flatchat(Chris)
Supporter
302 hyd. lifter fail
- Thread starter flatchat
- Start date
Terry Oxandale
Skinny Man
Can't say I've ever seen anything like this in probably 30 years of SBF performance related fun. Some folks run the hydraulic lifters with a neutral lash (no compression of the lifter at the base circle, but also no lash as well) in order to prevent "pump up", but that was never an issue I ever had to deal with. That practice would perhaps load up the spring clip, causing it to pop out and spew the internals?
flatchat(Chris)
Supporter
Hi Chris:
I have seen this before in one of my buddies 351 Windsor old stock car engine. One popped out the clip went to the oil pan and into the pump through the hole in the stock pickup locked up the distributor and broke the distributor gear. Two weekends later it happened again. We replaced the whole set of lifters. We used Melling high volume pumps in those engines ithink sometimes the clips lose tension when lifters pump up.
I have seen this before in one of my buddies 351 Windsor old stock car engine. One popped out the clip went to the oil pan and into the pump through the hole in the stock pickup locked up the distributor and broke the distributor gear. Two weekends later it happened again. We replaced the whole set of lifters. We used Melling high volume pumps in those engines ithink sometimes the clips lose tension when lifters pump up.
The issue here is not the clip jumping out, but the failure of the pushrod cup at the top/valley end of the lifter, everything being equal & with no other failures evident the lifter would still be functional although its ability to meter the amount of oil up to the pushrod/rockers might be compromised. Now maybe Chris ( or is it Mrs Flatchat
) might have been unlucky to strike that one in a million lifter with a flaw in production, but its more likely that the valve spring combo is just not suitable for that particular engine spec ( cam/valves/operating RPM level ) where the springs are being operated in a rev range that they cannot cope & going into a 'surge' or resonance period, to check for this my first look is as above & check the end of the valve stem wear pattern as per the pics attached. The parts in the pic appear to have had very little use yet with no definitive mark, but there 'might' be a couple at the points indicated at the yellow arrows, if it was perfect there should be a mark like the pink one. To check further for this the spring/retainer/spring seat if removed should NOT be polished or show indications of rotation relevant to one another.
If the spring has been in a surge or resonant state to creat clearance in the valve train & the loads on that pushrod cup will be muliplied as the valve uis opened in the same manner as if you gave the pushrod a smack with a hammer at the same time. Over time this could also happen on cold starts where the lifters have to pump up where the springs bleed the lifter down. On that note if you have an oil surge issue with air being pumped into the system the same thing can happen.
) might have been unlucky to strike that one in a million lifter with a flaw in production, but its more likely that the valve spring combo is just not suitable for that particular engine spec ( cam/valves/operating RPM level ) where the springs are being operated in a rev range that they cannot cope & going into a 'surge' or resonance period, to check for this my first look is as above & check the end of the valve stem wear pattern as per the pics attached. The parts in the pic appear to have had very little use yet with no definitive mark, but there 'might' be a couple at the points indicated at the yellow arrows, if it was perfect there should be a mark like the pink one. To check further for this the spring/retainer/spring seat if removed should NOT be polished or show indications of rotation relevant to one another.If the spring has been in a surge or resonant state to creat clearance in the valve train & the loads on that pushrod cup will be muliplied as the valve uis opened in the same manner as if you gave the pushrod a smack with a hammer at the same time. Over time this could also happen on cold starts where the lifters have to pump up where the springs bleed the lifter down. On that note if you have an oil surge issue with air being pumped into the system the same thing can happen.
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flatchat(Chris)
Supporter
Thanks Jac , the pink bit gets nicely massaged in that exact area - although not as often as it would like these days.:laugh: I'll check for rotations, otherwise its going back together and hope that it was only the third in a million fault
The motor ran and sounded normal , the clip was intact and the push rod seat is loc solid in its housing
The motor ran and sounded normal , the clip was intact and the push rod seat is loc solid in its housing
flatchat(Chris)
Supporter
Engine is running sweetly again, every thing checked out OK, and apparently its a reasonably common occurance. (of late) Why ? I'm mystified
What you could try is cut the top out of an old rocker cover, weld a metal 'fence ' about 8" tall all around the cover, mark the retainers with a white crayon, hook your timing light up to the coil>dizzy HT lead and run the engine thru the rev range while observing the retainer marks, if the retainer/s- springs are rotating you have a spring problem at that particular RPM- a part turn of rotation now & again is not an issue, but ongoing rotation is.
