Carrera3.0 mystery motor Rosetta Stone help!

[mazing3]

Hi Gang. First post ever here but been lurking and learning for a long time. These forums helped me tackle a major re-do on a friend's 74 targa and then I fell in love with it. So in January I bought my own project. a 76 Carrera3.0. I've generally always been able to find what I needed around here but am finally stumped and frustrated enough to just ask for help from the experts here who have literally taught me everything I currently know about doing this and could never have gotten this far on my 2nd project without you and Wayne's books.

Little history.

I bought the 76 C3 back in January as a fun restoration project. Conquered all the rust & body work and it it is currently at the paint shop becoming GT3RS Orange. Just like that better than Continental. I'm cutting no corners anywhere on this car and it is my all consuming passion right now. I'm no rookie with all this but far from a pro. The chassis numbers all match and is indeed a real C3 but I'm eyeballs deep in the short block now and am starting to realize I do not really have the 3.0l motor I thought I had... It's not the end of the world but the history mystery here is driving me nuts and I'm trying to figure out what to do from here.

I have almost no history on this car and am the 3rd owner from what I can tell. Most of what I have figured out is from common sense. Some new nuts and hardware on the casing, some unusual numbers here and there, a full set of Divlar head studs (minus the broken one that put me into rebuild/while I'm there I might as well mode) and a few other things that seem to point to a potential previous rebuild. 11 blade fan is another sign.

So here are the facts and questions and thank you so much for any insights here:

1. The engine number space is blank but I do have a 930/2 stamp up there. The crank case number is 901.101.102.7R- Q1-- 7R is Mg right but doesn't the 930/2 indicate a I've not found a casting date but can someone give me a little insight as to the story on this case with the two referenced numbers? Does the 930/2 indicate this a 3.0l case? I'm a little foggy here.

2.
-cam housings are 901.105.111.1R don't have the cams out
-heads all have 911.104.342.2r K1819W with 46/40 valves and all have either an 8-74
or 9-74 casting.
From my research here these are supposedly 75-77 911s air injected? Not C3
-Pist/Cyl- They are the 8.5 Mahle Nikasils.

3. I don't have the case split yet (damn flywheel bolts need more coaxing) so can't get all the way at the crank yet. I don't know if this is right but didn't the C3 have a different crank?

OK that's it. For now I think. Can someone connect the dots here for me a little with all this now? What do I have here? I'm of the impression this is not the original 3.0L motor that should be in here but what the hell is it? This is where I get foggy again. I read time and again how bullet proof the 3.0s were supposed to be and the big Tq numbers this car was supposed to produce. What's making those two things happen and do I have the right stuff? I've never even driven this thing but I am the eternal victim of the "while I'm in there theory" so doing cams or pistons could be an option. My daily driver is a 997TT and am clear this C3 won't touch it but a little more reliable grunt would be cool without breaking the bank. Hell, I'm actually selling the Turbo when this is done because after this labor of love, blood and tears I'll value it it far more than the Blue Rocket anyway.

Oh, here are some pics. I had a little paint fun before tackling the whole tear down so just assembled some things to take a pic.

Robbie
76 Carrera3.0
07 997 TT- Cobalt Blue
99 Spec Miata Race car- yeah Cobalt Blue also. :-)

[Bill Verburg]

It sounds like someone installed a mg block 2.7

If it was a C3 engine the block, heads cam carriers etc would all have 930 casting #s

46/40 valves is correct for 2.4-2.7 mg blocks engines

the 930/02 in a C3 had 49/41.5

[myfast911]

930/02=-1976-carrera-3ltr-case-per-wanyes-book

[Bill Verburg]

Originally Posted by myfast911

930/02=-1976-carrera-3ltr-case-per-wanyes-book

yes, I did mention that in my post, but the rest of the data doesn't support that there is the correct 930/02 in his car.

[BURN-BROS]

Your case apears to be a 2.7 replacement case, anybody can stamp whatever they would like.

The 3.0 liter cases were aluminum and everything Bill said.

[jpnovak]

My guess is that it was a factory replacement case for the 2.7. These are unnumbered. Someone then stamped the incorrect engine type into the mag case. The number should have been stamped 930/02 not 930/2. Evey one I have come across has the "leading" zero right of the slash.

Either way I think this is the incorrect motor for the car. Do the cylinders measure 90mm? If so, it would be a 2.7. If they are 95mm then you have a bastard 3.0. 95mm cylinders in a 2.7 case is NOT GOOD.

[mazing3]

yeah the sinking feeling I was having is being confirmed here.

The only thing that was giving me hope was indeed the 930/2 which is not 02. check the pic. I found a lot out about this car as I stripped it down to bare metal and it has had a colorful life. As in 5 layers of paint. My soda blaster guy was having a monumental task until I whipped out the paint stripper.

The cylinders are indeed 90mm assuming you measure that on pure ID. The pistons right about the same.

There are quite a smattering of 930.xxx part numbers in here though. Odd things. Like the lower valve covers only and oddly the right chain housing but not the left.

I did pull the broken stud today as well as a few others just to see what was up since I planned to go back to steel anyway. Oddly, the broken one actually had a case saver stuck to it too. This being a mag case, am I now screwed with being able to do a case saver again or am I in nutsert mode now? Or again, screwed?

So now I have to decide what to do about all this. I got the car for 7k with what is now a questionable 70k on the odo. The bod really is in great shape. needed nothing on the frame jig and the interior was gorgeous. It sat for the past 6 years and I have addressed all the usual suspects from that and done tons of work.

But the problem now remains... I can't in good conscience badge this thing as a C3 just because it looks like one. I jumped on it because I thought it really had the 3L but guess that is out now. Funny thing is that it even still had all the federalization all over it. Had being the operative word. I bet this thing was making just a little more than my Miata in terms of HP. Better looking though of course. I really want the 3L to make this car correct or I could just go nuts on upgrades. Not even started to look for a 3.0 motor yet as I'm just reading all this.

So do I have some fun with cams and pistons, try to find a real euro 3.0l (doesn't sound easy) or just lose my mind completely and stuff in a 3.2 or better. Keeping in mind that this isn't a cost is no object endeavor what kinds of collective thoughts do we have? I bought the car because it was a C3 and have been very attentive to keep it that way and original in everything I've done so far. One idea is throwing a few bucks and some TLC at this motor and selling it as a rebuilt tip top 2.7. From what I've seen rebuilds go for it could end up being a steal for someone. Just thinking out loud but could take the $$ from that and do my super 3.0 like I wanted.

None of this is the end of the world as all of this is part of the fun to me. Damn thing doesn't have A/C anyway and it's getting hot in Atlanta now. Works out well because with this hiccup I may not be driving it until the fall anyway. LOL

Thanks for your ideas guys.

BTW BURN-BROS... great avatar. I'm flying out to New Orleans to see the first show of the summer tour with them on the 19th!

[mazing3]

the pic

[Bill Verburg]

JMO, but I'd find a nice 993 engine for it.

[mazing3]

yeah, that's something I was thinking about too. Don't know much about them but it's all learnable.

Now a 3.6RS seems like an interesting idea too Bill. :-) you are already a great advisor and a bad influence all at once. :-)

[BURN-BROS]

Originally Posted by mazing3

BTW BURN-BROS... great avatar. I'm flying out to New Orleans to see the first show of the summer tour with them on the 19th!

Envious I am! Have a great time.


As far as your motor goes sorry about the bad news, but there is literally endless amounts of choices you can go with. Roll with it and take your lemons and make lemonade.

[mazing3]

yeah man, thanks. The Tool show is going to be awesome as usual.

I'm sort of getting excited about this now. You are right, I've been looking around and there are tons of getable motors out there for this. I'm sure there must be a limit as to what won't actually fit in there though. Saw a 996TT motor on ebay for 14K but that's a bit outta reach in both $$ and sanity. 2400lb car with that thing in there....could be fun!
Think I will just continue the rebuild of this 2.7, do it right and then sell it off. Close friend of mine just had her 74 Targa rebuilt to the tune of 11K. Selling one that was already done and just needs to be transplanted for much less can't possibly be that hard to do I would think? I only paid 7K for the whole car even with this wonky motor. :-)

[edgarcia737]

I have a 1977 C3. My cases have a 930 part number. S/n 6660024 type 930/02. The stamp on your case looks different than mine. It might be worth finding a 930/02 motor.

Like looking Porsche

[BURN-BROS]

The cheapest route is getting a good used motor and sticking it in(duh)
The 3.6 route is very popular as it's relatively cheap for the performance.

Source a good core and build a motor that you would like. This way you get to put in real cams, a choice of induction,etc...provided that the car does not have to pass smog.

A twinplugged MFI 3.2 short stroke with DC60 cams is a great combo.

This one was done by Henry @ Supertec.


BTW, if I sourced a C3 engine it would NOT go back to stock config. It would either be a 2.8 short stroke or a 3.0 short stroke. If you wanted a stock config, buy an 78-79 SC engine.

[jpnovak]

66x98mm. 3.0SS would be my choice!

[mazing3]

hmmmm.... OK, that's twice now on the SS idea.... It's time for me to humbly put on my "not all the way up to speed" hat. :-)

I've only been playing with CIS cars for about a year and have no real problems with stock stuff but my personal knowledge base doesn't venture too far out of the box right now. Would you mind explaining the SS to me a little bit. Heck, I don't even know what components should be 66 and 98mms to even do this. What are the benefits of the SS? For some reason I though Tq suffered a little with a shorter stroke but again, I'm wearing my clueless hat right now. LOL

Thanks!