911t-2-3.0sc

[PorscheTSC]

Hello Board I am still thinking about rebuilding a 3.0SC for my 1970 911T but have a few additional questions. Others have told me in order to do this the 901 tranny must be replaced with a 915 tranny no way around it . Is the tranny change out a must? Can the 901 be beefed up to handle a 3.0SC ? I ask only because Im also told that to change the tranny out requires axle change outs which they say is no simple task. Any thoughts on the tranny issue?

Secondly I favored the build in Wayne's book which called for S cams. It stated the engine would put out in both low and high end. Others say the S cams will kill the low end and that a Solex grind or E would be a better choice. Thoughts on this ?

Finally my last question is not engine related. Has anyone on the board ever upgraded a late 60's or early 70's 911 to 16" wheels and tires. If so was it a major task . I have read where the inner front fender lip might have to be rolled. Any thoughts on this.

My aim is to give this car fast block to block city power and gradual windup at top end. Once at top end though I want all it has to give I never speed ,I just drive fast , only when no others are around .Nothing like a nice stretch of highway,no one around, clear visibilty for miles with your speedometer pegged . Don't forget the detector though as last I done this in a Saab 900 turbo my ticket was marked 125 mph in a 65 mph zone.Almost went to the pokey for that one if not for a lot of well thought out BS On a serious note thought many thanks for everyones help on the board so far. I look forward to your thoughts on the above.

-------------------------------------------------------Many Thanks,
---------------------------------------------------------Randy

[PorscheTSC]

Apolgies Board it seems I made an error in this post . My current tranny according to the specs seems to be a 911 transmission . Given this do you think it would hold up with a 3.0SC. Perhaps a heavier clutch,better oiling system etc? Thanks

[HarryD]

Randy,

I am assuming you have a 5 speed.

It is easy to tell if you have a 901 or a 915 tranny, just tell us if first is by itself (901 tranny) or is fifth by itself (915 tranny).

[PorscheTSC]

Hi Harry , When sitting in the drivers seat 1 st is to the left and down , reverse is to the left and up, second is middle -up , 3 rd is middle down,
4 th is to the right -up and 5th gear is to the right and down .

[HarryD]

Originally posted by PorscheTSC
Hi Harry , When sitting in the drivers seat 1 st is to the left and down , reverse is to the left and up, second is middle -up , 3 rd is middle down,
4 th is to the right -up and 5th gear is to the right and down .

Randy,

You have a 901 Gear box then with the "dog-leg" 1st.

I know a buddy of mine has a built up 2.7L with a 901 box and it seems to do ok including his "top fuel dragster starts" in AutoX and frequent visits to redline.

You might want to contact some one who rebuilds these things to get an idea if you can use your existing box.

If you are thinking of building a higher output engine, it might be wise to consult with some of the Porsche engine builders who specialize in building these types (not MM). The is a lot of detail you need to get into if you want a strong, high output engine.a

[fintstone]

Sounds like a 901 which is correct for a 1970 911.

[jluetjen]

It sounds like 911TSC has the "correct" transmission for his car. The 911 transmission was a 2 year only model ('70 and 71's only) between the 901 and the 915. You can think of it as a 901 with a 915 style clutch. It should be fine for your use as long as you don't abuse 1st gear. 2nd through 5 should handle a 3.0's torque just fine. 1st on the other hand is mounted outboard of the intermediate plate and suseptable to abuse if you start to put a lot of torque into it.

The overall life of the transaxle might be deminished some, but that will most likely be impacted more by the driver then by the engine. If you're going to abuse the transaxle, a 901/911 will give out before a 915. If you treat it right, both boxes will work great for you and in fact the 901/911 was lauded for the lightness of its shifting action in stock form. 915's never seem to get that praise.

It would most likely make sense to worry about replacing the transaxle when and if the transaxle starts to fail at some point in the future.

[PorscheTSC]

Many Thank to all. Again though my apologies for the second post .I meant to say it has the 911T Tranny I forgot the "T" ,hazards of running late night red eye on the keyboard

Has anyone on the board ever swapped out a 901 for a 915 tranny in an early T model? If so was it truly a lot of work to get the transaxles and mounting proper for the changeover? Take Care All.

[Wayne 962]

Right - the 901 transmission will work fine with the 3.0 case and flywheel, providing that you have the correct adapters. This is what we do in the 914 world for 914-6 conversions.

As for your cam selection, your comments about low-end torque really only apply to smaller displacement engines. When you get to 3.0L and larger, the limiting effects of the high-lift cams are minimized by the increase in displacement. So, 'S' cams with a 3.0 will still feel very powerful, and shouldn't be as "peaky" as the 'S' cams in a smaller displacement engine (like the 2.0). See the Engine Rebuild Book for more info on this topic...

-Wayne

[911pcars]

You can search the archives on this common swap, but briefly:

yes, it can be done.









Oh, here's more:
Tunnel needs to be bumped outward to clear 915. BFH should do it.
Change shift housing to 915-type
Change clutch and flywheel to match
Change clutch cable to match gearbox
If late gearbox (~'77 on), convert to electronic speedo
Repeat use with BFH to gain clutch arm clearance with heat exchangers
Depending on gearbox, may need to swap to compatible CV joints and/or change over to late alloy control arms and use stock 915 CV joints and axles.
If late alloy control arms are installed, change to late rear shocks too.
If using late alloy control arms ('77 on), update rear sway bar (early alloy control arms use the same sway bar mount).

Otherwise, it's a bolt on.

Sherwood Lee
http://members.rennlist.org/911pcars

[PorscheTSC]

Again My thanks to all . I currently have the 2.2 engine and tranny down out of my 70T car. Two weeks ago I pulled off from a traffic light and suddenly heard a lot of not so good grinding ,valve tapping etc,then the car shut down about 25 yards later. I just opened the motor to find no major damage. It seems that I spun the brass distributor drive bushing. This motor and tranny is original to the car so my plan is as follows.