Steve Wood (PANAVIA)
Lifetime Supporter
(popcorn)
flatchat(Chris)
Supporter
To clarify - Its only happened to me this once, but, talking to other racer boys it has happened to them :huh:
flatchat(Chris)
Supporter
Yeah me too, or else it might become an OH&S issue and then he'll have to counciled.:laugh:
Is what you're say Jac, that faulty or weak springs that cause rotations or is there another issue
Is what you're say Jac, that faulty or weak springs that cause rotations or is there another issue
Yes, and also can be just wrong combination of spring/retainer/valve for that particular cam lobe profile. Only way to be really sure is look for multiple or completely shiny pattern on end of valve stems or check retainer/spring/spring seat interface for 'shiny' surface which indicate lots of rotation or with a strobe light as per earlier post, if the valve train is getting those indications then it means that it is operating in a 'loose' state at some time during its operation & the pushrod/lifter cup being the weakest link fails. For most part if you have the valve train specced by the manufacturer then you 'should' be OK, but really it doesnt take too long to do the strobe check once you have the modded rocker cover... I remember some tourist boats I worked with in Q-Town NZ, they were having no problems until they changed suppliers for the jet unit impellors, the 'new' impellors dropped the operating RPM to 3800 from previous 4200, Speed remained the same, so they were happy, but not for long as motors started dropping exhaust valves- lost about 4 motors before someone suggested perhaps the 3800 rpm was the culprit- bingo!
I have been reading this thread with interest, I don't feel I have much to give, but a lot to learn here. Basically we are talking about the possibility of 'valve bounce' and it's consequences. Since I just converted my engine to hydraulic roller lifters and am still in the first couple of hundred miles, I am listening to the engine carefully and will make periodic examinations of the valve stem markings etc. So far I have only taken her up to 5000rpm and all seems well. On the way to mot test I heard a short period of squeaking noises when I slowed off the motorway. I put down to pushrod/guide interaction and checked and found some with shiny marks, but no squeaking since then, pushrods are hardened.
My major components are all matched Edelbrock so I don't have any obvious worries, just being careful.
In the past, my mini Cooper engine was limited by valve bounce, I only did it once and it was clearly audible and the engine stopped accelerating so I didn't rev to that point again. Maybe not enough power to break the valve train but it was obvious.
Summing up I have a couple of thoughts / questions
1 Would we normally expect a period of valve bounce that was able to cause damage to be audible?
2 Are roller cam components (i.e rollers and pins) more susceptible to damage due to over rev compared to flat tappet components?
btw I do like the idea of making oil guards so as to directly observe the top end valve components.
regards
Dave
My major components are all matched Edelbrock so I don't have any obvious worries, just being careful.
In the past, my mini Cooper engine was limited by valve bounce, I only did it once and it was clearly audible and the engine stopped accelerating so I didn't rev to that point again. Maybe not enough power to break the valve train but it was obvious.
Summing up I have a couple of thoughts / questions
1 Would we normally expect a period of valve bounce that was able to cause damage to be audible?
2 Are roller cam components (i.e rollers and pins) more susceptible to damage due to over rev compared to flat tappet components?
btw I do like the idea of making oil guards so as to directly observe the top end valve components.
regards
Dave
btw I do like the idea of making oil guards so as to directly observe the top end valve components. regards Dave[/QUOTE said:
Like Dave, I've been watching this thread with interest. I'm in the midst of building a 302 with Dart CNC heads and a solid roller cam with Ti valves and shaft rockers. Hoping to rev to 7500. I think one of the keys is working closely with the cam supplier to make sure springs/retainers are appropriately matched for the application and for each other.
I would not mix and match components here as even if they're excellent quality, they may not be well suited to one another. I've also been told by several engine builders to stick with tried and true shaft rockers: T&D and Jesel. Tolerances with other suppliers supposedly aren't as good with a higher risk of failure. I'd be interested in the experience of others
I would not mix and match components here as even if they're excellent quality, they may not be well suited to one another. I've also been told by several engine builders to stick with tried and true shaft rockers: T&D and Jesel. Tolerances with other suppliers supposedly aren't as good with a higher risk of failure. I'd be interested in the experience of others
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Buying all the matching parts is one thing but checking for correct geometry,pushrod length and spring pressures/installed height/bind is another. Nothing should be taken for granted because of the variables that exist in engine building. Everything should be checked and then checked again.
Bob
Bob
Hi Shaun, when I bought the car it was all standard with hydraulic flat tappet. I changed the cast iron heads to Edelbrock performer rpm, and later changed the standard cam for an Edelbrock 2221. I chose this cam as it matches the heads, their springs and manifold so no worries about compatibility. I never considered solid lifters as I am not looking for high rpm, and I preferred roller lifters as I don't have to worry about break in and Zinc additives, hence ended up with hydraulic roller lifters.
btw interesting article on valve springs here What you need to know about valve springs
best regards
Dave
btw interesting article on valve springs here What you need to know about valve springs
best regards
Dave
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