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HOW TO: Installing a Fuel Pump Lash Cap in an LT1 and Checking for Proper Clearances

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HOW TO: Installing a Fuel Pump Lash Cap in an LT1 and Checking for Proper Clearances

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Old 10-11-2017, 12:27 AM
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Such amazing information!!!!!!!!!!!
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Old 11-20-2017, 09:59 PM
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Ant, first off thank you SO much. You are a godsend. My question is related to finding base of circle. If the base of circle is reduced to give us our +32% fuel lobe, then wouldn't that tool bottom out before reaching it? Or will the tool you mentioned not sit flush at base of circle on a stock fuel lobe?
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Old 11-21-2017, 04:32 AM
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Originally Posted by ChrisG23 View Post
Ant, first off thank you SO much. You are a godsend. My question is related to finding base of circle. If the base of circle is reduced to give us our +32% fuel lobe, then wouldn't that tool bottom out before reaching it? Or will the tool you mentioned not sit flush at base of circle on a stock fuel lobe?
Your logic is not flawed sir. The tool is designed for the stock system, and thus bottoms out properly on a stock fuel lobe. So yes, the tool does bottom out before finding true base of circle on a 32% cam lobe. However, our tool is meant to find where the lobe is and where it isn't. So it isn't critical to measure the base of circle itself, just the lobe. The 32% lobe isn't as different from a stock lobe as you would think either surprisingly.
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Old 11-21-2017, 04:49 AM
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Originally Posted by FYREANT View Post
Your logic is not flawed sir. The tool is designed for the stock system, and thus bottoms out properly on a stock fuel lobe. So yes, the tool does bottom out before finding true base of circle on a 32% cam lobe. However, our tool is meant to find where the lobe is and where it isn't. So it isn't critical to measure the base of circle itself, just the lobe. The 32% lobe isn't as different from a stock lobe as you would think either surprisingly.

then is is possible to skip out on the tool entirely and use cam timing position to locate base of circle and maximum lift for adjusting the lash cap for proper preload and lift?

and again, I just want to thank you for an excellent technical write up that literally has taught me all I know about this subject, and has given me the confidence to tackle a cam swap on my own.

Last edited by ChrisG23; 11-21-2017 at 04:52 AM.
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Old 11-21-2017, 07:33 AM
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Originally Posted by ChrisG23 View Post
then is is possible to skip out on the tool entirely and use cam timing position to locate base of circle and maximum lift for adjusting the lash cap for proper preload and lift?

and again, I just want to thank you for an excellent technical write up that literally has taught me all I know about this subject, and has given me the confidence to tackle a cam swap on my own.
First off, thank you! I am always trying to help the community!

Based on your question, I went back and re-read my guide from the standpoint of “do I need the special tool or not”. In my opinion, it’s still prudent to use the tool. The tool is used to find base of circle, as well as the highest point of the lobe later in the process. Could you use something different? Perhaps. But the tool fits into the hole in the valley cover perfectly and stays perfectly upright when you are turning the cam to locate the highest point. If you used a flat piece of metal or something similar, it may not yield accurate results. For the cost of the tool it’s not something I would chance personally. Plus you can always sell the tool when you are done using it.

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Old 12-16-2017, 08:11 PM
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I am installing a Texas Speed cam with 32% fuel lobe, they supplied a lash cap. I have my valley cover off. It looks like there is a factory lash cap on the end of the push rod. The cap wobbles like it is mounted on a ball stud? I have not tried to pry it off. The new cap might fit over it/on top of it, but would take some force. Does this sound right?
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Old 12-16-2017, 08:31 PM
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Originally Posted by SteveOO View Post
I am installing a Texas Speed cam with 32% fuel lobe, they supplied a lash cap. I have my valley cover off. It looks like there is a factory lash cap on the end of the push rod. The cap wobbles like it is mounted on a ball stud? I have not tried to pry it off. The new cap might fit over it/on top of it, but would take some force. Does this sound right?
Thanks Steveoo
Do not try removing the wobbly top. That is part of the HPFP lifter and is NOT a lash cap. Your lash cap will fit on top of it..

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Old 12-16-2017, 08:59 PM
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Originally Posted by FYREANT View Post
Do not try removing the wobbly top. That is part of the HPFP lifter and is NOT a lash cap. Your lash cap will fit on top of it..

Ant
How much force should it take? I am concerned if it is not seated it will distort my pre-load measurements. It does not just slide on over the lifter.
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Old 12-16-2017, 09:30 PM
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Originally Posted by SteveOO View Post
How much force should it take? I am concerned if it is not seated it will distort my pre-load measurements. It does not just slide on over the lifter.
Mine had the same "tight fitment". I chose to use some emery cloth and sand down the inner rim of it to allow it to fit better.
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Old 01-06-2018, 09:07 PM
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Has anyone else taken the time to do this? I have the smaller lashcap ready to go but can't find that kent moore tool. I emailed 3 people about the tool, hopefully ill hear something back on Monday.

