Flat tappet cam & timing chain wear after 10 k

[Mike T]

During the tear down I first noticed a couple of thousandths dish in the lifters and figured the cam was going to be worn out and I also figured the timing chain would be stretched since I've heard about problems with the particular brand that I installed. I did my best to insure the pre load was correct and to lube/break the cam in as recommended..... this is what I found.

Lifters were all dished about the same amount none were really worn more than the others

The timing chain fit was very good now loose after 10k (cam bearings look good)

 

[Mike T]

The cam lobes all measured short but fairly even.

#1 I 1.448 E 1.466

#2 I 1.446 E 1.466

#3 I 1.449 E 1.464

#4 I 1.450 E 1.468

#5 I 1.448 E 1.466

#6 I 1.449 E 1.466


The lift at the valve should have been .448 intake & 472 exhaust but the measurements now show .406 intake & .433 exhaust.

This equals on average -.042 intake & -.039 exhaust

 

[SS/GN]

What brand is that?? I am calling Nick and ordering the chain he uses from T/A. Looks like you saved the motor. I recently installed a Comp cams chain in a BBC and a Edelbrock in a SBC and both are getting replaced with a billet gear set up with less than a summer of driving.

 

[Mike T]

Lunati cam and Pro Gear timing set. I don't want to fault the product producers because the timing set & the cam were purchased about seven years ago and a lot may have changed by now... IE some sort of material problems that has since been corrected.

The cam could have been due to a lot of things or possibly something I did. I'll be installing a roller this time around because I believe it will be a little more forgiving.

 

[fastblackracing]

This is very interesting, what oil and what valesprings/poundage were you using?

 

[Nick Micale]

The chain being loose is caused by wear of the cast cam gear. I have seen wear like this even at 5K miles with the cast gear sets.

This is the reason I pushed TA to build timing set with a link chain and a billet cam gear.

We had field tested 2 brands of link chains under extreme field conditions and extreme spring pressure, and actually split one cam gear, and tore out the keyway on the other gear.

Hydraulic roller cams with more than 50% spring pressure than stock will quickly affect a cast gear.

As far as flat tappet cams we use ZDDP paste on the cam lobes and lifter face upon installation, and always add ZDDP+ at each oil change,

Synthetic oil will drain down off a metal surface after a couple days and regular oil will not, which is one reason cam manufacturers specify do not use it.

 

[Mike T]

This is very interesting, what oil and what valesprings/poundage were you using?

I ran 10-40 Valvoline with ZDDP additive, springs were 108# Lunati and Zpaste was used on the lobes and lifters.

 

[Bob Davi]

I put a brand new timing chain, nice and tight on a BB chevy, then went to the dyno. After about 40 minutes of break-in time plus about ten pulls, I removed timing cover to swap cams. If I had not been the one to put the new chain on I would have never believed it was new...it had stretched about like the one you show in the picture. My machinist/engine guy said he sees them stretch like that in the first 30-60 minutes of run time, then they stay there and run for many , many miles.....

Depending on how many miles on the engine, I don't always replace timing chains and oil pumps every time I do something. If they are working I leave 'em alone. Both of those parts last a LONG time and work fine for tens/hundreds of thousands of miles. JMO, but I wouldn't lose too much sleep over that chain.

Bob

 

[fastblackracing]

I have had the best results using the rollmaster timing sets and I use them exclusively, The T/A set Nick mentioned looks promising and I may use it on my next build. Every other brand timing set I have used shows excessive wear even after short run time. They are all junk IMO.

 

[Mike T]

I believe in Nicks findings of gear wear but in my particular case the supplier (third party not Pro Gear) said that the chains were a problem and he has corrected this with a quality chain that he's found. I received it and FWIW it's made in Germany.

My machinist/engine guy said he sees them stretch like that in the first 30-60 minutes of run time, then they stay there and run for many , many miles.....

I thought about this possibility as well....if this is the case they should do a run-in at the factory so that it's pre-stretched for a lack of a better term.

They are all junk IMO.

This is what I've been hearing as well.