327 head problem...

[Impalaguru]

I've got a problem on my hands. It seems the rebuilt 327 "461" heads I bought this spring weren't quite what I thought they were. I have developed an issue with a pushrod rubbing a groove into the guide plate on #7 intake and the same issue on #3 intake. All others seem to be OK. #7 intake is the worst.

To me it appears as though the screw-in rocker studs were not installed exactly in line with the valve. The #7 rocker is touching the valve on the outer edge of the rocker.

So...what's the best plan of attack? Should I cut my losses and find another head to rebuild? Try and salvage the existing head? Start over completely with a new pair? Or just pull the 327 and install a 409?

Any help would be appreciated.

Ross

 

[Ronnie Russell]

Ross, Experiment with the guide plate. Cut the plate into 2 pieces and see if you can get the alignment you need . Then you can weld the 2 pieces back together. After re-reading your post....... If the rockers are tracking straight, why not just die grind the guide plate slot to clear the pushrod? The pushrod wants to track there so why not give it some clearance?

 

[Ronnie Russell]

Ross, Stock pushrods are not compatible with guide plates. Hardened chrome-moly, .080 wall are needed. I will be spending the day modifying some sbc guide plates that are "off" . 8 true rockers,, 8 that have rocker roller on the edge of the valve stem. I will take some pictures and maybe you can get some ideas from the pictures. Of course, if I fail,

 

[boxerdog]

Perhaps the stock pushrod holes in the heads were not enlarged, and are out of alignment with the guide plates?

If so, Ronnie's fix may work, or you may have to slightly enlarge the pushrod holes so that the guide plate is the only point of contact, then adjust the rocker alignment from there.

Or did I read it wrong???

 

[Phil Reed]

Or just pull the 327 and install a 409?

Any help would be appreciated.

Ross

Ross..........................??????? Look at YOUR history. Look at OUR history!!! Seems a no-brainer to me!!!!!!!!!!!!!!!!!!! You've answered your own question!!!!!!!!!!!

 

[Ronnie Russell]

Yep, Dave has it right. I am working on vortec heads. Pushrod hole is about 7/16 diamiter. A #461 head would need the pushrod holes opened up. There still may be some gain by playing with the guide plates. Would have to pay special attention about interferance at the head. Sorry about picture quality, the camera distorts the the true relationships. First 2 pics are before. #1 int., #3ex., #5 int ( not pictured) and #7 ex. all have rocker rollers hanging off the valve stem. Opened up the guide plate on left stud hole and deepened the slot and straightened it out some. You cant 't ell from the camera angle distortion but all the rollers are now centered on the valve stems. A lot of trial and fit time.

 

[58 Apache]

Those Heads look familiar

Sorry Ronnie I should have sent the Manley guide plates that I had all fixed up for those heads. Just for my own knowledge what lenght push rod did you end up with?

 

[Don Jacks]

Thanks for the heads up guy's.I'll have to keep a really close eye on this when I get my re-done Vortecs for the 408.I've been running stock stamped rockers up to this point.

 

[Ronnie Russell]

Derry,,,, 7.950

 

[Impalaguru]

Thanks for all the help guys!!!

Phil, I have earmarked my 63 block for the red car! Maybe Tom K has another engine lying in his basement for the convertible?

What I have right now looks like the "before" pictures Ronnie posted. I just went out to the garage to do some comparative measurements. I took my dial caliper and measured from outside to outside of each stud.
#1: 2.150"
#3: 2.137"
#5: 2.150"
#7: 2.139"

I then measured some stock heads I have and they were all 2.143". The cylinders I am having troubles with are #3 and #7. Are those 11 and 13 thousandths of an inch giving me my troubles?

The first pic shows how the rocker is touching the valve stem. You can also see the half-moon groove worn into the guide plate. The second picture isn't great but you can see that the rocker is at an angle. I do not have chrome molly pushrods. I am running +.100 stock type push rods.

Is there still hope?

Thanks

Ross

 

[Ronnie Russell]

Ross, The most important question is, have the pushrod holes in the heads been enlarged? If not, you have a "can't win" situation with the guide plates. Either way, take the guide plate off of the worst aligned pair. Put rockers back on and set each at zero lash. Rotate engine several times. Check the natural rocker alignment at "down and up". If your pushrod holes in the heads have not been enlarged, you may be able to simply take the guide plates off and be good. Especially with stamped steel rockers. BTW, those must be some darn good pushrods. You have a battle of pushrod against guide plate and the pushrod won. Let us know what you find. Uh oh, After restudying picture, I don't think you can fix it. For the rocker tip to move right to left, the pushrod needs to go left to right. That is what the guide plate did when it was new. I'm afraid Ross is correct and the some of the studs are mis-drilled. Check and replace worn rockers when needed and drive the crap out of it , as is.

 

[raymar58409]

Is it possible the push rods are bent?? Try turning the push rod and see if the rocker moves back and forth. Just a thought.

Ray

 

[Tom Kochtanek]

Ross quips: "Phil, I have earmarked my 63 block for the red car! Maybe Tom K has another engine lying in his basement for the convertible?"

As a matter of fact, I have one at the machine shop this very minute . It actually crawled into my Dodge PU the other day just before I was headed for the shop!

This is the set of engine components I had Tony Schaffer go over in preparation for final assembly. Since it was a "lower performance build" and Tony knew I liked to get my hands dirty, he just sleeved the block, R&R'd the rods, cut the crank and balanced everything. Not it's assembly time .

Good luck figuring out your situation, I am confident that things will be all good!

TomK

 

[Impalaguru]

Thanks for all the info, guys! My fears were confirmed by Ronnie's post. For now I guess I will massage the guide plate and run it.

Since I've never removed screw-in studs on a small block, or any engine for that matter, do I need to worry about coolant coming out? I wasn't sure if the studs went into a water jacket. What should I use on the threads when I reinstall them? Loctite? Torque spec? Or just TIGHT!

Thank again!

Ross

 

[58 Apache]

Ross Provided they were done right when they were converted to screw in studs they should be dry in 461's. Going back together I put sealant on the threads just from habbit and torque to 65 ft. lbs.

 

[skipxt4]

Ross: Permatex #1 or #2 (Brown) works perfect.