Marking mystery on my camshafts? BM

[Micke]

Hello,

porsche 911 camshafts BM 620 9. and here it is probably the shop BM ? ok long time ago !

And heads have marking IMS, the shop ? and the date I think 12/90,, this is how we do !


Is this something somebody knows what shop made this? built on a 3,2 Carrera case 3,4 L stoke 74,4 cylinder 98 mm, it was running well but was built in 1990 by somebody in Boston as what I think? MFI pump set up by Gus in LA

Twin plug compression 10,5 and that was good on all cylinders, but the car had been standing for a long time.

So it is a bit off-race and street engine fun to drive, but as you can see it was time to rebuild as the camshaft lock is good in my eyes but just these numbers on them!

As you can see on heads and other stuff, it was time for a refresh! stamps 12/90 and the shop maybe

Thanks

[Micke]

But fun if somebody sholud know-how made in the USA, will measure them up next week, I do think it is S or E camshafts from the start because it is an MFI engine old school, but one of the most fun engine I bean driven and start to drive Porsche 1981, so have driven most of them. This one has an enormous nice power band, so it is not a race spirit camshaft, somebody got it very correct for a street and weekend race car,

Spec

3,2 case 1984 Carrera Stroke 74,4 heads SC, Heads intact 40 mm and ex 40-41 will see better after cleaning and rebuild, and interesting intake job will run exchanger the new one from SSI 41 mm Big bore

MFI set up T- bodies 40-42- and stacks 42-46 on the top, MFI Pump set to RSR spec on high RPM, a very interesting setup with a special space came, Pump we have run in the test bench will do the last calibration when we run the car, it will run a bit rich on low RPM, but as Porsche made all pumps back in the days so they were running very rich stock, this is the way of cooling an air-cooled engine as well and nobody cared about the fuel cost.

98 mm pistons and a very nice job on enlarging the cylinders and the car doset have many mils, I bean driven 10,000 km in the last 6-7 years

Twin plug and compression were from 10,5-10,6 it was a small oil leak on one cylinder head.

But what is cool all this was built back at end of 80, it sholud be nice to know how built the engine in the first place! and the car is a 72 T that was modified in the early days of 1973 like spare cars for racing by Waslak Polak, and that was the normal way they both T cars and ordered racing parts from Werk 1 for smaller race teams, then the car was sold without the engine, the race team kept the 2,5 L engine for the car as spare.

But overall, it is pretty stock 72ST set up, has 1328 seats, and other typically ST jobs are done and have no rust, will build a 2,5 L engine as well so we can compete in historic racing, so the 3,4 L engine will be more for fun!

I sholud say it is a very modern Hot rod engine that guys build these days,, and I was 100% sure it was 70,4 stroke how the car was revving so quickly up to 7,400 RPM first I had it set to 8,000 RPM but it is a bit risky and not for a street car!

Thanks

T-and stacks ready !

[stownsen914]

A few cam grinders I can think of:
- The usual still active ones: Webcam, Elgin, Dougherty (not sure if he was around back then). The designation doesn't look like any of theirs.
- Garretson, the GE20, 40, 60, etc. Doesn't look like theirs.
- Logicam (formerly Dial-in Cams) - they did 911 cams for a while. I think I might have had a set of theirs but couldn't find a reference anywhere.
- Crane - they did Porsche cams for a while. I think their designation was p-xxx.
- Integral - they may have been around that long ago? Not familiar with their designations, might be worth checking.

There are others today, not sure what else may have been around 1990-ish. At the end of the day, if you measure them to get lift, duration, and lobe centers, you'll have most of the info. you need.

[Matt Monson]

I asked a couple of my older engine builder friends and nobody knew. The one comment I will make about your analysis is that the cores can’t be E or S. 4 bearing cams didn’t come out until the 3l engines.

[Micke]

Thanks, guys The mystery is still in the air! will look more on the other camshafts and maybe there I can find something? just fun to know how made, as I wrote they still look good and have been driven too much I think as the rest of the engine is just dirty, the same pistons and cylinders are nice inside, and the MFI pump is E pump and stacks so this was my thinking that they used an E or S camshaft, but back in the days, this was comen built at the end of 80 or early 90th, ok most guys just the 70,4 stroke and SC case, head work looks nice and we have measured up 3 C/P and still nice just the rings are a bit of! Then the pistons have a very high dome.

But will use Tomes CAM Doctor to figure it out! But that they grind off all number of the camshafts? it is some work as well? but a fun winter project!

[Matt Monson]

You said it was in the Boston area? The first builder that comes to mind is Jerry Pellegrino at EPE. It wouldn’t hurt to call and ask him if it’s one of his.

[Micke]

Was found the marking on the camshaft GE-60 see pix, and that matched well with how the engine was running as well, a lot of torque, but will measure up them anyway, Splitting the case after + 30 years,, still looks perfect, a bit of dirty oil just so it was time for splitting and cleaning it up all engine, The car was standing a lot as it is a 72 car ST build from Vaslak Pollack from 1973, but still rust free and most of the racing parts are there, pity the race team kept engine and gearbox when they sold the car in the late 70th.

Pistone's 95 P 30 marking, But 98mm, 98 P sholud makes more sense? But good it is Mahle. So we should be able to get the correct rings 1,5x,1,5x4,0 mm.

Did somebody come across these piston types? done is very high!

