'69 427 Bent Push Rod
Burning Brakes
Joined: Jul 2016
Posts: 767
Likes: 74
From: Blaine MN
At this point I wouldn't be concerned about lifter type, the push rods bending on on the Intake Valve is telling you where to look. low V/P Clearance, Spring Bind or Retainer physical contact with guide is the cause. When you bought it was it already clattering?
With tester springs it's easy to measure the full open height, you can then put the real springs in a Vise/Arbor press compress it to that height and measure coil clearance, the testers also let you check the retainer clearance easily.
I hope you find it with out pulling Manifold/Heads, that's how my rebuild/upgrade started (Oh, it's apart, now's the time for ......)
My nickel is on V/P contact from over rev or just not enough clearance, good luck, I'm waiting for root cause
With tester springs it's easy to measure the full open height, you can then put the real springs in a Vise/Arbor press compress it to that height and measure coil clearance, the testers also let you check the retainer clearance easily.
I hope you find it with out pulling Manifold/Heads, that's how my rebuild/upgrade started (Oh, it's apart, now's the time for ......)
My nickel is on V/P contact from over rev or just not enough clearance, good luck, I'm waiting for root cause
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
At this point I wouldn't be concerned about lifter type, the push rods bending on on the Intake Valve is telling you where to look. low V/P Clearance, Spring Bind or Retainer physical contact with guide is the cause. When you bought it was it already clattering?
With tester springs it's easy to measure the full open height, you can then put the real springs in a Vise/Arbor press compress it to that height and measure coil clearance, the testers also let you check the retainer clearance easily.
I hope you find it with out pulling Manifold/Heads, that's how my rebuild/upgrade started (Oh, it's apart, now's the time for ......)
My nickel is on V/P contact from over rev or just not enough clearance, good luck, I'm waiting for root cause
With tester springs it's easy to measure the full open height, you can then put the real springs in a Vise/Arbor press compress it to that height and measure coil clearance, the testers also let you check the retainer clearance easily.
I hope you find it with out pulling Manifold/Heads, that's how my rebuild/upgrade started (Oh, it's apart, now's the time for ......)
My nickel is on V/P contact from over rev or just not enough clearance, good luck, I'm waiting for root cause
What is the clearance between valve head and the block deck on a BBC suppose to be?
And, I have seen the gap between the valves in the head so tight you couldn't slip a piece of paper between them. Then, when they get hot . . . . . . .
Just sayin' if it were coil bind, you would think at least one of the springs would have broke.
Thread Starter
Racer
Joined: Apr 2013
Posts: 302
Likes: 16
intake lift .500
exhaust .505
Plenty retainer to guide clearance
.840 on the intake
.800 on the exhaust
,
Thread Starter
Racer
Joined: Apr 2013
Posts: 302
Likes: 16
At this point I wouldn't be concerned about lifter type, the push rods bending on on the Intake Valve is telling you where to look. low V/P Clearance, Spring Bind or Retainer physical contact with guide is the cause. When you bought it was it already clattering?
With tester springs it's easy to measure the full open height, you can then put the real springs in a Vise/Arbor press compress it to that height and measure coil clearance, the testers also let you check the retainer clearance easily.
I hope you find it with out pulling Manifold/Heads, that's how my rebuild/upgrade started (Oh, it's apart, now's the time for ......)
My nickel is on V/P contact from over rev or just not enough clearance, good luck, I'm waiting for root cause
With tester springs it's easy to measure the full open height, you can then put the real springs in a Vise/Arbor press compress it to that height and measure coil clearance, the testers also let you check the retainer clearance easily.
I hope you find it with out pulling Manifold/Heads, that's how my rebuild/upgrade started (Oh, it's apart, now's the time for ......)
My nickel is on V/P contact from over rev or just not enough clearance, good luck, I'm waiting for root cause
Thread Starter
Racer
Joined: Apr 2013
Posts: 302
Likes: 16
I will check coil bind tomorrow. going to extreme cylinder heads here to have them checked.
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Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Now compress the spring in a vice and check the length compressed.......then subtract that from the installed height number.....that number should be more than your lift.
If not....you found the problem.....if it is then you are back to searching.....
Exhaust installed height is checked including the rotator. Comp and other companies make a thick seat to eliminate that.....nobody runs them anymore.....especially after hardened exhaust valve seats became a thing.
Jebby
If not....you found the problem.....if it is then you are back to searching.....
Exhaust installed height is checked including the rotator. Comp and other companies make a thick seat to eliminate that.....nobody runs them anymore.....especially after hardened exhaust valve seats became a thing.
Jebby
Thread Starter
Racer
Joined: Apr 2013
Posts: 302
Likes: 16
Now compress the spring in a vice and check the length compressed.......then subtract that from the installed height number.....that number should be more than your lift.
If not....you found the problem.....if it is then you are back to searching.....
Exhaust installed height is checked including the rotator. Comp and other companies make a thick seat to eliminate that.....nobody runs them anymore.....especially after hardened exhaust valve seats became a thing.
Jebby
If not....you found the problem.....if it is then you are back to searching.....
Exhaust installed height is checked including the rotator. Comp and other companies make a thick seat to eliminate that.....nobody runs them anymore.....especially after hardened exhaust valve seats became a thing.
Jebby
When the spring is compressed in the vice... Do you mean all the way to bind? Then measure the spring? Or Just to cam lift @ .500?
