Moparts

Why did I bend a pushrod?

Posted By: galen

Why did I bend a pushrod? - 11/09/10 03:22 AM

Today I really needed a stress break so I took the car for a short drive. Drove around a little while and warmed everything up good. Ran it up to about 7200 through 1st and 2nd. Felt something. Backed out heard the miss and clatter. So far I have pulled the rockers. One lash cap is MIA. Pushrod is bent but still in place. Running offset lifters on the intakes and the correct amount of threads on adjusting screws. No galling, adjuster is ok. Good wear pattern on other lash caps. Going to pull the valley cover in the morning to check the lifter. Failure was #1 intake, 440-1s, Harland Sharps, Cam is not real radical. 263/270at.050. .690-lift. #1 cylinder leakdown ok. Springs 230#seat. I am running a smith brothers .083 wall 3/8 pushrod. What should I look for? Is it a pushrod strength issue. I had 2500 miles on it before but always shifted at 6800, this is the first at 7200.
Posted By: Bad340fish

Re: Why did I bend a pushrod? - 11/09/10 03:28 AM

Could the lash cap have come dislodged and cuased a piston to valve issue? Sorry to hear about the damage! Kind of makes a stress reliever go the wrong way.
Posted By: 602heavy

Re: Why did I bend a pushrod? - 11/09/10 03:40 AM

Not saying it's you're problem but never had much luck using .083" pushrods in an RB when exceeding 600lb spring pressures , those .145" walls are belt & braces.

Maybe go find another stress reliever. , just kidding.
Posted By: Old School

Re: Why did I bend a pushrod? - 11/09/10 04:01 PM

Quote:

Not saying it's you're problem but never had much luck using .083" pushrods in an RB when exceeding 600lb spring pressures , those .145" walls are belt & braces.

Maybe go find another stress reliever. , just kidding.


same here,i use .120" wall mantons.i have similar spring pressures.
maybee the lash cap broke. i've had it happen to me. it sucks when that tool steel bounces around in the motor. find that cap ,if you can.
Posted By: Cab_Burge

Re: Why did I bend a pushrod? - 11/09/10 05:49 PM

I had a Smith Bros 3/8 .083 wall heat treated pushrod break in two pieces during a dyno test at 5600 RPM, it knock the top of the roller lifter off, bent the pushrod beside it and ended up dropping into the lifter bore gauging it and the cam lobe I had Smith Bros custom make them, told them all about the motor specs, spring pressures, intended RPM and so on I help some other local racers that own a dyno, they had one of there Smith Bros pushrod break the top off of one during a dyno test also I replace my Smith Bros with a set of seies 3 Manton .120 wall that Terry Manton recommended and that motor made 8 more HP at 300 RPM higher during the next dyno test, A,B,A after fixing the motor Smith Bros did replace the two bad ones free but didn't offer any other help on replacing or fixing the bushing, lifters and camshaft ( I didn't ask them to either )
Posted By: Dodgem

Re: Why did I bend a pushrod? - 11/09/10 07:58 PM

Yea I have bent a couple and am going to a .120 wall next year for my roller cam.
My last one went sitting idling in tech line last TT (for me) day and what a racket!! Made enough noise to be a kicked rod!
In with a spare and off for some TT fun.
Usually intakes too with that big offset!

Posted By: galen

Re: Why did I bend a pushrod? - 11/09/10 08:37 PM

Got it apart today. No needles were left in the lifter. Roller is worn down and it took the nose off the cam. Still have not found the lash cap. All other 15 lifters , pushrods ,etc. are fine. Pushrod was not bent as bad as I first expected but maybe .030. Could the lash cap have broken first and beat the lifter out? Taking pictures and will post when my kids come over to help. Am going to go with the mantons and a new cam/lifters. Galen
Posted By: CompWedgeEngines

Re: Why did I bend a pushrod? - 11/09/10 09:57 PM

No, lifter failed first, then out went the lash cap and subsequent issues. Not sure though if it simply was a catastrophic lifter failure, or something else that cause a lobe failure, but I'd put my money on bad lifter.
Posted By: Cab_Burge

Re: Why did I bend a pushrod? - 11/10/10 03:36 AM

Quote:

No, lifter failed first, then out went the lash cap and subsequent issues. Not sure though if it simply was a catastrophic lifter failure, or something else that cause a lobe failure, but I'd put my money on bad lifter.

