Jessel rockers
08-04-2004 | 08:28 AM
#11
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Posts: n/a
Re: Jessel rockers
Thanks Lmarth-- True we have surprised a few. We modified the hatch just a bit and it looks stock when you first see it. My Buddies all give me a hard time because a lot of the time we are just out crusing slow and we keep a lot of stuff up under the cuddy. It really is a family boat, we just put some umph behind it. Fun in the Sun!
08-05-2004 | 09:12 AM
#17
Charter Member #601
Joined: Dec 2000
Posts: 3,276
Likes: 5
From: Holland, Mi USA.
Re: Jessel rockers
Cstraub69,
"Your better off with an aluminum rocker. Yes they are not as rigid as a steel rocker but they absorb harmonics in the valvetrain. Steel rockers amplify harmonics that is why the Cup boys run aluminum."
And what type of problems do you see with amplified harmonics, valve float at lower rpm? or damage??
I have been running Crower SS rockers for years and the only complaint I have is they dont properly line up with the valve stems in some cases. I have had to cut and weld push rod guide plates to compensate. Next time around it will be T&D or Jessel or a shaft type setup.. with more fingers and valves to mess with..
Thanks
Dick
"Your better off with an aluminum rocker. Yes they are not as rigid as a steel rocker but they absorb harmonics in the valvetrain. Steel rockers amplify harmonics that is why the Cup boys run aluminum."
And what type of problems do you see with amplified harmonics, valve float at lower rpm? or damage??
I have been running Crower SS rockers for years and the only complaint I have is they dont properly line up with the valve stems in some cases. I have had to cut and weld push rod guide plates to compensate. Next time around it will be T&D or Jessel or a shaft type setup.. with more fingers and valves to mess with..
Thanks
Dick
08-05-2004 | 09:48 AM
#18
Guest
Posts: n/a
Re: Jessel rockers
Dick,
The most detrimental was spring harmonics and premature failure of the valve spring. In testing of components by the boys in NC, valve springs would last longer with aluminum rockers.
I would also recommend on any boat engine with 600HP or more to run a single or dual tapered pushrod to prevent deflection. Deflected pushrods rebound after max lift and can cause lifter damage after a period of time. The large 7/16" tapered stuff prevents this and in most cases is worth some extra hp. I had this happen to Jasper engines 2 years ago in a 417 CID SBC dirt engine. You could tell the deflection was happening by the SCFM fluctuation on the dyno sheet. I told them to change the pushrods, quite long, 9.500". Well they decided the next morning to pull her one more time and she spit 2 pushrods out. I had some 7/16" to 5/16" single tapers made for them and the engine picked up 40HP, which for any engine is a sizeable gain.
Chris
The most detrimental was spring harmonics and premature failure of the valve spring. In testing of components by the boys in NC, valve springs would last longer with aluminum rockers.
I would also recommend on any boat engine with 600HP or more to run a single or dual tapered pushrod to prevent deflection. Deflected pushrods rebound after max lift and can cause lifter damage after a period of time. The large 7/16" tapered stuff prevents this and in most cases is worth some extra hp. I had this happen to Jasper engines 2 years ago in a 417 CID SBC dirt engine. You could tell the deflection was happening by the SCFM fluctuation on the dyno sheet. I told them to change the pushrods, quite long, 9.500". Well they decided the next morning to pull her one more time and she spit 2 pushrods out. I had some 7/16" to 5/16" single tapers made for them and the engine picked up 40HP, which for any engine is a sizeable gain.
Chris
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