If more than 1 person has done this procedure and also come up with the .060 lash cap being the correct one id just install that cap, but would prefer several others confirming the same results first. Otherwise ill just wait on the tool

Last edited by 555ctsv; 01-06-2018 at 09:08 PM.
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Old 01-07-2018, 09:49 AM
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Originally Posted by 555ctsv View Post
Has anyone else taken the time to do this? I have the smaller lashcap ready to go but can't find that kent moore tool. I emailed 3 people about the tool, hopefully ill hear something back on Monday.

If more than 1 person has done this procedure and also come up with the .060 lash cap being the correct one id just install that cap, but would prefer several others confirming the same results first. Otherwise ill just wait on the tool
I will sell the kent moore tool now that I am done with it. I paid $50.
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Old 01-07-2018, 12:35 PM
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Originally Posted by SteveOO View Post
I will sell the kent moore tool now that I am done with it. I paid $50.
That would be awesome! Pm'ing now

I think we had something like this going around back in my ctsv days. I bought a Hawk balancer install tool and it just kept getting sold around the forum. Very helpful
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Old 01-12-2018, 09:04 PM
  #33  
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Thanks to SteveOO for selling me that Kent Moore tool. In the middle of all this right now. Trying to rotate the engine without having to move the steering rack
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Old 01-14-2018, 12:44 AM
  #34  
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Well i got it all done today. Same results, the .060 cap was the winner for me (and the onlynsize i tried). I also reinstalled my supercharger today, it was off being rebuilt.

Car is running great so far but haven't driven it much as im on an NA tune right now.

Hopefully this proves to be a good idea long term
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Old 01-14-2018, 02:38 AM
  #35  
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Originally Posted by 555ctsv View Post
Well i got it all done today. Same results, the .060 cap was the winner for me (and the onlynsize i tried). I also reinstalled my supercharger today, it was off being rebuilt.

Car is running great so far but haven't driven it much as im on an NA tune right now.

Hopefully this proves to be a good idea long term
Great to hear you got it all done and that she’s running great! Mines still running great too 2500 miles later.

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Old 01-15-2018, 09:09 AM
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Originally Posted by 555ctsv View Post
Well i got it all done today. Same results, the .060 cap was the winner for me (and the onlynsize i tried). I also reinstalled my supercharger today, it was off being rebuilt.

Car is running great so far but haven't driven it much as im on an NA tune right now.

Hopefully this proves to be a good idea long term
Hey Kenneth! What do you have up your sleeve these days?? Rebuilding the blower?
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Old 01-16-2018, 10:56 PM
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Originally Posted by C7&7 View Post
Hey Kenneth! What do you have up your sleeve these days?? Rebuilding the blower?
Hey man congrats on your recent upgrades!

The day before that last 1/2 mile race in November I went to change my blower oil and found some metal flakes in it. Metal bits plus the rain and i decided to just skip the event. Sent the blower off to be inspected and Vortech said it needed to be rebuilt.

I had been hearing a noise for a while, turns out that noise was fuel related but im still glad i got the blower freshened up as well.
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Old 01-16-2018, 11:03 PM
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Originally Posted by 555ctsv View Post
Hey man congrats on your recent upgrades!

The day before that last 1/2 mile race in November I went to change my blower oil and found some metal flakes in it. Metal bits plus the rain and i decided to just skip the event. Sent the blower off to be inspected and Vortech said it needed to be rebuilt.

I had been hearing a noise for a while, turns out that noise was fuel related but im still glad i got the blower freshened up as well.
Dis you get the lash cap installed and did it correct the noise?
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Old 01-17-2018, 12:14 AM
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Originally Posted by FYREANT View Post
Dis you get the lash cap installed and did it correct the noise?
Yes sir, but i haven't put any miles on the car yet. Gotta find time to get it up to the shop to load the blower tune


A while back the sound went away for a couple weeks by just replacing that low psi fuel feed line with the check valve in it; but the sound eventually came back. This time I put in the lash cap, a new lt4 pump, and another new low psi feed line; so im eager to get some miles on it to see if the sound comes back. I can't see why that little oem check valve started making noise on me twice now

This is the service bulletin mentioning the low psi feed line issues
http://www.corvetteactioncenter.com/...2017-1338.html

Last edited by 555ctsv; 01-17-2018 at 08:18 AM.
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Old 05-17-2018, 02:43 PM
  #40  
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I just wanted to say thanks for this great writeup. I installed an LT4 fuel pump on my stock cam and stock valley cover LT1. I measured for preload and max lift clearance using this guide and found it very helpful. FYI the pump was perfectly fine and did not require a lash cap.

Oh, and since I didn't have the tool for checking lobe location, I used a large socket with an outer diameter just smaller than the hole size, then I put a short extension into the socket from the wrong end (insert the extension from the size that typically goes onto the bolt/nut). I then used this as my height tool. i put the extension side down because it was small enough to sit on the lifter plunger, and then the socket was low enough to touch the opening walls and stay in place. I wrote on it with a marker for measurements. I had to use the extension because when I tried just dropping the socket in there alone, the plunger went through the 1/2" opening for the wrench and wouldn't ride the lifter.

Last edited by StarFox; 05-17-2018 at 02:48 PM. Reason: Info about tool height checker replacement
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