When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
As many of you know, I've been obsessing over my bad valve tip pattern. The patter is too far towards the exhaust so I need shorter pushrods. But when I do that, it lowers the roller-tip rockers far enough to bind on the rocker stud. I'm sure the stems have been ground down and made too short.
But I may have a solution. Would pedestal-mount roller rockers allow the rocker to sit lower than the stud mounted roller tips I'm using now? I've seen Scorpion pedestal mount rockers and I believe the Ford B351 fit Olds stock heads as well. But I'd like to know if this is going to solve the problem before shelling out $300-$500 bucks.
Also, the vids I've watched show the Ford guys NOT using guide plates with the Scorpion pedestal mount rockers. If this is a possibility for my iron J heads, this would lower the rocker as well.
So again, would anyone happen to know if the pedestal mount roller rockers sit lower than stud mounted roller tips?
Thanks guys.
The Ford rockers use a sheet metal channel section that goes under the pedestals to prevent them (and thus the rockers) from rotating sideways, so that serves the same function as guide plates. I suspect they actually have a higher pivot point than the stock rockers. The correct fix is different pushrods.
Thanks for the illustration Joe. I appreciate it. But the issue isn't the pushrods, per se. Yes, I need shorter pushrods but, even though that corrects the valve tip pattern, it lowers the rocker (comp cams roller tip) to the point that it binds on the rocker stud. The guide plates aren't helping this scenario either, but that channel in the illustration looks to be a bit thinner, which might help.
Even if these pedestal mounts solve my issue, I'm a little unclear about how to set the lifter preload with the shims and still get the rocker to sit low enough. I'll see if I can work that out on paper.
Is that the Comp 1442 rocker kit? I've got that setup in a 455 that I built. The pushrods needed to be longer to prevent bottoming. In any case, the problem with the pedestal rockers is that you can't independently adjust lifter preload AND contact pattern. The shims will change both at the same time. There aren't enough degrees of freedom.
By the way, I used the Crane 36655 stud and guide plate kit in my motor. The studs don't have the thick hex. You need to use double nuts to install them in the heads.
Well that's that, I guess. I'm not giving up correct preload for a better pattern. But that stud kit looks like it might do the trick. I looked for studs with a lower shoulder but didn't have much luck. Are those 5/16 in the head and 3/8" on top? I might see if I can find just the studs and use them with my guide plates as those appear much much thicker and will put me right back to where I am.
Yes, I'm running the Comp Cams roller tips but with trick flow pushrods. Which, if these studs work out, might be up for sale soon, lol. Thanks Joe, you're the best!
And just in my own defense; I used an adjustable pushrod length checker and checker springs and this was the best pattern I could get with these valves. If these studs don't work out, I may have to go with lash caps, recessed retainers, and 10* locks. Oh, and of course new pushrods.
While the Crane guide plate system looks thick, I suspect it is less thick than a conventional guide plate and the thick hex on the studs you have. Note that the small flange on the stud actually goes into a counterbore in the cast bracket. Also, since there is no large radius at the base of the stud, there's additional clearance there as well.
I found just the studs on Summit but, oddly enough, not on Crane's site. Just the complete kit. I can also purchase a complete setup for a single cylinder if I want to confirm your thoughts on the thicknesses.
Thanks again, Joe.
I should be able to get you a measurement on the thickness from the mounting surface on the head to the top of the flange on the stud or the cast guide plate bracket - whichever is higher.
I should be able to get you a measurement on the thickness from the mounting surface on the head to the top of the flange on the stud or the cast guide plate bracket - whichever is higher.
Of course that would be awesome but I'd hate to put you out.
Okay, dumb question maybe but what gives with self-aligning rockers? It's said that they shouldn't be used with guide plates. PRW makes a full roller (small block ford that Copper Cutlass is running) that is self-aligning. Could I ditch the guide plates all together? https://www.summitracing.com/parts/p...view/make/ford
Thanks Joe, I'll check it out over Thanksgiving break. I hope it wasn't too much of a pain.
And that's including the channel, yes?
No problem - I actually have a second set of heads with this setup sitting in my shop right now. And yes, that measurement is fully installed on the heads.
Hey Joe, and everyone, assuming the new studs solve my problem (and I'm confident they will), when measuring for new pushrods (with an adjustable pushrod), do I apply the half turn preload before testing the valve tip pattern? I would think that would be necessary. But also, I had a thought; when tightening the polylock to get the preload, will the checker springs be too weak and open the valve instead of compressing the lifter?
I would only worry about factoring in the pre load if you still think you will have clearance issues. which I don't think it will be with these studs.
Do you mean clearance of the rocker to the retainer? Oh, you mean binding on the stud. I don't think so either but I'd like to avoid that again! And won't preload change the pattern?
If I remember correctly, the last time I did this, I used a solid lifter (self made), got the pattern as close as possible, and then added the preload length to that figure. Copper, should I run less than a half turn with these rockers, do you think? Is it a full turn is 060, and a half turn = 030? Maybe I should try 020.
Last edited by Macadoo; November 27th, 2019 at 09:00 PM.
Half turn with your pitch i belive it about .040 preload. Running less preload has some advantages. For me whem i decided to start playing with it I found going from half turn to like 1/8 about .010 the idle smoothed out and the engine revved much better. I did however have the lifters that had the snap ringss not the little wire spring clips. The snap ring lifters allow 0 preload I have heard that lifters with the wire style will come apart at 0 preload over a short period of time. I haven't necessarily hear anything about running them with just .010 like falling apart but I was being cautious. I also meant your binding on the stud as far as preload goes. I remember when i had similar issues I would loose that clearance at the rocker arm studs with the pre load. As far as the pattern goes it might move slightly but the main thing is as long as its near center with no sweep you are good. You dont have to be dead nuts center . in theory if you have no sweep then the valve should be oening up straight as long as the pattern is near center within reason.
