Camshaft /Tappet settings

[marcusaurailius]

Can any one tell me why the gaps on a upgraded camshaft are bigger than on an OE one

eg, standard TR 6 , 35 65 35 65, 250 cam lift, 10 thou clearance, after market cam, same duration, but a little more lift, 25-40 more, but any thing from 16 to 24 thou clearance,

this is even if the cam is ground on a new ..blank..

also , why does one have to set the tappet settings ..wider.. with 1.65 ratio rockers, as opposed to OE 1.5 ratio ones, or so i have been told, but not why,.

i have been told conflicting things, but seeing as we have some..camshaft type... Guru,s on here, maybe I ,and others will end up being a bit wiser!!!

regards Marcus

 

[evelrod]

Something that no one has mentioned...

It is assumed that we all know how to set valve lash, that we all have "the feel"....That is simply NOT true. Unless you are one of the few "techs" that actually CAN set valve lash by feel (I find these individuals few and far between) or are in possession of a P&G or some tool like it, then I could easily understand why you could have the variety of measurements you seem to be getting.

This ability is not something you can learn from a book, it must be taught by someone that already knows. Some very competent mechanics I have known never seem to get the knack! Good thing about all this, in reality, a few thou one way or the other on a pushrod engine, at least, won't make a huge difference in the long run.

Rod

 

[Tmoose]

I think The go-no-go feeler gages ground to 2 thicknesses ( 0.002 inch step) are pretty handy for evaluating where I am. Before I got a set of those I spent too much time deciding what was a tight 0.006 inch, etc, etc.

 

[patprimmer]

I absolutely agree with Rod. Most cannot get repeatable readings closer than a few thou, but also that it does not matter. If you could get away with as little as 0.006 and you set at 0.010, no problem if it really is 0.008 or 0.12.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[patprimmer]

Opps. that last figure obviously should be 0.012

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules