Pulled the Cam/Valvetrain: Results
Thread Starter
Melting Slicks
Joined: Apr 2000
Posts: 2,145
Likes: 1
From: Ft. Walton Beach, Fl USA
Pulled the Cam/Valvetrain: Results
I pulled the cam/valvetrain this morning. But before I did that I did some rotating of the motor to see how things lined up. I have a slip-fit balacer so that made it much easier to check the positions of everything after each rotation.
With the timing marks at EXACTLY 12 and 12 the balancer showed 8 degress BTDC. With them at 6 and 12 the balancer showed 8 degrees BTDC. The cam is installed 4 degrees advanced and it has 4 degrees ground in. Is that why it shows 8 degrees with the timing marks EXACTLY aligned?
The cam itself looks pristine. I can't visually see anything wrong. It has a good lifter wear pattern in the middle of each lobe, no obvious wear to the gear, no wiped lobes. The rockers are all fine and the pushrods are straight.
However, I do believe my #6 exhaust lifter is collapsed. I've never seen a collapsed lifter before but I think this is obvious. The lifters have the "c clip" type retainers set in a groove . All the lifter plungers except #6 are up against the retainer. #6 plunger is in the down position, about a 1/4" or so from the retainer. Is that a collapsed lifter? They are SPEED PROS. I hope I can buy just one.
Now, would a collapsed lifter keep the motor from firing or would it just make it run ruff?
With the timing marks at EXACTLY 12 and 12 the balancer showed 8 degress BTDC. With them at 6 and 12 the balancer showed 8 degrees BTDC. The cam is installed 4 degrees advanced and it has 4 degrees ground in. Is that why it shows 8 degrees with the timing marks EXACTLY aligned?
The cam itself looks pristine. I can't visually see anything wrong. It has a good lifter wear pattern in the middle of each lobe, no obvious wear to the gear, no wiped lobes. The rockers are all fine and the pushrods are straight.
However, I do believe my #6 exhaust lifter is collapsed. I've never seen a collapsed lifter before but I think this is obvious. The lifters have the "c clip" type retainers set in a groove . All the lifter plungers except #6 are up against the retainer. #6 plunger is in the down position, about a 1/4" or so from the retainer. Is that a collapsed lifter? They are SPEED PROS. I hope I can buy just one.
Now, would a collapsed lifter keep the motor from firing or would it just make it run ruff?
Burning Brakes
Joined: Apr 2004
Posts: 847
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From: Des Allemands LA
Sounds like the lifter is collapsed, but if you are putting a new cam in you must use new lifters as well. Used lifters (flat tappet) on a new cam will wipe the lobe quicker than a cat can lick it's butt. How did the cam gear look?
Thread Starter
Melting Slicks
Joined: Apr 2000
Posts: 2,145
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From: Ft. Walton Beach, Fl USA
Originally Posted by ltlevil
Sounds like the lifter is collapsed, but if you are putting a new cam in you must use new lifters as well. Used lifters (flat tappet) on a new cam will wipe the lobe quicker than a cat can lick it's butt. How did the cam gear look?
Race Director
Joined: Sep 2002
Posts: 10,362
Likes: 5
From: San Diego - Deep Within The State of CONFUSION!
Originally Posted by nastee383
Its a roller cam/lifters, don't need new lifters for a new cam. Cam gear looked fine.
Thread Starter
Melting Slicks
Joined: Apr 2000
Posts: 2,145
Likes: 1
From: Ft. Walton Beach, Fl USA
Originally Posted by GrandSportC3
Hmmm.... seems that so far, nothing would indicate a real reason why the engine wouldn't fire... 
Very strange..
Very strange..
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Thread Starter
Melting Slicks
Joined: Apr 2000
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From: Ft. Walton Beach, Fl USA
Originally Posted by MotorHead
Distributor shaft ( inside housing ) not busted ?
Melting Slicks
Joined: Jan 2004
Posts: 2,672
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From: New Cumberland PA
Originally Posted by ltlevil
Used lifters (flat tappet) on a new cam will wipe the lobe quicker than a cat can lick it's butt.
My money is on the cat!
Thread Starter
Melting Slicks
Joined: Apr 2000
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From: Ft. Walton Beach, Fl USA
Originally Posted by bobs77vet
why are your timing marks on cam and crank at 12 and 12 instead of 6 and 12?
Melting Slicks
Joined: Feb 2003
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From: Auburndale Florida
2025 C2 of the Year ('64-'66) Finalist - Unmodified
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its a long thread....not sure if it was posted..
Have you Ck'd the voltage TO the coil???
Just my 2 cents worth....I am curious now...
best of luck
Mark
Have you Ck'd the voltage TO the coil???
Just my 2 cents worth....I am curious now...
best of luck
Mark
Last edited by mbeeman350; Oct 10, 2005 at 08:43 PM.
Race Director
Joined: Sep 2004
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From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by nastee383
That's where they are when the motor is at TDC on the COMPRESSION stroke. When a timing set is initially installed at 6 & 12 the motor is at TDC on the EXHAUST stroke.
Thread Starter
Melting Slicks
Joined: Apr 2000
Posts: 2,145
Likes: 1
From: Ft. Walton Beach, Fl USA
Originally Posted by bobs77vet
i guess that explains why you have 8* BTDC on both 12 @12 and 6 @ 12.
Thread Starter
Melting Slicks
Joined: Apr 2000
Posts: 2,145
Likes: 1
From: Ft. Walton Beach, Fl USA
Originally Posted by mbeeman350
its a long thread....not sure if it was posted..
Hsvr you Ck'd the voltage TO the coil???
Just my 2 cents worth....I am curious now...
best of luck
Mark
Hsvr you Ck'd the voltage TO the coil???
Just my 2 cents worth....I am curious now...
best of luck
Mark