Born in 75's 3.2 build

[75 911s]

Originally Posted by obscene

hey

Benny! After your drift car, you gotta go 3.4 with me!

[obscene]

Originally Posted by 75 911s

Benny! After your drift car, you gotta go 3.4 with me!

I'd have to sell it to afford the 3.2L!


I'm getting pretty good with the LS stuff though... Maybe I could just....

[75 911s]

Hi guys, my paint and interior is finished so I'm turning focus back to my 3.4 project.

I'm researching pistons and cylinder setups. My first question deals with compression ratio as it relates to pump gas. I think I'm pretty set on 10.5 and I'm liking the CP x-forged 98mm pistons. I can only get 91 pump gas here but I can get 100 octane at a station about 12 miles away. With 10.5 and a twin plug setup, I think I want to be running a bit higher octane than 91 correct? I'm also in a hot environment, I've heard this can lead to detonation. Will mixing the race gas in be a total pain? Will it be necessary? Can I squeeze by with 91 for road trips (here to Cali and back is all 91)

My second question is CP pistons in my Mahle 3.2 cylinders. EBS can bore and plate for a pretty good price but I came across a post about different alloy types. In a nutshell, Mahle uses a proprietary alloy, and the CP use 2618. The differences can cause slap, blowblack and excessive wear if the ring gaps are not perfect. So my question is, should I opt for more expensive Mahle pistons with the bored stock cylinders? or should I buy Nickies to go with the CP pistons? Or should I be fine with the CP pistons and modded mahle cylinders?

Thanks for any feedback.

As a side note, I'm looking at Pauter rods - the two I see are an F which is for stock dimensions and a FLT which is a lightweight version. The price is the same for both sets, why would anyone NOT buy the lightweight versions?

[75 911s]

More questions. Just got my case back from a local shop who hot tanked it to remove a lot of the grime. They also used a wand like tool to blow out the piston squirters. I guess just an air hose attachment of some type and some redish oil (forget what type.)

The studs for the case halves got a bit baked. There's a bit of rust and corrosion. So I'm wondering if it's worth the effort to pull all the case half studs and replace with new hardware. I've been looking around and I don't see any mention of it. Wayne's book doesn't address this that I can find.

To pull the studs I would double nut and heat. For new case half studs (the perimeter studs not the head studs) What loctite should I use if any?

Also I have a bit of staining on the exterior. Call me uptight, but I want the bottom of the case to be uniform. What to use to get an even raw look besides vapor blasting which I'm ruling out due to not wanting to pull the squirters.

[HaroldMHedge]

Just read your thread, what great documentation.

Originally Posted by 75 911s

So about that grey sludge...whatya think?

I had a similar sludge in my 83 911SC ROW case following a piston landing failure and the engine had ground up some of the piston fragments.

[Trackrash]

Are you saying your studs are rusted? Try a wire brush to shine up the studs. If the threads are not corroded they should be good to reuse. The perimeter studs use locking nuts so no loc-tite is needed or desired.

[75 911s]

Originally Posted by HaroldMHedge

Just read your thread, what great documentation.

I had a similar sludge in my 83 911SC ROW case following a piston landing failure and the engine had ground up some of the piston fragments.

Interesting. Yes I found the IMS gear missing some chunks out of the teeth.

Originally Posted by Trackrash

Are you saying your studs are rusted? Try a wire brush to shine up the studs. If the threads are not corroded they should be good to reuse. The perimeter studs use locking nuts so no loc-tite is needed or desired.

They aren't bad. Just a few spots on the tops and edges. The tops that will be visible. Yes I hit them with a brass brush, but I kinda wanted fresh blingy hardware (studs) there. I'm talking about the case half studs along the perimeter. I was wondering how many people pull these and replace with new hardware. I guess I wanted a bit more bling with either replating these or getting new cad/yellow zinc hardware. So I was referring to the loc-tite when seating the new perimeter studs back in the case.

I was thinking of sending it all to a batch to be re-plated as the hot tank seemed to take off any of the remaining original zinc coating.

It's probably way more work and expense for something that is primarily bling? What do you guys think?

[75 911s]

I've been stuck on the progress of my engine because I've been goofing around with some other minor projects for the car. A few weeks ago I decided to start putting one foot in front of the other for this journey.

I packed up my oil pump and shipped it out to Glenn Yee Motorsports I gave him a quick call to let him know it was arriving and Glenn was responsive and happy to answer my questions a second time.

The turn around was just a few days and I received the pump bubble wrapped and in a nice sealed baggie. Sadly, it's hard to see the nice details of the rebuild through the plastic but the pump looks great and turns very smoothly. I'm not taking it out until I'm ready to pop it in the case.



The oil coating is a protective coating that he applies. It comes with a straight forward instruction sheet as well.

