Guide plates
- Thread starter Dan Hunt
- Start date
What are you working on and with what parts?
Sorry about that
Pushrod guide plates on 690 heads.
found that the outer push rod holes make the pushrods bind.
It's about .030 to far out,if I cut the plate I'll take about .080 out.
I thought you knew what I was thinking, sex
Next time I'll read before posting.
Pushrod guide plates on 690 heads.
found that the outer push rod holes make the pushrods bind.
It's about .030 to far out,if I cut the plate I'll take about .080 out.
I thought you knew what I was thinking, sex
Next time I'll read before posting.
Are the push rod holes in the heads drilled out?
What brand of guide plates do you have?
They have to be drilled to run guide plates. You cant have the push rod held at two point in the middle.
Those should work for your heads, but you have to drill out the push rod holes in the heads first, then you have to check that the push rod does not touch the hole in the head through all of the valve life.
You will bend a push rod if you run guide plates and not drill the holes in the heads.
Are the push rod holes in the head that have the wear in the same slot in the guile plate your having problems with?
Are the push rod holes in the head that have the wear in the same slot in the guile plate your having problems with?
Can't remember but I think I'm going to go through them and grind the side that interferes. make sure I have clearance all the way up and down. Should be OK.
I always drilled my race car heads( small block) but I used offset lifter and rockers( shaft rockers)
I always drilled my race car heads( small block) but I used offset lifter and rockers( shaft rockers)
Just wondering if a valve guide was installed in the wrong place.
LA is right you have to choose either use the slots or use the guides but you can't use both.It doesn't matter what brand of head it is if it has close tolerance pushrod holes for guiding the pushrods they have to be drilled out to allow use of guideplates.The guideplates if decent quality are more likely to center the rocker arm on the valve stem than the slots.If you look at factory heads that came with screw in studs and guide plates such as Z-28 and LT-1even though may use same casting that used slots in other applications they drilled them out for use with guide plates.
It's not a matter of required,its a matter of the number of points of contact,with the normal 3 ,lifter,guide slot or guide plate,and rocker arm the pushrod still has some freedom of movement to change its axis to stay aligned with the lifter seat at the bottom and the rocker arm at the top.With 4 points of contact,lifter,guide slot,guide plate,and rocker arm,the combination of the guide slot and guide plate greatly restricts the pushrods ability to pivot its axis to follow the up and down movement of the lifter and rocker arm,which will impart side loads on the pushrod tips,best case scenario this causes unnecessary wear on the tips and lifter and rocker arm seats,worst case scenario causes at minimum bent pushrods.I would be willing to wager that close inspection of pushrods run with a combination of guide slots and guide plates at minimum would reveal higher than normal wear at the areas where they pass thru the slots or plates.The only scenario where this wouldn't happen is if the lifter bores,guide slots,guide plates,rocker studs,and valve stems were all in perfect alignment for every cylinder,but the odds for this to happen is astronomical so personally I would choose one or the other,more is usually but not always better.