Thanks for the input. I don't have enough room under the hatch for chillers. So that's out as an option. I'll have some testing to do in the spring. If I did change to smaller pulleys, would i see any change in midrange performance.

cocktails,what kind of carbs do u have ???

Or go to gaffrigperformance.com


I dont know if that will resolve ur problem ,but i think they will help either way.

[QUOTE=daredevil;2778512]cocktails,what kind of carbs do u have ???

Or go to gaffrigperformance.com


I dont know if that will resolve ur problem ,but i think they will help either way.[/QUOT

Carbs were original holley 750 Double Pumper. Nickerson Modified to flow about 930CFM

Maybe. Boost may start coming in at slightly lower rpms than before the switch.

Do you have an opinion.?? I always thought my setup wasn't putting out the power that I should. I have had many people over the years tell me how surprised they were that I was only getting 550-600 HP with a 502 and 420 Blower. Even when I dyno'd the engines we just couldn't get the motor to spin more than 5100 rpm on the dyno. That's all she had.
I looked at the Gaffrig arrestors Not cheap. Don't want to spend 1K is it's not going to help a great deal.

Thanks again

I would think you should be at least 600hp and closer to 650hp. The Merc 600SC used a 420 blower. Maybe try comparing your specs to the 600SC specs.

What are your cam specs???????? flat tappet or roller???

[QUOTE=cocktails;2778531]WOW, i think ,,,thats way tooooo much flow for a 420 .

a buddy of mine runs twin 1100 HP with a 8-71 and only has twin 800 on there , putting out 11 # of boost .
Its not about how big it is, its how fast (velociti), they put the air thru the carb.( AIRFLOW, NOT AIRVOLUME )!!!
BIG IS NOT ALWAYS GOOD !!!!

This may sound stupid,,,,,,,,but are u shure they are 420's ????

A friend of mine had the 454 blowers on a 502 engine and thats what happend..........

he could not get up in RPM ,because the blower needet so much power to keep up with the airflow the 502 needs.

We took the blowers of and ran it with a carb ,,,,boom spun the damn thing up to 6 K with no problem.

Checked the blower and shure enuff come to find out its for a 454 insted a 502,,,i cant tell u anymore where to look ,,,but it shure sounds like same problem to me !!!!

The can is a B&M Blower cam made by crane. Flat tappet
283 Int 293 Exh 60overlap
Duration @.050 236 INT. 246 Exh. Overlap 13
Lift @cam .325" Int. .336" Exh.
Lift @valve .553" Int. .571" Exh.
Centerline 114

[QUOTE=daredevil;2779231]When I put this project together I sent the carbs to Nickerson with all of the engine specs and that is what he came up with.
The fuel curves look good on the dyno sheets that I remember.