WTF is that loud wisssssss sound (motor)help
 

twin built up 302 motors in my older boat. Edelbrock Alum heads, Scorpion roller rockers Edlebrock performer intake, speed Demon 650's MSD dist, ign box, blaster coils, Comp chain and gears and Comp Cam. Max timming at 36.
Kodiak Alum exhaust and risers.
At max throttles I get a loud hissing sound that comes in at about 4400- to 4800 rpms port motor only. Sounds like a turbo blowing off. Still runs good but loud... then when you pull back throttles this one seems to back off harder. Any ideas?
I swapped carbs that didn't do it.
No hissing from idle up through the rpms so can't tell if there is a vac leak.

how much hp did you get out of the 302's??

Fixx
 

vacuum secondaries? make sure the throttle blade's are opening up all the way..Secondaries could be hanging up on the base gasket??

X2

sweet!!! a thought
 

I'll check.. but that seems to easy in my life.....ha:lolhit:

I dont think thats it
 

I checked to see if the secondaries would open freely by opening the throttle and moving the linkage. Seems to move real easy.. Now the motor wasn't started.... I guess I'll check that next with motor running. Just hard to do on the water with hatch open etc..
I just don't know what else can cause such a loud shhhhhhhh sound at open throttle... And not open throttle from a dead stop.. Only at the highest RPM...
I have all my timing coming in at 1500.. Maybe 36deg is too much. But plugs look good and no pinging..:hitit: