Adjustable rocker arms?

I am thinking about adapting some sb chevy style rocker arms to the HO 4 liter head. Has anyone succeeded/failed? The bolt-on rocker setups are rediculously expensive!! It looks to be rather simple if the stud bosses were milled a bit and then threaded for a screw in stud. But then again I haven't even started messin with it! Any ideas from all of you Jeep gurus out there? Thanks.

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93 Cherokee Sport
4.0, ax15, 2" RE BB, 30x9.5 MTR's
Stock exhaust, plugged n rattling cat haha,
0-60 in over ten seconds. Mods soon to come!

Might one enquire as to why you want to do this? There's no real reason for adjustable rockers on the 4.0 that I can see, since the hydraulic 242 valvetrain actually does what it's supposed to...

The idea behind adjustable rockers is mainly to help with setting lash in mechanical/solid valvetrains. Since the hydraulic system is self-adjusting, there's no need for the extra moving parts.

If you are having trouble with lash or spring tension due to head or deck milling, the better solution (involving less work and less $ overall) would be to get pushrods made to the corrected length. Your machinist can help you with that.

5-90

Dr.Dino seems to be the engine guru around here and would probably know a little more about this, try shooting him a PM.

i dont see why it wouldnt work...

EDIT: his website is here:
http://www.jeep4.0performance.4mg.com/

The whole idea is to convert the stock valvetrain over to roller. If one could swap the stock valvetrain over to stud mounted roller rockers it could probably save a few hundred bucks or so? Since Chevy parts are so much cheaper and readily available why not try it? It's just an idea but I wanted to get some feedback from people who might know better! Thanks.

OK, here's my $0.02 on roller rockers for the 4.0:

Higher ratio roller rockers produce HP/TQ increases by reducing valvetrain friction, increasing valve lift, and effectively increasing cam duration. Big Block Chevy 1.7 ratio roller rockers can be installed on all 4.0 HO heads except the newer small-port type ('99 and later). The entire assembly fits within the stock valve cover with no clearance problems. If you retain the stock camshaft, valve lift is increased from 0.424" to 0.450". It's not a simple bolt-on job though as you'll find out in this link:

http://members.tripod.com/~Mojo_Page/Rokr1.htm

There are many sets of 1.6 ratio roller rockers available on the market but the Yella Terra YT6627A are the only currently available roller rockers that fit under the stock valve cover and use standard 5/16" sized rocker arm studs. Quadratec.com sell each set for $440:

http://www.quadratec.com/cgi-bin/sg...2&UREQC=3&UREQD=4&FNM=10&UID=2004081213010460

Others (Yella Terra YT6328, Crower 73648-12, Crower 72848-12, Harland Sharp S40096, Mopar Performance/Hesco P4529885) require either a valve cover spacer for clearance ($80 from Hesco) or the rocker arm stud bosses of the cylinder head to be drilled and tapped for 3/8" or 7/16" studs.

Wonder why the setup wont work on the 99 and newer heads? I've read about problems drilling out the holes on the 4.0L heads for 3/8 screw in studs. I guess the stud boss can crack from the reduced wall thickness. Comp Cams makes a 3/8 stud that has a 5/16 bolt on the head side.

From seeing the '01 head from my wife's Jeep, it looks to me that a Ford Style pedistal mount system could easily be made to work. The problem with just using the Ford 1.7 set up is the rockers likely do not have the correct dimensions. But if you could get Crane to send you a setup with the Ford bolt down pedistal set up but with the BBC rockers it'd be a pretty quick bolt on.

Another company that my be able to help out is Scorpion. They make pretty nice rockers and they're cheap.

Dr. Dyno, you forgot to mention that RR increase power also because they do not flex like a stamped steel rocker. Thus retaining thier true ratio. They also reduce wear at the valve tip and the fulcrum. No question RR are the way to go if you can make them work, even if you use the same ratio that came stock.

B-loose

Bloose said:

it looks to me that a Ford Style pedistal mount system could easily be made to work. The problem with just using the Ford 1.7 set up is the rockers likely do not have the correct dimensions.

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That's right. I've compared the Ford 5.0 rockers to the ones from the Jeep 4.0 and the Ford's are smaller so they won't work.

Comp Cams makes a 3/8 stud that has a 5/16 bolt on the head side.

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These studs combined with Ford BB or Chevy BB shaft-mounted RR's might just work though.

Dr. Dyno said:

That's right. I've compared the Ford 5.0 rockers to the ones from the Jeep 4.0 and the Ford's are smaller so they won't work.



These studs combined with Ford BB or Chevy BB shaft-mounted RR's might just work though.

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Did you mean stud mounted???

I also wonder if someone like Scorpion makes bolt down pedistal type rockers for BBF/Ford Clevland? It would be nice if we could figure out a low cost RR set up for our 4.0's.

B-loose

Yeah, I've been trying to figure out a low cost solution for a while. Unfortunately my Ford 5.0 pedestal mount rocker idea is dead in the water.
Ford or Chevy BB shaft-mounted rockers might work since these can be used with 3/8" studs but stud-mounted rockers are going to require 7/16" studs. The rocker stud bosses on the 4.0 head would probably crack if you attempt to drill & tap them to 7/16".

Bloose said:

Did you mean stud mounted???

