Rocker ratio

Any body ever put in a set of 1:6 Rockers in a 350 mag, with the stock cam that has a LSA of 109?
Any trouble with Reversion?

Based on 1:5 rocker ratio
Specs - roller lifter Merc Part No 431-811658
Duration @ .050:
197 intake,
207 exhaustValve
lift in inches:
.430 intake,
.450 exhaust
Lobe centerline degrees:
106 ATDC,
112 BTDC
Lobe Separation Angle in Degrees:
109

Re: Rocker ratio

Going from 1.5 to 1.6 is not hard, BUT!!!
You need to make sure that it will not "coil bind" the valve springs.
Put one of the 1.6's on and HAND roll the engine over until you are at max lift and check the valve spring for coil bind. You will need a feeler gauge to get an accurate reading and then ask an engine shop that know your engine type what the min clearance is and if they think yours is ok.
If you can't get a feeler gauge between the valve spring coils, they are bound and you will need different springs.
You will also need to make sure there is clearance for the push rod, as that is where the difference is on the new rocker.

FYI, 1.6 on the intake only produces better results than if you put them on the exhaust also (on a street motor).

Re: Rocker ratio

Forgot this :1988 Mercruiser 350 Mag (SBC) Pre Vortec , Hydraulic roller tappets

My plan is to use after market 64cc heads designed for Roller hydraulic tappets. I'm not worried about coil bind and lift is still with in the
.480 peak. what concerns me is this cam has a very low LSA. Although the valve full seating will occur at the exact time regardless of Ratio. The overlap and duration will be slightly increased.Most aftermarket cams with this type of lift use an LSA of 112.
So I wanted to know if anybody has done it with issue.

Re: Rocker ratio

Find a copy of the book Small Block Chev Marine Performance by Dennis Moore, everything you want to know and then some.

Re: Rocker ratio

Thanks for the thought. But a book that cost $400 dollars is really not what I had in mind . Do you think if I glued that book to the top of the engines it would be the same as buying 64 cc heads for a $200 more than the book. HMMMM?????? Some how I think this got lost in translation. The question was if any one has put 1:6 Rockers on a stock SBC 350 roller tappet cam that has an LSA of 109.

Re: Rocker ratio

Doubtful you will get an answer on this forum. Call a cam tech support line, and run your question by them. It's what they do.

Re: Rocker ratio

scoflaw said:

Doubtful you will get an answer on this forum. Call a cam tech support line, and run your question by them. It's what they do.

Click to expand...

Yeah cam manufacturers know that, or maybe even a tech at Summit Racing will know.