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-   -   need help figuring out setting up rocker arm geometry (http://www.hotrodders.com/forum/need-help-figuring-out-setting-up-rocker-arm-geometry-221610.html)

inkfreak1976 07-12-2012 09:19 PM

need help figuring out setting up rocker arm geometry
 
im building a 351 clevland, .030 over, flat top pistons. im running 60cc aussie heads. the problem im having is, im trying to find the best push rod length, but im having a problem with the push rod popping out of the cup on the rocker arm, when its rolled over, i can tell that its rubbing on the rocker arm and is getting pushed out. ive tried many different push rod lengths in order to correct this issue. im thinking if i grind off some of the area where its rubbing that would fix this issue but i want some different opinions.
im using comp 17045-16 1.73 rocker arms, arp 100-7101 (7/16-20-1.90) and manly guide plates 42163-8.
im looking for other reasons that this would happen if any. let me know what ya think thanks

S10 Racer 07-12-2012 10:06 PM

What cam lift are you using? I would not grind on the rockers.:nono: A picture of your setup showing the issue would help.

inkfreak1976 07-13-2012 12:58 AM

3 Attachment(s)
the cam specs ; intake: cam lift.370 valve lift .629// exhaust: .374-v .636 with a 108 lobe center 83 deg overlap. this is a solid flat tappet cam, new with new lifters running a timing gear at 0 deg timing marks. ( stock marks ) pic one is of set up of no.1 ex valve @ zero lash, #2 pic is of full open and shows the problem how its coming out of the cup. #3 is of the lifter sweep at 4 full revolutions. i had to push it back into place so it didn't pop out of the arm cup. ive tryed this at many differnt push rod lengths to get a near center this is the closest that ive gotten to center for the sweep.
i dont want to grind into the rocker arm if all possible, but i have yet to find any other solution at this time, when it poped out earlyer i got out some feeler gauges and a .0120 sliped in ther so i figure at about .0240 that should give enough clearence if i have to grind on it. what ya think.

S10 Racer 07-13-2012 03:15 AM

What diameter pushrods are those? If they are 7/16, you might try 3/8". Use chrome moly pushrods w/heavy walls to prevent flex.

ap72 07-13-2012 05:57 AM

Quote:

Originally Posted by inkfreak1976 (Post 1573381)
the cam specs ; intake: cam lift.370 valve lift .629// exhaust: .374-v .636 with a 108 lobe center 83 deg overlap. this is a solid flat tappet cam, new with new lifters running a timing gear at 0 deg timing marks. ( stock marks ) pic one is of set up of no.1 ex valve @ zero lash, #2 pic is of full open and shows the problem how its coming out of the cup. #3 is of the lifter sweep at 4 full revolutions. i had to push it back into place so it didn't pop out of the arm cup. ive tryed this at many differnt push rod lengths to get a near center this is the closest that ive gotten to center for the sweep.
i dont want to grind into the rocker arm if all possible, but i have yet to find any other solution at this time, when it poped out earlyer i got out some feeler gauges and a .0120 sliped in ther so i figure at about .0240 that should give enough clearence if i have to grind on it. what ya think.

Your first problem is that your setting it up wrong, forget about the "centered pattern" you want th smallest pattern. You'll either need lash caps or shorter pushrods to get that.

Your pushrods are too long.

Your rocker arms could be way wrong too but id start with a much shorter pushrod.

Richiehd 07-13-2012 07:44 AM

Quote:

Originally Posted by ap72 (Post 1573397)

Your rocker arms could be way wrong too but id start with a much shorter pushrod.

Agreed. Pattern doesnt look all that bad, but you are atarting way high in the rocker. Shorter pushrod will bring the rocker closer to the head, further down on the stud.

cobalt327 07-13-2012 08:02 AM

Quote:

Originally Posted by inkfreak1976 (Post 1573353)
im building a 351 clevland, .030 over, flat top pistons. im running 60cc aussie heads. the problem im having is, im trying to find the best push rod length, but im having a problem with the push rod popping out of the cup on the rocker arm, when its rolled over, i can tell that its rubbing on the rocker arm and is getting pushed out. ive tried many different push rod lengths in order to correct this issue. im thinking if i grind off some of the area where its rubbing that would fix this issue but i want some different opinions.
im using comp 17045-16 1.73 rocker arms, arp 100-7101 (7/16-20-1.90) and manly guide plates 42163-8.
im looking for other reasons that this would happen if any. let me know what ya think thanks

Apparently, this isn't all that uncommon, rockers may need relieved as you mentioned- Ford 335 "Cleveland" Series Engine Forum: Broken Rocker Arms

http://i81.photobucket.com/albums/j2...h/fullshot.jpg

ericnova72 07-13-2012 08:50 AM

Most all Jesel rockers(shaft rockers) have a cut to clear the pushrod for the problem you have, but I woulddn't try it with the cheaper version Cast(:pain:) body rocker you have.

A billet aluminum rocker you could cut a clearance relief in.

