Moparts

Lifter preload on a 340?

Posted By: EvilScamp

Lifter preload on a 340? - 01/01/12 07:41 PM

I have valvetrain noise in my 340 and starting with the simplest first to try and locate the noise, i want to make sure that the push rods are the correct length but don't know what the preload of the lifters should be, any help would be appreciated.
Posted By: fourgearsavoy

Re: Lifter preload on a 340? - 01/01/12 07:48 PM

Quote:

I have valvetrain noise in my 340 and starting with the simplest first to try and locate the noise, i want to make sure that the push rods are the correct length but don't know what the preload of the lifters should be, any help would be appreciated.


Are you using adjustable rockers?
Gus

Attached picture 6996024-mysavoy.jpg
Posted By: 72Swinger

Re: Lifter preload on a 340? - 01/01/12 07:56 PM

I think I remember a Pure Stock guy using .020 preload. But maybe it was .010??? Bob Karashain or somethin.....
Posted By: EvilScamp

Re: Lifter preload on a 340? - 01/01/12 09:13 PM

Quote:


Are you using adjustable rockers?
Gus



No just stock rockers.
Posted By: TJP

Re: Lifter preload on a 340? - 01/01/12 09:39 PM

most camshaft / lifter manufacturers recommend .020 to .040 preload. there are several different ways to accomplish this with adjustable rockers being the easiest IMO.
Posted By: 6PakBee

Re: Lifter preload on a 340? - 01/01/12 10:35 PM

Quote:

most camshaft / lifter manufacturers recommend .020 to .040 preload. there are several different ways to accomplish this with adjustable rockers being the easiest IMO.



I always tell people 0.030 if they ask because it's something you can easily check with a spark plug wire gauge. Intake has to be off of course.
Posted By: RapidRobert

Re: Lifter preload on a 340? - 01/02/12 01:18 AM

Always noisy or recently? If always as said check preload. If recently while idling press straight down vertical on each rocker arm on the lifter end with the wooden handle of a hammer & the offender will get noticeably quieter. Remove it & dissassemble/clean it & reinstall but dont pump it full of oil ahead of time, preoil the whole system. Still bad get a new lifter and go thru the cam breakin procedure. On mockup make sure the new lifter is free in its' bore by cleaning the bore/lifter w brake kleen then lightly oiling both w WD40 then raise the lifter off of its' lobe with your finger then release it & it must fall back onto the lobe with a resounding "thunk" and if not the bore/lifter is too tight & must be honed (or try another lifter).
Posted By: Dave Watt

Re: Lifter preload on a 340? - 01/02/12 01:36 AM

Quote:

Always noisy or recently?


I'm curious too.
It could be the rocker shafts are incorrectly installed which doesn't allow oil to the rocker arms.
How is your oil pressure?
Posted By: RoadRunnerJD

Re: Lifter preload on a 340? - 01/02/12 03:46 AM

Quote:

Always noisy or recently? If always as said check preload. If recently while idling press straight down vertical on each rocker arm on the lifter end with the wooden handle of a hammer & the offender will get noticeably quieter. Remove it & dissassemble/clean it & reinstall but dont pump it full of oil ahead of time, preoil the whole system. Still bad get a new lifter and go thru the cam breakin procedure. On mockup make sure the new lifter is free in its' bore by cleaning the bore/lifter w brake kleen then lightly oiling both w WD40 then raise the lifter off of its' lobe with your finger then release it & it must fall back onto the lobe with a resounding "thunk" and if not the bore/lifter is too tight & must be honed (or try another lifter).


Very good response! Comp Cams says the lifters should be set at .030-.040 for optimal performance or 1/2-3/4 turn past 0 with adjustable rockers. You can loosen the preload by shimming the shafts with the stamped rocker arms but if you have to increase the preload for one lifter, you have a different problem than the length of the pushrods.
Posted By: EvilScamp

Re: Lifter preload on a 340? - 01/02/12 03:58 AM

Always noisy sounds almost like a bearing but it's definately in the valvetrain. Can't pinpoint exact location of noise, when it's running and standing on the left side it sounds like the noise comes from the right when standing on the right sounds like it's on the left side.
Tryed the old broomstick to ear against the valve covers but still can't pinpoint it.
The rocker shafts are definately installed correct i even pulled them off to double check.
Oil pressure is about 60 pounds.
Posted By: MR_P_BODY

Re: Lifter preload on a 340? - 01/02/12 04:06 AM

Quote:

Always noisy sounds almost like a bearing but it's definately in the valvetrain. Can't pinpoint exact location of noise, when it's running and standing on the left side it sounds like the noise comes from the right when standing on the right sounds like it's on the left side.
Tryed the old broomstick to ear against the valve covers but still can't pinpoint it.
The rocker shafts are definately installed correct i even pulled them off to double check.
Oil pressure is about 60 pounds.



