[Formulas]

Not saying cam / lifters are the issue or not..... but when iam planning out engine build details the heads get ALOT of attention early on namely how much lift is desired and how much lift is possible

with the top of guides cut down for PC seals with a reasonable step to locate shims i cut the top of the guides down more to only have enough room accept a PC seal as low as possible+ a small extra margin... then insert intended valve / keepers / retainer using a weak spring that i got from my old damaged landscape pop up sprinkler heads ... see and record how much max travel there is then measure my seals protrusion over top of guide then do the math to come up with max valve travel before crunch then + a little safety margin then figure installed height of valve springs and go from there ..

thorough planning and alterations is the only way you will achieve KNOW max acceptable lift

a D'port head has to be massaged some to take .540-.560ish lift unless longer valves are used or more aggressive machining is done

store bought heads everything should be checked and verified or just plan to operate well under published data

food for thought like most ignition problems are blamed on the carb.

[mgarblik]

Not sure if this will help explain but this is what I know and my understanding of the subject and I think reasonably accurate. All the cam companies people seem to talk about on this forum grind cams. Crower, Comp Cams, Isky, Bullet/.Ultradyne, Howards,LSM, Clay Smith, and dozens of others. Most have CNC cam grinders but are not often used on flat tappet stuff and low production legacy stuff like our Pontiacs. Most of our old, flat tappet stuff is still ground on ancient manual cam grinding machines, some dating back to the days our ancient engines were new. Not necessarily a bad thing at all as long as the masters, and the machinery are maintained and in good shape and operated by people who know how to grind cams! (Old Guys). Very few aftermarket cam companies make their own cam blanks and they would be billet blanks not flat tappet stuff that is cast. LSM makes some billet blanks and Comp makes some. May be a few others. Everyone has to source cast blanks for flat tappet cams and NONE ARE US MADE ANYMORE. They come from China or India, that's it. So if you have a new flat tappet cam ground it may be NOS and MAY be US made. But most likely Chinese or made in India and will have a much higher probability of being a piece of crap. To make matters worse, the majority of these smaller cam companies do not do their own heat treating in house. They send a pile of Cams out for heat treating in a batch to a vendor they trust. But the quality of the heat treatment is hit or miss as well.

So here you are as an end user, or an engine builder, stuck right in the middle of this pissing contest between the core supplier in China/India, the cam grinder, the heat treating shop. A fresh engine full of metal paste from a flat cam and ruined lifters, an angry customer or engine owner and everyone else pointing fingers and blaming each other. It's a bad situation with no 100% solution.

Many say "Why not just go to a roller cam?" That would be a great solution IMO IF they didn't have a long list of their own problems with defective roller lifters. Will try to get the latest updates form ALL the cam grinders at PRI in a few weeks. Best place to get the latest, honest information IMO.

[OG68]

Originally Posted by mgarblik

Most of our old, flat tappet stuff is still ground on ancient manual cam grinding machines, some dating back to the days our ancient engines were new. Not necessarily a bad thing at all as long as the masters, and the machinery are maintained and in good shape and operated by people who know how to grind cams! (Old Guys). .

I saw a few grey haired Old Guys at Crower cutting the cams.

[Steve C.]

Not necessarily related, but might be of interest. Includes a few shots inside Crower.

Regrinding a Camshaft - Behind the Scenes @ Crower Cams

https://www.youtube.com/watch?v=A-tLEzZn_4o


.

[Jay S]

Melling cams and other white box grinds that are ground by CMC get ground in very exotic CNC machines that grinds the cam in a few minutes with stunning accuracy. The down side is they do so many cams in a day, QC isn’t the best, especially when it comes to cam core issues. Other than that, just like what Mike said, most every flat tappet cam is ground on the manual Berco type machines, they have more variation. I think Comp may grind some flat tappet cams on CNC grinders.

Those guys at Crower need to drink an extra cup of coffee before the fire up their grinders …. The flat tappets from Crower seem to vary in how they are ground pretty wildly. Part of why I said you need to check cams out and Crower is no different. I have seen the 60919 come out looking like a single pattern cam, I have seen them mess up the LSA and it measured 116. The worst was the cam that had an extra 18* of exhaust seat timing on it. All on what is suppose to be the same cam. I like Crower, but they need to move that cam grinder that does those cams out of that dark corner of the shop!

[67Lemons]

Originally Posted by Jay S

Melling cams and other white box grinds that are ground by CMC get ground in very exotic CNC machines that grinds the cam in a few minutes with stunning accuracy. The down side is they do so many cams in a day, QC isn’t the best, especially when it comes to cam core issues. Other than that, just like what Mike said, most every flat tappet cam is ground on the manual Berco type machines, they have more variation. I think Comp may grind some flat tappet cams on CNC grinders.

Those guys at Crower need to drink an extra cup of coffee before the fire up their grinders …. The flat tappets from Crower seem to vary in how they are ground pretty wildly. Part of why I said you need to check cams out and Crower is no different. I have seen the 60919 come out looking like a single pattern cam, I have seen them mess up the LSA and it measured 116. The worst was the cam that had an extra 18* of exhaust seat timing on it. All on what is suppose to be the same cam. I like Crower, but they need to move that cam grinder that does those cams out of that dark corner of the shop!

Really disappointing to hear that! I’ve only heard good things about their grinds