Cam Question

sgarrelts01 · Dec 14, 2009

Since i am going to a Carb set up, what about the cam. I see on CompCam website they have Carb Roller cams and EFI. What is the difference.

Is their select few cams i can use. What would happen if i put a EFI cam in a carb set up.

I don't want to do custom right now. But i was a cam with a very aggressive idle that will help me get to 350-400hp at the rear wheels.

Also a question about the Ford Cams,

What ford cam packs the most power and aggressive idle

If the cams go in order wouldn't the X or Z cam be the biggest

Are they capable of being used with a carb set up.

Tanus · Dec 14, 2009

X or Z will work fine with a carb, ive had both, specs are close but the Z definatly likes a bigger gear ratio( 3.73 at least, preferably 4.10) and higher RPMs like 3,500-6,500. Both idle pretty smooth

Tanus · Dec 14, 2009

oh yeah, carbs suck, if you plan to drive on the street your wallet will hate you.

sgarrelts01 · Dec 14, 2009

Tanus said:
oh yeah, carbs suck, if you plan to drive on the street your wallet will hate you.

Wallet already hates me.

BlackVert · Dec 14, 2009

i think the EFI tag has to do with the valve timing and overlap and the way some computers are programmed. some computers like to squirt the fuel on the back of the intake valve when it is closed. in that case, when there is a good bit of overlap, some of the fuel will go out with the exhaust before it is ignited, which can cause the computer to think that there is a problem.

going the other way (using an EFI cam in a carbed setup) you should not have that problem.

at least, that is my understanding ... if i am way off base here, i hope someone will chime in and set me straight.

i have to ask though ... why go carbed?

sgarrelts01 · Dec 14, 2009

BlackVert said:
i think the EFI tag has to do with the valve timing and overlap and the way some computers are programmed. some computers like to squirt the fuel on the back of the intake valve when it is closed. in that case, when there is a good bit of overlap, some of the fuel will go out with the exhaust before it is ignited, which can cause the computer to think that there is a problem.

going the other way (using an EFI cam in a carbed setup) you should not have that problem.

at least, that is my understanding ... if i am way off base here, i hope someone will chime in and set me straight.

i have to ask though ... why go carbed?

Main reason, its going to save me about 1000. I need a new intake anyway. New MAF, New injectors, and so on.

So using a EFI cam i should be fine in a carb set up.

BlackVert · Dec 14, 2009

mind you, i'm not trying to change your mind or anything, but ...

- a decent carb is not cheap either
- you will also need to do some fuel system work ... pump, pickup, ...
- then there is the distributor/ignition system to be addressed as well

i researched going carb for my 410 and decided that what money i might save would not be worth the headaches of the conversion and lack of tunability.

i'm showing my age here, but back in the day, a carb that was happy in the summer months would be less happy in the winter months unless you tweaked it, and vice-versa.

and while a carbed setup can make great power in that WOT high rpm application, it's generally worse than an EFI setup for the variable rpm (ie - street) application, from both the power/torque perspective and the fuel efficiency perspective.

are you building a race car or one for the street? and do you have to worry about passing emissions for this car?

just some thoughts, not a sermon ...

revhead347 · Dec 14, 2009

Carbs work ok. They start to get cheaper when you get up above the 500hp range, when one would otherwise have to start buying expensive injectors and bigger everything. Other than that, the fuel injection parts have gotten so cheap there really is no advantage. And you can get a Road Demon carb for not a whole lot of money. They aren't the best, but totally decent for the street.

Kurt

sgarrelts01 · Dec 14, 2009

BlackVert said:
mind you, i'm not trying to change your mind or anything, but ...

- a decent carb is not cheap either
- you will also need to do some fuel system work ... pump, pickup, ...
- then there is the distributor/ignition system to be addressed as well

i researched going carb for my 410 and decided that what money i might save would not be worth the headaches of the conversion and lack of tunability.

i'm showing my age here, but back in the day, a carb that was happy in the summer months would be less happy in the winter months unless you tweaked it, and vice-versa.

and while a carbed setup can make great power in that WOT high rpm application, it's generally worse than an EFI setup for the variable rpm (ie - street) application, from both the power/torque perspective and the fuel efficiency perspective.

are you building a race car or one for the street? and do you have to worry about passing emissions for this car?

just some thoughts, not a sermon ...

