Promax Question

[tabme]

I just picked up a fresh rebuilt (2 hours on it)225 promax with 260 porting,the heads are cut to 32cc. My question-is this too much compression with 93 octane. The motor will be on a fish/Ski boat about 1500 lbs--26/4 blade Trophy plus prop. Thank you

[KIRCHNER]

Youll need to do a comp. test. my225 has150lbs with 32 cc heads, runs fine. your porting might change those specs. Thats alot of prop for 1500lbs, my 2 cts.

[tabme]

Thank You for the reply. Yes soon as mount it will do compression test. What timing are you running on your motor-we have 93 octane here hoping than enough. Thank You

[roadkill636]

Exhaust port height and head gasket thickness and bore size and ring gap will all affect the compression.

What is the porting measurements?

[tabme]

I just got this powerhead 2 days again so i have no real specs yet. Exhaust chest is completely machined and polished that i can see,there is head studs on it also. It is a Mag Motor.

[roadkill636]

Exhaust chest won't affect compression. And MAG mota aint got nutty to do with Promax.

[KIRCHNER]

25* 93 works for me. you say MAG, meaning a mariner?

[tabme]

No sorry--It is a powerhead built by Mag Machine Service. I am thinking i was going try 23/24 degrees with the weight of the boat. Thank you

[perfmarine1]

Just get a 5 gal of race fuel and bump the octane up a bit. You can't trust the fuel these days. Here is the site to convert octane. I use 110 race fuel to mix with, don't take much.

http://www.bazellracefuels.com/Calcs/OC1.htm

[Dave Strong]

Just get a set of 34cc heads and run it, 32cc is a bit tight.

Dave

[tabme]

Thank You Guys always appreciate the help and advice. I going to see if anyone would like to swap a set of stock Promax Natural Heads or 34/35cc heads for these 32s. These are Promax C-3 Natural heads in Great shape. Thank you