Economical replacement rocker arm set?
- Thread starter WSUTARD
- Start date
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WSUTARD
Well-Known Member
So something like this? https://m.summitracing.com/parts/cca-7958-1
yellow rose
Overnight Sensation
So the exhaust valves are low. Are all of them on that side low?
If so, just find the low ones and put longer pushrods in those holes only.
At this point we are just going off the average stem height. We have no idea if they are correct. But most of them aren't making noise so they must be close to correct. We can see that the exhausts are low, effectively making the pushrods shorter and losing lifter preload.
The options are longer pushrods where the stems are low, or convert to adjustable valve train. Either will work. The second option is more expensive.
If so, just find the low ones and put longer pushrods in those holes only.
At this point we are just going off the average stem height. We have no idea if they are correct. But most of them aren't making noise so they must be close to correct. We can see that the exhausts are low, effectively making the pushrods shorter and losing lifter preload.
The options are longer pushrods where the stems are low, or convert to adjustable valve train. Either will work. The second option is more expensive.
rustycowll69
Well-Known Member
there is a gap, hard to say how much from picture. You can use some feeler gauges to get a more numeric idea of the gap. It doesn't look horrible. you've got a 1.5 ratio to consider, so it would be proportionately less difference on the pushrod length. Like was posited by another poster, it could be related to hard seat installation, and poor seat finishing to not compensate for stem height. It's pretty common with Chevy engine builders/automotive machinists, not aware of Mopar rocker shaft concerns.
yellow rose
Overnight Sensation
It's not as big a deal with stud mounted rockers as you can just screw the adjuster down.
If WSU really wants to step up and convert to adjustable rockers I will donate a set to the cause. Then he only needs to buy pushrods.
WSUTARD
Well-Known Member
I am more than happy to take you up on your offer Yellow. I'm assuming that I would need these push rods then? https://m.summitracing.com/parts/cca-7821-16
The gap on the valve is only .0059" (.15mm) so I think a 7.550 is going to be too long anyway.
rustycowll69
Well-Known Member
keep in mind that it's better too long than too short. you can shorten too long 3piece pushrods, but you can't lengthen them. If you can't be absolutely sure about the length, my advice is go long.
nm9stheham
Well-Known Member
Good job on running it down. That valve tip gap is not all that much. This points more and more to:
- a low base circle on the new cam, or something amiss on the length of the lifters.
- OR that cam lobe is failing....
I would really be wanting to know why this gap suddenly opened up, especially since it appeared right after some high revving.
Also, take that lifter out, and look closely at the base of that lifter for signs of damage, and peer down in there to look at that lobe while you rotate it slowly around. It would be a lot smarter to pull the intake to examine the cam. I would not hesitate to get an extra couple of the new lifters and put a new one in that hole, and break it in.
If cam lobe and lifter are all good, then you should also examine the underside of the rocker shaft at that point and the mating rocker for #3 ex. to see if either or both are worn. .003" wear on the underside of the shaft, or in the rocker body where it wears on the shaft, will raise the valve side of the rocker by about .005". Look at that pushrod too.
If cam, lifter, rocker and shaft are all good, then you might get lucky and get rid of that one gap by swapping around the 4 RH rockers around on that shaft and/or the pushrods. There is nothing absolutely sacred about keeping pushrod and rockers in exact order like there is about keeping lifters with specific cam lobes. Or just get another rocker. Also, pull the pushrods and lay them carefully side by side to see if that one is short, and roll them across a pane of glass to see if any are bent.
You can also get specific length pushrods built or make them yourself from Comp parts. The former will run around $180 shipped from Smith Brothers in Oregon, and the latter will cost a bit over $100 and your time. But at that point, it's making more and more sense to swap rocker types.
- a low base circle on the new cam, or something amiss on the length of the lifters.
- OR that cam lobe is failing....
I would really be wanting to know why this gap suddenly opened up, especially since it appeared right after some high revving.