I also wonder if someone like Scorpion makes bolt down pedistal type rockers for BBF/Ford Clevland? It would be nice if we could figure out a low cost RR set up for our 4.0's.

B-loose

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You got that right B-loose! Who wants to pay $$400+ for a set of 12 roller rockers, when you can get a set of 16 for a V-8 for 169.00? I'm working on it. Maybe I'll come up with something?

Funkytee.

Dr. Dyno said:

Yeah, I've been trying to figure out a low cost solution for a while. Unfortunately my Ford 5.0 pedestal mount rocker idea is dead in the water.
Ford or Chevy BB shaft-mounted rockers might work since these can be used with 3/8" studs but stud-mounted rockers are going to require 7/16" studs. The rocker stud bosses on the 4.0 head would probably crack if you attempt to drill & tap them to 7/16".

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That's right, I forgot that the BBF and BBC rockers are only available for 7/16 studs.

What about AMC V8 rockers? I thought those were the same as the I6's?

B-loose

Just looked, Scorpion does make a set of 1.73 BBF pedistal mount roller rockers. Just over $200 a set and you'll have 4 spares. Or buy 4 sets get the 5th free

http://www.nthcoast.com/ScorpionRockers.html

B-loose

Bloose said:

That's right, I forgot that the BBF and BBC rockers are only available for 7/16 studs.

What about AMC V8 rockers? I thought those were the same as the I6's?

B-loose

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I don't know for sure but if they are, that's very good news.
The minimum stud size is going to be 3/8" so if you want to avoid drilling and tapping the rocker stud bosses in the head, the answer might be to use CompCams CCA-4542-16 studs ($69.69 at Summit Racing). They are 3/8" but have a 5/16" base thread to screw into the head.

Bloose said:

What about AMC V8 rockers? I thought those were the same as the I6's?

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I just looked them up. The AMC V8 rocker arm pivots and bridges are the same as those of the I6 but not the rocker arms themselves.

The adapter plate for the BB Chevy rockers was only used on that head because it was probably an earlier type 258 head that had shaft-mounted rockers. That wouldn't be necessary on our 4.0 heads but in any event, using BB Chevy rockers raises a different problem. They all require 7/16" studs. The stud bosses on the 4.0 head will crack if any attempt is made to expand them from 5/16" to 7/16" so essentially, the BB Chevy rockers are a no go.
The AMC V8 rockers are NOT the same as the I6 versions, even though the rocker arm bridges and pivots are, so I don't think these will work either.
I do have another idea though and it might just work. The Crower aluminium 1.6 ratio RR's for the AMC/Jeep I6 (part # 72848-12) mount on 3/8" studs, so the CompCams 4542-16 studs (5/16"->3/8") should be compatible. Stud-mounted rockers require guideplates so these will be CompCams 4842-6 units. When you use guideplates, you must also use hardened pushrods to avoid scuffing and wear from the guideplates. Crower 70158-12 pushrods are specific for the AMC/Jeep I6, are 9.625" long, and are chrome moly steel. As you can see, the cost is beginning to escalate. To summarize the parts list:

Crower 72848-12 roller rockers: $257
CompCams 4542-16 rocker studs: $69
CompCams 4842-6 guideplates: $18
Crower 70158-12 hardened pushrods: $40

The total so far is $384, and we still don't know if they'll clear the stock valve cover. At the very least the internal baffles will need to be cut. If the valve cover needs to be raised, add another $80 for Hesco's spacer.
Now we're over the $440 that Quadratec.com charge for the Yella Terra YT6627A non-adjustable RR's that bolt straight in under the stock valve cover with no hassle. You can get the same ones directly from Yella Terra in Australia for $485AUD ($380 US) so I might take that route.
The Yella Terra YT6328 adjustable RR's cost $536AUD ($420 US) but they require the Hesco valve cover spacer, so total cost if you use these will be $500.

Interesting..

I'm going to be strokin this winter and thinking about the RR just because I'm going to do a head rebuild. Been searching a bunch and found this:

http://home.everestkc.net/greyhnds/rocker.html

Which appears to be the same concept except using Crane studs which are 5/16 x 3/8.

Hodge

Yeah, I've seen that page before Hodge regarding the Harland Sharp units. Just remember:

"The following machining operations are required to install the rocker arms:
Mill stud bosses 0.400"
Drill and tap stud holes deeper (to match studs) and chamfer"

The parts list and cost for that set-up will be:

Harland Sharp S40096 roller rockers: $285
CompCams 4542-16 studs (Crane's are special order): $69
CompCams 4842-6 guideplates: $18

That's $372 without adding the Crower pushrods ($40) and the cost of machining so by the time you're done, it'll still cost over $400 for the whole nine yards.

Right.. I just got done running the numbers. Looks like that Yella-Terra setup is looking more and more appetizing. Just have to see if my local shop can get them for me. Are they a quadratec special? I can't find them on their site.. Just the YT-6328 which may require machining.

Hodge

Dyno,

What about the Scorpion Pedistal mount BBF rockers?

B-loose

Bloose said:

Dyno,

What about the Scorpion Pedistal mount BBF rockers?

B-loose

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Dunno? It's all about finding the right dimensions to match the distance from rocker stud to valve tip. You could easily clearance the pushrod holes if needed. Other than that, using the comp studs combined with some minor milling, it should work!

FUNKYTEE