roller rockers

[dwg86]

Anyone done any research to see if a sbc or sbf roller rocker will on the 4.0? They sure are a ot cheaper than the ones for the 4.0.

[John]

Any parts are cheaper than those for the 4.0! But to try and shed light on your question. Have you seen this?http://members.tripod.com/~Mojo_Page/Rokr1.htm
John

[Alex22]

Its easier to make a set fit on a 4.0 head than the AMC 6 because of the individual rocker arm pedestals.
Another member used a set of AMC rocker arms: viewtopic.php?f=8&t=317&st=0&sk=t&sd=a&start=15#wrap
If you look at the second page you can see how he milled down the rocker pedestals and used a set of Chrysler magnum V8 rocker arm studs with a 3/8 upper and a 5/16 lower that will screw directly into the jeep head and a set of Chrysler magnum guide plates. You will have to drill and tap the hole deeper. If you search the part number Maize gave it comes up as an Oldsmobile part in the comp catalog, but it has the same specs as a Chrysler stud.

I'm working on using a set of roller rocker arms on my stroker build. From what i've seen so far, once you mill the pedestals down to get the correct rocker arm geometry you have a few options. If there are any 5/16 threads remaining in the head then you can drill and tap them deeper and use the studs and guide plates used by Maize.
5/16 base with a 3/8 top
5/16 base with a 7/16 top
3/8 base with a 3/8 top
3/8 base with a 7/16 top
The 3/8 base is the better option of the two because I have seen the 5/16 base rocker arm studs bend and break on an engine before. Maize used Chrysler magnum guide plates on his build, if you want to use a 3/8 base then the Oldsmobile guide plates have the correct center to center distance for the studs. I have not test them on an assembled engine yet though.
Big block Chevy and 351C Ford rocker arms look like they have the correct pivot length, There are probably more out there but I haven't checked yet.

If you want a larger ratio but don't want to spend the money on roller rockers then the stock type stamped steel 351C rocker arms are a possibility. The stampings are nearly identical with the exemption of the fulcrum radius and the distance from the pushrod hole to the fulcrum. The best part about the Ford rocker arms is that they use a piece of C-channel to keep the rocker arms aligned so you don't need to use pushrod guide plates. They are not a drop on piece though because they need a 3/8 rocker stud. You will need to use a rocker arm stud with a 5/16 base and 3/8 top and the pedestals might have to be milled down to get the correct geometry.

~Alex

[Plechtan]

I have been looking for a roller rocker with at least a 1.7 ratio, only one i could find was the Yella Terra, but I will be running solid lifters, so i need an adjustable rocker. Can't seem to find anything. Looks like that you are stuck with 1.6 because of the relationship of the pedestal to the spring. Shaft mount rockers would be a great solution, but nobody seems to make them. Anybody have any different information?

[dwg86]

Call Harland Sharp. I think they have a set of 1.7 for the 4.0 or can make a set.

[SIXPAK]

Jesel-best product bar none. Very stable and you don't constantly readjust them. You mill down your pedistals and reatp them A steel bar bolts to the pedistals then the a shaft holds paired rockers. They are pricey though.

[Plechtan]

Do you happen to have the part numbers to use for a 4.0?

[Alex22]

Jesel-best product bar none. Very stable and you don't constantly readjust them. You mill down your pedistals and reatp them A steel bar bolts to the pedistals then the a shaft holds paired rockers. They are pricey though.

Which Jesel set are you planing on using for your build?

~Alex

[SIXPAK]

Have aset allready. Bought new in 1989. I have a 1.6 set and 1.7 set.

[Alex22]

Have aset allready. Bought new in 1989. I have a 1.6 set and 1.7 set.

Jesel makes alot of different rocker arm styles for lots of different engines, Which engine were they designed to run on?

[Plechtan]

Have aset allready. Bought new in 1989. I have a 1.6 set and 1.7 set.SIXPAK

PM me if you want to get rid of the 1.7 set.

[SIXPAK]

Have aset allready. Bought new in 1989. I have a 1.6 set and 1.7 set.

Jesel makes alot of different rocker arm styles for lots of different engines, Which engine were they designed to run on?

I think that there are BBC, not 100% on that.

Sorry Plechtan, I'll be keeping both sets. Not sure of the part number it has been many years since I bought them.

[6TIME]

I have been looking for a roller rocker with at least a 1.7 ratio, only one i could find was the Yella Terra, but I will be running solid lifters, so i need an adjustable rocker. Can't seem to find anything. Looks like that you are stuck with 1.6 because of the relationship of the pedestal to the spring. Shaft mount rockers would be a great solution, but nobody seems to make them. Anybody have any different information?

I have done the 3/8 screw in rocker stud conversion on a 7120 head as a research project just for this subject. I made some trips to the junkyard and collected many rocker arms from various inline and V-8 engines. I noticed that all of the V engine rockers were shorter in length. This is due to the angle that the pushrods are oriented with the centerline of the valves. Most all OHV inline motors had the pushrods more parallel in relation to the valve centerline creating a setup needing a longer rocker arm. I found that in order to run any common V-8 rocker on the AMC I6 two things will have to be done: relocate the rocker arm stud locations, and the pushrod holes will need clearancing. The rocker arms that I have sucessfully run on my 4.0 are from a GM 250ci I6 and the ford 240/300 I6. I have seen roller rockers for the 250 around as well as the Ford I6. The 250's stock rocker ratio is 1.7 while the 240/300 is 1.6. Crane, Crower and Harland Sharpe make some for the 250 in 1.6, 1.7, or 1.75 ratio and 3/8 or 7/16 studs. I hope this might help.

[Plechtan]

It looks like the best solution would be the shaft mount style. This is 2 rockers on a common shaft, the shaft is bolted to a machined metal base, that is then bolted to the pedestals. Of course you have to machine the head to allow the base to bolt on, the big advantage is that you can move to pivot point of the rocker wherever you want.
The stud mount rockers do not give you the same range of ratios.

[SIXPAK]

Jesel set up is the same as you desribe Plech