robert miller

Thanks buddy.

WS6JJP

I wanted to bring this back up again. So obviously you want the HPFP to have some kind of preload as always talked about on here but exactly how much preload are we looking for? I seen mittens mention.030, is this a good amount?

FYREANT

proper preload depends on the application. It is best to ensure you have some preload when on base of circle, but not so much to the point that it bottoms out the shaft on the eccentric. This should always be measured for each and every build.

WS6JJP

Thanks for the reply, right now I have .039” but I’m wondering if it should be more (as you said as long as it’s not bottoming out the pump). This is with a stock LT4 HPFP and an aftermarket cam with a 32% fuel lobe.

mittens

From what I gather, in general, you need the lash cap on the LT1 pump, and don't need it on a LT4 pump. to make use of the larger fuel lobe.

but messure for sure.

WS6JJP

Yeah i definitely measured and the .039 preload is where it’s sitting now with an LS7 lash cap. I’m just wanting to know what the correct amount of preload is. I’ve heard .030 all the way to .060. Anyone know for sure?

FYREANT

Thats not quite accurate. When I installed my cam with 32% lobe and LT4 HPFP a lash cap was -required- or I would have had zero preload.

WS6JJP

Do you remember what your preload measurement amount was by any chance? I know you’re supposed to have some kind of preload on the pump but no one ever says exactly what amount is correct. It’s always check your preload but nothing specific.

16C7Z51

I just ordered a complete cam package from Aaron at BTR stage 2 with 38% lope, the kit didn't come with a cap so I called BTR they sent me an 8mm cap.

LT1

FYREANT

I do not. Im sure there is an “optimal” amount of preload, but im not sure that it will matter nearly as much having some preload vs not..

WS6JJP

I got ya. I’ll keep looking / asking around. I’ll report back if I get an answer

Jaycajun

That is interesting. I recently called BTR about a Gen V LT1 cam that has a 38% fuel lobe and he specifically stated it did not require a lash cap. I asked him about the lack of any preload and he stated several times "No lash cap is required". Confusing.....

FYREANT

I think the multiple different stories confirms, they don’t really know

Ant

JHEBERT

If you don’t use the lash cap, the extra lift fuel lobe will be of no benefit, as the the extra lift comes from a smaller base circle. I’ve brought this up several times here and elsewhere. Talk to the cam manufacturer, not the guy selling the parts. Better yet, talk to the guys building and tuning them

John

FYREANT

Exactly. This is exactly why I wrote the measurement guide for the forum. Everyone still questions me about it because such and such reseller said the lash cap isn’t necessary. Why? Cuz they sell parts. They have no effin idea.

Ant

16C7Z51

Exactly right. This is why I ordered the cap, oh and a 160 degree thermostat

mittens

Good luck with that 160 Therm..

I installed one with my cam swap... and pulled it back out. Changed the fan seettings back as well. we tried every setting in HP tuners, and that does not address the issue.

on the C7 the dash changes as the car warms up... with the lower threm it never gets to the 175 mark normally.. which results in the Dash always showing you its not all the way warm, a lower red line, and the Shift lights happen WAY early....

was more annoying to me to have the dash all messed up then the 20 degrees in cooling.

I have a thread on the issue as well.

16C7Z51

Thanks for that information, Ill keep the stock thermostat in. We have the exact same cam kit, kooks headers set up. Can you inform me on anything else’s that may help with my install in a few weeks?

Higgs Boson

I can tune it without an issue. Who is tuning your car for the 160? I put a 160 in three of my personal C7s so far.