devilfish

Long post. Sorry about my bad English, not my main language.

I have problems to align my valvetrain.

This is the componets involved.

1991 SB 355
Jegs ( canfield ) 197cc alu heads.
Hyd roller LT4 hotcam
Stock new hyd lifters
TrickFlow 1:6rrs

I measured the pushrod length using a modified hyd lifter ( that couldent collapsed under pressure ), when I hade my intake off. I whas aiming for the lowest wearpattern. I ended up with stock length.

The probleme I have now is the alignment of the rocker tips vs the valvetips.

I hade to change a valve seal this winter ( got a fouled plug on no8 cyl ). And when I took of the rockers I noticed strange wearmarks on the valve tips.

Its on the the intake valves I can se that something is not right.
The Jegs ( canfield ) heads has offset intake valves , ( I got this verified from Canfield tech as well ). So the intake rocker sits at a angel from the rockerstud ( se pic no:1 ).



The exhaust rocker on the other hand is "strait", so I have no probleme there..

The probleme I saw is noticeable on ALL my INTAKE valve tips wearmarks. It seems that only a small amount of the rockertip actual touch the valvetip under load. ( se picture no:2 )



Its amlost as if the rocker tips is tilted to one side ( se pic no:3 ). Allowing only half of the tip to actual make contact with the valvetip?




What I did now whas to get some adjustable guideplates, to se if I could align the rockers better against the intake valvetips. BUT I ended up with exact the same measure as with the Canfield stock guideplates. So no improvement there.

And now im a bit lost on what to do. And what I have missed.

As this is my first build, am affraid im perhaps over analyzing this, and that this perhaps is not such a big deal?

One more thing that strucked me is the amount off "internal" play I have on my trickflow rockers. That play also add some difficulty center the rockers over the vavletips during the installation of the guideplates ( se MOVIE link ). Perhaps that adds up to the probleme as well?

http://www.youtube.com/watch?v=521Ix9kUx28

My next ide whas to get rid of the guideplates and use self aligned rockers. But I dont know if there are any down sides using those. And im sure many others got this heads to work with guideplates..

Best Regards

Anders

mr.beachcomber

The valve tip's wear pattern indicates abnormal wear. According to the instruction sheet for the Jeg's heads, "The fact is if you are using stock length pushrods your valve train is probably wrong". Start over and measure your pushrod length using an adjustable pushrod (such as Jeg's # 270-99726-2).

Please note that Jeg's also states that "Custom guideplates for 5/16” pushrods are included. When installing guideplates, take note that one pushrod slot is longer than the other. The longer slot is for the intake valve pushrod".

devilfish

Thanks for the answer.

The wear pattern on the exhaust valves, looks ok, indicating that at least those pushrods have the correct length.
Wouldnt a to long/short pushrod show a wear pattern on the valve tip that is either to much towards the intake side, or the "outer" side of the valve tip?
In this case the wear pattern is "off-set"/skew horizontal. As the rocker tip seems to "dip" on the side under load.
But perhaps a to long/short pushrod also can present it self in this manner?

And about the guideplates, yes I have mounted them as the instruction said.

Best Regards

ANders

mr.beachcomber

Judging from what I have read about the Jeg's heads, the larger than stock 2.050" intake valve is probably offset to the side in order to fit inside the combustion chamber requiring that each guide for the intake valve pushrods have a longer slot to maintain the correct geometry with the valve stem.

Since Jeg's indicated that stock length pushrods probably would not work, I think that the additional length is pushing the rocker arm's tip to make an angled contact with the valve stem resulting in the wear pattern that you are seeing. Also, I believe that Jeg's specified standard (1.5:1) roller rockers for the heads - not 1.6:1. The combination of the longer pushrod and higher rocker lift may be too much for the valve geometry.

To be on the safe side, I would re-check both the intake and exhaust valve pushrod lengths to make sure that you achieve the correct geometry and wear patterns. You may want to switch to 1.5:1 roller rockers also.

devilfish

Talked to Canfield ( the one that makes the Jegs head ).
ANd 1:6 rocker should work with no problem.


The wear patter on the exhaust valves is "spot on", but perhaps I need diffrent length on the intake valves? I will re-check the intake valve pushrod length. Paint the vavle tip and turn the engine by hand. Se if I can alter the wear pattern with diffrent length on the pushrod.

THanks

devilfish

Today I got some interesting update on my problem..

What I did whas to install a adj push rod, unfortantly I have the intake on, so I hade to use the hyd lifter. BUT the ide whas just to se trends.
I tried both to shorten and to lengthen the push rod, but the trend whas the same. The rocker tip wouldent make a wear mark all the way across the valve tip, it did just touch one side of the valvetip. As I posted abow..
What I did now whas to make sure the lifter whas on the bas of the cam, then I droped in the rocker on to the rocker stud. Then I gently pushed down the rocker, with my hands, and rocked it left and right, just to see the wear mark on the valve tip ( i hade painted the vavle tip with a magic marker first ). Here I found out the problem...

No matter how hard I pressed down the rocker, I couldnt make the rocker tip touch the entire valve tip, it did just make a mark on one side of the valve tip. Just as I showed abow!
This must mean 2 things.

1: The rocker stud holes are misaligned in the head, making the the stud NOT 90 degrees when screwed in.
2: The rockers are the problem. BUT i tried the abow method with 4 diffrent rockers ( all trickflow ). They all cant be bad?

Do guys have any more theory?

ps: I did the same with the exhaust valves with great results..

mr.beachcomber

First off, the only way to check valve train geometry is to rotate the engine through its four cycles and then check the wear pattern. That being said, you should have been able to adjust the pushrod's length while the lifter was sitting on the cam's base circle to make full contact on the valve stem.

To check the intake's rocker stud's alignment, screw in the stud without the guide plate, torque it down, and then use a metal square to determine if the stud is correctly aligned. If that checks out okay, try the same procedure again except using the guide plate under the stud to see if the guide plate is distorting the alignment.

If the stud's alignment checks out both times, I would start to suspect the roller rocker arms. (Your video did show more movement about the roller rocker's trunion's axis that I would have expected.)

INMYBLOOD

I can't understand the tilt? Are your rockers made for the studs in the heads? IE: are you putting 7/16 rockers on 3/8 studs? They should always run flat on the end of the valve. The angle(not the tilt) could mean you need off set lifters?

devilfish

Found this thread. This is EXACT the same issue as I have.

http://speedtalk.com/forum/viewtopic...=16068&start=0

mr.beachcomber

Thank you for the link. After reading through all five pages of comments, it sounds as if the problem you are experiencing requires a fair amount of re-machining to fix as the source of the problem lies within the original machining of the heads themselves. There is no simple solution other than to live with the problem and/or use lash caps to protect the valve stems.

The Canfield Heads business was sold off a while back so there is no possibility of getting anything except a rebuilt cylinder heads from Jeg's in exchange for your current heads. Even that does not guarantee a resolution of the problem.

Just as an aside, I have never had any problems with AFR heads over the years and wouldn't hesitate to replace the Jeg's Canfield heads with AFR's if at all possible moneywise. Good Luck!

devilfish

Thanks for the answer..

I took the heads off, and gave them to my mechanic. We se if they can fix them, install new studs..

ZZ71S

You could always try a old fashion stamped rocker