454 stroked to 496
 

I just got a new boat (baja) with a 454 stroked to a 496.
It has merlin oval port heads on it, this is the cam specs on the comp cam. I was just wondering what everyone thought.
cb xr274 r-10
valve adjustment intake= .016 exh.=.018
gross valve lift intake= .639 exh = .646
duration @ .015 tappet lift intake = 274 exh.280
valve timing @.015 open intake = 31
exh. 74
closed intake= btdc 63 abdc
exh. = bbdc 26 atdc
duration @ .050 intake= 236 exh= 242
lobe lift intake= .3770 exh = 3810
lobe seperation = 110.0

You'll need a long riser or dry exhaust. My guess is that LSA will probably incur reversion unless your motor has a decent exhaust setup like CMI, Lightning, Stellings etc.

I have the same LSA and have had issues already so am converting to dry exhaust.

That's my thoughts anyway. I'm sure far more knowlegable people than I will chime in too!

I was told the exhuast on it is a gil's dry exhuast, but water comes out the exhuast tips.

Lots of lift and little duration so exhaust means a lot. How do the hoses run on those Gils? Is the water just dumped at the ends?

If they were dry exhaust water would not be mixed with the exhaust. It would run through the pipes to cool them then through a dump. Wet exhaust are fine if you have long risers and the correct cam. I would be concerned with the LSA at 110, does not look like marine specs. Send "RMbuilder" a PM and ask him to take a look at your thread. He is the cam "Guru", you may want to have him grind one to your engine specs. Better safe than sorry.

That engine should be a monster with that solid roller in it.

GILs will have a dump for the ecess water and then mix at the tip.

Some of them have extra holes and just mix at the tip.

Do your tail pipes run solid all the way past the transom or do they have a rubber connecting hose to an exhaust tip.

If they go all the way out the back, then you should be OK.

BTW, that much cam probably makes power to almost 6000 rpms......

How many hp is that engine?

I would guess about 600hp at 5800rpms.

When you guys talk about reversion when does this occur?? With boat off or running?

When you guys talk about reversion when does this occur?? With the boat running? ive heard of it when its off