jas2730

iTrader: (7)

Okay, I'm assembling my 113 aluminum heads with 1.5 ratio comp ultra golds, 3/8 7.800 length hardened push rods, comp 3/8 hardened guide plates, and a flat tappet cam and lifter set. When I install the guide plates my rockers make contact with the rocker stud when tightened the extra 1/2 turn past finger tight. Helpful insight only please.

AlkyIROC

Check your valve train geometry. You probably need longer pushrods. If the pushrods are the correct length for the geometry, you'll need shorter screw in studs to compensate for the extra height caused my the guide plates. You could also have the stud bosses under the guide plates machined down the thickness of the guide plates.

Oh the joy of using non OEM parts.

grumpyvette

reading thru these links should help

http://forum.grumpysperformance.com/...hp?f=52&t=1376

http://forum.grumpysperformance.com/...php?f=52&t=181

http://forum.grumpysperformance.com/...le+flat#p19333

jas2730

iTrader: (7)

My geometry is spot on without the guide plates but when I install the plates the rockers contact the hex nut on the stud. I been reading online that there are lower profile studs for roller rockers that will fix this issue. Does this sound like something I should look into?

grumpyvette

lets be clear, before going further, your describing the rocker binding at location (B) not location (A) or (C) correct?



if thats the case the push rods or the rocker studs or the guide plates are wrong for the application OR you never had the cast rocker bosses in the heads correctly machined for the screw in studs


standard screw in rocker studs to use with or without guide plates require the rocker stud boss be machined for required clearance

there ARE screw in rocker studs that can be used WITHOUT machining the bossed but they CAN NOT be used with guide plates and DO frequently result in cracked rocker bosses.


stock cast rocker bosses must be machines to gain clearance for guide plates and screw in studs

EACH type of engine and every set of rocker guide plates and studs will effect how far the rocker boss must be machined for clearance but on most sbc engines the boss is machined down about .360, CHECK WITH YOUR MACHINIST AND HAVE THE PARTS AVAILABLE TO MEASURE

jas2730

iTrader: (7)

Yes, they're hitting at location B. These are 113 heads so they should've been set up for my application from the factory. That being said, if my geometry is perfect without the guide plates I should be able to measure the plate and order a push rod that makes up the difference. Correct?

AlkyIROC

Nope

If geometry is perfect without the plates then adding the plates doesn't change the geometry. All it does is move the rocker stud up higher. If the rocker can't go down far enough on the stud then the stud bosses will need to be milled down so the plates give a same stud height as installing the studs without the plates.

As soon as you change the pushrod length, you change the geometry.

I love my shaft rockers. I doubt I'll ever go back to pedestal rockers. They're well worth the extra money.

jas2730

iTrader: (7)

Damn it! Damn it! Damn it! Lol.

grumpyvette

WHY? IM I ,getting the feeling you never had the cast cylinder heads rocker bosses correctly machined for the required clearance for guide plates and screw in studs!

jas2730

iTrader: (7)

??? While I appreciate your opinion and insight the way you deliver it is not something I care for at all!

jas2730

iTrader: (7)

As stated before, these heads came equipped with screw in studs and guide plates. The only changes are the rockers, pushrods, cam, and lifters.

zraffz

Switch to the studs with the collar instead of the nut. Unless you have insane springs it won't do any damage.

grumpyvette

let me say that it was never my intention to do anything but help resolve your problem, not in any way get you upset, sorry if I said something you took exception too.

jas2730

iTrader: (7)

The way you use exclamation points and how you word your responses seems condescending.

AlkyIROC

Install longer valves which will need longer pushrods to keep the same geometry and will move the rocker higher on the stud. Of course spring install height will also need to be checked with longer valves or a whole bunch of shims will be needed under the springs.

jas2730

iTrader: (7)

Honestly fellas my wallet is tapped out. I can't afford to go that route. I may be at a point where I have no choice but to pull these heads and put the stockers back on since they have guides built in.

Damon

Don't get frustrated. You're $25 from a fix. Which is what Alky said in the first post- you need longer sticks. Summit has a set of inexpensive house-brand hardened sticks for the SBC in stock and +.100" length (7.900") which will fix the issue.