Won't be driving it past September.

Also i was told for the fuel that i could just get a regulator and adjust the psi down to what it needs to be.

Have a brand new MSD dizzy in a box that im just going to take back an exchange for one so i can use carb.

BlackVert · Dec 14, 2009

sgarrelts01 said:
Also i was told for the fuel that i could just get a regulator and adjust the psi down to what it needs to be.

you might double check this ... you are going from 40psi down to 6-7 psi. that's a big difference.

is passing emissions an issue for you?

so this is a warm weather car ... race only or street?

also, what mods are you planning?

corey97svt · Dec 14, 2009

I have been through all types of **** trying to run a return style regulator and cut 40 down to 6. Sumped gas tank is a must. Stay FI if all possible !!! For your resale values sake. I would much rather have streetability over a couple of extra horses on the top end.

sgarrelts01 · Dec 14, 2009

BlackVert said:
you might double check this ... you are going from 40psi down to 6-7 psi. that's a big difference.

is passing emissions an issue for you?

so this is a warm weather car ... race only or street?

also, what mods are you planning?

I live in Michigan so no emissions.

Street/strip

i am either doing AFR 185 or 205 heads, Its already a 331 stroker, doing the Eddy Air Gap with a most likely holley 750. Going to go 4.10 gears, it has aluminum drive shaft. Cam at this point is unknown. Just trying to find one so my car will rumble but match the intakes rpm range.

and if i have to change the tank or anything like that ill just go to a fuel cell. and run new lines.

LethalInjection · Dec 14, 2009

EFI cam's generally have a wider lobe separation angle. The "carb" cams can run tighter lsa's without worrying about the eec freaking out. They are just more aggressive. You CAN run them in EFI applications, but you have oftentimes have to tune the eec to behave with the tighter lsa and greater overlap. The manufacturers just list them that way so ppl don't freak out if they pay a bunch of money for a cam and it idles all weird. Alot of ppl will blame it on the cam, gripe, and say bad things about it then instead of figuring out how to tune their eec to deal with it. They may not even know they need to do this. Not good advertisement and alot more complaints to deal with.

revhead347 · Dec 14, 2009

EFI cam may also suggest the HO firing order. The firing order really isn't an issue as long as you know what it is, and run your spark plug wires accordingly.

There is no chance of effectively getting that fuel injection fuel pump to work with a carb. You're going to have to pull the gas tank, and put a pickup tube in there, and wire in a different pressure fuel pump. Or sump the tank.

Kurt

sgarrelts01 · Dec 14, 2009

revhead347 said:
EFI cam may also suggest the HO firing order. The firing order really isn't an issue as long as you know what it is, and run your spark plug wires accordingly.

There is no chance of effectively getting that fuel injection fuel pump to work with a carb. You're going to have to pull the gas tank, and put a pickup tube in there, and wire in a different pressure fuel pump. Or sump the tank.

Kurt

What is sumping the tank.

revhead347 · Dec 14, 2009

It's cutting a hole in the bottom of the fuel tank, and welding in fittings for fuel to come out of. So the fuel is extracted from the bottom of the tank, instead of being taken out of the top.

Kurt

sgarrelts01 · Dec 14, 2009

revhead347 said:
It's cutting a hole in the bottom of the fuel tank, and welding in fittings for fuel to come out of. So the fuel is extracted from the bottom of the tank, instead of being taken out of the top.

Kurt

So then i take it i would have to get a external fuel pump, and the brand new trick flow one that is in my take is pointless

revhead347 · Dec 14, 2009

sgarrelts01 said:
So then i take it i would have to get a external fuel pump, and the brand new trick flow one that is in my take is pointless

Either way, the one in your tank can not be reused.

Kurt

sgarrelts01 · Dec 15, 2009

revhead347 said:
Either way, the one in your tank can not be reused.

Kurt

that sucks, less then 10 miles on it. Oh well

LethalInjection · Dec 15, 2009

The fuel pump for the sequential fuel injection in these cars is a higher pressure lower volume pump. Carb setups run MUCH less pressure, but are rated at relatively high volumes. The pump you have now is designed to supply 39+ psi at a certain flowrate. The carb pumps are designed to run below 10.

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