Lifter preload question
- Thread starter JimG
- Start date
turbofabricator
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- Joined
- Mar 7, 2004
ACTUALLY..........I have gained 2 tenths and 2 mph on a 30,000 T-Type (mostly stock, 'cept for chip, filter ect.) by adding .032" thick washers between the shaft and pedistals. The '87's had more factory pre-load than the earlier V-6's to help quiet the valvetrain down a bit. I really was AMAZED that it made THAT much difference. A few dollars worth of washers and it picked up 20-30 hp. You will have to just try it and see if the lifters make more noise. If you install .032" washers (5/16, AN thin washers) and it makes noise, then remove them and go back to stock. You have to let the engine run a few minutes to bleed off/pump up the lifters. I think that it is a good idea to try to optimize EVERYTHING you can on these engines. This isn't rocket science, and only takes about a half hour to do. Just start the engine up with the washers installed and leave the valve covers off. Let it idle for a few minutes and listen for noise. They also make .016" washers, too. They do not move the shaft up the thickness of the washer. It has to conform to the pedistal so it actually moves the shaft up about .035-.038" depending on the position of the moon or something.
Try it, and see what happens. You could do it right and install adjustable pushrods, and get it exact, though. They run about $130 a set.
Try it, and see what happens. You could do it right and install adjustable pushrods, and get it exact, though. They run about $130 a set.Lifter Preload
I would venture to guess that when you installed the washers the lifters wouldn't pump up as much thus preventing premature valve float. The washers caused your motor to RPM higher with better valve control before valve float occurred due to minimum lifter pump up. Like you said the better way is to install adjustable pushrods. Thanks for the info and it is food for thought when running with stock components.
As a side note I remember adjusting my rocker arms with a hydraulic cam for minimum lifter pump up on a Chevy small block to increase its RPM limit way back when.
I would venture to guess that when you installed the washers the lifters wouldn't pump up as much thus preventing premature valve float. The washers caused your motor to RPM higher with better valve control before valve float occurred due to minimum lifter pump up. Like you said the better way is to install adjustable pushrods. Thanks for the info and it is food for thought when running with stock components.
As a side note I remember adjusting my rocker arms with a hydraulic cam for minimum lifter pump up on a Chevy small block to increase its RPM limit way back when.
ACTUALLY..........I have gained 2 tenths and 2 mph on a 30,000 T-Type (mostly stock, 'cept for chip, filter ect.) by adding .032" thick washers between the shaft and pedistals. The '87's had more factory pre-load than the earlier V-6's to help quiet the valvetrain down a bit. I really was AMAZED that it made THAT much difference. A few dollars worth of washers and it picked up 20-30 hp. You will have to just try it and see if the lifters make more noise. If you install .032" washers (5/16, AN thin washers) and it makes noise, then remove them and go back to stock. You have to let the engine run a few minutes to bleed off/pump up the lifters. I think that it is a good idea to try to optimize EVERYTHING you can on these engines. This isn't rocket science, and only takes about a half hour to do. Just start the engine up with the washers installed and leave the valve covers off. Let it idle for a few minutes and listen for noise. They also make .016" washers, too. They do not move the shaft up the thickness of the washer. It has to conform to the pedistal so it actually moves the shaft up about .035-.038" depending on the position of the moon or something.
Ken,
thanks for that! always looking for cheap horsepower. Do you suggest that if i get some valvetrain noise with the thicker washers, one should try again with the thinner (.016") washers?
Another dumb question....how many washers are needed?
thanks again
Jim
turbofabricator
Well-Known Member
- Joined
- Mar 7, 2004
Yes.....what ever you can do to maintain pre-load to around .020" is going to help. On a high HP engine, we use .000-.005" pre-load. It does help. Even a "little" noise is OK. Just don't want to hear an individual lifter tapping. Lay a straight edge across the valve stems, too. If there is a variation of over 010" you will have to go with adjustable push rods to get the pre-load correct.
You will need 6 washers One on each pedistal. You can vary the angle of the rocker shaft by putting washers under the middle and on one end, if there is a variation on the machine work. The machinig tolerance from the factory is fair, at best. That's why every engine needs to be checked carefully. Hence the term "Blue printing"
If $130 won't kill you, go with adjustable push rods. They are time consuming to install correctly, though. You will need two high quality open end 3/8" wrenches. Do NOT use cheap Chinese wrenches or they will strip the lock nuts. I also have a 3/8" crows foot that really helps when adjusting them on the car. They are easy on an engine stand, but a PAIN on the car. It won't be a ten minute job. Good luck.
