excalibur82

My friend had his engines built this past season . They are 454 stroked to 496 with merlin grumpy jenkins heads custom grind rooler cam m1 procharger without the box he put the hats on it. They made 800hp @ 5800 rpm with the small pulleys and 735 with the stock ones. They were dynoed at nickerson. The boat is a 86 35 cafe racer with trs. When running the boat as soon as it hits 5300 the boost goes to zero and motor drops right to 4000 rpm's . We checked spark , fuel, switch the blowers, intercoolers, carbs and that motor still does the same thing... Could it be valve springs?? Thanks Robert

HaxbySpeed

They are fairly prone to belt slip at higher RPM/boost levels but generally don't drop to zero. May want to check tension. Also, if the motor starts to detonate even a little, or go into valve float it'll really slip the belt and sometimes chuck it. I'd check everything drive related. Make sure your balancer didn't spin on the crank, make sure your drive pulley is tight on the charger, etc. Should be something obvious.

excalibur82

Ran it with the hatch off and never heard it slip or even saw any belt dust. Balancers are brand new. I am Thinking it could be belt slip.

Young Performance

What belt are you running? 8 rib?
Eddie

excalibur82

It is a 8 rib belt.

fantastixvoyage

iTrader: (1)

Could very well be belt slip. Their tensioners can go weak over time so it can appear to be set right but then slip at higher rpm. Don't think they were all that much, might be worth checking into.

excalibur82

It is a 12 rib belt..

ezstriper

look for black dust around...mine looses boost...but not to 0 when belt goes away

articfriends

iTrader: (1)

Did you try the big dia pulley, if it is slip they tend to slip alot less than the full kill ones although the only time my boost ever dropped to zero the key was out of the blower pulley and it was randomly slipping, Smitty

keegan

Valve springs. Sounds like you are blowing it straight into the exhaust.