[JFM-jr]

Does anybody know how much more fuel a lash cap (stock cam) and a ZL1 low side pump would afford the fuel system. Relatively inexpensive overall but wondering what the results would yield.

[parish8]

I don’t think a lash cap does anything without a cam that has a reduced base circle fuel pump lobe.

You could use some of the instructions listed in this thread https://www.corvetteforum.com/forums...learances.html to determin if in the stock configuration there is some preload on the pump. If there is a lash cap will do nothing but move the stroke up a little and maybe bottom out the pump.

[oldman]

correct

[JFM-jr]

How much more do the stock LT4 injectors flow over the LT1s and do they fit in our fuel rail? They were shockingly inexpensive when I looked.

[Atomic Ed]

This needs to be tried by someone to get to a definitive answer. Fyreant, who wrote the article for the corvette forum, eludes to a gain in fuel flow with even a stock HPFP on a stock cam; 25%?

I had planned on going through his setup to measure my own setup this winter, but broke my wrist and I'm now sidelined until this late spring.

Please give this a try. I'll even offer to split the cost of the Kent-Moore tool between us so we both can do this.

[oldman]

Originally Posted by Atomic Ed

This needs to be tried by someone to get to a definitive answer. Fyreant, who wrote the article for the corvette forum, eludes to a gain in fuel flow with even a stock HPFP on a stock cam; 25%?

I had planned on going through his setup to measure my own setup this winter, but broke my wrist and I'm now sidelined until this late spring.

Please give this a try. I'll even offer to split the cost of the Kent-Moore tool between us so we both can do this.

everything you ever wanted to know:

https://www.lingenfelter.com/product...l#.WmI8dqaWyUk

what is this tool and why do you need it?

[JFM-jr]

Originally Posted by Atomic Ed

This needs to be tried by someone to get to a definitive answer. Fyreant, who wrote the article for the corvette forum, eludes to a gain in fuel flow with even a stock HPFP on a stock cam; 25%?

I had planned on going through his setup to measure my own setup this winter, but broke my wrist and I'm now sidelined until this late spring.

Please give this a try. I'll even offer to split the cost of the Kent-Moore tool between us so we both can do this.

This was why I thought it helped as well. Im not saying he is correct but imparticular are these bits i circled below.

[oldman]

interesting, gets tricky as you will be close to bottoming out the pump. .015 I highly doubt this lash on a lob (lowest acceleration) provides that much pressure.

[parish8]

I think I have what’s needed to see if there is any preload with a lt1 pump and no lash cap. If there is preload I do not see how a lash cap would do anything. I will report back later.

[Atomic Ed]

I was thinking the same thing about trying to check the slop at the bottom of the stroke with a dial gauge instead of the Kent-Moore tool. If there is some slop, a correctly fitted lash cap should yield an overall longer stroke of the pump rod.

Fyreant's posting suggests that he has done this enough times to be confident about his statements. But I would want to measure very carefully before installation of a lash cap in my engine.

[parish8]

Yeah. That tool seem unnecessary. Should be able to get it closer with a dial indicator.

[Atomic Ed]

Thanks for taking on the effort Parish8!

I'm sidelined for quite a while.

[parish8]

I bottomed out the lifter. Both the lt1 pump and a Lingenfelter pump have about 030” of preload.

I put on a lash cap. .080 I think, it came with my cam. Then I topped out the lifter. The lt1 pump completely seated without a gasket. Just for reference The Lingenfelter did not. It stoped about .010 short of seating.

What this suggests to me is a lash cap on a stock cam and stock lt1 pump will just move the plunger up in its stroke but not increase the stroke.

This also shows that the Lingenfelter pump does have a shorter stroke than a stock pump.

[wnta1ss]

Originally Posted by parish8

I bottomed out the lifter. Both the lt1 pump and a Lingenfelter pump have about 030” of preload.

I put on a lash cap. .080 I think, it came with my cam. Then I topped out the lifter. The lt1 pump completely seated without a gasket. Just for reference The Lingenfelter did not. It stoped about .010 short of seating.

What this suggests to me is a lash cap on a stock cam and stock lt1 pump will just move the plunger up in its stroke but not increase the stroke.

This also shows that the Lingenfelter pump does have a shorter stroke than a stock pump.

Your results make sense to me. A lash cap does not increase the stroke. The purpose of it obviously is to correct the preload when a lower-base-circle fuel lobe is used on the cam. If your preload is already correct then it does not help, it's only needed if you have lash instead of preload.