Part of the service is to port the oil openings as well as polish the internal bores. I might be mis-wording that but I wanted the heart of the oil blood line to be working in tip top order.



This led me to re-inspecting my IMS gear. The damage to the gear is really minor looking -it's a few tiny edges are chipped off, so I'm debating replacing it. The gear is $250 so you can see my hesitation. I will be replacing the chain gears however. I'm looking at the Sebro brand. I'm also looking at the IWIS non masterlink chains. Looks like they have a 'racing' chain for a few dollars more.

Long shot but anyone have a Las Vegas based machine shop they recommend for crank polish, magnaflux?

[Bigtoe32067]

Don’t leave us hanging. How’s this going?
I like what you’re doing with the ITB’s. I changed a bunch of my perimeter studs because they were corroded pretty bad. I red loctited them in.
I think the gray sludge you found is just ground aluminum powder from wear on the case and possibly that scratch/gouge you found. Sludge from oil and steam would be more brownish like chocolate milk.
Keep up the good work
Oh and I’d send my crank to Ollie’s if it was me.
Tony

[75 911s]

Originally Posted by Bigtoe32067

Don’t leave us hanging. How’s this going?
I like what you’re doing with the ITB’s. I changed a bunch of my perimeter studs because they were corroded pretty bad. I red loctited them in.
I think the gray sludge you found is just ground aluminum powder from wear on the case and possibly that scratch/gouge you found. Sludge from oil and steam would be more brownish like chocolate milk.
Keep up the good work
Oh and I’d send my crank to Ollie’s if it was me.
Tony

Thanks Tony. Work was stalled as I changed direction on the car that this was going into. I lightened my 75 to a point where the 2.7 was satisfactory. I also want to keep that car 100% analog. No computers, no EFI. The 2.7 #'s matching motor will eventually get a 2.8RS treatment.

So that led me to looking around for a widebody roller which I sourced a dry 77 a few weeks ago and began stripping to the tub. I have a new thread started on it in the Tech forum under the very original name "Born in 77" I figure it would be easier to search for my stuff that way. :-)

As far as the motor goes, this 3.4 will be much better suited to the widebody IROC tribute I'm building.

I ended up buying IMS and camshaft sprockets, but there was some drama with those recent gears. I returned them to Pelican and my next step was to buy main bearings. I'll be sourcing those from my local Porsche dealership. I was also given a new IMS shaft with sprockets so now I need to send my crank out.

I'll be including this build in my new youtube series. I'll link it here when I launch the channel. Thanks!

[Harpo]

Some where I read that if you replaced the chains or gears that you had to replace the other.

[75 911s]

Good question. You mean like the IMS gear is marked 0 and matching it to a 0 drive gear that is on the crank?

Then yes they will match. Or were you talking about chain sprockets?

[Harpo]

I was referring to sprockets and gears?

[75 911s]

Originally Posted by Harpo

I was referring to sprockets and gears?

Having talked to about half a dozen professional air cooled engine builders, the consensus seems to be new chains are fine on old sprockets. In fact original sprockets are preferred due to failure of some new reproduction sprockets (see recent cam timing thread in this forum).

Oh, I think you may have been talking about matching cam to IMS sprocket? Yes probably preferable to match brand on those I would think - but funny thing is, SEBRO brand is literally half price of Porsche, but someone said Porsche sprockets are made by SEBRO... So they are made in the same factory? I don't know. That's just what I read on the same thread mentioned above. It's a moot point for me since I'll be using the original sprockets.

[Trakrat]

Originally Posted by 75 911s

Thanks Tony. Work was stalled as I changed direction on the car that this was going into. I lightened my 75 to a point where the 2.7 was satisfactory. I also want to keep that car 100% analog. No computers, no EFI. The 2.7 #'s matching motor will eventually get a 2.8RS treatment.

So... what happened to the 3.2 you took apart?

[75 911s]

Originally Posted by Trakrat

So... what happened to the 3.2 you took apart?

The 3.2 project has entered yet another phase. I'm not sure if I noted this in this thread already but I picked up a wide body project that I'm making into an 74 Carrera 3.0 RSR tribute. I use the word "Tribute" loosely as it will be more my own custom design.

Originally I was going to do a pretty mundane 3.4 conversion. I think I'm moving off into a more interesting build based on this case, which I will disclose at future point here.

I sent the case, crank, heads, rockers, valve covers, and cam towers to Ollies.

I did it in two separate orders and I have received everything back but the rockers and the case to date.

Everything looks OK so far but I'm inexperienced. I had them twin plug my 3.2 heads and cross drill / groove the crank.

I put the crank away before getting pics.

The heads were mostly clean, but still some residual 574 around the edges that I thought would be gone. I always expect perfect work. Also you can see some grease or a stain. So more cleaning to do here.