You will need 6 washers One on each pedistal. You can vary the angle of the rocker shaft by putting washers under the middle and on one end, if there is a variation on the machine work. The machinig tolerance from the factory is fair, at best. That's why every engine needs to be checked carefully. Hence the term "Blue printing"
If $130 won't kill you, go with adjustable push rods. They are time consuming to install correctly, though. You will need two high quality open end 3/8" wrenches. Do NOT use cheap Chinese wrenches or they will strip the lock nuts. I also have a 3/8" crows foot that really helps when adjusting them on the car. They are easy on an engine stand, but a PAIN on the car. It won't be a ten minute job. Good luck.
Lee Thompson
New Member
- Joined
- May 24, 2001
I have a ?
If you used something other than a standard hardware store washer--better explain what you used because I can see tightening down the bolts and snapping the ears off the pedestal. Unless you used a specialty washer you are changing the once 15/16 saddle to a much lesser dia. with the addition of a washer. I actually did this once and broke 2 ears off before I kicked myself for not studying it more before attempting the shimming of the shaft. I use strips of .020 thick shim stock.
If you used something other than a standard hardware store washer--better explain what you used because I can see tightening down the bolts and snapping the ears off the pedestal. Unless you used a specialty washer you are changing the once 15/16 saddle to a much lesser dia. with the addition of a washer. I actually did this once and broke 2 ears off before I kicked myself for not studying it more before attempting the shimming of the shaft. I use strips of .020 thick shim stock.
ChrisCairns
Senior Member
- Joined
- May 24, 2001
I run zero preload on my 109 block. I haven't had it to the track since changing the preload last fall to see if it would give me more horsies so I can't comment on that, but the noise DIDNT increase at all. Still sounds like a sewing machine....
12
turbofabricator
Well-Known Member
- Joined
- Mar 7, 2004
Where do you install the extra six? Last time I installed rocker shafts, there were only THREE bolts on each side. Maybe I better call the guy up and have him bring it back............
:biggrin: <<If you used something other than a standard hardware store washer--better explain what you used because I can see tightening down the bolts and snapping the ears off the pedestal. Unless you used a specialty washer you are changing the once 15/16 saddle to a much lesser dia. with the addition of a washer. I actually did this once and broke 2 ears off before I kicked myself for not studying it more before attempting the shimming of the shaft. I use strips of .020 thick shim stock.>>
Yes, I have seen that happen to another guy, too. He used grade 8 washers because he though it would be better than AN washers (that I told him to use). So, here goes repeating it again. Use AN washers that are .032" thick,(AN960-516L) Pegasus - AN960 Flat Washer (100 pack) or you could also use shim stock, too. DO NOT USE GRADE 8 WASHERS!
Where do you install the extra six? Last time I installed rocker shafts, there were only THREE bolts on each side. Maybe I better call the guy up and have him bring it back............
<<If you used something other than a standard hardware store washer--better explain what you used because I can see tightening down the bolts and snapping the ears off the pedestal. Unless you used a specialty washer you are changing the once 15/16 saddle to a much lesser dia. with the addition of a washer. I actually did this once and broke 2 ears off before I kicked myself for not studying it more before attempting the shimming of the shaft. I use strips of .020 thick shim stock.>>
Yes, I have seen that happen to another guy, too. He used grade 8 washers because he though it would be better than AN washers (that I told him to use). So, here goes repeating it again. Use AN washers that are .032" thick,(AN960-516L) Pegasus - AN960 Flat Washer (100 pack) or you could also use shim stock, too. DO NOT USE GRADE 8 WASHERS!
just bieng a smart@#$!!!!!!
I always prefer to do things the correct way, so I would be interested in the adjustable pushrods.
I am not that experienced with these cars. You describe the pushrod install while in the car as a challenge, is there a tutorial available??
As always, the knowledge and guidance all of you provide is invaluable.
thanks
Jim
turbofabricator
Well-Known Member
- Joined
- Mar 7, 2004
Jim, I'm just two hours south of you.(Ok maybe 3.5 hrs. with the border crossing ) You can bring it over, or call me and I can walk you through it. PM me for a number. I might be installing a set for someone, real soon. Might have to make it a Saturday pushrod fest.
) You can bring it over, or call me and I can walk you through it. PM me for a number. I might be installing a set for someone, real soon. Might have to make it a Saturday pushrod fest.