Definately looks like you need lash caps to make the end of the valve longer.

As has been mentioned, go for the narrowest pattern on the valve tip, don't worry so much about centered, if it is off center but makes the narrowest pattern, that is where it should be.

Go here and read this about correct geometry, and why the method given by many big companies is incorrect http://www.aera.org/ep/downloads/ep1...2010_20-30.pdf

Irelands child 07-13-2012 09:25 AM

I think a part of your problem is that the 17000 series of Comp Cams roller rockers is that they are kind of a 'fits all engines' basic casting with minor mods to make it fit your engine vs a Chevy. With the very large and bulky casting, they make up much of their strength by sheer size.

Comp Cams has a pretty good forum - CPG Nation Forum - Powered by vBulletin - which I used when I had some problems a while back.

inkfreak1976 07-13-2012 02:37 PM

i think im going to mess around a bit with maybe shorting the rod a bit witch is 5/16 ( someone had asked before) and i also think im going to call comp. ive seen a few articles saying that its not uncommon to grind a little clearance out for the push rod play. but im gonna do some more playing around first.

1BAD80 07-13-2012 04:02 PM

valve train geometry from CompCams
COMP CamsŪ - Sorry...

advice, get rid of the 2 piece pushrod tips and get the one piece .

You will find them braking off and going down into the motor.
I had this happen to me along time ago along with some other's esp with lift over .500

Only grind at last resort & look at the obvious as that is the one that bites ya

inkfreak1976 07-13-2012 09:09 PM

Quote:

Originally Posted by 1BAD80 (Post 1573532)
valve train geometry from CompCams
COMP CamsŪ - Sorry...

advice, get rid of the 2 piece pushrod tips and get the one piece .

You will find them braking off and going down into the motor.
I had this happen to me along time ago along with some other's esp with lift over .500

Only grind at last resort & look at the obvious as that is the one that bites ya

thats just one that i made a adjustable push rod out of one of the old ones, because i was told i needed a longer push rod and the adjustable on that i had wasent long enough, so i took a old one cut it, drilled it and tapped it got some threaded rod and put one together. thats why im going threw all this is to get the proper length of push rod to order.

inkfreak1976 08-01-2012 06:34 PM

ok its been a while since ive posted, on here on this subject. but i thought that id let people in on where im at. ( not any farther than before) ive tryed probly every method that ive found on the net includeing the ones convenently posted on her from comp. and others thank you. but heres the problem in order for me to o what there telling me to do by lineing up trunion with the center of the valve stem. the push rod length is 8.936 and thats getting it really damn close but not perfect, but when rolled over this is where the push rod is still getting pushed out of the cup, altough its not binding up i would want to try and start my engine like this. and also the retaining nut isnt getting to many threads to my likeing.
but ive noticed and was wondering if anyone would know about the reason for this, but i meusured the valve stems to the keepers because ive noticed that the intake is larger .1120 to the exaust @ .0590 and was wondering if this could be the reason im haveing so many problems.
so from there i have no idea, ive checked everything i checked the cam the timeing of the cam, i check to make sure that wasent on crack. i just cant get this thing to line up. i got some really nice set ups, but the sweep is more to the intake side i would say it marks on the edge. not even close to the center of the stem. what should i do here should i take my heads back to the machenist and ask what the hell, like most of my freinds are saying or am i doing something wrong.

ap72 08-01-2012 08:36 PM

Quote:

Originally Posted by inkfreak1976 (Post 1579250)
ok its been a while since ive posted, on here on this subject. but i thought that id let people in on where im at. ( not any farther than before) ive tryed probly every method that ive found on the net includeing the ones convenently posted on her from comp. and others thank you. but heres the problem in order for me to o what there telling me to do by lineing up trunion with the center of the valve stem. the push rod length is 8.936 and thats getting it really damn close but not perfect, but when rolled over this is where the push rod is still getting pushed out of the cup, altough its not binding up i would want to try and start my engine like this. and also the retaining nut isnt getting to many threads to my likeing.
but ive noticed and was wondering if anyone would know about the reason for this, but i meusured the valve stems to the keepers because ive noticed that the intake is larger .1120 to the exaust @ .0590 and was wondering if this could be the reason im haveing so many problems.
so from there i have no idea, ive checked everything i checked the cam the timeing of the cam, i check to make sure that wasent on crack. i just cant get this thing to line up. i got some really nice set ups, but the sweep is more to the intake side i would say it marks on the edge. not even close to the center of the stem. what should i do here should i take my heads back to the machenist and ask what the hell, like most of my freinds are saying or am i doing something wrong.

For the second time, forget comp's method, its wrong. You need the pushrod that gives the smallest pattern. What you're doing makes it way too damn long.

Next your rocker arms may not fit right- not uncommon for unique heads.

First try to use the right pushrod length (much shorter) then look into the rockers.

ap72 08-01-2012 09:12 PM

as a ball park try .400" shorter to start.


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