anips

Thanks for the update

mechron

i do not post much lately, but do i read this right?? you put new lifters on the origonal used cam... if so THIS IS A BIG NO NO!!! it is a recipe for cam/lifter failure. Never put a new lifter on a used cam nor a used lifter on a new cam, not even 1. new lifters need a new cam and a new cam needs new lifters (this is the inviolatable rule with flat tappet cams, solid or hydraulic, roller cams being the exception)

flat tappet cams are ground with a slight taper across the lobes like this / , way exagerated but a slight taper. the lifters are ground with a slight crown like this (= , this allows the the lifter to rotate on the cam. each lifter wears to its matching lobe. even replacing a lifter to a different cam lobe will result in failure.

i know what i'm talking about, i had a repair shop for 30 years in Cal, now retired. even in the early 70s cam-lifter failures were common. i fixed tons of them from corvettes to mom and pop grocerie getters.

this was the time when GM had the aluminum/nylon cam gears (i made tons of money replacing those, thanks GM..

Of all my cam/lifter replacements was a lady, a regular customer came in with a miss and a clack, this was like around 1975. upon pullimg the valve covers one rocker was not moving at all. the teardown of the engine revealed a flat lobe and a lifter so worn and cupped that it had a hole in the bottom that oil poured out of.

so, repace the the cam and lifters toghter, as long as you duing that degree the cam.

GCD1962

I understand what you are saying, but if the cam is ok (no worn lobe) and the new lifters have the crown I can not see why it wouldn't work just fine as long as the lifters spin as necessary. A new cam and new lifters have the same requirement and both will take the needed "set".
Time I guess will tell, but I think it will be just fine.

claf

Somewhat off target but here's another spring story. Years ago I bought a pair of 2.02 heads , fully ported and polished from a former stock car racer. (This particular style of head was outlawed by the track.) Stuck them right on my 340 HP '62 and everything was fine, for a while. Eventually they began to punch up through the rockers ! After going thru all my spare rockers eventually they ate the camshaft. Never did check the spring pressure but since designed for circle track use they must have been strong. Brand "General Kinetics". Still using those heads but with stock springs. Bob

Westlotorn

You can change lifters on a cam safely if you follow break in procedure just like it is done on initial start up on any new engine. Local Shops and GM Dealerships have been doing this for years. I built a 2.8L for my son's S10 in 2002. New lifters were on backorder and could not be had so I cleaned and ran the old flat tappet lifters on the new cam in this all new engine. I broke it in very carefully and they worked perfectly until I sold the truck years later and many more miles on them.
If you don't break them in all bets are off, you will have failures.
When a vehicle came back for warrany with one tapping lifter GM would replace the one tapping lifter and send the car back out.

A little history, at this time Hy Lift had gone out of business and Eaton stopped making flat tappet lifters to concentrate on Rollers. Standadyne was supplying GM production and the aftermarket could not get lifters for a short time. The only option for new lifters was Moresa Mexican made lifters and they were known to fail 20% of the time, this was why I chose to use the old used factory Eaton lifers. It was not my choice but they worked out great.

mechron

not so guys, i had to garantee (sp) my work at my shop. with flat tappet cams cam and lifter replacement together was a no brainer. one whiped lobe or one fubared lifter=a comeback. i did a lot of drag racing with solid lifter corvette cams back then (the early 70s) i learned early on--NEVER PUT A USED LIFTER ON A NEW CAM, or vica versa. i threw cams and lifters away because i was experinting. the 30-30 cam was great, but there was a .017 GM cam i also used in the 70s.
also a wiped lobe or lifter will send iron powder through the engine, while the oil filter will catch most of it i have seen the worst cases. main and rod bearings are toast, cranks are toast, the piston rings and cylinder walls are scored.

i ran a gasser in the early 70s out of my shop at fremont raceway, now long gone.

anips

yea, to bad about Fremont, night drags were cool early funny cars, frt. engine fuelies, altered's, cars like Gas Rhonda Mustang, the Pure Hell 55 chevy with a jato rocket asist rearend things you'll never see again, getting back to the cam, when I was a kid I built a 292 sb chevy in auto shop for my 55, a friend had a fairly new 283 solid vette cam who wanted to change it out for a Crower, so I put it in my new rebuilt motor with a new set of lifters, well it lasted about a month and it went away, after talking to a few mechanics of the day they told me the same thing, you don't do that, so I pulled the motor pulled it apart boiled the block, crank, new bearing, rings, oil pump, and put the new 30-30 chevy had just come out with in, thats one lesson I never forgot....I know the OP doesn't want to hear this but if it were me I'd pull the cam and lifters and replace em with new just in case, " its pay me now or pay me later"

vt65

now Kerrmudgeon that just isn't right!