Pat Haener

Have a GenV 502 Mag. Recently added EMI THunder exhaust with short stainless risers and merc silent choice. I am considering a cam change in near futureand would like to stay with hydraulic flat tappet cam. I have access to a torquer plus cam or a ultradyne 288/296 on 110 cl. would reversion be problem with either? which would offer most usable power thanks in advance for any help!

nordic95

Contact Bob Madara( RMbuilder) here on the web site.He has a vast knowledge of cam shaft selection.I have used him a few times for my custom grind cams and he is the man.


Nordic95

rmbuilder

Pat,
The Ultradyne camshaft is one of Harold Brookshires original designs for Mercruiser. It was used in the early 80's for the Cyclone 440/460 platform.

288º/296º rated duration
231º/239º @ .050"
.550"/.558" Mercruiser spec
.550"/.575" UD spec
110º LSA

The cam is proven as to durability and reversion free.

Without knowing which Torquer Plus cam you are considering it is impossible to make any performance comparison. If you staying with a flat tappet design I would be very selective in your core and lifter choice.
Bob

Donzi502

I have done a vast amount of research on this. Keep away from 110 centerlines. 114 is safe for wet exhaust. Then you can run some lift without getting to bumby on the idle. 230 @ 50 is enough duration as well. You can go a little more buy what do you gain for the extra risk? 5-10 HP. The compression loss from water in the bore will soon eat that up. Also remember to goose the gas before you shut down. Here is my pick for what its worth.

int 226 @ 50
ex 230 @ 50
int lift 575
ex lift 595
114 loab separation
Install on a 110 loab center

This should give you 200 thou valve to piston clearance as well but you will need to check. It will be at its closest 10 degrees ATDC. You will need springs at 120 on the seat and about 450-480 at max lift and roller rockers and rocker covers and new adjustable chain and good pushrods and screw in studs and time and a hole lot of cussing when things dont fit. Its a good idea to have taps on the water logs so you can empty the manifolds and and fire up for a second to dry any possible reversion when parking up for the day as well.
This cam really needs compression in the 9s as well so theres not much point going bigger with 8.6.
Thats my opinion for what its worth and its working well for me on a 454. Your 502 will be better i should think.

Good luck and let us know what you go with.
Jas

SB

iTrader: (1)

Good info RM.

I'm concerned about his exhaust. I have seen handfuls of people with Eddie Marine's with long risers revert with cam's like this.

He has a short riser + silent choice.

Also, 502's will revert before a 454 if everything else is the same other than cubes.

Call me a worry wort - but I'm worried about that exhaust system. Something to look into further I think.



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