Last edited by coppercutlass; November 28th, 2019 at 05:19 AM.
I was going to say the same thing. The half turn will make a minuscule difference to the pattern, and the checking springs won't let you set the preload anyway.
I was going to say the same thing. The half turn will make a minuscule difference to the pattern, and the checking springs won't let you set the preload anyway.
Mondello says to make 1 full turn on his full roller rocker arms. A machine shop guy told me to make a "half turn" to produce more vacuum. Is this true?
@ELY442 I tried almost a full turn when I first built this motor (because I didn't know any better) and it didn't want to idle at all. After months of playing with the carb idle circuit, Copper taught me about preload and its effects.
@all, the cam specs call for one-half turn but I might try just a wee bit less. somewhere between 1/4 and 1/2 turn, just to see if there is any improvement.
SO, just to double check; set the adjustable pushrod as close to my current pushrod length as possible, subtract just a tiny bit (since my current pattern is towards the exhaust side), tighten the polylock until just zero lash, and the length of the adjustable pushrod will be what I need (assuming the pattern and sweep are good)? Don't add another 030 for preload? And then hope there are pushrods of that length available.
@coppercutlass If I'm looking at the geoometry diagrams correctly, the closer one gets to the center of the tip, the smaller the sweep, and vice-versa. I realize I'll never get it perfect but it's very off-center right now and the sweep is quite large. Mostly, this is for my piece of mind. I've saved almost half of what I need for a couple of Mondello aluminum heads but then realized with all that extra flow, my new Street Demon may be too small. And the extra power might overwhelm my stage 2 trans, and ...and...and.... Lol. I'm going to put that cash into the AFR and some other needed upgrades/repairs.
Mac try this next time. Go as tall as you can. On my current SBO a longer pushrod had a perfect pattern but due to the ford rocker arm i had clearance issues with my 550 + lift and i was smacking the poly lock pretty good since there was not enough clearance in the rocker arm body. ( quirks of a ford rocker arm and higher lifts) . I was at 8.650 and I found a mopar pushrod at 8.468 that got me really close to center with a thin pattern and no sweep along with a thin poly lock for a girdle I only have about .040 clearance between the rocker arm body and poly lock. The 8.650 which was longer would have been perfect but you know.... I like doing things the hard way lol and found why ford rocker arms are harder to run on higher lift cams. Now there is ford rocker arms with longer slots but usually for more hardcore race applications. My buddy runs the crane gold's for a ford with no issues on a 600+ lift cam. So in short next time try a taller length on the adjustable checker. If you haven't already.
@coppercutlass I get what your saying but going higher would be impossible because of the shorter valves. Will I have trouble with these ford rockers and .512 lift and regular polylocks?
I'm going to go about 3/8 turn and see how it feels. I don't want to trash my lifters, lol.
You won't thrash the lifters at .020 at zero preload you smack the spring clip with the plunger when the valve closes and eventually they pop out eventually. Specially at extended higher RPM.
You shouldn't have issues with the ford rocker arm at your lift.
Last edited by coppercutlass; November 29th, 2019 at 11:56 AM.
You won't thrash the lifters at .020 at zero preload you smack the spring clip with the plunger when the valve closes and eventually they pop out eventually. Specially at extended higher RPM.
You shouldn't have issues with the ford rocker arm at your lift.
Excellent. I've got the new studs and checker springs. I borrowed an air compressor from an oldsmobuddy and have the spark plug hole adapter (if I can find where I stored it). Now just waiting on the rockers. Christmas break, here I come!
So, here's where all this landed:
I ordered and received the crane studs (only the studs) and was pretty confident they would work. I didn't go with the entire kit because I saw a vid on Youtube where a dude was using that kit with the same small block ford full roller rockers that I'm upgrading to and he had clearance issues. But the crane studs actually have a small shoulder under the base that's meant to fit inside the guide. So I chucked each stud up in my drill press and used a Dremel with a cutting wheel to shave down the shoulder. Took about 5 seconds on each stud. I was careful not to take any more material than necessary, leaving the shoulder wider than the shaft of the stud. But after all this I just couldn't get the guide plates adjusted. Hand tighten the the studs, place the pushrods (new, shorter), rockers and hand tighten polylocks, adjust the plates so the roller tip is centered on the valve, remove the polylocks and rockers, then double nut each stud and torque down. Seemed simple enough. It wasn't. Every time I tried, the guide plate would move slightly.
However, as it turned out, the ford roller rockers had a much larger clearance on the underside of the rocker than the comp cams roller tip rockers (see pic) and cleared the taper on the comp cams rocker studs just fine. Go figure. Also, and this was me not thinking ahead, there was no way I was getting the #8 cylinder pushrods out with the AC box in the way so I ended up removing it. Luckily I haven't installed the new compressor yet so it wasn't a bid deal.
Thanks for the help everyone.
About half the rod still inside head. Full roller rockers Comp cams rocker on top I think the witness mark is weak because of the light pressure of the checker spring and the very oily roller tip but this looks much better than what I had.
Last edited by Macadoo; December 23rd, 2019 at 04:55 PM.
Oh, and I forgot to mention; the stock, notched valve covers clear this setup just fine. I installed each cover with no gasket and cranked the engine over several times while holding the cover in place with my hand. No noise, no feeling of knocking. I measured it out first and it's close but I think I'm good.
November 22nd, 2019, 09:05 PM