I will be oredering in some parts and will be rebuilding the original motor . I plan on using the project in Waynes book to take it from a 2.2 to a 2.4 (10:1 comp).I will be installing a set of PMO carbs in place of the original Zeniths. My plan is to have this project finished within the next 3 weeks. I will then use this set up to get the car back on the road asap.
While driving the car with the above setup I am going to obtain a 3.0SC core which will get a fresh rebuild as well. I can then take my time on the 3.0 project as the car will be running while I build the other power plant. This will save me a lot of aggravation and make the 3.0 project more enjoyable. Once complete I will drop the 2.2(2.4) out and put the 3.0 in . Since the 2.2 is an original numbers match deal I will preserve it well put it on a shelf to always be available for the car.

As I work on these things I will be on the boards to search the minds and wisdom of the Pelican Parts board wizards Advice and ideas are always welcomed. In my past years I was a Saab Turbo builder but am now a converted Porsche lover .

[Wayne 962]

Originally posted by PorscheTSC
It seems that I spun the brass distributor drive bushing.

Technically, there's no such part. I think you mean the brass distributor drive gear. Even so, this gear doesn't typically fail all by itself, and if it did, I can't think of any way you'd hear 'valves knashing' like you describe?

Have you torn the engine down yet?

-Wayne

[PorscheTSC]

Hello Wayne , Good to hear from you. Your correct I meant to say the distributor drive gear. I have not torn the motor down yet but will be doing so in the coming weeks. As I pulled from a traffic light the car lost time and and the valves danced for about 25 yards then the car shut down. When I tried to turn it over all I was able to get were a few puffs and backfires. On its delivery back to my garage I pulled the distributor only to find many many small brass filings on the shaft and the inner walls of the housing. My thinking was that the only brass part in that portion of the engine was the distributor drive gear ? but maybe not.

I did a compression test ,was not the greatest not the worst .
Cylinders 6,5,4,3, all check at 125. Cylinders 2 at 130 . Number one cylinder is at 135. I plan on tearing the engine down in the next couple weeks to see just what happened.I may find a much worse disaster inside that little beast I still plan on doing the SC build but I also want to get the car back on the road quickly for weekend drives. Given this I have a fresh 911S -2.7 on the way setup with 2 ready and also fresh webbers. As soon as this hits the doorstep I will as they say be back on the road again.
I will then tear down the 2.2 and start my search for the 3.0 project.

This also seemed puzzling to me as well Wayne. My thoughts were how could one spin the distrib drive gear. The funny thing was I had posted on another site but mentioned nothing about thinking it was the gear although I did. A reply to the post came in from Roy at MM ( I know board the reputation is not good ). Either way to my surprise Roy say " You spun the distributor drive gear .The good part is probably no major damage. The bad part is you have to drop the motor and tear it down"unquote. He did'nt try to sell me any services,just forwarded his thoughts. I had already thought the same but still cannot envision how this would happen. One of the reasons why I look forward to opening the engine .

Take Care , Randy
1970 911T
1998 Cadillac Catera
2002 Ford E250 Cargo Van

[Wayne 962]

If the gear is damaged, then there should be really no audible noise from the valve train. One test would be to spin the engine with the starter with the distributor removed, and listen carefully. The valve train should be okay if the distributor gear is toast.

In general, the distributor gear doesn't have a lot of force placed on it. Can you spin your distributor after you take it out of the engine, or is it frozen?

-Wayne

[PorscheTSC]

I will give it a try tomorrow when I get back in from work . I will try turning it over with the starter minus the distributer. I cannot recall the distrib. being frozen but will double check. I was also thinking that it would seem the only way that gear could get stripped would be for the distributor unit to lock up. Im almost certain though it is not locked up but will double check as Im not positive. I was just at a loss as to why all the small gold brass filings ( which are very small in size).

When I do open the motor ,barring no major damage I will be doing a rebuild just for fun. I want to try your 2.2 to a 2.4 engine pic. The one with high dome S pistons and a final compression of
10:1 . This sounds like a nice finished project.My parts will come from Pelican for certain. For now the 2.7 which is on the way will serve to get the car back on the road. It is a very fresh engine complete with webbers. It was pulled in favor of a larger built 3.O for a track racer Porsche. The price was good as was the warranty so I gabbed it to get my car up and running while I work on the other engines. If the car is running I'll not rush as much and will be able to take my time with the 2.2 and 3.0
Once these projects are complete I will most likely go ebay looking for nice roller Porsches to drop two of these engines into.
In all honesty the 2.2 needed to be opened anyways as the prior owner failed to keep it sealed up tightly so the oil drippings were becoming annoying

I will post on the distributer tomorrow. Again many thanks for the post Wayne ,take care

---------------------------------------------------------------Randy

[PorscheTSC]

Hello Wayne as promised I checked the car a short while ago. Things look good for the valve train but not for the engine perhaps. I pulled the distributor again only this time I noticed the bottom corners of the teeth on the distributor are slightly chewed off (hence the small gold filings in the engine) . When I turn the car over with the distributor out the valve trane is quiet . The car however turns over kind of rough and about every rotation I get a rapping noise . This rap is in no way muffled though and almost sounds as if it is coming from the starter / flywheel/Clutch area. Then again though I will not know for sure until the engine is taken apart. When turing the car over I hear this rap best when leaning out and listening below the car. It is also a heavy rap much heavier than a valve would make. This is also a noise that is below the heads and intake . Not Good Huh ? Good thing I have the other engine on the way . Thanks again and take care.