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If I can't get those noisey anti-pumps to quiet down (thanks Gerry for the tip on setting preloads) can I install new lifters on my existing cam? The motor has run for only about 500 miles since my rebuild. A frient tells me mew lifters/old cam is ok, but new cam/old lifters is a no-no.
Thanks
You've got, basically, the correct information. I PREFER to change cam and lifters as a set, but there have been very large numbers of lifters replaced on an existing cam with no problems. Under warranty, if a lifter or two needs to be replaced, GM doesn't "spring" for a complete new cam and lifter set; dealership technicians simply replace the bad lifter(s) and that's it. They've been doing this for a LOT of years.
i always "polish" the bottoms of new lifters on # 400 wet and dry emery paper using oil as a lube. if the lifters have a "dark" color bottoms i do not do this but with lifters that show a "swirl pattern" i polish out the "swirl" marks. also coat the lifter bottoms with "molykote" and change the oil filter after the breakin because the "molykote" will plug the oil filter when the oil cools off.
I've used the same meathod as Clem for many years and never ate a cam lobe. I've also scuffed good used lifters and put them on used cams in work car engines that didn't really matter and have had no cam problems. Knock on wood.
This advice about scuffing new lifters and polishing the swirl marks off new lifters sounds fishy to me.
I've heard exactly the opposite, new lifters have a contact surface that is designed to retain oil during the cam's break-in period. It seems this advice is contrary to the intentions of the lifter manufacturer.
John - GM's power book also shows this mild honing process to reduce risk of lobe damage during break in. I have done it as well and it has never failed me...Craig
Think of all the shim-over-bucket DOHC engines out there. I have three.
Everytime you swap a shim to change the clearance, you're essentially installing a different "lifter" because the contact is between the lobe and shim.
I've been using new and used shims on my Cosworth Vega for over 20 years and the cam lobe height is still within factory spec.
Prior to installing a new or used shim, I just inspect the surface carefully to make sure it doesn't have any burrs or nicks.
john,GM states the finish on their lifters is too "aggresive" and they recommend this method. i have been building engines since the 60s and i use this method all the time on GM lifters. some after market lifters come with a black coating and i do not remove it. the article is on page 5-49 of the chevolet power manual #6. i posted #400 grit and i have used that successfuly but chevy recommends #600. they also state that used lifters that have some crown or convex curvature across the bottom are quite satisfactory for reuse. i can scan you a copy if you wish.
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