Cam break in and hi ratio rockers


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By slick56 - 11 Years Ago
Is it worth the time breaking in the cam with standard rockers, then changing to the 1.54's after the initial

20-30mins, or would i be ok with the 1.54's straight up?

A lot of scary talk about cam break in lately...

Thanks, Al.
By aussiebill - 11 Years Ago
slick56 (3/11/2014)
Is it worth the time breaking in the cam with standard rockers, then changing to the 1.54's after the initial

20-30mins, or would i be ok with the 1.54's straight up?

A lot of scary talk about cam break in lately...

Thanks, Al.


Too much crapping about hypertheorical stuff here, doesnt matter what rockers you use to run it in, have you forgotten both ratios are on different y block engines, and dont require this change.
By Ted - 11 Years Ago

The difference in valve spring loading between 1.43 and 1.54 is not much assuming stock camshaft specs. My experience has been that running a reduced rocker arm ratio or reduced valve spring tension for camshaft break-in purposes typically doesn’t help if there’s an underlying problem with either the cam or the lifters. There have been several documented instances where the camshafts went ‘bad’ after restoring the rocker ratio or valve springs. These failures were after the cam was broken in with the low lift ratios or break in valve springs being pre-installed. Metallurgy is typically the suspect in these particular cases. Here’s the link to a list of items which can contribute to cam / lifter failures.

http://www.eatonbalancing.com/blog/2012/11/06/camshaft-and-lifter-failure-causes-2/
By slick56 - 11 Years Ago
Ted (3/11/2014)

The difference in valve spring loading between 1.43 and 1.54 is not much assuming stock camshaft specs.




I have installed a Mummert Y-270-S camshaft with 105lb springs


.
By Ted - 11 Years Ago
slick56 (3/11/2014)
I have installed a Mummert Y-270-S camshaft with 105lb springs

Knowing the lift on the camshaft would help but assuming less than 0.470" lift, then there's still not enough difference to warrant using 1.43:1 rockers for break-in versus running the 1.54:1 rockers. If the lift is 0.470" with 1.54:1 rockers, then figure about 0.033" less with 1.43:1 rockers. if knowing the rate of pressure per inch on the valve springs, then the exact amount of over the nose pressure present with both sets of rockers would give an accurate number for the difference in pressure between sets of rockers. I suspect no more than 10 pounds and it is probably much less than that.