Did you change cams... if so you most likely need
new push rods... they cut the base down farther to
give more lift
Posted By: ThermoQuad

Re: Lifter preload on a 340? - 01/02/12 01:20 PM

The type of oil used makes a difference in valvetrain noise. This was made very evident by changing the oil in 2 high perf engines that were "noisy" but ran well.

Use an oil flat tappet cam specific.

Here is a manufacturers guide to preload.
This may be the best advice you will find.

Attached picture 6997528-lifterpreload.jpg
Posted By: RoadRunnerJD

Re: Lifter preload on a 340? - 01/02/12 07:06 PM

Quote:

Always noisy sounds almost like a bearing but it's definately in the valvetrain. Can't pinpoint exact location of noise, when it's running and standing on the left side it sounds like the noise comes from the right when standing on the right sounds like it's on the left side.
Tryed the old broomstick to ear against the valve covers but still can't pinpoint it.
The rocker shafts are definately installed correct i even pulled them off to double check.
Oil pressure is about 60 pounds.



Pull the valve covers check the preload at the base circle on each cam lobe by turning the pushrods and seeing if there is any decent tension on the pushrods? You could also buy a set of adjustable rocker arms and set your preload with them. There are usually some used 273 adjustables for sale in the Moparts A engines. Get the correct shafts with them if you do.
Posted By: scratchnfotraction

Re: Lifter preload on a 340? - 01/02/12 08:20 PM

how many miles on those rockers/PR/shafts??

how many miles on lifters and cam?

are the lifters in correct order on the shaft for offset?

I have had many make noise that you could not track down when no exhast leak was confirmed first.

eggshaped rockers with a worn thin fulcum or grooves on the shafts,rocker cups and PR ends worn down,lifter cups worn,lifters pluged up solid with carbon deposits...or combo of all of the above have been the culprit.

not to mention the oil and a flat tappet cam wear issues the last few yrs.

the hydro lifter is self adjusting as long as it/valve train is within specs,wear down any of the valve train and it can get to haveing the lifter rattle/ticking/tapping at any or all of the contact wear spots.

once the lifter pumps up to max hieght,it cant adjust for mech failure.

dont forget,you have a t-chain/fuel pump along with a dist/itermed shaft running off the cam and will add to the mech sound of a engine as it idles. add in the wear of those items and you multiply the mech sound chasing

Posted By: EvilScamp

Re: Lifter preload on a 340? - 01/04/12 01:43 AM

Not sure what the lift and duration of the cam is it was in the car when i got it, i do know it's a bit bigger than stock you can hear the lope in it when it's running.
I would love to get a set of adjustable rockers but money is at a minimum right now i just want to fix what i have.

Next question is what is the easiest way to check the preload, i figure i'm gonna have to pull the intake off.
Posted By: Dartcuda

Re: Lifter preload on a 340? - 01/04/12 03:24 AM

Remove left valve cover . Cylinder #1 at TDC , using a straight edge scribe a line on #1 pushrods. Loosen rocker shaft to no preload , scribe a second line . Measure distance between lines = preload .
Posted By: EvilScamp

Re: Lifter preload on a 340? - 01/05/12 12:53 AM

Thanks everyone for the help it's much appreciated!
Hopefully i can figure the noise out now!
Posted By: RapidRobert

Re: Lifter preload on a 340? - 01/05/12 01:58 AM

post the outcome!
Posted By: EvilScamp

Re: Lifter preload on a 340? - 01/15/12 10:04 PM

Ok i got the push rod tool from Summit to measure the push rods, it looks like the push rods are .050 to long!
Apparently they are collapsing the lifters to far but not enough to bend the push rods, could this make the sound that i been hearing?

The rods i pulled out are 7 1/2 inches long and according to the tool with the .030 preload accounted for i need rods that are 7 7/16 long.
I'm thinking now that the heads are shaved and/or the block has been decked and he just reused the factory rods.

I don't know exactly what has been done to this engine but i do know that the previous owner did some pretty crappy work on other parts of the car and cut alot of corners, apperently he did the same with the engine work!
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