Lifter Tick

1972ScoutII

1972ScoutII

Member
I have a 1972 Scout II with a 69 corvette small block. I was rebuilt buy the previous owner.

I have been trying to track down a ticking problem that comes and goes usually when warm

it looks like the lifter arms were re-used, I am not sure if this is common practice.

Here pictures of what I have found so far. Should these be replaced? The guide plate is scored would this cause a ticking sound?

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Any help would be greatly appreciated
 
If it were my engine I'd replace the lot, balls and rockers because the damage I see on the ball is from mixing up the mated ball and rocker or a fractured rocker at some time, they are all suspect. Better yet buy a set of roller rockers. Good needle fulcrum rockers for a sbc are in expensive now days.

Hard to say for sure what is causing the tick. Lots of things can do that. Is the cam a solid or mechanical tappet?

I don't see guide plates in your photo so I don't know what you are referring to by "the guide plate is scored".

Fyi the head casting number 3947041 indicates that it is 69-70 350 300 hp could be a vette mill. Hydraulic cam was stock for that.
 
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The ball is what I was calling the guide plate since I think that is what they called them on summit racing.

I think they are hydraulic lifters

thanks for the fast response it is helpful
 
Not that I have 1/100 the experience of Robert kenney, but I agree...

The rocker arms and balls should be replaced.

If you buy new rocker arms, a new ball and nut (the one in your pic does not look that great) are included.

Might use the rock auto catalog for reference:

the guides are shown (here, I think - look under push rods). They also should not show wear (if your engine uses them).

Link was useless -- go to 69 corvette 350 / engine / push rods -- both the push rods and guide plates are shown.

You should also check the tips of the push rods for wear.

The one (push rod) in your pic looks ok.

You should feel "wear" if you run your finger tip across the "shiny part" of the rocker arm(s) (contact part with the valve stem) in your pics.

In my very limited experience (corvairs), the worn ball would produce a "squeak" as opposed to a "tick"... (when my ears were young...)

good luck

oops -- there are two "types" of "stock" rocker arm balls -- smooth and grooved (not grooved like the ones in your pcis). I have no idea of the pros and cons -- maybe Robert kenney does...

Forgot #2 -- iirc, my corvair mechanic had a "rack" where he kept rocker arms and their respective balls, nuts and push rods "in position" so that they went back in the same place on the engine.
 
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This thread is being moved to "gas engine tech" which is it's appropriate repository.

As Robert kenney advised, I'd replace the entire valve actuation assembly with appropriate aftermarket/performance parts that are dirt cheep for chev apps.

And if the rocker studs have not been converted to "screw-in" style, do so now!

The pushrods are "beat" as far as I'm concerned since obviously the hydraulic valve lash/travel has been exceeded. Pushrods are dirt cheep too.

Based upon your pics and my experience, when that engine was supposedly "rebuilt", the old valve train components were reused and should have been replaced at that point.
 
Thanks for moving it I saw I was in the wrong sub-forum after posting.

I am going to order some roller rockers and some new pushrods.

I dont see any threads, so I will assume they press in.

I am not sure it something I want to try to do myself or with the heads installed.

If I have to pull them it might be worth just buying new heads
summit racing sum-152123 - summit racing® cast iron cylinder heads for small Chevy - overview - summitracing.com


I am hoping the lifters were replaced...

Thanks for all the helpful feedback
 
Screw summitt!

If you are going to work with chev mousemotors then buy one of the definitive compiled references for sbc engine building. Those explain in explicit detail all the ins and outs of this stuff.

There is no more widely documented engine used anywhere in the world! And in my view if the heads are correct to that '69 design level engine, that alone is enough to keep this stuff together but repaired/upgraded correctly! Machine shops (and diy dudes) install the screw-in rocker studs hundreds of times a week, it's the primary thing to do on any sbc when contemplating any change in valve train!

If screw-in studs weren't done when that engine was rebuilt, then I'd suspect the whole job that was done! If you are going to pull the heads, pull the engine and inspect the entire operation.
 
So it surely doesnt have screw in studs, looks like one has started pull out, this is were I though I was hearing the noise with my stethiscope

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Can the screw in studs be installed while the heads are installed?

