Question about the Olds F85 Rocker Arms

castlesid · December 03, 2009, 07:15:16 PM

In one of the pics of the F85 rockers you can see an oil hole on the valve side, presumably to positively oil the rocker tip and possibly to add some cooling for the valve springs which could be important for circuit racing use.

Kevin.

mabie1978 · December 07, 2009, 09:00:52 AM

Well according to Mark up at D&D there is not a way to use them on the Rover application. So they will end up for sale sometime in the near future.

But thanks for all the questions and advisement.

mabie1978 · December 08, 2009, 03:18:20 PM

Hey guys, Ted from Eaton Balancing sent me an ad he ran across regarding the rockers but other than that he had not seen them before for an Olds application. Here is the ad in case anyone is interested, they look similar with exception to the adjuster having a cup on it for the push rods.
Thomas Rockers ad 01.jpg

NixVegaGT · December 08, 2009, 05:26:05 PM

Bitchin'! So these were around to eliminate hydraulic lifters. Interesting. I went on "street view" and looks like there is nothing there but a few VX3 tags. I wonder what happened with them.

roverman · December 09, 2009, 04:47:41 PM

Story is, Mr Thomas, first name, Doubting, never tried mass marketing and therefore doubted the true potential for the market, much like England for aftermarket, Rover engine parts, heads, intake manifolds were produced, didn't sell to their expectations, possibly based on less than ideal marketing, so just gave-up! Sad near-misses, roverman.

castlesid · December 09, 2009, 05:27:49 PM

Nick,

Where the ad says collapse the hydraulic lifters, do you think this means that they are converted to solid lifters?

Also made of Magnesium so any original ones might have age related issues?

Kevin.

castlesid · December 09, 2009, 05:33:36 PM

Found this Wikepedia link that shows Bill Thomas of Thomas automotive Products as a Charter member back in the early days of SEMA

http://en.wikipedia.org/wiki/SEMA

Kevin.

roverman · December 09, 2009, 06:45:51 PM

"Bill Thomas Race Cars", in Anaheim int the 60's. Famous race cars, "Cheetah", faster than a speeding Cobra and more $Pricey now. Michelle- you din't mention they were, magnesium.In the pic' they looked like maybe cast steel ? Even more cool than alum. roverman.

mabie1978 · December 09, 2009, 08:36:56 PM

Art, I am guessing that I have both. I only brought in two loose ones from the box but one is a bit more silver while the other looks like cast steel. Magnet sticks to the steel one but not the other, at first I thought maybe someone tried to paint it a silver color but evidently the metals are different. I will get the rest of them in the box tomorrow and see what it looks like.

roverman · December 09, 2009, 09:42:00 PM

Michelle, another clue is mag. is approx 1/4th weight of steel. roverman.

nalle · December 09, 2009, 09:58:46 PM

I think I would like to get hold of a set of these.... do they have the same 1.6 ratio still?

mabie1978 · December 10, 2009, 01:18:55 PM

Oops I was wrong, I think they are all magnesium. The magnet I was using was so strong it was picking up on the metal parts in the rockers. So I guess someone did try painting them.

NixVegaGT · December 11, 2009, 11:02:33 AM

Wow, Michelle. You are super lucky to have those rockers. What is the reason why they won't work on the Buick/Rover shafts? I don't get it.

roverman · December 11, 2009, 12:51:04 PM

Michelle and all , I think you were told no was because Olds "stand" is wider than Buick/Rover? Shafts should be same dia. at .812". Maybe put a spacer to make-up the differance? Double check the off-sets in a mock-up. Good Luck, roverman.

ryan.creaturo@gmail.com · May 14, 2016, 09:09:32 AM

Hmmm, Don't know if anyone is still following this thread or not, but interesting. I have a set of these Thomas adjustable rockers off a buick engine. Don't know much about the buick rocker shafts bc I have an Olds F85 with the olds engine. I'll throw up some pictures later. They look very similar to the ones posted by the original poster, but instead of F85 they say B.S. my guess would be that stands for buick special?

tr8todd · May 16, 2016, 04:10:03 PM

Timely thread comeback. I've been wondering what these adjustable rockers are from. They came with that unassembled high performance dry sumped Olds engine I picked up with the home made car I bought. I came to the conclusion that they were probably Volvo rockers, because that was the hot setup 20 years ago. About the time this engine was conceived.

BlownMGB-V8 · May 17, 2016, 10:33:25 AM

Todd, are those rocker shafts actually fed from both ends? Bit over the top I'd say.

Jim

tr8todd · May 17, 2016, 12:08:57 PM

No, just one end. Other end is plugged with blue anodized AN type fitting. Also came with hollow push rods that I assume were designed to oil up to the adjustable tip in the rocker arms. My intent is to remove anything and everything that had to do with the dry sump and put it together as a nice stout Olds 3.5... with bigger valves, adjustable rockers, a big cam, new flat top pistons, ARP bolts, and every other neat part that came in boxes with this project. Putting this back to gather will be first on my list as soon as I finish the LS3/TR8 project.

MGBV8 · May 17, 2016, 12:33:20 PM

Check the rocker ratio. Unless they have been modified they will be around 1.5

BlownMGB-V8 · May 17, 2016, 03:25:18 PM

That'll cut into your base circle...

Jim

tr8todd · May 17, 2016, 04:09:13 PM

I seem to remember those Volvo rockers are 1.55. From the number on the cam box,I found some info and others here found some other info. Even with the 1.55, the cam that came with the engine should have somewhere in the vicinity of .500 lift. I'm not even sure they are Volvo rockers. Just an educated guess. Once the whole engine goes together, I'll take a little time to figure out exactly what all the pieces add up to. I can only hope, that the fella that went to all the trouble and expense of putting this thing together, had an idea what he was doing. After all, he was able to build this and its pretty cool.

mgb260 · May 17, 2016, 04:31:42 PM

Todd, Volvo rockers are steel and bushed to fit the smaller rocker shaft. Originally 1.5 ratio. They are offset drilled and tapped with larger 3/8" adjuster from 5/16" toward the shaft to get 1.55 ratio. Stock ratio is advertised as 1.6 but is actually closer to 1.55.

DiDueColpi · May 18, 2016, 05:59:37 PM

Those are the Volvo rockers for sure Todd. From the B-18 / 20 / 30 series engines.
And despite all the claims to the contrary they are all machined to pretty close tolerances.
Checked properly they will show a 1.55 to 1 ratio almost every time.
The issue with them is that the adjuster screw tilts away from the center line of the rocker. So the farther out that it is screwed the lower your rocker ratio gets. This leads to all the conflicting ratio reports.
But for an engine builder it's actually an advantage. Size your pushrods so that the adjuster is almost fully retracted and you come very near to a 1.6 to 1 ratio. Shorten the pushrods to extend the adjuster and you can get to 1.48 to 1.
As Jim said, having a machine shop offset drill the adjuster holes to accept a 3/8 adjuster screw gives you all the latitude in rocker ratio that you could ever want.

Live like you mean it.
Fred

roverman · May 18, 2016, 07:17:34 PM

Todd, "looks" like your application is using the Olds shafts,(smaller than Volvo). I would worry about the Olds shaft for cracking/breaking, in your application, as they are even weaker than the Buick shafts, because of the 7/16 " head bolt through them. Good Luck, roverman.

DiDueColpi · May 18, 2016, 08:09:40 PM

Sorry Art, but those are the Volvo rocker shafts. Should be good to go!
Are those pedestal bolts just temporary Todd? As they look far to short to be the Olds headbolts.

Fred