Posted By: WILD BILL

Re: Why did I bend a pushrod? - 11/10/10 03:41 AM

I just hope that's all it is and you can get it back together with out much pain
Posted By: Bob_Coomer

Re: Why did I bend a pushrod? - 11/10/10 03:50 AM

Also, Dont dismiss a tight valve guide. I have seen them be a hair to tight and something's gotta give.
Posted By: galen

Re: Why did I bend a pushrod? - 11/10/10 03:59 AM

Lash cap was in the pan. After checking everything you guys are right. Lifter failed. Pushrods,sockets and adjusters dont even have wear marks.My valve lash never moved and I change my oil every 500 miles. This engine does see a lot of 1500 to 2500 rpm street time. Lifters I had were supposed to oil the rollers. 2500 miles on them. What do you guys think of the isky lifters with no needles. The price is a little high for my taste. But now I have to buy a new cam, lifters, probably an oil pump and maybe bearings. This car is still my stress relief, gotta fix it.
Posted By: galen

Re: Why did I bend a pushrod? - 11/10/10 04:02 AM

Quote:

Also, Dont dismiss a tight valve guide. I have seen them be a hair to tight and something's gotta give.

Thanks Bob, I will check that also. I am going to pull it out at this point and tear it down.
Posted By: 383man

Re: Why did I bend a pushrod? - 11/10/10 07:03 AM

Sorry to hear about that. That is one reason I decided to go flat tappet cam in my new eng as I drive it alot on the street. Ron
Posted By: Anonymous

Re: Why did I bend a pushrod? - 11/10/10 01:53 PM

Hard to beat Crower lifters marsh performance aka Moparts Connection-- board sponsor has them in stock--The Comps are JUNK
Posted By: polyspheric

Re: Why did I bend a pushrod? - 11/10/10 03:24 PM

If there's any question about "is it enough?":
1. biggest possible improvement is to go larger diameter until it won't fit - there is no 10mm or 13/32" OD commercially available, but it would help if 7/16" won't fit.
With same .120" wall, and rating 3/8" as 100 units for a base:
10mm = +21%
13/32" = +36%
7/16" = +80%
1/2" = +198%
2. increased wall thickness is far less effective, only do this when #1 is not possible.
Posted By: B G Racing

Re: Why did I bend a pushrod? - 11/10/10 05:37 PM

Quote:

If there's any question about "is it enough?":
1. biggest possible improvement is to go larger diameter until it won't fit - there is no 10mm or 13/32" OD commercially available, but it would help if 7/16" won't fit.
With same .120" wall, and rating 3/8" as 100 units for a base:
10mm = +21%
13/32" = +36%
7/16" = +80%
1/2" = +198%
2. increased wall thickness is far less effective, only do this when #1 is not possible.
Easy comparo for pushrod wall thickness: it's pretty close (never exactly) to new ÷ old.
.120" ÷ .083" = 45% stiffer



45% stiffer,if only I duplicate that.Bigger is always better,so I'am told
Posted By: Bob_Coomer

Re: Why did I bend a pushrod? - 11/10/10 06:34 PM

Quote:

Hard to beat Crower lifters marsh performance aka Moparts Connection-- board sponsor has them in stock--The Comps are JUNK



Bull
I have been running them for years, best lifter in there price range.
Posted By: bwdst6

Re: Why did I bend a pushrod? - 11/10/10 06:55 PM

Quote:


2. increased wall thickness is far less effective, only do this when #1 is not possible.
Easy comparo for pushrod wall thickness: it's pretty close (never exactly) to new ÷ old.
.120" ÷ .083" = 45% stiffer

That estimation isn't even close. I'm calculate that with a .375 OD pushrod going from a wall thickness of .083 to .120 (or an ID of .209 to .135) the increase stiffness is just 9%. And considering the additional mass one would be adding to the valve train I would say it isn't worth it!

moment of inertia = pi(OD^4-ID^4)/64. ID^4 is the killer.
Posted By: polyspheric

Re: Why did I bend a pushrod? - 11/10/10 07:21 PM

You're right - I typo'd it!

