Flat tappet cam break in
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Melting Slicks
Joined: Apr 2002
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From: Norfolk VA
Flat tappet cam break in
Was flat tappet cam break in necessary when the corvette engines of c3 era were being produced and the aftermarket in the past? About when was this procedure necessary in the aftermarket?
Last edited by Oldguard 7; Oct 26, 2016 at 12:52 PM. Reason: Typos
Race Director
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I'm not familiar with what the factory did but as far back as the 60's you had to break in a new cam shaft when replacing it. The lobes and lifters were coated with moly break in grease and the engine was run at various RPMs for about 20 minutes.
Le Mans Master
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From: Sarver Pa
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I used to work in a GM garage in the early 70's. Changed a lot of cams. GM had their own assembly lube and instructions. Installed some "3/4 race " cams too, Crane was insisting on their moly lube and proper break in.
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It was always a concern but remember.... GM used very mild spring pressures and gentle loves on even the performance cams. And they still went flat sometimes
Cams are a lot more aggressive today with stouter valvesprings by far. We also have the issue of old blocks with worn lifter botes etc. Then throw in some imported lifters and cam cores the deck is stacked against you. When the OEMs were buying millions of cams and lifters the economy of scale tricked down to the hot rod world. With that production gone there's little incentive to make better parts.
If using a solid solid cam get the lifters with the EDM hole in the face for improved oiling. Double-triple ck that the lifters rotate in their bore as the cam is turned If they don't it will flatten quickly.
I think some of your best cores are coming from the smaller cam companies. They aren't trying to compete with the Summit and Jegs truckload orders and bottom feeder prices. They use the best components because their reputation is on the line.
The last few flat tappets I've used were pretty nasty ones and all went well. They were from Crane. I've also used some from Isky and Crower over the last few years and never had an issue with any of them.
Jim.
Cams are a lot more aggressive today with stouter valvesprings by far. We also have the issue of old blocks with worn lifter botes etc. Then throw in some imported lifters and cam cores the deck is stacked against you. When the OEMs were buying millions of cams and lifters the economy of scale tricked down to the hot rod world. With that production gone there's little incentive to make better parts.
If using a solid solid cam get the lifters with the EDM hole in the face for improved oiling. Double-triple ck that the lifters rotate in their bore as the cam is turned If they don't it will flatten quickly.
I think some of your best cores are coming from the smaller cam companies. They aren't trying to compete with the Summit and Jegs truckload orders and bottom feeder prices. They use the best components because their reputation is on the line.
The last few flat tappets I've used were pretty nasty ones and all went well. They were from Crane. I've also used some from Isky and Crower over the last few years and never had an issue with any of them.
Jim.
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
It was always a concern but remember.... GM used very mild spring pressures and gentle loves on even the performance cams. And they still went flat sometimes
Cams are a lot more aggressive today with stouter valvesprings by far. We also have the issue of old blocks with worn lifter botes etc. Then throw in some imported lifters and cam cores the deck is stacked against you. When the OEMs were buying millions of cams and lifters the economy of scale tricked down to the hot rod world. With that production gone there's little incentive to make better parts.
I think some of your best cores are coming from the smaller cam companies. They aren't trying to compete with the Summit and Jegs truckload orders and bottom feeder prices. They use the best components because their reputation is on the line.
The last few flat tappets I've used were pretty nasty ones and all went well. They were from Crane. I've also used some from Isky and Crower over the last few years and never had an issue with any of them.
Jim.
Cams are a lot more aggressive today with stouter valvesprings by far. We also have the issue of old blocks with worn lifter botes etc. Then throw in some imported lifters and cam cores the deck is stacked against you. When the OEMs were buying millions of cams and lifters the economy of scale tricked down to the hot rod world. With that production gone there's little incentive to make better parts.
I think some of your best cores are coming from the smaller cam companies. They aren't trying to compete with the Summit and Jegs truckload orders and bottom feeder prices. They use the best components because their reputation is on the line.
The last few flat tappets I've used were pretty nasty ones and all went well. They were from Crane. I've also used some from Isky and Crower over the last few years and never had an issue with any of them.
Jim.
Never had a failure with them either but ones from the marketing giant...every single one of them failed in less than 1000 mi;didnt matter what prelube break in procedure, nothing. Just went flat FAST...this was back in the late 90s too.
Even had a HR here for awhile that didnt see 18k;was going to make a lamp out of it but rusted too quickly lol
Went back to Isky with Crower lifters real happy. No its not cheap but neither is rebuilding a just rebuilt engine
You want cheap.... youll pay the price so dont cry
Every day we see "whats the cheapest" then another failed thread.
Coincidence?
yeah pricy stuff can fail too but still
Have run some smaller name cams with NO break in....warm it up time it and start driving. No issues
IMO imported crap is much more the issue than oil
Too bad GM isnt making thier good lifters anymore
Last edited by cv67; Oct 26, 2016 at 03:55 PM.
Le Mans Master
Joined: Jan 2006
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From: Butler Pa
I'm not sure when that happened, but during the early and mid 80's I replaced about half a dozen flat tappet cams. Other than coating the lobes with a good moly lube, nothing special was done. Put it together, fire it up and drive away. Never had a problem.
Had a 1976 L-82, 4-sp
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From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
I believe the 305's were the worst for cam failures. That would be in the early/mid '80's.
Last edited by resdoggie; Oct 27, 2016 at 10:59 AM.
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