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All the carb spacers in the world will not get you 5 more mph. Check in the last issue of powerboating mag , Teague had an article on carb spacers.

try a good 850DP and then with a 1" spacer...should pick it up

I have about the same motor. Adding a 2" spacer pulled 20 more hp (back to back pulls). I tried a 750 and was only pulling 715 cfm through the carb. Isn't there a cfm reading on the dyno sheet? I put on a 850 and pulled 757 cfm. I can't remember how many extra hp's that added, but was enough for me to throw down on a couple barry grant 830 mighty demon's. I'm happy now.

Quote:

Originally Posted by redcorvetteman3 (Post 3197732)

Im running a stroked 496 dart alm 310cc heads elderbrock air gap intake full roller motor.Motor dynod wet with acceseries @500 hp 600 trq.peak hp was at 3800.Motor runs and pulls great to about 4800 4900 then thats it. First question Im running a Barry Grant sea demon 750 is this enough carb? Would a carb spacer change my peak hp, trq rpm to a higher rpm. Would I gain any hp overall.If so what combo, Ive read on here people using 2 in spacers one with 4 holes then a open hole.With the hole type should they be the same size as the carb mine are 1.4 dia.

IMHO, if you can get your hands on this Holly 4150HP, works great on 500 C.I. motors. Don't be fooled by the size. This is really an 850 body with a 750 throttle plate. The lower rpm of your motor will really like the increase in velocity. Course, greatly depends on the cam you have. Do you have your cam card?
http://www.summitracing.com/parts/HLY-0-80496-1/

You are wasting your time until you get new exhaust.