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Cast Iron rocker stand and valves off B directly o 912

Posted: Mon Aug 12, 2019 10:54 pm
by Frederick Bitneris
Has anyone installed 356B cast Iron rocker stand and valve assembly onto 1967/68 912 head.
I am rebuilding a "bits and pieces" 912. The case was cast in December 1967 with @ same era heads BUT came with ast iron rocker stand. I have another 912 engine and checked the cast iron stand against the alloy stand and valves, and they measure about the same.
Any help greatly appreciated as I am reluctant to purchase a set of alloy stands and associated rockers.
Frederick

Re: Cast Iron rocker stand and valves off B directly o 912

Posted: Tue Aug 13, 2019 12:16 am
by Ron LaDow
First, welcome. You will get much information, and more opinions here.
My opinion is that the factory, early on, found the ferrous rocker gear to be bad news. Unless you've done some testing to show they're wrong, I'd suggest you take the factory's advice.

Re: Cast Iron rocker stand and valves off B directly o 912

Posted: Tue Aug 13, 2019 8:31 am
by Vic Skirmants
Ron LaDow wrote:
Tue Aug 13, 2019 12:16 am
First, welcome. You will get much information, and more opinions here.
My opinion is that the factory, early on, found the ferrous rocker gear to be bad news. Unless you've done some testing to show they're wrong, I'd suggest you take the factory's advice.
I don't understand the "bad news" comment. The alloy stand had intake rockers with a greater ratio for more valve opening, the exhausts were the same ratio.

Re: Cast Iron rocker stand and valves off B directly o 912

Posted: Tue Aug 13, 2019 9:47 am
by Dick Weiss
Frederick,

As Ron said, it would be better to install the later rocker assembly having the intake rockers w/their
1.13 lift ratio and keep the 912 engine as OEM/stock. The only thing different between the 2-rocker
frames is needing a matching 3rd flanged head-bolt for the required 3rd bolt. Carefull, the frame
bolts are 15mm hex head 10 x 45 (900 155 008 00); You can't use the 3mm longer 17mm hex head bolts
to clear the intake rocker shaft support block and I just removed a steel rocker frame from a '59 engine and a head-bolt came out w/it (it bottomed out) and I had to use a vice to hold it tightly to remove the bolt!!!

Finally, all the rocker tips should be redressed (if needed), the rocker bores and shafts
not worn (.002" max. clearance), but the existing pushrods can be reused.
I may have a complete set of the later assembly, but the 15 x 45 bolts may be needed via Stoddard.

Regards,
Dick

Re: Cast Iron rocker stand and valves off B directly o 912

Posted: Tue Aug 13, 2019 7:42 pm
by Frederick Bitneris
Thank you all for your input. Lucky for me I have a complete rebuilt 1965 912 engine also. This "bits and pieces" engine is to be a "spare".
Dick, could you confirm your rocker stand and valve assembly would fit a 912/1967/8 engine.
Also, my email is crystalwoodsfb@bigpond.com. I am interested in your offer and any photos would be appreciated.
Frederick

Re: Cast Iron rocker stand and valves off B directly o 912

Posted: Fri Aug 16, 2019 7:59 pm
by Frederick Bitneris
I am trying to find my way around this site without too much success. I posted 2 X previous responses, but I think they did not go through.
Thank you all for your input. Luckily, I have a spare rebuilt 1720cc BIG BORE unit to compare with, etc, which I am installing into my 1964/65 SC.
Dick , thank you for your offer of alloy rockers [and I think], the valve train that goes with it. I am very interested and would appreciate a response as to photos and cost.
You may contact me directly on crystalwoodsfb@bigpond.com. This is in Australia
Frederick

Re: Cast Iron rocker stand and valves off B directly o 912

Posted: Wed Aug 21, 2019 9:38 am
by Al Zim
The 356 Normal and industrial engines used the iron rocker stands through 1963. In 1964 model year the Normal was discontinued and the aluminum rocker stands were used on all the engines. In my opinion the aluminum stands were cheaper and easier to manufacture. Undoubtedly there will be some power loss when using the iron rockers, but it has been my experience that this is inconsequential in normal driving situations. I CAUTION YOU not to use aluminum push rods with cast iron cylinders unless you increase you valve clearance. The result will be burned exhaust valves in a short period of time.
Put the engine together the way it was designed to be and save yourself the embarrassment when you go to sell it. al zim