Also, take that lifter out, and look closely at the base of that lifter for signs of damage, and peer down in there to look at that lobe while you rotate it slowly around. It would be a lot smarter to pull the intake to examine the cam. I would not hesitate to get an extra couple of the new lifters and put a new one in that hole, and break it in.
If cam lobe and lifter are all good, then you should also examine the underside of the rocker shaft at that point and the mating rocker for #3 ex. to see if either or both are worn. .003" wear on the underside of the shaft, or in the rocker body where it wears on the shaft, will raise the valve side of the rocker by about .005". Look at that pushrod too.
If cam, lifter, rocker and shaft are all good, then you might get lucky and get rid of that one gap by swapping around the 4 RH rockers around on that shaft and/or the pushrods. There is nothing absolutely sacred about keeping pushrod and rockers in exact order like there is about keeping lifters with specific cam lobes. Or just get another rocker. Also, pull the pushrods and lay them carefully side by side to see if that one is short, and roll them across a pane of glass to see if any are bent.
You can also get specific length pushrods built or make them yourself from Comp parts. The former will run around $180 shipped from Smith Brothers in Oregon, and the latter will cost a bit over $100 and your time. But at that point, it's making more and more sense to swap rocker types.
mullinax95
Well-Known Member
I recommend contacting Mike at B3 Racing Engines LLC - Performance Engine Building and Mopar Valvetrains
Mike WILL get you up and running again... just got to contact him.
Here is my recent walk down the road with rockers B3 Racing Engines Geometry Kit
PRW roller rockers might cost more but they are good rockers. If your valve train geometry is off you will not see any effects short term but long term you might.
I would like to suggest you read all of B3 Racing Engines LLC - Mopar Rocker Arm Geometry Tech
You will learn the why and what for on all of it. lol
Had to purchase custom length pushrods. Got them made at Manton in which they use the good material to make their pushrods... same as Smith Brothers. Cost me $146
They don't play around they shipped them out in no time. Talk to Al.
Mike WILL get you up and running again... just got to contact him.
Here is my recent walk down the road with rockers B3 Racing Engines Geometry Kit
PRW roller rockers might cost more but they are good rockers. If your valve train geometry is off you will not see any effects short term but long term you might.
I would like to suggest you read all of B3 Racing Engines LLC - Mopar Rocker Arm Geometry Tech
You will learn the why and what for on all of it. lol
Had to purchase custom length pushrods. Got them made at Manton in which they use the good material to make their pushrods... same as Smith Brothers. Cost me $146
They don't play around they shipped them out in no time. Talk to Al.
WSUTARD
Well-Known Member
Took the lifter out. The base looks as it should. Swirl marks and convex. Internals look fine. No real dirt in there other than the oil. The side of the lifter does have a gash which I think is from manufacturing.
I rolled all the pushrods on a glass weight scale. I'm not 100% sure the glass of the scale is true but all the pushrods seemed to have just a tiny "curve" to them. I could see the ends touch and then barely lift off the surface as I rolled them. They seemed to all have he same amount of "curve" so this leads me to believe that my surface wasn't 100% true.
So my next step is to clean the lifter with minieral spirits, check the cam lobe for proper wear then reassemble.
If the ticking doesn't go away then I am going to switch the rockers around and try again.
Thoughts?
I rolled all the pushrods on a glass weight scale. I'm not 100% sure the glass of the scale is true but all the pushrods seemed to have just a tiny "curve" to them. I could see the ends touch and then barely lift off the surface as I rolled them. They seemed to all have he same amount of "curve" so this leads me to believe that my surface wasn't 100% true.
So my next step is to clean the lifter with minieral spirits, check the cam lobe for proper wear then reassemble.
If the ticking doesn't go away then I am going to switch the rockers around and try again.
Thoughts?
rustycowll69
Well-Known Member
after reassembly, soak the lifter in a clean light oil, maybe rislone, atf, whatever, in a bowl or glass until the air bubbles escape from the orifices. Not necessary to pump lifter up, in fact Comp instructions advise against that.
nm9stheham
Well-Known Member
The pushrods sound OK. Come up with some way to lay them in a trough or groove with some sort of stops clamped snugly at the ends as a size gauge to see if #3 ex. pushrod is particularly shorter than the others.
