thoughts on runninig stock 12v cam

crewcabxlt

crewcabxlt

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Apr 1, 2008
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tempted to build another p-pump motor-more for efficiency and towing. i want to use a stock 12v cam so i can run mechanical lift pump. this needs to be a budget build . do i give up much performance doing this?
 
My experience with stock cams on high hp engines is not good. The heavy valve springs definitely take a toll on stock cams. Throw rpm's in the mix and it turns questionable.

I'd put a cam in it(if you can afford it) while it's out and also just run a good mechanical lift pump off the front cover but that gets a little pricy. It all circles back to budget.
 
thanks for reply-not a hi h.p. build, ive got all the stuff to put one together except fuel supply. dont want to run an electrical lift pump, dont want to buy an aftermarket cam really either.if performance is hurt too much ill put in a low mileage 12v cam. anyone else done this?
 
So you want to run a 12v cam with a 24v head? You've got homework to do!
 
maybe not enough homework-not an expert. ive built 2 p-pump 24v motors,both have run excellent but i sold one and the other was for a friend. i know the 24v cam has some differnces that make it better but how much ? ive got a low mileage 01 and all the p-pump stuff to build it but dont want to buy a cam or lift pump if the 12v cam will work decent.
 
yes you can run a 12valve cam in a 24valve my cousin has done 2 like that so to elminate the electric fuel pump
However i plan on running a waterman fuel pump off the front cover on my fummins
 
You can run a 12 valve cam in your 24 valve. The only difference is the fuel pump lobe for the lift pump which is what you are after anyway. Also I think the 12 valve cam has slightly less lift, which you would probably never notice on a low hp build.
 
Minutely smaller lift, and a narrower LSA compared to the VP cam.
 
The 24 valve cam is on 108 LSA while the late 12 valve is on a 102 LSA. The worst is the CR which is on a 98 LSA

Most aftermarket cams give you the option of a fuel pump lobe. All of the ones I grind start with the fuel pump lobe on the UGL (unground lobe) cores.
 
crewcabxlt said:
tempted to build another p-pump motor-more for efficiency and towing. i want to use a stock 12v cam so i can run mechanical lift pump. this needs to be a budget build . do i give up much performance doing this?
Click to expand...

Use the stock cam.
 
If you have the motor apart, a cam is one of the biggest bangs for the buck in improving airflow and reducing EGT.
 
A cam can change spool up and help slightly with egt's but on a budget it shouldn't be very high on the list.
 
Just stick with a 12V. A ppump 24V offers no efficiency or budget advantages over a 12V.
 
thanks for the responses. ive built a few motors and pulled a few cams, doesnt bother me in or out of the truck. i tried a regrind a few years ago and wasnt too impressed. i must confess im trying to keep it cheap because even though ive built p-pumped 24v for other peaple and they really run well i still dont see a huge advantage over a properly built 12v , i have a great 24v engine and a 913 pump + all the parts and maybe want to do more because i can.
 
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