Cam Question !!!

[Ratickle]

I am going to give you my gut feel from everything I've dug into. I cannot find a single, hydraulic roller, cam anywhere with your specs. My guess is the 243 is transposed 234. So, here's my best guess......

You have a ZZ502 shortblock with edelbrock heads. You really should also check on the exhaust valve material type. But, here is what I believe you have:

http://www.s-series.org/htm/tech/GMP...ts/027-033.pdf

That shortblock came with cam specs of:

Camshaft ....................... 12366543 Hydraulic roller
Lift: .527" I, .544" E.
Duration @ .050” 224° I, 234° E.

Here are the specs from Summit automotive.

Brand GM Performance
Manufacturer's Part Number 12366543
Part Type Camshafts
Product Line GM Performance Hydraulic Roller Camshafts
Summit Racing Part Number NAL-12366543

Cam Style Hydraulic roller tappet
Intake Duration at 050 inch Lift 224
Exhaust Duration at 050 inch Lift 234
Duration at 050 inch Lift 224 int./234 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.527 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.544 in.
Valve Lift with Factory Rocker Arm Ratio 0.527 int./0.544 exh.
Lobe Separation (degrees) 110

That camshaft is used in almost every GM 502 Crate High Performance engine sold, and is sold by a lot of after-market people also. Double check the 243 vs 234 and you should have your answer.

[Ratickle]

And, if that is what you have, here is what you need to know.....

[1stoutlaw]

YUP----I'm sorry I wrote 243 instead of 234-----it is a 502/502 w/the edlebrock rpm heads----inconell exhaust and stainless intakes---Man you found more info than the engine builder has sent me soo far----you can google the engine if you want----just put in 5026hp-----it will be the 1st response from googgle's return list-------
SO what about water reversion problems?????? What do you think-----mild or wild cam ?????? Thanks !!!!

[old377guy]

see? once again, it's not what you know but who you know

[1stoutlaw]

OK---anyone------if the "overlap" is 9 degrees and the LSA is "110", in which Ratickle, thank goodness found all the needed info,,,,,,,mild or wild cam ??? Water Reversion w/ GIL Exhaust ???? Still waiting on my Cam Specs from the engine builder but I'll betcha Raticle has the right cam specs !!!!!! Thanks,, MIKE !!!!

[ROGUE]

That sounds like the cam. I would think 9 deg overlap is nothing. I run 75 degrees overlap. Im sure there are a bunch of people who have experience with that engine. I hope they set up those heads properly for a roller cam.

Hmm, those timing numbers may be at .050 and if so that overlap number is meaningless. Need the numbers at .005 or .006.

[1stoutlaw]

Thanks---Rogue---the engine builder has not sent me the cam specs yet --But Ratickle I believe found the specs----you seem to have alot of knowledge and if you are wrong I certainly won't blame you---------I'm taken then at 9 deg overlap---vs. your 75 which are sooo far away--I should be fine with wet/Gil Exhaust----if you don't know--thats fine just say your not sure----!!!!!! Thanks Mike !!!
PS: My wife's cousin, who is helping me dress this engine, does not know----He says when we 1st start it---we can look into the exhaust after we shut her down, and see if there is water---I would prefer to have the best answer beforehand---YUP, my stomach is nercous----Thanks for any help !!!

[Ratickle]

Read this thread about the engine on Speedwake....

zz502 cams?? [Archive] - Speedwake 2.0

My gut feel, should be okay, but do not idel for extended lengths of time. Rev it up a bit once in awhile just in case....

[Ratickle]

Here's another tidbit...

The book Big Block Marine Performance by Dennis Moore list the ZZ502 roller cam as one of the cams he recommends.

[1stoutlaw]

Great Info Ratickle----you guys have helped me out alot---w/my Gil's I believe I will be good to go-----I printed out the cam info you dug up also to have--ya, the engine builder never sent me the cam specs, at least as of yet....I never heard of Dennis Moore but that will be a book I will look into---
Thanks so much----Mike!!!

[ROGUE]

Be very careful about what you read, or for that matter listen to. And be very careful about any engine builder who would even use the term "radical" to describe a cam, especially when that cam is quite mild. Good Luck and hope it all works out for you.

[htrdlncn]

the engine builder finally got off his seat and sent me the L.S.A. number which is "110".....

I personally would not run a 110 overlap on a marine engine with gil maniofolds unless it was dry to the tips,,
just my opinion though..
I had my cam custom made, and it has 114 overlap to avoid reversion..

[1stoutlaw]

Thanks guys for all the input-----When I say the engine builder said the cam was radical-I'm assuming it was a kid working in "customer service" not a engine builder---which really got me P----off, cause if it was a radical cam in their add for the motor they should tell everyone---thats why I think its someone working the desk--in fact he still has not sent me the "cam spec sheet" and I think Ratickle hit the numbers right on----Hopefully this Sat we will get the engine started for the 1st time on the floor----The game plan is then to pull the exhaust and look inside for water----I hate to go to dry exhaust mostly because my Gil's are brand new and I hate to have new pipes welded-----and I am told dry exhuast are SUPER loud----but if I have to I will !!!!! Again thanks to all of you !!!! Mike

[ROGUE]

And remember, reversion happens at Idle, the lower you idle the greater chance, so when checking be sure to set the idle rpm low enough to mimick what idle you will have when in gear. That will depend on the prop and the carb but I check mine at 700 just to be real safe. Ive never tried to do it on a stand but you need to make sure the water flow is similar to what it will see in the boat.

[Griswald]

I ran that cam for a couple seasons w/ Stainless manifolds and had no issues with reversion at all. Nice lopey idle, too.

[Ratickle]

Do you recall where the water came in on your manifolds, and what your idle was at in gear?

I have read some stuff where they say to make sure you rev it up a bit right before shutdown. Any truth to that?????


And last thing for you cam guys, why is 112 or 114 overlap actually less prone to reversion than 110? My mind refuses to work that way!

[1stoutlaw]

ROGUE, thanks for the info-------GRISWALD you are making me feel better-----RATICKLE, I have not run the motor yet so I don't know where of IF water will come back down the manifold---HOPEFULLY the motor will be started on this Saturday, on a motor building table AND we will know then !!!! I'm confident that I will be OK!!! I will post a photo of the motor complete, on the table next week !!!! Again-Thanks for all the input !!!! Mike !!!!

[ROGUE]

Do you recall where the water came in on your manifolds, and what your idle was at in gear?

I have read some stuff where they say to make sure you rev it up a bit right before shutdown. Any truth to that?????


And last thing for you cam guys, why is 112 or 114 overlap actually less prone to reversion than 110? My mind refuses to work that way!

Its not overlap, those numbers reflect lobe seperation angle. So, the intake and exhaust lobes are seperated by 110 degrees which makes them closer, or 114 which has them farther apart. Obviously, the closer they are, the greater the overlap. Overlap is measured at .005 valve opening and its the degrees that the intake and exhaust valve are open at the same time. Hope this helps.

[1stoutlaw]

OK---I have water reversion after all !!!!! I have ordered a set of custom risers from Stainless Marine here in Florida...I'm told the riser will go up 12" and the water won't mix with the exhaust til the very end of the pipe !!!! We installed the engine in the boat, all plumbed,wired and ready to go----just waiting on the exhaust !!!!!!! Is this what they refer to dry exhaust, although there still is water mixing in the end ???? Louder ??? Be careful what you wish for---I.m learning that after this 2 year project !!!
Thanks for everyone's thoughts and info---!!!!!!
Mike-----Tampa Bay