What do we learn from this: don't rely on memory, if you actually data.
Thanks.
Posted By: Brian Hafliger

Re: Why did I bend a pushrod? - 11/10/10 07:46 PM

Quote:

Hard to beat Crower lifters marsh performance aka Moparts Connection-- board sponsor has them in stock--The Comps are JUNK


He's running my lifters, and they are far from junk.
Solid roller cams are very unforgiving and it can be the spring, lash or pushrod that will likely be the FIRST thing to rear it's ugly head.

Already talked with Galen and I'm fairly certain it's not the lifter that caused the problem. Instead of pointing fingers we talked and went over everything...GOOD CUSTOMER!!

I agree the pushrods should be .120 wall 3/8 or .085 wall 7/16 IMO but that's not what caused this to happen.
Might be time to change the lobes for more "street" driving this time around.
Brian
Posted By: roadhazard

Re: Why did I bend a pushrod? - 11/10/10 07:55 PM

So what "caused" the lifter to fail?

I'm no engine builder however,

My theory is the push rod was flexing and pole vaulting the valve train causing the lifter to seperate from the camshaft. Possibly flat spotting the roller needles and or fracturing them when the roller was reintroduced to the camshaft leading to the destruction.

It would be interesting to see what the roller needles look like on the other 15 lifters.

Sorry about your broken toy Galen
Posted By: CompWedgeEngines

Re: Why did I bend a pushrod? - 11/10/10 08:00 PM

The question then becomes was it a lifter failure due to lack of lubrication at low speeds? I do not think a 230# seat pressure spring, is putting that much of a DIFFERENCE in load on his set up going from 6800 to 7200 just ONCE.I have many many BBM engines running .083 and .095 pushrods in bracket race engines with never a failure. Is the stiffer pushrod better? 100% yes. Is this what caused Galens breakage? I hardly doubt it.

Does he really have that aggressive of a lobe in that engine where it was surging or bouncing to the point of failure? ( I dont know his cam, apparently you do, so asking is it that aggressive?)

Again, its not a radical piece, and the RPM was not out of range for a 230/650ish spring.
You know and I know thta lifters just simply dont " fail". ( I am NOT bashing the lifters here, has nothing to do with the " brand" here in my opinion) It would have to have been surging for a long time to beat the needles out of it.

Just my , send me a PM if you want instead of here. Not sure if its " all on the table" here. Thanks.


And yes, Galens a good dude.
Posted By: galen

Re: Why did I bend a pushrod? - 11/10/10 09:32 PM

Thanks for the help guys. I am going to send the lifters to Brian so he can take a look at them. The cam I am running is a comp RX296 R8. 263/270 at .050. Lift is .650/.651 with 1.5s. I am running a 1.6 Harland sharp and a 943-16 spring. I had to go with a plus ..050 retainer to get my spring height. I aired on the side of clearance and set the installed height at .950. In doing so my spring pressure may be lower than I expected. I am going to check all spring heights and pressure and will report my findings. I have to figure this is an error on my part. I am thinking a few little ones that added up to my failure. My main objective is to find out why and prevent it next year. I will keep you all posted and run the game plan by you on the repair. No hole in the world block, no broken head, thankfull for that. I went from brad Penn to Royal purple, that may have been a mistake also. Going to look at some bearings. I have pics but I have to get my kids over to help me get them off this stupid camera. It's still good to be a mopar guy
Posted By: polyspheric

Re: Why did I bend a pushrod? - 11/10/10 10:38 PM

Can't rule out pushrod flex as a contributor, but even good roller tappets can't take any air gaps - the needles just snap and escape, the roller wheel collapses onto the axle, blah.
Even though this may not be a quality problem at all, you must examine the other 15.
The Harley-Davidson roller test (since they all have them since 1929) is:
1. does it rotate freely, no scratchy spots or drag
2. end-play is the same on all tappets
3. zero up-&-down play
Posted By: 440Jim

Re: Why did I bend a pushrod? - 11/10/10 10:56 PM

Quote:

I had to go with a plus ..050 retainer to get my spring height. I aired on the side of clearance and set the installed height at .950. In doing so my spring pressure may be lower than I expected. I am going to check all spring heights and pressure and will report my findings.

