swapping to a 12mm head

[colhel59]

i have a VE/1261100L954 pump off of a cummins engine was wondering if it was possible to swap the 12mm head on too my azz pump unsure if the number on this pump thank in advance

[Rabbit on Roids]

looks like its a 6 cyl cummins pump? you need 4 cyl parts for 4 cyl engines.

[colhel59]

definetly a 4 cyl pump i typed the number in wrong VE4/1261100L954 sorry about that and another questoin would i swap the cam plate too its a di engine its coming from.

[Rabbit on Roids]

you need the pump head, springs, cam plate and maybe some other things.

why would you want a 12mm head? your gonna have an effective redline of like 4 grand now. dave cross was making almost 200 horsepower with a stock 9mm head. i would try and make power with a smaller head, and make up for it. so i could still have lots of rpms to play with. thats just my thoughts tho.

[darrenjlobb]

How on  earth do you manage to make 200hp on a 9mm head?.....what else do you do to these things?

[truckinwagen]

I have a 12mm pump in my car, and have no issues with spinning high RPM's.

on a four cylinder you can spin a 12mm VE pump in excess of 6000 RPM before there are issues(thats plenty fast) its the 6-cylinder VE pumps that can only spin 4000RPM

I have a complete 4BTA pump in mine, and the only modification is the governor spring, which allows me to go to 4500RPM, but the pump is capable of much more. runs like a dream, and fuels much better than a turned up 9mm pump(was a real beast until the supercharger blew up)

I say go for it, you wont be sorry.
(I dont have much info about the pump head swap though, sorry, as I swapped the whole pump)

-Owen

[53 willys]

I think 12mm is way to big...least for my car it would be...I'm gonna take my 11mm head off and put my 9mm back on.
my .02

[truckinwagen]

it depends what you want from your car.

I was building an all out grunt machine, so the 12mm pump did really well for me, for a family hauler I would stick with a 9 though.

[colhel59]

I was going for the freebi factor, since i got the pump for free thought maybe i could use this pump to mod mine it was just a thought tho. I still have to swap the azz into my 92 gti, going to keep it stock till shes in there.

[fatmobile]

The 12mm pump injects the same amount of fuel in a shorter stroke.
 Sooo when you are at higher RPMs the proper amount of fuel is injected quicker,..
the plunger doesn't have to travel as far before the breaking pressure is reached.

[truckinwagen]

yep, the same amount of fuel in a shorter injection event.

makes it rattle louder, but it keeps the injection(all of it) in the proper timing under heavy throttle.

again, I would not do a bigger pump head in a family cruiser, but makes a bunch of power.

-Owen

[53 willys]

I cant imagine a 12mm be "good" for anything but a track beast...my 11mm injects more fuel then my turbo can clear at 25psi it's stupid smokey...my 11mm does not run well turned down either..it's all or nothing.
I think my stock 8mm head was better fully maxed out then this 11mm.

mind you this is at 4,500ft above sea level..

pm me if you want a low mile 11mm pump head and springs

and my car is no famliy wagon...it's waaay to smokey for that...it's barely daily driver style at this point...
some one should buy my car from me so I can buy a A3 diesel...lol

[truckinwagen]

I will admit that there is much less pedal definition between a little and alot of fuel, but I plan on changing the distance from the pivot that the throttle cable attaches to the pump arm, so it takes more pedal travel to move the throttle. that should make it easier to drive down low.

honestly most of my drivability issues come from bad motor mounts, not the pump though...

[darrenjlobb]

"rabbit on roids"

So are you running the 12mm camplate as well as head etc?

Was it from a DI engine ? Or IDI?

How does it run....

And how much boost was running to make 200hp from a 9mm head, was that on pure derv? no propane etc?

[Rabbit on Roids]

"rabbit on roids"

So are you running the 12mm camplate as well as head etc?

Was it from a DI engine ? Or IDI?

How does it run....

And how much boost was running to make 200hp from a 9mm head, was that on pure derv? no propane etc?

me, im running a bone stock turbo pump, only has gov mod and LDA messed with. it still has a 9mm head in it. i never built 193 horse with a 9mm, dave cross did. he owns passenger performance. hes kinda a big deal. builds really cool stuff too. i dont know how he did it, but he did on nothing more than diesel and compressed air.

i have nothing more than a stock 9mm head in my pump as of right now. i may play around with a different head in the future, but for now, 9mm is way plenty.

if i were to swap in a larger head, i would use the cam plate, springs, shim, head, everything to make it work right. the pump, springs, shim, and cam plate are all matched specific to the pump head from what ive gathered.