problme is i dont know if the motor really "ran well" when they purchased it.
I have checked the igniition timing, checked the carburetor and gas flow, no ready for compression test, valve timing, and question if the vibration could be valve timing or internal, or could it be flywheel??
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
they probably installed the wrong cam. what are the specs. if they installed a mustang cam which creates power hi in the rpm range that will kill any low end you might have had.
the proper flywheel balance is 50oz but the flywheel should have been purchased for that year motor.
the proper flywheel balance is 50oz but the flywheel should have been purchased for that year motor.
Elder User
Joined: Aug 2002
Posts: 662
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From: CA
I think the changeover year for 302 flywheel weights was 1984. Someone here will correct me if I'm wrong.
What that means is that 1984 and on 302's use a 50 oz. imbalance flywheel, and 1983 and back use a 28 oz. imbalance. Put the wrong flywheel in there and you'll eventually distroy the engine (probably break the crank).
I agree that the cam in there now probably has way too much duration, that, or it's degreed way off.
What that means is that 1984 and on 302's use a 50 oz. imbalance flywheel, and 1983 and back use a 28 oz. imbalance. Put the wrong flywheel in there and you'll eventually distroy the engine (probably break the crank).
I agree that the cam in there now probably has way too much duration, that, or it's degreed way off.
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Hotshot
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i checked to see that the plug wires were correct location. then pull the plugs and the color looks good. i removed the valve cover and put dial indicator on the intake valve. turned crank slowly watching the crank shaft. vavle opens 30 degrees before TDC, full lift at 106 after TDC and full close at 260 AFTD. I think those would be "average" numbers for a stock to mild cam from COMP CAM if i red their web page right. I am starting to believe the flywheel is wrong as the vibration is terible, they did crack the header where to joins the exhaust pipe to muffler. it vibrates BAD. the problme i have is it has absolutely no power when you let the clutch out. will hardly pull itself off the line. idles bad, but will set there and run , with sugnificant vibration. guess i will help him pull the motor for vibration, but i dont see how that hurts the power???? any more ideas welcome.
Elder User
Joined: Aug 2002
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From: CA
A silly question: Are you sure this is a 302? A 351 looks the same except for a somewhat higher deck height, however the firing order is much different. Otherwise it's almost certain that you have the wrong flywheel.
Hotshot
Joined: May 2004
Posts: 12,170
Likes: 5
From: The hills of No. Calif.
Originally Posted by Polkat
I think the changeover year for 302 flywheel weights was 1984. Someone here will correct me if I'm wrong.
What that means is that 1984 and on 302's use a 50 oz. imbalance flywheel, and 1983 and back use a 28 oz. imbalance. Put the wrong flywheel in there and you'll eventually distroy the engine (probably break the crank).
I agree that the cam in there now probably has way too much duration, that, or it's degreed way off.
What that means is that 1984 and on 302's use a 50 oz. imbalance flywheel, and 1983 and back use a 28 oz. imbalance. Put the wrong flywheel in there and you'll eventually distroy the engine (probably break the crank).
I agree that the cam in there now probably has way too much duration, that, or it's degreed way off.
As for casting numbers, they're on the block under (above if the engine's right-side up in the vehicle!) the starter, you usually have to pull the starter to see them.
They won't tell you if it's a 351W or a 302 though, you need to check the deck height on the block for that. Basically, if the top water pump/timing cover bolts on each cylinder bank are right up against the deck, it's a 302. If there's about an inch of gap there, it's a 351W.
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