12 replies to this topic

[fuzzypumper]

Hi,

I bought some roller rockers a while back for the 253 or 308, as shown below and I'm thinking of putting them on soon.
However I was wondering what studs I will need and where to get them from?

Also do you really need the guide plates?

Thanks for the pending replies.

[myss427]

You will need screw in studs (heads will need to be machined and taped for 7/16 studs), guide plates stop the rocker from falling off the roller tip!

[fuzzypumper]

Yeah? Machining?
I was under the impression you can get something like a 3/8 to 7/16 stud that you can just screw in without machining anything. Can anyone verify this for me?
Can someone tell me or post a picture on how the guide plates are mounted with this type of stud mounted roller rocker?
Also can anyone recomend where I can buy these locally? Melbournes eastern suburbs.
Thanks.

[Litre8]

You used to be able to buy the 3/8" to 7/16" screw in stds, I ran them on my turbo 6. The machining that may be required is to allow clearance between the bottom of the roller rocker and the 'head' of the screw in stud, machining the post down to allow clearance with the correct rocker geometry (esp. if you run guideplates too, which I would think is a wise move for that style of rocker which is free to rotate).

[fuzzypumper]

Thanks Guys,

Do you think I'm likely to have valve seal issues with the roller rockers higher ratio pushing the valve further and the seal seeing the part of the valve stem it hasnt seen for 10years?

[enderwigginau]

As said, you'll need a few things done.
Tops of the stud bosses need to be machined down.
May need to tap or re-tap the stud holes to take the new studs to suit.

What is the part # of those rockers? The box will tell you what size stud you will need.

Most sixes are press in studs, and best bet is to replace with screw in.
Not too sure about V8s though.

Best practice would be to replace the valves as well, but if you have a good look, check that they are still true and there is no lip where the seal has been stopping, you should be fine.
Check your lifters as part of the process - for hydraulics, always check the bleed down when adjusting the valvetrain.

Grant..

[micklx]

I learned the hard way about the need for guide plates.
Back in 1985 when I was an apprentice mechanic in a small country town, working mostly on tractors, farm machinery and Kawasaki farm bikes I had a HR Panel Van that was used for towing my dirt bike around because i didn't want to take my Torana into the bush on dirt roads etc.
The HR had a 161, but even back then I was into wrecking Holdens and I had acquired a recently reco'd 186, a 173 Yella Terra head, extractors from an LJ, WW2 carb and manifold and a 35/75 cam.
The extractors fouled the bellhousing - ever seen what a HR bellhousing does when you take to it with an oxy torch?
Anyway, I decided that to use that cam I needed adjustable rockers so I bought a set of screw in studs, drilled out the head and retapped the threads to accept the new studs and used 186 rocker arms on the 186 head.
This engine transformed the HR Van, it was now fun to drive and would easily beat 173/202 engined LH/LXs.
After a few weeks, it started to misfire and rattle. Some investigation showed that one of the rocker arms had twisted sideways and was loosely sitting half on/half off the valve. So I loosened the nut off, put the rocker arm back where it should be and put the rocker cover back on.
Bear in mind that I had no money and no access to all this great info on the internet.
It happened again.
I fixed it.
It happened again. etc etc etc After a few times, I took a pair of 173/202 rocker arms, drilled out the hole, ground the lower part of the pivot and put this over the screw in stud. Every time the engine started to miss I did this to the offending cylinder. This happened over a period of a couple of months, you could never tell when the next rocker would decide to fall off the valve.
One day on the way to my GFs house it happened, when I removed the rocker cover I noticed the stud had snapped off. Obviously I had to get home, so I figured if I removed the 2 lifters from that cylinder I'd be right. When I left to go home at about midnight, the oil light came on. Well nobody had told me removing the 2 lifters would result in low or no oil pressure. It was 18 km's to my house. The oil light was on the whole way. Next day, I made up a new stud, fitted the modified 173 rockers and kept driving it.
A couple of months later I fitted a 161 YT head which I bought for a bargain, it had heaps of port work and roller rockers, I had fixed the rocker problem without actually realising that the 149/161/179/186 heads could run with no guide plates but 173/202 heads need guide plates if used with single type rockers. I used that engine in 2 more cars, a HR Sedan and an EH ute. The drive home with no oil pressure can't have done it too much harm.
In standard or lightly modified form they are a tough engine.

[fuzzypumper]

Thanks,
I took SShatch355 up on his offer.

JNR_ATE , yes your taking about the ST-2033 which are shaft type(paired) , bolt on adjustable and they dont need guides because of there design.
As i have found out mine are the old stud type which definately need guides otherwise they will rotate off the top off the valves.