I have a rebuilt Commando with Purple Shaft 284 set(including valve springs)+ Mopar Perf titanium retainers. Now the stock adjustable rockers won’t clear the springs or retainers. Allready cround off quite a bit. Which aftermarket rockers would?
273 mech rocker problem
- Thread starter onbuicks
- Start date
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Grinding on any rockers is not a good thing at all. It's an indication the rocker shaft needs relocating. Mike at @B3RE can help you. After speaking with him and letting him fix me up with a rocker shaft relocation kit, there's no way in hell I'd ever grind on any rocker arm. It's not the correct way to do it, I don't care how long who has been doing it. Call Mike. He will help you out.
B3 Racing Engines LLC - Performance Engine Building and Mopar Valvetrains
B3 Racing Engines LLC - Performance Engine Building and Mopar Valvetrains
I agree there Rusty. I ground on mine for clearance and still had to shim the shafts up to get close to correct. I wish I hadn't. I wouldn't mind installing some beehive springs and retainers. They are a lot smaller on the stem end.
Is it just me or is there almost no stem above the keeper in photo post 1 might that be part of the issue.
The retainers and valve stems and springs are not correctly matched to each other?
The retainers and valve stems and springs are not correctly matched to each other?
Look at the bottom of the spring.
Those are not the correct spring assy for that cam.
Would love to know what the seat pressure is and what the pressure is at .484.
Those are not the correct spring assy for that cam.
Would love to know what the seat pressure is and what the pressure is at .484.
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65TerrorCuda
Well-Known Member
The retainers are def sitting too high.
Did you use +0.150 height locks along with the spacers?
Did you use +0.150 height locks along with the spacers?
Locomotion
Well-Known Member
Titanium retainers usually have a bigger diameter to use with bigger diameters race springs. That appears to be part of the interference issue. Cool option but unnecessary. I like the beehive spring option if you can find one with the appropriate specs. Beehives solved the same problem on my Dart Sport.
65TerrorCuda
Well-Known Member
Is that rocker worn or just a shadow? Beveled edge?
Worn.....mushed out of round....or something.
If it's not some big race secret what beehive springs did you run on your heads?
Locomotion
Well-Known Member
I used Comp Cams 26056 beehives set up to have near 200 lbs closed & 400 lbs open. But this is on IHRA Crate Stocker engines with .474" lift, lots of duration, steep ramps and Schubeck/Smith flat tappet hydraulic lifters with a "composite puck". I did run about 160/360 lbs until I "accidently" found out I was getting valve float. I couldn't tell going down the track and was VERY lucky. It could have been a lot worse. After bumping up the pressures, car ran a little better and valve adjustments remained more accurate between checks.
With all the talk about tool steel lifters, coatings, etc., I'm sure that's not the best set-up, but it worked for me. My Aspen has (now legal) solid Schubeck/Smith lifters. Considered but never got around to shimming the hydraulics to run solid. Some people hate them because they can shatter and destroy the entire engine. But I never had a problem.
As for retainer-to-rocker clearance, I originally had 273 and ductile iron Crane Rockers which I reluctantly had to relieve before switching to beehives. The few broken, relieved aftermarket and Crane rockers that I saw over the years concerned me and I did break at least one Crane myself. I switched to Harland Sharps when roller rockers were allowed and stayed with the beehives. But I don't think mild relieving for clearance would be an issue on a milder street engine...as long as the springs & retainers aren't much bigger than OEM.
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Beehive springs is the way to fix this problem. They require 10-20% less tension than parallel springs, so your valvetrain will also be under less stress.
For that cam, aim for 120-130 Lbs on the seat with BHs.
You have ground the rocker in one of the most stressed areas of the rocker. Not good. At least using BH springs reduces the stress on it. Conical springs such as the Comp #7228 is another option.
For that cam, aim for 120-130 Lbs on the seat with BHs.