I agree, check the springs. Not enough spring pressure can cause the lifters to get beat up, especially as the rpm goes above 6500 etc. Besides the installed height, the street driving (how many years?) may have caused the springs to lose tension.

I don't know for sure, but some might say 275/675 pressures and 0.120" pushrods would be the preferred setup. But don't expect the lifters to last forever.
Posted By: Brian Hafliger

Re: Why did I bend a pushrod? - 11/11/10 03:38 AM

Definitely need to check springs I.H. and check again for pressure. When hot they lose approx. 20lbs. on the seat so if they were close to 200 cold then that is biggest problem but not sure that's what the springs are so we have to wait.

Pushrods probably didn't help anything and if the springs were weak allowing valve bounce this would be amplified by the thin wall pushrods.

Galen, did you go to a thinner oil when you switched to Royal Purple? Thinner oils allow more spring temp too.
Brian
Posted By: polyspheric

Re: Why did I bend a pushrod? - 11/11/10 06:25 AM

Thinner oils allow more spring temp too

I suspect (no actual data) that thinner oil may have lower surface tension, and form smaller droplets in the cover, get around better, and cover more area before draining.
I'm surprise that I haven't seen more remarks about something already in use elsewhere: a lower spring cup on the spring OD, normally used to prevent chafe and locate the spring (rather than a seat on the guide OD) with a taller lip than normal. The cup retains some oil, and when the spring is really moving, it acts like a bird in a birdbath - it splashes the oil out of the cup very nicely.
Posted By: Brian Hafliger

Re: Why did I bend a pushrod? - 11/11/10 07:22 AM

Quote:

Thinner oils allow more spring temp too

I suspect (no actual data) that thinner oil may have lower surface tension, and form smaller droplets in the cover, get around better, and cover more area before draining.
I'm surprise that I haven't seen more remarks about something already in use elsewhere: a lower spring cup on the spring OD, normally used to prevent chafe and locate the spring (rather than a seat on the guide OD) with a taller lip than normal. The cup retains some oil, and when the spring is really moving, it acts like a bird in a birdbath - it splashes the oil out of the cup very nicely.



I guess I should state that what I mean is super thin oils like 5 or 10wt don't seem to cool as well as 30wt. I don't have any data myself but I've been told this by and oil rep. I guess that doesn't mean it's correct?
Anybody have any real data on oil viscosity's affect on cooling????
Brian
Posted By: polyspheric

Re: Why did I bend a pushrod? - 11/11/10 05:51 PM

AFAIK the most important factors in using oil to transfer heat are:
1. volume
2. motion (is it passive, or does it drain away constantly)
3. area (how large a heated surface is washed)

Oil from the rockers etc. that can "find" a narrow deep channel to the drains is going to do less than oil that must pass over the exhaust guide bosses, exhaust port rooves, and spring bases first. Examine your head's upper surface - sometimes there are obvious areas where a simple piece of sheet metal creates a longer path.
Some engines have drains adjacent to hot spots - here, drilling the drain slightly oversize 1/4" deep and inserting a thin tube 3/8" tall (old conduit, etc.) makes the oil pool out and cover the hot area 1/8" deep before reaching the drain opening. This is even possible with some pushrod holes. Remember to analyze this as the engine sits in the chassis, both as to front/rear and left/right.
Posted By: hemi-itis

Re: Why did I bend a pushrod? - 11/12/10 01:52 AM

Galen,do you ever blow the tires off hard in 1st and then click 2nd gear ??That creates HAVIC in the valve train Don't ask how I know Here is a picture of your lifter

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