What is wrong with summit parts, I have ordered quite a few things and have always been happy with parts quality wise and they are made in the usa
 
There is nothing wrong with summitt parts, except most of the time stuff is cheeper elsewhere! It's the summitt "tech" and smokeblow marketing I have an issue with. These kinds of mousemotor performance upgrades have been out there since about 1959!

Your picture also shows the typical oem pressed-in stud being sawed in half by the rocker arm also, a few more hours it would have left the scene entirely.

Screw-in studs can certainly be installed with the heads in place, you just have to take pains to protect the penetrations from debris penetration. It's not a quick and dirty Saturday morning deal either.
 
While in skilled hands machining the rocker stud boss detail is possible I don't recommend it. Would not do it my self without pulling them.

The stud boss needs to be milled square and shorter to make room for the hex at the base of the stud and a 1/8" thick push rod guide plate. The threading operation needs to be well controlled and needs to be absolutely straight/perpendicular to the boss top.

Look around for pricing but $309.00 each assembled and with 2.02/1.60 valves it would be tough to beat. Iirc those castings are dart iron eagles just an more economical build up.. Good heads. Chambers are bigger 72cc though and will net a considerably lower compression that with your existing heads @64cc.

Here is what I would do.. Considering the push rod guide holes in heads show a bunch of wear I would pull the heads. Have the machine work done for the screw in studs and while you are at it have guide plates installed. Have the head guide holes enlarged to 7/16+ so the guide plates can function correctly.

Also have the guides checked and valves lapped.

You will need hardened push rods to work with the guide plates. Still cheap.
 
Re rocker arms

I noticed that there are two different rocker arms shown for your era engine -- rocker arm ratio = 1.5 and 1.6.

I do not know the importance of this, but the two rocker arms are a slightly different "size". This applies to stamped steel (stock) rocker arms as well as roller rocker arms.

I assume that your new rocker arms should have the same rocker arm ratio as the rocker arms used currently on your heads.

I assume Robert kenney and / or michael mayben can speak more authoritatively about this subject.
 
Good eye I noticed that too. I am thinking of going with 1.5 all around with my new ones.

I think I May have found a problem with my current plan though. With the wear on the pushrod guide I wonder if I will still have the problem with noise even after all new hardparts.

Still need to do more research
 
Oem gen I sbc's only used 1.5's the 1.6 and 1.7's are a good power adder for low and mid torque due to an increase in valve velocity. I run them in all of my flat tappet builds. It helps the engine begin to approach roller cam power characteristics.

Make sure you have room for the added lift and go for it. @.5 lift @ the valve you will gain .033 lift and about 2-3 degrees effective duration with the 1.6's

the guide wear is a problem, that's why I recommended installing guide plates.
 
In prehistoric times we used a tool similar to the fixture linked to perform the machining operation on the rocker stud pads without removing the head. It was somewhat more substantial though and I "think" it was produced by sioux (May have been sourced from kwikway??) as part of the valve train reconditioning line of machine tools commonly used back then.

We turned the tooling using a large gear-reduction 1/2" drill motor, the type that will break an arm or wrist when the cutter hangs up.

Yes...it makes a big mess. But a shop vac takes care of that along with careful protection using masking tape, etc. And while any penetrations in the head are still sealed up, we blow solvent/compressed air on the entire operation as the last point of "cleanup" before unsealing everything.
 
So I if I want to fix the guide problem I need to install guide plates.


I am assuming that if I do all new valvetrain parts I will still have a issue due to the valve guide issue

so option one is to buy this

comp cams 4729 - comp cams stud boss cutting tools - overview - summitracing.com

Then get out the hole hawg and start grinding away

I am tryin to do some out of the box thinking on how to solve this problem

1) get some guide plates, either find some washers that fit in the holes or cut some meta to fit (they look like mild steel to me) and then weld them shut

drill for the same size tap that I plan to run down the rocker stud hold. Bolt it in place using the other rocker stud and tap the whole thing as if it was one peice then screw the stud in.

This avoids the need for shouldered studs since it threaded and head in with just the threaded studs ( I also found that the 1970z/28 came with this type stock)

it also avoids the need for grinding down the stud boss becuase there is plenty of clearance for just the 1/8 inch plate

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So I tried to pull that stud and in broke, maybe they are threaded. It looks like it May have a rib at the bottom

so no I left trying to weld a nut on, this is fun

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