Thanks

[Micke]

some more pix ,,

[Micke]

Interesting this with pistons that you call 95 P 30, I got information from an old racing colleague a bit for my time!
Mahle and Wahl made 1974-75 pistons that were 98mm with the marking 95 P30 and were used in the RSR engines of the larger race teams (until Porsche stopped them). They had 22mm piston bolts as I have on mine! so here probably I can find the correct piston rings 1,5x,1,5x,4,0 mm

So it was a bit of cheating from some racing teams on the RSR 74-75 cars back then!

https://wahl-spezialkolben.de/en/

[dannobee]

Mahle used the same forging die for both pistons. No cheating involved, only using what you already have.

I assure you, anyone tearing down an engine in competition will have the requisite tools to measure cylinder diameters.

[Micke]

Yes for competition , A got from an old racing colleague a bit for my time of racing ! Porsche stopped them both Mahle and Wahle to make them with 22mm piston bolts as I have on mine! so here is probably the problem to find then in this measures on the rings 98 mm 1,5x,1,5x,4,0 mm,, I hope Wahle have some old ones left or they produce new ones,, they produce all sort of funny measure you like .

But these days you are banned for life from historic racing if FIA finds out that you use these ones 98 mm in RSR 2,8 or 3,0 RSR, ok not too simple to find out! but you can make compliance and that happens!

[Micke]

Was just an interesting story to share! for my hot rod engine, it is just fine!

[Micke]

Some small updates on the rebuild,, weight on pistons and con rods were perfect,, and funny for an engine built + 30 years ago!

Heads are in the machine shop, and the crankshaft and all parts will be balanced as always!

Thanks

[Micke]

Parts start to clean up nicely and new parts arrive step by step! it was time for a good cleanup after 30 + years, we will higher compression a bit to 11,+ and changes the setting of the MFI pump a bit, and then all other normal parts when you do a full rebuild, Rev limit to 7,300-7,400. hade here on 8000 RPM with headers but it is no reason for the street driving. Heads ready next week open them up a bit more and install some race stuff that we had around and made some new porting, and all balancing of the crank, flywheel, pulley, and new pressure plate.

And will not use the air box in plastic due to fire risk, will go for K&N or see whatever we have around.

[Micke]

Work coming along! crankshaft was in good balance and is balanced with the new pressure plate.

Heds are in progress as we will open the intake side to 40mm, guys in the machine shop need the MFI T-bodies to fit perfectly with the heads! out port will be 41-42 mm to fit the new heat exchanger from Dansk's new big bore set, will be interesting to see how they will play out, the muffler looks very cool! or I sholud say all the set.

Thanks

[Micke]

Some progress was cleaning up the engine bay and front compartment! and it was turning out good, engine compartment this old group 4 reinforcement in the corner! was so dirty there before so did not seam the,, but it was an old spare race car back in the day,
The same plats for the reinforcement for the hat shelf for the harness, this was just covered inside the car, will get some pictures of this

The engine works at full speed! we will start to tackle the breaks and shocks and
see what sway bars and torsion bars the car has, amazing rost free from 1972, and not any sign of any accidents, floor, and all metal are still original just the normal front pan was changed. Will still not do any bigger modifications that jeopardy the FIA inspection for the 2,5 L class, The 3,4 L MFI twin plug engine will be more street and a bit of track

Heads sholud be back in a week or 2, then we start to pot the engine together.
Still doing some experiments on how I will set the MFI pump as I think I will have a rev limit at 7,400-7,600 RPM but will see after dyno even if it can be 7,300 RPM with GE 60 cams, will see ver we have the peak, so set the pump to full RSR spec can be a bit too much and it will run rich on low rpm and the idle is always tricky when you race pump.


Thanks,

[beech33pilot]

I'm enjoying the build pictures. Curious why the new clutch disc has much less friction area compared to the old one. Anyone have an idea? My first thought is just a cost reduction.

[Micke]

It is sport clutch kit we normal use when we have of extra power ,, from FVD and this is a good kit ! the old one was not bad, but when you do all this work !

Exclusive line of clutch kits is culmination of Porsche Genuine Parts, ZF Sachs Race Engineering GmbH Parts and Motorsports Parts that have been developed to work together without compromise. They offer a silky-smooth release, superb drivability, can handle more torque (354 ft/lbs. / 480 NM max.) than comparable stage type recommendations.

We specifically chose a clutch disc with torsion springs that function as a vibration damper between engine and gearbox, which provides an effortless release in 1st gear. This kit is suited for daily use and offers a superior driving experience. This kit also uses a lightweight ZF Sachs Race Engineering GmbH aluminum pressure plate.

[911 tweaks]

thanks for sharing your build Micke...Looks like a fun build...!!
what is the FVD p/n for that clutch kit?
thank you

[Micke]

just fun to share, this is just a clean-up of the engine and front compartment old race car from 1972! the engine was replaced at the end of the 80 or early 1990 as the heads were built and modified then, I had the car for many years and used the car for track and street and was thinking all the time it was a 3,2 L short-stroke engine, but turned out to be 3,4 L,74,4 stroke and C&P 98 mm.

Then we run MFI and the twin-plug system, she was always running very well and very funny to drive. But it was time for a good clean-up and rebuild of the engine and we will improve some smaller parts to get some more hp, the engine builder back in the day made nice work and it was not the first engine he or she built!

Some pictures of the heads will be ready in some weeks, this is how the old engine builder built it! this just steps one clean up and the valve seats are done, we will open up a bit more and the MFI throttle bodies are ready so the heads guys can match them to the intake 100% and to the new heat exchanger from SSI Dansk 41-42 mm out.

Adjustable sway bar front 22 mm, old funny race type so you can change fast at the track! will be re-plated and restored suspension bearings and so on.
Will check the rear when we get that fare! step by step .