roller rockers??

[mach1 454]

i have a 1975 20ft mach1 with a 454 chevy and a berkley pump. the engine is basically stock except for the cam and the intake and carb. the cam is a mild cam with a semi lumpy idle(not sure what lift). the intake is a edlebrock topped off with a carter 650 http://free.***boat.net/ubb/frown.gif
i know thats a pretty damn small carb. my question is, would roller rockers make a difference in performane wise and how much horsepower and speed would i pick up? and also would a 750 holly vacume seconderies make a difference? how much speed and horsepower could i pick up if any with the bigger carb and roller rockers? any help would be nice! thanx
mach1 454

[77charger]

rockers arent going to make that much difference esp.for the price.The holley carb will help more i'd prefer the double pumper model over the secondaries.i have a vac seondaries 750 it works well after mods(spring kit and a rear metering block)but i got the carb for free.But if i were to buy new i'd get the dp.

[mach1 454]

Originally posted by 77charger:
rockers arent going to make that much difference esp.for the price.The holley carb will help more i'd prefer the double pumper model over the secondaries.i have a vac seondaries 750 it works well after mods(spring kit and a rear metering block)but i got the carb for free.But if i were to buy new i'd get the dp.
thats what the carb is. its a holly double pumper with vacume secondaries 750. will it make a big differince? thanx
mach1 454

[77charger]

a double pumper is not a vacum secondarie carb.if it is a double pumper it will have mechanical secondaries.If you have the vac.secondarie model get a rear metering block which will allow you to make jetting adjustments to the secondaries.overall it will help.

[Hotcrusader76]

MACH1,
Vacuum secondary carbs (Holley 750 3310's) would work great on your set-up. I agree in that you need to set it up correctly such as secondary metering block reconfig. and some massageing of the idling circuits. Fortunately I have a side business selling rebuilt and modified holley carbs that I build with any color, config., or mods you desire. Go to Ebay and look up user ID tpc_racing or search under Holley 750 Bracket Warrior.

[1stepcloser]

Roller rocker arms will reduce friction in the valve train and (theoretically) increase horsepower. I'm sure you have seen ad's claiming 15-25 HP. I doubt that, But they are a good idea for their wear reducing qualities. However for the money, I would first replace that carb with something like a 750-800 cfm mechanical secondary holley piece. The mechanical secondary version will really wake up your bottom end and midrange when you snap the throttle open. http://free.***boat.net/ubb/biggrin.gif

[rivercrazy]

I'd ditch the Vac Sec carb. Get a duel feed double pumper mech secondary set up of 800-850 cfm. You will notice a difference. http://free.***boat.net/ubb/biggrin.gif

[BOFH]

You never said what you are spinning. Where is all your power? A 454 flows 650 CFM assuming %100 volumetric efficiency. Most stock engines run %70, and highly tuned engines hit about %90, so it is really 450 to 600 CFM.
Just making one thing better will do little to a balanced engine. Roller rockers may help a (very) little, but high ration rockers will help more. With the heads breathing better, you may spin a bit higher, and then a 750 will help as well.
On carbs, you do NOT want a mechanical secondary, unless you are all out race. Vacuum secondaries have MUCH better driveability, and save a bunch in gas. Also, I like Carters over Holly, but that is personal preferance.

[BOFH]

Ooops... All of that was calculated at 5000 rpm. Of course, if you spin it faster, you will use more air. I gues I should have said that in the first post. <DOH!>

[schiada96]

A big advantage roller rockers have is reduced oil temp, that helps alot on valve spring life.