school me on squirter cam colors

[lilredridinghoo]

hi folks,

as i´m going on trying to eleminate some carb misbehaviors (stumbles if i put the pedal down in idle) i wanna change the squirter pump cam.

i bought a set of cams from Quickfuel ... my problem now is:

which color effects what....or is there a ascending order like the white one is the mildest, then comes the blue one etc....

just to get a hint, what will/should happen when i play with the cams

thanks a lot in advance

 

[RustyRatRod]

They change the pump discharge curve. In other words, they can increase or decrease the amount of time and the amount of fuel the pump discharges into the engine. It's generally something you just have to play around with to get the best one for your application. I like upgrading Holleys to the 50cc pump kit. that way, there's no possibility of having a discharge that's too lean. You can always back off the cam, but when you get to the biggest one and need more pump volume, you're kinda stuck.

 

[Rob R]

Change the shooter first...try a 37 and go from there

 

[lilredridinghoo]

ok.. maybe i should have write what i have done first.... and what carb/engine

its a nearly stock 273 with a 525 road demon jr. sitting on a offy 360°intake

i had allways problems, when the engine is hot, if i push the pedal hard to the floor, it nearly dies, and comes back when i lift of my foot.

as i was told that Demon carbs are allways a bit to rich, i changed the squirter first from 31 to 28 and it became some positiv effect, but it´s still present, when it´s really hot outside now in the summertime here in Germany.

therefore my next intension was to change the squirter cam to adjust time and amount of fuel.

 

[RustyRatRod]

That carburetor is too big for that engine. That's most of the problem.

Here's a simple formula:

d = Displacement in Cubic Inches. (d x 2) - 15% = CFM

EXAMPLE: d = 273 (273 X 2) = 546 (546 - 15%) = 464.1 CFM

I bet a 450 would make it run like gangbusters.

 

[lilredridinghoo]

That carburetor is too big for that engine. That's most of the problem.

Here's a simple formula:

d = Displacement in Cubic Inches. (d x 2) - 15% = CFM

EXAMPLE: d = 273 (273 X 2) = 546 (546 - 15%) = 464.1 CFM

I bet a 450 would make it run like gangbusters.

thanks StrokerScamp - i know for this issue.... beside this i wanna keep this carb, as i would put a well-stuffed 318 in it next year.

i´m going also to restrict the idle-feed circuit with smaller inserts and maybe put also slightly taller air-bleeds in it - to make it more suitable for the 273

 

[dgc333]

The formula is calculating the actual air flow potential of the engine with an 85% volumetric efficiency which is where most street engines are.

The 525 CFM rating of the Demon carb is at a 1.5"Hg pressure drop across the carb. If you have that much pressure drop on the engine it's a restriction and the carb is not big enough. You want less than .5"Hg drop on the engine at WOT. The Demon carb will flow much less than 525 CFM at a .5"Hg pressure drop.

I would say the 525 Road Demon is not too big.

If you go to the Holley web page and look up their pump cam kit they have a chart with the different shapes of the flow for the various colored cams. There is not a huge difference between them so changing them is only going to be fine tuning.

 

[abodyjoe]

.
i have a ton of holley info saved on my site. http://www.moparmisfits.com/showthread.php?t=12165