Pushrod guide alignment problems.
Thread Starter
Instructor
Joined: Jan 2003
Posts: 233
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From: IL
Pushrod guide alignment problems.
Im having a problem with the final assembly of the valve train on my 85'. the pushrods are binding on the built in guide grooves that are in the top edge of the head. They are pro topline torquers. The binding exists on the #1,4,5and 8 exhaust push rods and the 2,3,6 and 7 intake pushrods . when you drop the pushrod down through the slot everything is fine until the pushrod makes contact with the lifter socket then the misalignment occurs. has anyone had this problem if so what is the cure? should I get the heads opened up or is there a possible underlying problem?
Drifting
Joined: Jul 2000
Posts: 1,861
Likes: 1
From: Bremerton WA
St. Jude Donor '09
Re: Pushrod guide alignment problems. (black85vette)
This is a very common occurence when using cylinderheads that are not specific to a roller engine block. I've personally seen it a few times. I've only ever seen an issue with interference on pushrods hitting the casting on the "intake wall." Most recently on a set of AFR 220 heads and a set of Pro Topline 180cc iron heads. The easiest fix is the oval out the stud holes in the guideplates so the guide can shift over just slightly thereby pulling the pushrod off the "intake wall."
You have to be very conscious of the placement of the rocker tip on the valve, though. Have to make sure you're at least 80% or more covering the valve tip or accelerated rocker tip wear will occur. For instance the AFR 220 engine took out two comp cams roller rockers in about 3000 miles. That was after we shifted the guide plates and clearanced the intake wall (we broke through paper thin walls twice and had to have it welded!)
Be very cautious about grinding the intake wall unless you are certain about how thick it is. You should get enough clearance from a tiny guide plate shift.
Cory
P.S. If you're ever thinking about AFR 220's on a roller block do yourself a favor and get the offset lifters. That would have made everything so much easier for us!
You have to be very conscious of the placement of the rocker tip on the valve, though. Have to make sure you're at least 80% or more covering the valve tip or accelerated rocker tip wear will occur. For instance the AFR 220 engine took out two comp cams roller rockers in about 3000 miles. That was after we shifted the guide plates and clearanced the intake wall (we broke through paper thin walls twice and had to have it welded!)
Be very cautious about grinding the intake wall unless you are certain about how thick it is. You should get enough clearance from a tiny guide plate shift.
Cory
P.S. If you're ever thinking about AFR 220's on a roller block do yourself a favor and get the offset lifters. That would have made everything so much easier for us!
Race Director
Joined: Aug 2000
Posts: 11,506
Likes: 4
From: Vancouver,Wa.
Re: Pushrod guide alignment problems. (black85vette)
You have a camera? My heads are getting built right now and I think I will run into the same problem. They are the Protoplines to.. :(