A notable air cooled engine builder saw my heads from a picture I posted on my IG and thought the twin plug holes needed more finish work to smooth the rough cut edges. I don't know what I'm looking at really so I need to research that.

I also picked up these bearings. Going to have to measure them yet. Might be selling the newly refreshed crank and bearings if I go a more exotic build to honor my widebody project. The bearings don't have the measure tics from the factory, but were made in Poland.





After talking with a few friends, it seems the 3.4 is sort of an inbetweener build. It doesn't necessarily do anything particularly well. Like for instance, the earlier engines are known to be rev monsters. The later have more torque. That's got me looking at changing stroke. Still looking at 98mm pistons though.

Port sizing on the Carrera seems large. Why not take advantage with more displacement via longer stroke?

I'm also going to keep the Carrera pump for my 2.7 build and opt for a gt3 pump.

As for look. I picked up a 2nd hand set of new in box Sheridan Amber tins/shroud. So I'm leaning toward a vintage look. JB Twin plug with dizzy, amber shroud, PMO carbs. A very analog race motor as my car is early 70's look. Of course the real carrera 3.0 had 3.0 MFI race motors, but it's not a clone, it's only a tribute. :-)

[75 911s]

This build has dragged out far too long and it's time to kick it to a new level.

I did document a lot of the fresh parts from the engine in my Wik's Garage episode on Ollies if you want to check it out.

Shortly after making that video I began to doubt the direction of the build (3.4) So upon a friends recommendation I gave William Knight a call.

William and I discussed my goals and we put together a plan for a 3.55 build. I purchased a 996 GT3 4.0 motorsport crank from William and immediately listed my 3.2 crank which sold after about two weeks.





The case is still at Ollies, so my next step is to source a GT3 Oil pump. I'll use the 4 rib Carrera pump shown earlier in this thread in my 2.7 build.

I also have exhaust now too. Brian from Rarlyl8 built me some beautiful 1 3/4 headers and I opted for a slightly used MK RSR style 2/2 muffler.

Lastly, I received my jugs back from US chrome. I sent the stock Carrera jugs to be bored out to 98mm and plated. Sorry, but I can't find pics. They came back really nice with the exception of one of the cylinders. One was pitted badly right around where the rings would be. Luckily my friend just bought all new P&Cs for his 85 and had his used jugs available for free.



I measured them and inspected them side by side and the seem to be identical so I sent one of my buddies jugs back to US chrome and it came back as nice as the others. With shipping and everything the total came out to about $1200. The extra cylinder was another $200 to cover the replacement, so I have $1400 in cylinders now. I'm not sure if I would have been better off buying new, but it's done now.

I'll need to source custom pistons via William and I think I'm going with Carillo rods.

So plan is to get this bottom end together by June of this year.

[LukasM]

Nice work so far Duane, I'm subscribed!

I've been wondering about a GT3 crank conversion as well, given the crazy prices that used 3.2 Carrera cranks are worth nowadays.... Not that much cost in upgrading if you wanted stronger rods anyway, or would have to factor ARP bolts + rebuilding/resizing.

Also very interested in your GSXR ITB setup, your seller did a nice job with those!

[75 911s]

Thank you Lukas.

Well one minor update on the build. I'm ready to finally move forward with the custom CP pistons, and the gt3 rods. I think the rod lengths are the same as the Carrera rods going off my memory from looking at the CP catalog last week, but obviously the stroke means the wrist pin will be further up in the middle of the piston. So standard GT3 rods should work, I just need to make sure they will clear the gt3 oil pump as well.

If you remember I had my original cylinders bored out, one came back with worrisome pits:





So of course I had to source another one that was similar and have it sent off and wait for it to get back.

William Knight wanted the cylinders measured so I tried to get my local machinist to measure them, but they couldn't get it done. So William had me send my cylinders off to CP for measurements. I got six pages back from them showing the cylinder measurements in 12 or so dimensions for each cylinder. I'll post the readout for one cylinder at a later time.

I'm still torn on what intake I will use. I have a core MFI pump and a core set of throttle bodies. I also have a fuel console. The basics are there to make this an MFI car like the original RSR. One side of me wants to go with that vintage setup. The other wants me to go with the modern EFI solution. I'll finish the short block first.

[winders]

Originally Posted by 75 911s

Well one minor update on the build. I'm ready to finally move forward with the custom CP pistons, and the gt3 rods. I think the rod lengths are the same as the Carrera rods going off my memory from looking at the CP catalog last week, but obviously the stroke means the wrist pin will be further up in the middle of the piston. So standard GT3 rods should work, I just need to make sure they will clear the gt3 oil pump as well.

The GT3 rods are longer than the Carrera rods. The GT3 rods are 130mm while the Carrera rods (964/993 as well) are 127mm.