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Topic Review (Newest First)
08-08-2012 11:34 PM
inkfreak1976 Ok, for those that are interested in this post still i have officially found out the problem
I was told to call comp to get the specs and measurements of the rocker arm to check if they were possibly boxed wrong. and while talking to the tech, the reason the push rods were coming out of the seating cup, was the type of rocker i was trying to run was a cast aluminum stock replacement, and that being said, the thickness of the metal around the main bearing trenion had to be thicker, which is fine for stock, but i was told that they would nt have have held the 440 open spring pressure nor the lift that im using. so back to summit they went and im going with some scorpion roller rockers. the specs match up fine. and im told i should be really happy with the switch out. so for anyone that might have the same problem, take the time and call the company of the part your getting, summit doesn't know any specs unless provided by the company that makes the product. and most rocker arm companys dont post this with summit do your home work. and for the price, scorps will work great.
08-01-2012 11:43 PM
cdminter59
Rocker arm geometry

I checked the Manley website. The stock 351C push-rod is 8.400 long for hyd lift cam. Another forum said solid lift cams use 8.500 length push-rods. This is a 5/16 x .080 heavy wall diameter. It is a starting point for your push-rod checker. Take a black marker color the valve tip. Setup push-rod checker and roller rocker arms. Then spin the roller to leave a witness mark. It should be near center towards front of valve tip. Not dead center. After getting the correct length that leaves this mark as said measure push-rod checker. Another thing you may want to check into a set of Crane Gold roller rockers.
08-01-2012 09:12 PM
ap72 as a ball park try .400" shorter to start.
08-01-2012 08:36 PM
ap72
Quote:
Originally Posted by inkfreak1976 View Post
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.
08-01-2012 06:34 PM
inkfreak1976 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.
07-13-2012 09:09 PM
inkfreak1976
Quote:
Originally Posted by 1BAD80 View Post
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.
07-13-2012 04:02 PM
1BAD80 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
07-13-2012 02:37 PM
inkfreak1976 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.
07-13-2012 09:25 AM
Irelands child 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.
07-13-2012 08:50 AM
ericnova72 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() 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
07-13-2012 08:02 AM
cobalt327
Quote:
Originally Posted by inkfreak1976 View Post
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

07-13-2012 07:44 AM
Richiehd
Quote:
Originally Posted by ap72 View Post

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.
07-13-2012 05:57 AM
ap72
Quote:
Originally Posted by inkfreak1976 View Post
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.
07-13-2012 03:15 AM
S10 Racer 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.
07-13-2012 12:58 AM
inkfreak1976 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.
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