Take apart another lifter to see how the parts go in and see if they are identical. The little disc with 4 holes looks a bit curved and maybe needs to go in one particular way.
Been trying to think up a way to check the rockers to see if #3 is bent upwards at one end more than the others. I'm drawing a blank on something easy.....Swapping it with another RH rocker might show that right up.
Take apart another lifter to see how the parts go in and see if they are identical. The little disc with 4 holes looks a bit curved and maybe needs to go in one particular way.
Been trying to think up a way to check the rockers to see if #3 is bent upwards at one end more than the others. I'm drawing a blank on something easy.....Swapping it with another RH rocker might show that right up.
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nm9stheham
Well-Known Member
BTW, this my not be possible with the intake on..... Look into the lifter bore for #3 ex and several others and see if the holes in the sides of the lifter bores are all about the same in each one. My son's 340 block had 1-2 unusually small side holes near the center of the passenger side lifter gallery, where the drilling of the interior of the lifter gallery was not done completely through at the factory. We had to assure ourselves that the lifters' waist bands would reach those unusually small side holes at some point in the lifter movement to get oil into the lifter.
That's just a reeeeeally long shot...so I would not pull the intake for just that.
That's just a reeeeeally long shot...so I would not pull the intake for just that.
yellow rose
Overnight Sensation
If you want the 273 rockers PM me your info and I'll dig them out tomorrow and send them over to you Monday. You should have them by Tuesday.
And it would be good to talk to Mike at B3 and see what he says.
And it would be good to talk to Mike at B3 and see what he says.
WSUTARD
Well-Known Member
Your Inbox is full. I can't PM you.
yellow rose
Overnight Sensation
yellow rose
Overnight Sensation
Ok shoot me a PM. I cleaned my box up.
WSUTARD
Well-Known Member
I got a chance to check out the lobe on #3 exhaust. Looks fine to me. Check the video. Sorry about the grunting...!!!
yellow rose
Overnight Sensation
You're tougher than me. I'd have pulled the spark plugs so I didn't have to turn it over and fight compression.
The lobe looks fine BTW.
The lobe looks fine BTW.
nm9stheham
Well-Known Member
Yes and Yes. I like the 'tool noises' LOL.
Lifter gallery hole looks normal too.
WSUTARD
Well-Known Member
Today I:
Cleaned the #3 intake and exhaust lifters. Made sure the pushrods were all the same length.
Switched the #1 and #3 rockers
Videoed the cam lobes to ensure they were wearing correctly.
And the tick is still there.
I guess my next trick will be to switch to Yellow's adjustable rockers and new pushrods.
The quest continues.
Cleaned the #3 intake and exhaust lifters. Made sure the pushrods were all the same length.
Switched the #1 and #3 rockers
Videoed the cam lobes to ensure they were wearing correctly.
And the tick is still there.
I guess my next trick will be to switch to Yellow's adjustable rockers and new pushrods.
The quest continues.
rustycowll69
Well-Known Member
look at you, diagnosing this! good job!
WSUTARD
Well-Known Member
I'm afraid it had something to do with the heads. Maybe the valve guide is warn and allowing the valve to get weird in there.
72RoadRunnerGTX
Member
Eric, Using the stethoscope, did the noise move to #1 with the rocker or remain at the #3 exhaust valve.
rustycowll69
Well-Known Member
do you know what type of guide you have? if it is really thin-wall, it's called a guide liner. If it is like 3/32" thick or so wall thickness it is a replacement guide. They can be iron or bronze. Have you felt around the spring retainer and spring seat, while the engine is running? Perhaps, if it comes to that you can remove the keepers, retainer, v. spring, v. stem seal and look for any anomalies. But you have to be able to keep the valve from dropping in the cylinder. It can be done, but you have to be careful.
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