Quote:
Originally Posted by 64speed
I have driven nothing but classics cars for a very long portion of my younger life all with flat tappet cams. I have always used rotella in those engines and never had a problem. At break in on a new engine I would use rotella with a bottle of zddp stuff dump right in the lifter valley right before startup. The only lobe failure I ever had that had anything to do with one of my SBC builds had to do with a neighbor who was chasing a ticking sound and couldn’t wait for me to get home and he tightened the **** out of all the rocker arms. Flattened damn near every lobe.
|
Since I did probably 75 SBC "Tune Ups" during the late 70s all the way through the 90s, I highly doubt your neighbor hurt the cam and lifters in his chevy. I first saw a bad cam and lifters, and valve guides in 1977 in a 305 Impala that I had serviced since it left the dealer at 17,000 miles. It had regular oil changes with high quality oil and filter and it still went south early.
After that time it was ongoing to have primarily 305s come in ticking or missing and have bad cam and lifters, and also need valve guides. It was a chevy problem, not oil related, nor could it be solved by additives. The heads also cracked for whatever reason around the valves. It was a serious problem, some say with metallurgy, others blame poor machining of the too soft blocks, too soft cam cores, improperly hardened lifters, plenty of blame to go around and it cost consumers a ton of money.
As near as I can tell it all started in 1977 and I haven't any idea when chevy/GM finally solved the problems, seems like the late 80s early 90s was about the time it quit happening.
Pontiac didn't escape it either, I've seen plenty of 301s with flat cams in them beginning in 77 when the 301 first appeared, it also had a soft block. At 60,000 miles the cylinders were worn so bad you couldn't remove a piston without ridge reaming the block. This was uncommon with Pontiac blocks previously. I had many Pontiac engines with 100-150,000 miles that I could slide the pistons out of the bores by just knocking the carbon ridge off of them.
The 2.5 Iron Duke had a soft block also, they would egg shape the bores and wear the cylinders out and end up filling the air filter housing up with blowby and oil, at less than 50,000 miles. This is when the 2.5 also had the piston rock/knock, sitting at a traffic light next to one of these GM cars, you knew from the sound it was a 4 rather than a V6 option.
This is the time GM lost their market share as they should have.