Having perfect rocker geometry is nice, but is isn't always achievable. When you have the rocker grinding into the stud hex you install longer sticks and to hell with rocker geometry.

Factiory heads were never equipped with big fat aluminum roller rockers by the mothership. Hence, they didn't have to design the extra rocker stud clearance into them. And if you're using a higher lift cam you should know that higher lift is achieved by reducing the base circle diameter, not making the lobes taller. So that shortens the "effective" length of the pushrods a little bit as well. Your head gaskets might be thicker than stock. Also the factory designed their valvetrains with the rockers "leaned back" a little more than the common "mid lift point" rocker geometry school of thought would have them anyway. Just a few reasons why slightly longer sticks are not to be feared in situations like this.

Don't sweat it too much. It's not a cop-out. I have to do this kind of "steal from Peter to pay Paul" kind of compromise fairly frequently with AFR heads (which I use often in my builds). They move stuff around in subtle ways vs. stock and I've found it's difficult to achieve "perfect" reocker geomety with them. I often have to resort to longer sticks for exactly the reason you are having issues. Never has it caused an issue.

jas2730

iTrader: (7)

The hardened rods I have came from summit and at a $100 they were the cheapest. Would I be better off keeping my rods and replacing the studs?

AlkyIROC

First of all, I'd be very skeptical that your geometry is correct. Your 7.800" pushrods are stock length. You've changed a lot of things so there's no guarantee you need stock length pushrods.

When checking the geometry, you should be using lightweight checking springs so you don't collapse the adjustable pushrod. The area of sweep should be on the center of the valve tip but this isn't always the best geometry. You want the margin line to be as small as possible. If a smaller line is slightly inward or outward from the center of the tip, it's still more acceptable than a wider sweep over the direct center of the tip. If the small margin line is on the outside edge of the valve tip then you have a serious issue.

One of these things works just as well and you don't need the checking springs to use it. The theory is with the lifter on the base circle of the cam, you slip this over the rocker stud. It should contact the valve tip at the same time it contacts the pushrod. If one is higher or lower than the other then a different length pushrod is required. No margin sweep across the valve tip required.



Instructions
http://static.summitracing.com/globa.../pro-66789.pdf

jas2730

iTrader: (7)

So, I went and took some measurements and I came up with 7.925 as the length of rod needed for my application. Only problem is I can't find them in 3/8 diameter to work with the guide plates I already have. I don't want to change rod and guide plates and end up with another unknown variable. Anyone know where to find them. I've checked Summit and Jegs.

jas2730

iTrader: (7)

Found a set of Manley pushrods for $192. ... Ouch! Still looking.

Damon

Why the big 3/8" pushrods for a flat tappet cam small block?? Standard 5/16" diameter sticks should be more than sufficient. And 5/16" guideplates are cheap.

That's why you can't find inexpensive sticks. 3/8" stuff on a small block is normally only used with some pretty hard-hitting roller cam setups ($$$).

jas2730

iTrader: (7)

I know, I know. It was a greedy move to start. I figured 3/8 would be better at the time when I was looking for 7.800 length rods. Hindsight being 20/20 I now realize that was unnecessary.

jas2730

iTrader: (7)

So close....yet not.

RBob

iTrader: (1)

Check with Smith Brothers, they do nothing but pushrods.

http://www.pushrods.net/

RBob.

AlkyIROC

Well if you want to get picky about good pushrods, buy these

http://www.mantonpushrods.com/

jas2730

iTrader: (7)

Ha ha! You guys are getting way out of my league! I'm not getting picky, just trying to find the right length. It seems that 7.925 is hard to come by at a reasonable price! I'm thinking of saying screw it and going with these and seeing how close they get me!
http://www.summitracing.com/parts/SUM-1457950/

AlkyIROC

Many times the perfect length isn't an option. You then pick the closest length to what you require. If what you need is 7.925 then it's probably half way between 2 common lengths so going shorter or longer to 7.900 or 7.950 isn't a big deal. Get whatever is more available which would probably be the 7.900 as it's 0.100" longer than stock. That will probably fix your rocker stud issue.

Your choice from Summit will do fine. I wish I could get 16 pushrods for $100