You have ground the rocker in one of the most stressed areas of the rocker. Not good. At least using BH springs reduces the stress on it. Conical springs such as the Comp #7228 is another option.
Thank You for all that information. Springs are MP4120249, which came with the cam. Exhaust valves are shimmed because the Ferrea exhaust valves were a bit longer(to achieve correct installed height). Shafts are new. It is only shadow on the rocker, but those can not be grinded enough.
So please, suggest correct springs(to replace 4120249) or rockers that might fit, if possible.
So please, suggest correct springs(to replace 4120249) or rockers that might fit, if possible.
249 spring is good to .500 lift. 1.65 installed height I believe.
They are the spring I have for my .484 purple stripe cam.
I would lose those retainers and keepers.
They are the spring I have for my .484 purple stripe cam.
I would lose those retainers and keepers.
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JDMopar
Well-Known Member
One other thing I noticed that hasn't been mentioned. Look at the tip of the rocker arm, in post #1, the contact patch area of the arm where it contacts the valve tip. Now look at the same area on the rocker in post #3 by @toolmanmike and compare how much more area there is at the tip of that rocker. It appears that the one in post #1 has been machined off quite a bit.
65TerrorCuda
Well-Known Member
Either get the correct length valves or relocate the rocker shaft. I would do both.
Dave999
Well-Known Member
shim up the shafts with general hardware washers
use a sharpy to colour the valve tips
rotate engine over to check clearance and you should have a clear scraped off ink, window on each coloured in valve tip. adjust shimming until the window on the valve tip varies across the widest part of the valve tip and the rocker tip pushes valve down before the rocker hits reatiner
when good measure the washer pack used and buy appropriate shims to set that rocker shaft up by the same value.
if it can't be done this way
get crane cams multifit retainers with offset, these are offset up or down, you need offset down.
these have a standard hole and you pair them with thicker or thinner collet to cater for stem diameter. It rasies seat and open pressure a little but could get you the clearance.
and/or off-set collets from the same source. you can raise or lower the retainer a smidge this way on a valve that is custom to the application. smaller increments than with retainers, and yes you can also get them in multi fit thicknesses for use in multi fit retainers.
this process should be done with a custom adjustable pushrod or a home made one with shims/small washers added into its length. cut rod in an accessible place where adding washers to its length won't clash with other hadware . wind/press in threaded rod into its middle
stick on some washers and put the other end of pusrod back onto the threaded rod.
aim to get a line through the rocker paralell to head/deck with the valve at half lift and maintain your nice pattern in the sharpy ink on the valve tip.
when all good, measure the washers you used to shim up the rocker shafts and get proper shims.
measure the shim washers you used to legthen your pusrods and get pushrods made longer by that much.
I've been through this on an aussie 6 with massive cut to block and head, stud mount 1.72:1 rockers off a ford, narrow stem ferrea valves suitble for edlebrock big block heads that were a smidge too long
offset collets and offset retainers from crane
and some smiths bros custom pushrods...longer..... got me bang on right
the tip of your rocker needs to press the valve down before the "armpit" of the rocker hits the retainer...
In my view a geometry fix attempt is needed before buying off-set rocker shafts.
This is just normal custom engine build stuff, that is avoided if you use a well worn recipe, where somone else did the hard graft. But is standard if all the parts come from a range of suppliers and were designed for another motor.
you have a lot of rocker tip, the current set up has the wrong bit of the tip hitting the valve tip, and too close to the rocker i.e too close to edge of valve tip. shifting the shaft up can make this worse if the same area of the rocker tip is used, but you have loads of tip space on that standard style rocker. I suspect the rocker shaft lift will get an area closer to the end of the rocker tip in contact with the valve tip and in a more appropriate place on the valve.
it may make it better it depends on how bad the geometry is how laid back your rocker is when the lifter is on base circle. really you can only see that if you watch a full cycle.
basically rocker should be neither biased tail down or nose down at half lift, and the contact between it and valve should be as close to the diameter line of the valve tip as possible
but nobody will know until you try
while you are in there and once all set up with correct lash, little smidge of lube on pushrod end at rocker, check for coil bind at full lift
check for retainer or bottom edge of collet, to guide or seal.... impact
put white line on all pusrods in paint or nail varnish just below rocker.
turn engine over with plugs out 10-20 times check all pushrod marks have moved round a little bit indicating that the lifters are turning if one doesn't what is wrong. find out first before trying to start it.
if they all turn you reduced the likelyhood of wiping the cam by about 99%
can't say i'm telling you the correct way to do this i just did what i had to and it worked for me
Dave
use a sharpy to colour the valve tips
rotate engine over to check clearance and you should have a clear scraped off ink, window on each coloured in valve tip. adjust shimming until the window on the valve tip varies across the widest part of the valve tip and the rocker tip pushes valve down before the rocker hits reatiner
when good measure the washer pack used and buy appropriate shims to set that rocker shaft up by the same value.
if it can't be done this way
get crane cams multifit retainers with offset, these are offset up or down, you need offset down.
these have a standard hole and you pair them with thicker or thinner collet to cater for stem diameter. It rasies seat and open pressure a little but could get you the clearance.
and/or off-set collets from the same source. you can raise or lower the retainer a smidge this way on a valve that is custom to the application. smaller increments than with retainers, and yes you can also get them in multi fit thicknesses for use in multi fit retainers.
this process should be done with a custom adjustable pushrod or a home made one with shims/small washers added into its length. cut rod in an accessible place where adding washers to its length won't clash with other hadware . wind/press in threaded rod into its middle
stick on some washers and put the other end of pusrod back onto the threaded rod.
aim to get a line through the rocker paralell to head/deck with the valve at half lift and maintain your nice pattern in the sharpy ink on the valve tip.
when all good, measure the washers you used to shim up the rocker shafts and get proper shims.
measure the shim washers you used to legthen your pusrods and get pushrods made longer by that much.
I've been through this on an aussie 6 with massive cut to block and head, stud mount 1.72:1 rockers off a ford, narrow stem ferrea valves suitble for edlebrock big block heads that were a smidge too long
offset collets and offset retainers from crane
and some smiths bros custom pushrods...longer..... got me bang on right
the tip of your rocker needs to press the valve down before the "armpit" of the rocker hits the retainer...
In my view a geometry fix attempt is needed before buying off-set rocker shafts.
This is just normal custom engine build stuff, that is avoided if you use a well worn recipe, where somone else did the hard graft. But is standard if all the parts come from a range of suppliers and were designed for another motor.
you have a lot of rocker tip, the current set up has the wrong bit of the tip hitting the valve tip, and too close to the rocker i.e too close to edge of valve tip. shifting the shaft up can make this worse if the same area of the rocker tip is used, but you have loads of tip space on that standard style rocker. I suspect the rocker shaft lift will get an area closer to the end of the rocker tip in contact with the valve tip and in a more appropriate place on the valve.
it may make it better it depends on how bad the geometry is how laid back your rocker is when the lifter is on base circle. really you can only see that if you watch a full cycle.
basically rocker should be neither biased tail down or nose down at half lift, and the contact between it and valve should be as close to the diameter line of the valve tip as possible
but nobody will know until you try
while you are in there and once all set up with correct lash, little smidge of lube on pushrod end at rocker, check for coil bind at full lift
check for retainer or bottom edge of collet, to guide or seal.... impact
put white line on all pusrods in paint or nail varnish just below rocker.
turn engine over with plugs out 10-20 times check all pushrod marks have moved round a little bit indicating that the lifters are turning if one doesn't what is wrong. find out first before trying to start it.
if they all turn you reduced the likelyhood of wiping the cam by about 99%
can't say i'm telling you the correct way to do this i just did what i had to and it worked for me
Dave
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