carb question
#11
03-24-2014, 05:50 AM
Might use this calculator from our Aussie friends
Carburettor Calculator, Which Carbie, Carburettor Information Perth - Holley Parts Wholesaler
Also, this Holley article might help,
Carburettor Calculator, Which Carbie, Carburettor Information Perth - Holley Parts Wholesaler
Also, this Holley article might help,
#12
06-21-2014, 02:54 PM
I'd agree, go with 600 to 650. Generally, less is better.
The vast majority of people changing carbs (and intake manifolds) get too much carb.
It does the reverse of what they wanted.
When you sock the gas pedal down, you lose the momentum of gas/air going into the heads, and that momentum is really important. The cam timing and such are intimately tuned for that momentum (it carries more gas/air into the cylinder even though the piston is starting to come back up). Same deal with the cam and the exhaust's velocity -- the exhaust is heading out even though the piston has gone over TDC and is starting to pull in new gas/air. It's really surprising how far you can use momentum to get more power.
When you lose air velocity, then the gasoline mist drops out onto the manifold, and suddenly you find that your car has a really soggy bottom end. When it's spun up to 3,000 - 4,000 RPM, it'll be fine, but a car usually lives a lot of its life basically idling.
That kinda thing makes going to the store for a gallon of milk into a real pain.
I have a 454 LS-6 engine (the 1970 LS-6, not the more recent ones) and it has a 650 on it, and it works beautifully. Why, as long as I don't touch the gas pedal, it's a very friendly car to drive! :-)
By the way, get vacuum-controlled secondaries. When the engine can take more mixture, it'll swing the secondaries open, and it'll be like when Wylie Coyote has just about caught the Roadrunner ... and suddenly the Roadrunner shifts gears and zooms off.
I hope this helps. I learned this the hard way.
-- Thanks,
Dave
The vast majority of people changing carbs (and intake manifolds) get too much carb.
It does the reverse of what they wanted.
When you sock the gas pedal down, you lose the momentum of gas/air going into the heads, and that momentum is really important. The cam timing and such are intimately tuned for that momentum (it carries more gas/air into the cylinder even though the piston is starting to come back up). Same deal with the cam and the exhaust's velocity -- the exhaust is heading out even though the piston has gone over TDC and is starting to pull in new gas/air. It's really surprising how far you can use momentum to get more power.
When you lose air velocity, then the gasoline mist drops out onto the manifold, and suddenly you find that your car has a really soggy bottom end. When it's spun up to 3,000 - 4,000 RPM, it'll be fine, but a car usually lives a lot of its life basically idling.
That kinda thing makes going to the store for a gallon of milk into a real pain.
I have a 454 LS-6 engine (the 1970 LS-6, not the more recent ones) and it has a 650 on it, and it works beautifully. Why, as long as I don't touch the gas pedal, it's a very friendly car to drive! :-)
By the way, get vacuum-controlled secondaries. When the engine can take more mixture, it'll swing the secondaries open, and it'll be like when Wylie Coyote has just about caught the Roadrunner ... and suddenly the Roadrunner shifts gears and zooms off.
I hope this helps. I learned this the hard way.
-- Thanks,
Dave
Thread
Thread Starter
Forum
Replies
Last Post