What shaft for ductile iron rockers?

[gkent]

Honing them is as simple as buying a brake hone and sticking it in your drill. And GO EASY - its amazing how much material is removed with only a couple strokes !!

 

[Jonas Nordstrom]

Honing them is as simple as buying a brake hone and sticking it in your drill. And GO EASY - its amazing how much material is removed with only a couple strokes !!

Thanks, what tightness should I aim for?

 

[gkent]

One thing that's worth considering ... what size are stock Mopar shafts? The rocker stands on the heads are machined to accept that size. If, for example, they're machined for .872 shafts then the .875's are not going to fit. That's something you don't want to start messing around with. Trying to bolt them down is going to bugger up either the shafts or the heads!

That said, I've owned a number of sets of Isky rockers like yours and NEVER had a set that didn't fit on a set of stock-size shafts. I used to use TRW shafts back in the day which were thicker than stock shafts and had a ground surface finish

Thanks, what tightness should I aim for?

I don't think you want any more than a thou. As long as they move freely but not loose.

 

[Lefty71]

so the nice Hughes 1620 shaft does not fit sadly....

what tightness should I aim for?

Wow, apologies if we've gotten off track here....

Do you know the original application for those rockers?? Are they factory or aftermarket. Not a whole lot of factory adjustables out there...... I do have some here tho, I'm going to have to look and see if I have shafts and what they measure... It would be good to know what the real clearance should be.... trying to think just where I could find that info.... maybe measure a different set??

 

[padam]

How are you measuring? Seems odd that they would be under .875.

 

[Jonas Nordstrom]

Wow, apologies if we've gotten off track here....

Do you know the original application for those rockers?? Are they factory or aftermarket. Not a whole lot of factory adjustables out there...... I do have some here tho, I'm going to have to look and see if I have shafts and what they measure... It would be good to know what the real clearance should be.... trying to think just where I could find that info.... maybe measure a different set??

Mine are factory max wedge rockers.

 

[Jonas Nordstrom]

How are you measuring? Seems odd that they would be under .875.

Ah wait, you made me go out into the garage and measure again and now I noticed that the shafts had been tourqed too hard, they are egg-shaped!
(I got them as extra parts when I bought a pile of original 440 stuff.)

....well, that explains a lot.

 

[Lefty71]

Mine are factory max wedge rockers.

Those look awful straight for max wedge... I have some of those too, and some others. I'll have a look at some of this stuff and report back.... Really hope were arent looking at some old 273 rockers there!!, but I'm not the greatest at just comparing by pix on sight....

 

[Lefty71]

they are egg-shaped

LoL, surpirised someone did'nt tell you to look out for that earlier....it happens, a lot.

 

[Jonas Nordstrom]

Those look awful straight for max wedge... I have some of those too, and some others. I'll have a look at some of this stuff and report back.... Really hope were arent looking at some old 273 rockers there!!, but I'm not the greatest at just comparing by pix on sight....

Thanks, that would be great.
I really hope i didnt buy 273 rockers for my 440 build!

 

[Jonas Nordstrom]

Better pics of mine, should be MW rockers, close to 1.5.

 

[Geoff 2]

Use factory shafts. Poly engines had the same type of rocker....& shafts & ran just fine.

 

[Jonas Nordstrom]

Use factory shafts. Poly engines had the same type of rocker....& shafts & ran just fine.

What about honing them or bush them before install.
Overkill or will it make them last longer?

 

[gkent]

What about honing them or bush them before install.
Overkill or will it make them last longer?

Nope. If they aren't scored from use then leave them as they are.

Factory shafts are junk. The one's you have pinched oval - new one's will be no better !!

 

[Lefty71]

Ok, a little follow up on the rocker confusion. I dug out the supposed MW factory rockers that I supposedly have.... they have the same markings as yours, identical. So, we have the same thing, whatever that is lol. I took them and tried them on some factory mid 70's plain old rocker shafts, and the ones that they came with...both .875".... They slid right on, and so did my Hughes aluminum rockers, although it was clear that the clearance was much tighter on the new aluminum ones. I think all these new .872" aftermarket shafts are really just to prevent galling on the new rockers (just a guess).

I'll try to put up some pix... but for now, check out this thread from a while back... very informative, and there were some smart cookies on this site, some of which I wish we still heard from.

rocker arm shafts

 

[gkent]

all these new .872" aftermarket shafts

??? Who says they're .872 ??? .003 in addition to whatever the rocker clearance is will spew oil like crazy/ You actually want a close (not tight) tolerance so there is pressure in the rocker otherwise the bottom surface won't get any oil. Spring pressures, etc will just squeeze that area dry.

What you want is a thick wall, round .875 shaft.

 

[Lefty71]

??? Who says they're .872 ??? What you want is a thick wall, round .875 shaft.

CHRYSLER Rocker Arms - 0.872 in. Shaft Diameter (in.) - Free Shipping on Orders Over $109 at Summit Racing


Just discussing whats out there... refer to post #13.... I did'nt say anyone should want these.

 

[1KoolBee]

After screwing around with crane and isky irons and fighting the galling issues and geometry, I found that Harland Sharps were actually the best value. Use the “E” versions for Eddy/Trick Flow/Stealth heads. Regular version for factory iron heads. No expensive “correction kits” or special shafts required.

 

[Cranky]

After screwing around with crane and isky irons and fighting the galling issues and geometry, I found that Harland Sharps were actually the best value. Use the “E” versions for Eddy/Trick Flow/Stealth heads. Regular version for factory iron heads. No expensive “correction kits” or special shafts required.

View attachment 1856606

Over the years I've torn down a bunch of factory big block engines and several had hardened shafts. Was it whatever the vendors sent them or did just the HP engines have them? I'm pretty certain that some of these came out of regular passenger car engines. Some shafts were fairly soft against the 'file test' and some were hard enough to mark the file. I've used the Isky ductile iron non roller rockers on factory 'hard' shafts and they did fine turning 7300 in the lights.

 

[Cranky]

One thing that's worth considering ... what size are stock Mopar shafts? The rocker stands on the heads are machined to accept that size. If, for example, they're machined for .872 shafts then the .875's are not going to fit. That's something you don't want to start messing around with. Trying to bolt them down is going to bugger up either the shafts or the heads!

That said, I've owned a number of sets of Isky rockers like yours and NEVER had a set that didn't fit on a set of stock-size shafts. I used to use TRW shafts back in the day which were thicker than stock shafts and had a ground surface finish


I don't think you want any more than a thou. As long as they move freely but not loose.

How many shafts have you had that didn't fit a stock head, factory or aftermarket? I can see an aftermarket shaft not fitting....and what size were the TRW shafts and how do you measure the saddles on a stock head....since they are not quite a full half round?