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Marv D · 01-11-2013, 01:02 AM

Well you may get drivability from a properly workling carb but consider this... to properly size a carb you take the cubic inches (355) times the MAXIMUM RPM you are going to be driving at (lets say you stab this thing and bring it up to 5500 rpm

355x6000 = 2130000
That number divided by 3456 tells you the cfm required ,, = 616cfm. Your 600 Holley was near PERFECT to 6000rpm.

Work the formula backwards and you are going to have to spin that little 355 to 7300rpm to need a 750cfm carb

Here,,, Holleys own page has some good information you should read.

I believe the Captian

had you headed down the right path. You have compression and a igintion tunning issue not a carb issue if the 600 was properly jetted for the elevation you live and drive. If the bolck is a standard 0.025" deck you have 9.6:1 compression. Todays crap fuels will have a hard time supporting that in an iron headed motor. And if the block has been decked, or Zero decked, you could have as much as 10.36:1. NO WAY are you going to run 10.3 with iron heads and anything less than 91 octane,, even then you better not be very agressive with the advance curve. But,, you can lead a horse to water......

01-11-2013, 01:02 AM	#10
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: Holley Question Well you may get drivability from a properly workling carb but consider this... to properly size a carb you take the cubic inches (355) times the MAXIMUM RPM you are going to be driving at (lets say you stab this thing and bring it up to 5500 rpm 355x6000 = 2130000 That number divided by 3456 tells you the cfm required ,, = 616cfm. Your 600 Holley was near PERFECT to 6000rpm. Work the formula backwards and you are going to have to spin that little 355 to 7300rpm to need a 750cfm carb Here,,, Holleys own page has some good information you should read. I believe the Captian had you headed down the right path. You have compression and a igintion tunning issue not a carb issue if the 600 was properly jetted for the elevation you live and drive. If the bolck is a standard 0.025" deck you have 9.6:1 compression. Todays crap fuels will have a hard time supporting that in an iron headed motor. And if the block has been decked, or Zero decked, you could have as much as 10.36:1. NO WAY are you going to run 10.3 with iron heads and anything less than 91 octane,, even then you better not be very agressive with the advance curve. But,, you can lead a horse to water...... __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral.