3.6 on carbs and MSD

[bruboy]

There are many threads on the 3.6 conversion and very good they are too!

However like many contributers to the forum I am considering either a rebuild and upgrade of my existing 3.0sc motor or going for the cheaper power route of the 3.6 conversion.

I am thinking that I would like to run the 3.6 on carbs and MSD so keeping the electrical modifications to a minimum as I will be fitting the 3.0 back eventually.

Has anyone done this and got an engine spec that works. Ideally the 3.6 will not be rebuilt so will be standard in all other respects.

My car is used for road and track days so the motor needs to be flexible and smooth running with no flat spots.

many thanks

[1972_911T]

Hi, is running a 3.6 on carbs only an idea because of the electrics as there really is all that much wiring to do I have just put a 3.2 in my 72 911 which is pretty much the same system. All the ecu is wired on the engine wiring loom which is seperate from the main car wiring loom except for a maybe 5 aditional wires for power and fuel pump etc. Most of the wiring in the 14pin connector stays the same and can be done by making an adapter rather than hacking up your wiring loom.

Noticed your in england, where abouts? im in yorkshire

Steve

[bruboy]

Hi Steve

yes carbs and MSD because I really dont want to hack up my loom plus I'm thinking 3.6 injection is a bit restrictive. Where abouts is the 14 pin connector?

I'm based in Southampton but currently live in Athens Greece, however will be back for a few track days this summer

[DW SD]

I don't know if a carb conversion (independent of engine size) from a CIS 3.0 requires no "hacking" either. Everyting can be done irreversibly. Carbs will require a lot more tuning attention, have tricky startup procedures (possibly) and the 3.6 conversion is definitely straightforward and totally reliable. I'd suggest rethinking these considerations and getting some expert opinions. My '71 had a 3.2 in it. and will have a 3.6 in it soon. The modifications are pretty straightforward in my opinion. I"m not worried about going back, but I definitely won't settle for anything that looks "hacked". This will look factory.

Doug

[jpnovak]

there have been some impressive HP numbers for a stock internal 3.6 and carbs... I know I have read values above 300 but can't find the post. I suspect that the individual runner of a carb could flow more air than the common plenum. this also allows for aggresive cams. Might was well take advantage of it.

btw, don't forget that you must change the whole spark side if you convert to MSD. The stock dist does not have any advance. This could be solved with a programmable advance box.

the only irreversable mod would be cutting the hole in the rear fire wall to run the wires to the motronic box.

[aigel]

My local club president runs a 3.6 equipped with carbs and MSD. Very nice. It is hopped up though, with carillo rods etc. I forgot what he's running but I think around 320 horses? It makes the 3.6 look era correct in his 72 RSR. Jerry Woods built it.

George

[Henry Schmidt]

We installed a 3.6 in a 75 911 back in 91. This was before the popularity of 3.6 conversions.
We used 46 mm Webers and a converted a 3.0 turbo distributor. There was a need to fabricate some sheet metal and because the 3.6 has no engine oil cooler we added a larger cooler. The engine was never dynoed but on the second test drive, the torque from this engine blew the second gear off the main shaft.
For my money, it's a very nice conversion.
As for tuning and starting problems, I would agree that EFI engines offer a certain ease as far as operator input but many carberated Porsches are on the street and working very well.
When cost and ease of installation (and return to stock) are the primary concerns Carbs and a distributor is a great option.

PS: when resale of the 3.6 is considered the converted engine may have more value.

[bruboy]

Thank for replies, general concensus seems its an OK idea.

I looked into the carbs option, I think all the parts come with the PMO installation kit so there is minimum of modifications to the fueling circuit when I need to convert back to CIS.

Very interested in the comments on the ignition circuit. Henry mentions using a modified 930 distributer, Jamie suggests a programmable advance box and the final alternative is to leave the stand ECU for fuel and ignition.

Any views on whats easiest,

I like Henry's suggestion that the engine will retain some value as well. I'm thinking that rebuilding the 3.0 will add very little value, also the cost for a fairly small power increases is very large. However buying a good 3.6, PMO's, modified distributer and SSI's for a 3.6 will give me a bunch of parts that should sell on easier at a later date when going back to 3.0

thanks

[GaryR]

Henry - dumb question but why would you not be able to use the stock twin distributor setup if you go to carbs?

I'm starting to plan a conversion in a 78SC, am a bit confused with my options at this point..

[Facey]

Hey!

I am doing a 3.6L swap on MONDAY!!!!
removing my 2.7L block (it is 3L now and very hot at that)

i believe the 3L is based on the 930 3L block, and hase been bored and stroked, it is using 100mm mahle pistons, has twin plug heads, using a crank fire ignition system (6 coils), the carbs are 46mm weber IDA's.....the rest of the engine is pretty radical (at least hotter than most), and i can't wait to hear it!

your idea sounds good to me....but why at some point will the 3l BE going back in?

[GaryR]

Originally posted by Facey
Hey!

I am doing a 3.6L swap on MONDAY!!!!
removing my 2.7L block (it is 3L now and very hot at that)

i believe the 3L is based on the 930 3L block, and hase been bored and stroked, it is using 100mm mahle pistons, has twin plug heads, using a crank fire ignition system (6 coils), the carbs are 46mm weber IDA's.....the rest of the engine is pretty radical (at least hotter than most), and i can't wait to hear it!

your idea sounds good to me....but why at some point will the 3l BE going back in?

I'm not sure about him but in my case I need to put the 3.0L back in order to race in PCA G-Stock class. I just want the 3.6 for DE's!