Cam question

phat46 · December 20, 2022, 06:22:24 PM

I haven't been back much lately, been too much going on to do much car stuff. If anyone remembers I built a 383 SBC stroker last Winter and it developed a tapping noise. I finally got around to pulling the engine back out of my '46 to investigate. I found a couple bad lifters and lobes on the cam, so it's time for a new cam set. I have a cam in another engine that I really like and think I will swap that into this engine. I am wondering about re-using the lifters from that, the good cam, in the new(er) engine. I read that some guys always use new lifters when swapping a cam and some guys re-use the already broken in lifters that were with that cam. I am leaning toward re-using the lifters, since they are already married to that cam, being sure to use them on the same lobe they broke in on. What thoughts on this one way or the other.

Crosley.In.AZ · December 20, 2022, 08:34:53 PM

I have moved a used camshaft and lifters from 1 engine to another engine. It had few miles on it. That was20+ years ago. There was no problems. Big Block chevy.

chimp koose · December 20, 2022, 09:45:01 PM

I would re use the lifters that you have . They have already established a pattern on their respective lobes . I would still use engine break in oil though , just in case .

kb426 · December 20, 2022, 10:59:49 PM

I have reused them before several times years ago. I was very careful to put them on the lobes they were with. I watched a video about cams and lifters the other day. One of the items mentioned was that the face of the lifter wasn't perpendicular to the lifter body. This has become such a common problem that most are using hydraulic rollers, period.

phat46 · December 21, 2022, 07:51:24 AM

KB426, My first thought was to go with rollers for a replacement..then I looked at the price for a retrofit set

The cam I want to use has 8-10K miles on it, so it's well broken in!

Pete · December 21, 2022, 07:53:14 PM

What you want to do can be answered by saying, sometimes it works and sometimes it does not.
All blocks are not the same even if same model and machined on the same machinery.
The best situation would be have the cam reground and lifters refaced.
There is no quick cheap solution.
Pete

"Been in the cam business 70 years"

enjenjo · December 21, 2022, 08:07:04 PM

What year is your block?

Crosley.In.AZ · December 21, 2022, 11:44:37 PM

I have watched a few youtube videos of engine builders testing new and old camshafts and lifters for hardness, correct machine work , etc. The testing of rockwell hardness of the parts was interesting. Even cams with worn out lobes were testing at a good rockwell number. The number was rediced some , likely from the heat produced as the lifter and cam lobe chewed on each other?

A popular thought on the higher failure rate of flat tappet camshafts seems to be incorrect machine work on cams and lifters. Angles not correct for lifter to rotate correctly. Cam lobes are actually slightly angled

phat46 · December 22, 2022, 02:02:32 PM

Frank, I really don't know what years the blocks are. The old one is a mid '70's smog motor, the new one is a four bolt block I bought freshly machined from a machine shop.

chimp koose · December 22, 2022, 03:42:06 PM

As I understand it the lobe is ground with a slight .004-.007" taper and the lifter face has a large 50" radius on it so that as the lobe goes by , it causes the lifter to rotate slightly . when either the lifter or lobe wears flat you will experience cam failure as the lifter will stop rotating and have continuous wear on the exact same spot .

Pete · December 27, 2022, 01:02:42 AM

The taper on the lifter is .0002 to .0003.
It is a TAPER, NOT a radius. If it was a radius, you would have POINT contact and the cam and lifter would decease in very short time.
The lobe taper can vary from zero to .002
The main thing that helps the lifter turn is the lifter bore offset.