Look to ID camshafts
- Thread starter dnudelman
- Start date
Jeff Stich
True Classic
These both look like cams for an 850 to me -the main drive gear has the correct pitch angle for a CCW rotation engine.
dnudelman
True Classic
Thanks, any simple way to tell if they are stock or have been ground to a different profile?
Jeff Stich
True Classic
Hard to tell - the photo's a bit dark, but the cam at the top of your photo (the rusty one) looks like it might be a regrind.
A few ways to notice a non-stock cam:
- Some cam grinders will mill down the shaft part of the cam (between the lobes) to produce a smooth, machined surface versus the regular bumpy cast-iron finish of the stock cam.
- A cam reground to use with a stoker crankshaft will often have the width of the lobes narrowed &/or the fuel pump drive lobe removed to allow more clearance for the crank throws &/or con rods (often combined with a milled shaft as noted above).
- A longer-duration regrind will have a more drawn-out arch of the cam lobe versus the very "pointy" lobe of a stock cam.
Is there anything written (etched) or stamped into either end of the cams?
Jeff Stich
True Classic
I think that may read "A6" instead. A good regrind from PBS for an 850 engine that has had performance improvements done to it (ie: higher compression, bigger single carb, larger valves &/or head porting, freeflow exhaust).
If it's in decent condition & you're looking to sell it, I'd be interested in it.
dnudelman
True Classic
That makes sense, I have several boxes of domed pistons. Some stamped 67. They came with a engine and kit that was raced in an 850 spider at Portland in the 80's. That engine was modified to CW rotation, now displaces 940CC and is in my vintage race car. Guy who did the work was Jim at Hawthorn Automotive in Portland.
dnudelman
True Classic
Here is another one. Came out of a 1040cc modified 843. Ran CW in a 600 chassis based race car, that is until detonation ruined a piston while chasing a tr2 at Olympia airport during a race.
Abarth 9/66 or 66/9. The drive gear is the same as the other two cams but this engine ran CW. Is there some other way to reverse the rotation other than the cam? Would this cam work in a CCW 903?
Thanks
Abarth cam is the middle
Abarth 9/66 or 66/9. The drive gear is the same as the other two cams but this engine ran CW. Is there some other way to reverse the rotation other than the cam? Would this cam work in a CCW 903?
Thanks
Abarth cam is the middle
myredracer
True Classic
Nice score on the Abarth cam. There appears to be no fuel pump lobe and the lobes are narrower so would have been intended for an engine with stroker crank. The lobes also appear to be pointier. Cam looks to be in great condition too.
Another way to reverse engine rotation other than changing from a 600/A112 to 850 cam or vice versa is to use a reverse rotation gearset that replaces the stock timing chain. The gears simply bolt on and very easy to do. These are still available. They are allegedly noisy though.
A problem with cams of unknown history is there could be a "flat" lobe or new bearings might be needed and IIRC, can be hard to find someone to do it nowadays. Easy to use calipers to check to see if the intake/exhaust lobes all measure the same. Failure to properly do a startup procedure on a freshly built engine can quickly destroy lobes on a good cam.
Another way to reverse engine rotation other than changing from a 600/A112 to 850 cam or vice versa is to use a reverse rotation gearset that replaces the stock timing chain. The gears simply bolt on and very easy to do. These are still available. They are allegedly noisy though.
A problem with cams of unknown history is there could be a "flat" lobe or new bearings might be needed and IIRC, can be hard to find someone to do it nowadays. Easy to use calipers to check to see if the intake/exhaust lobes all measure the same. Failure to properly do a startup procedure on a freshly built engine can quickly destroy lobes on a good cam.
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dnudelman
True Classic
As you might have guessed, it was in Adrian's hand grenade engine, yes stroker crank and big bore. Came with copper head gasket and a 40 DCNF
myredracer
True Classic
Huh... Sounds like something he would have done!
Jeff Stich
True Classic
The 9/66 is the month/year manufacture date code for September 1966. There might also be a 3-4 digit code stamped on the shaft itself, between valves #6 & #7 (intake valves for cylinders #3 & #4).
As Gil noted, a direct-drive gearset can be used in place of the timing chain/gears to reverse the rotation, an apt solution for a race engine (gear whine is part of the race experience!).
Yes, this cam can be used in a CCW 903. Note that this is a manufactured billet steel cam & thus will have a standard-size base circle, not the reduced base circle of a reground 850 cast iron cam. You might fish around in your box o' parts to see if the matching steel Abarth oil pump/distributor drive shaft is in there as well?
If you're bored & want to amaze the kids, you can hold this cam up vertically by the big end with 2 fingers, tap the cam with a pen & you'll get a ringing "dinnnnggg" sound verses a dull "dink" sound if doing the same with a stock cam.
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Jeff Stich
True Classic
Nice! That's an Abarth OT1000 74mm crankshaft - a very good score.
Is the Abarth cam you have also from this same engine? 843 style engine block? Is the crank original to the block? Is there an "AB 202" stamped onto the front face of the block below/to the right of the lower generator mounting stud? (If so, you might have an OT1000 block, as well).