You said to measure with the rotator for installed height. Should I include the shim as well?
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
The rotator is .300 thick. At least the eliminators are. https://www.summitracing.com/parts/c...EaAjqaEALw_wcB. How thick are the shims. The 781 was usually set up at 1.88 installed height. The umbrella seals stay on the valve stem and move with the valve. Idea being they still block top of guide when fully open. The positive seals attach to the guide and the valve slides in them.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Yes....compress it all of the way and measure.....that is "bind".
This is where a valve spring pressure checker/press comes in handy but we do not have that. We have your installed height number, the cam lift, and soon you will have compressed length.....with these three number you should be able to know if you are coil binding.
The mentioned 1.880 is correct for stock but you seen to be a little more than that.
Jebby
Thread Starter
Racer
Joined: Apr 2013
Posts: 302
Likes: 16
Installed height is just that....with everything installed. No there is no rotator on the intake. You got some 2.15 installed height number...now subtract the rotator and the shim.
Yes....compress it all of the way and measure.....that is "bind".
This is where a valve spring pressure checker/press comes in handy but we do not have that. We have your installed height number, the cam lift, and soon you will have compressed length.....with these three number you should be able to know if you are coil binding.
The mentioned 1.880 is correct for stock but you seen to be a little more than that.
Jebby
Yes....compress it all of the way and measure.....that is "bind".
This is where a valve spring pressure checker/press comes in handy but we do not have that. We have your installed height number, the cam lift, and soon you will have compressed length.....with these three number you should be able to know if you are coil binding.
The mentioned 1.880 is correct for stock but you seen to be a little more than that.
Jebby
That is installed height.
The intake installed height is 1.916 without the shim
Can the piston to valve clearance be measured at TDC with the heads installed? Was thinking the valves touch the top of the piston with the springs off. I could measure the travel of the valve from fully closed, slide the valve down until hits the piston. Wouldn't that tell me the piston to valve clearance?
Thanks
Mike
Last edited by Z06CE; Mar 12, 2019 at 01:21 PM.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Ok got you... Subtract the shims and rotator....
That is installed height.
The intake installed height is 1.916 without the shim
Can the piston to valve clearance be measured at TDC with the heads installed? Was thinking the valves touch the top of the piston with the springs off. I could measure the travel of the valve from fully closed, slide the valve down until hits the piston. Wouldn't that tell me the piston to valve clearance?
Thanks
Mike
That is installed height.
The intake installed height is 1.916 without the shim
Can the piston to valve clearance be measured at TDC with the heads installed? Was thinking the valves touch the top of the piston with the springs off. I could measure the travel of the valve from fully closed, slide the valve down until hits the piston. Wouldn't that tell me the piston to valve clearance?
Thanks
Mike
And it is not checked via peak valve lift but during overlap....you check it at 10 degrees before TDC on exhaust stroke and 10 degrees after TDC on the intake stroke.
https://blog.diamondracing.net/check...-the-right-way
Jebby
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
As Jeb said, the piston is a LONG way from the valve when valve fully open. And installed height is also minus approx .200 for umbrella seal thickness. Alla sudden that .815 clearance is mucho closer to actual valve travel. You want .050 more than valve lift minimum. You are closer to .100. You can see where if somebody put a .57 or .58 lift cam in there, bad things could happen.
Thread Starter
Racer
Joined: Apr 2013
Posts: 302
Likes: 16
As Jeb said, the piston is a LONG way from the valve when valve fully open. And installed height is also minus approx .200 for umbrella seal thickness. Alla sudden that .815 clearance is mucho closer to actual valve travel. You want .050 more than valve lift minimum. You are closer to .100. You can see where if somebody put a .57 or .58 lift cam in there, bad things could happen.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
It might just be cheap pushrods that got overrevved. But you are gonna know what you have for a valvetrain. I would see if you can get spring pressure at 1.9 and at 1.39. .505 lift. Do you have an arbor press or big vise? If shop wants too much to check springs get one of these: https://www.ebay.com/itm/JEGS-80538-...EAAOSwVEBbrWKL. Or just buy a new set. Comp cams has springs in the 120 lb seat pressure 300 open for around 110 bucks. Single springs. Would work with your existing retainers. The problem with valve springs is 1 year old ones look like 40 year old springs. Nice cost effective spring for .54r and lower 6000 rpm or so.
Last edited by derekderek; Mar 12, 2019 at 06:34 PM.
Burning Brakes
Joined: Jul 2016
Posts: 767
Likes: 74
From: Blaine MN
i agree the Jebby post 116 is probably the best course, but a quick check at TDC will tell if you are statically tight (shaved heads, decked block, thin Head Gaskets), if you got more than 0.250" your probably not hitting the Piston unless the cam has a serious ramp rate (the intake is opening during overlap) or way off cam card install specs. Radial V/P Clearance could still be a problem and I don't think there is an easy way to that with Heads on?
The Umbrella seal value quoted has to do with the retainer to guide clearance and it still could be what bent them (I didn't do any math with the numbers you posted though), I wish you were nearby, i have a nice little setup with an arbor press, pressure gauge etc. that makes this easy (vise and flying springs suck)
The Umbrella seal value quoted has to do with the retainer to guide clearance and it still could be what bent them (I didn't do any math with the numbers you posted though), I wish you were nearby, i have a nice little setup with an arbor press, pressure gauge etc. that makes this easy (vise and flying springs suck)