Original 2.2 needs rebuild - suggestions?

brockb · 05-19-2004, 08:17 AM

This is a pristine original 71 911T targa with matching numbers engine that was re-ringed once (poorly) by the original owner approximately 10k miles ago. Since purchasing the car, in addition to bringing it up to concours condition, I have had the original Zenth carbs rebuilt and upgraded by Motor Meister and replaced the marelli distributor with a new Bosch "S" distributor and wires. The car has always smoked and leaked oil and has so-so power. Recently Autoscope in Plano, TX diagnosed a light knock in the engine that is somewhere in the lower engine, not the heads.

Please excuse the lengthy description but I need some good advice. Obviously, if I am going to tear down the engine, I might as well do a quality rebuild on it. And if I am going to rebuild it, I have limitations and opportunities regarding components. I have been reading the porsche performance books, browsing the forums and talking to local porsche shops. Here are the questions I still have:

1. All the shops say the only sure rebuild is to use new P & C's. They indicate that a bore and new JE pistons is only recommended for racing applications where the engine has a short life anyway. Opinions?

2. If I go to new Mahle P&C's what is available and can I upgrade? With these Zenith carbs should I go to "E" P&C and regrind the cam to "E" specs? This will never be a track car just a beautiful street survivor.

3. This car is one of several collector cars I enjoy, so I will be dead and in the ground before I put another 50k miles on it. Should I not worry about building a 150k mile motor, and rebuild it with the existing parts and aftermarket upgrades? Also, I don't want to be too unside down in my invest ment in this car. Is there a less expensive way to build a reliable strong motor?

4. If I go the "re-use components" route, what configuration would deliver improved driving performance at a reason cost? Should I bore the cast cyclinders and fit 85mm pistons? Buy and refinish a 2.4 or 2.7 crank? What compression pistons? Should I regrind my cam to "E" specs? Has anyone on the forum done a 70.4 mm crank with 85mm pistons? With Zenth carbs and an "s: distributor curve, what compression and cams would you use?

5. Lastly, I am a decent shade tree mechanic but have never rebuilt an engine. If I go slow, read everything, use the forum, and get a good Porsche machine shop - can I reliably rebuild this motor?

Again, please excuse the length of this post. I will appreciate any input on any of these questions. Thanks!

rw7810 · rw7810's Garage

I'm in the process of rebuilding my 2.2 now. You didn't say what your $$ factor is. If it isn't a factor, then go for it. I found a set of brand new P&C (Mahle) for $600 from a fellow on this list. I think your "S" distributor is causing some power issues with the T cams, I would recommend going to the 911L curve. You also seem to be all over the map on what you are considering.

brockb · 05-19-2004, 10:54 AM

Yes, I am definately confused. I was under the impression that Mahle P & C were no longer available for the 2.2 and if they were the pricing I have seen is north of $2000. My budget is $8k and I would like to see if I could do most of the work and get it down to below $6k. You didn't mention what pistons, cams, etc. you used, i.e. "E", "S", etc.

rw7810 · rw7810's Garage

I've heard that about the non-availability of the Mahl P&C sets. Guess I was lucky. The overbore and Jegs sounds like a good optionfor you. I strictly kept it stock on my 2.2 except for a carrera oil pump, SSIs and all the recommended mods (Timecerts, oil springs, restrictors, idler arms, etc.)

Henry Schmidt · Henry Schmidt's Garage

Supertec can rebuild your long block with many performance upgrades and a 2 year unlimited mile warranty for something like your $6000.00 budget. All you do is take it out, pull off the ancillaries ( exhaust, carbs, fan and housing ) and we do the rest. Professional, speedy overhaul and the peace of mind that comes with a warranty.

jgparker · jgparker's Garage

I think I had these same questions a while ago too. I'll throw in my 2 cents.

1) Sound like someone is trying to sell you parts. I think few people on this board would replace P/C without evaluating them first. Too much money to just throw away.

2) Mahles are available, but expensive. A 2.2 E-spec engine makes a great driver; I have one of these myself.

3) Any quality rebuild will last you an eternity of street use at the mileage you drive. Unfortunately, any rebuild you do will put you upside-down in an early 911T, unless you got a really great deal on it.

4) Determine what parts will be reusable first, it may drive most of the decisions. I think E-cams are the best bang for the buck, if you are able to reuse everything else.

5) Go for it. Rebuilding a 911 engine is a great experience, and you'll be glad you did it. You have lots of great resources right in the DFW area too, like Ed Mayo and Al Zim and a very strong PCA region.

Good luck,

JP

brockb · 05-19-2004, 03:30 PM

Thanks JP, sounds like good advice. I think the key will be locating a quality Porsche machine shop in the Dallas area that will work with me. That and finding a fellow PCA member that has all the specialty tools. I guess I am going to have to start going to the PCA meetings.

Regarding the rebuild, so far the concensus is either build an E spec engine with new Mahle P&C's and an E cam, or, bore the exisiting cast cylinders to 85mm with JE 9.5:1 pistons and an E cam. I am still playing with the idea of using a 2.4 crank and rods but probably will pass on this if the 2.2 crank is still in good shape.

If anyone on the forum has experience with machine shops in the Dallas metroplex I would appreciate your comments.

camgrinder · 05-19-2004, 04:52 PM

http://www.jonesautowerks.com/ is in San Antonio TX.
And http://www.protechnik.com/
Is in Houston area..
Both are very high quality shops.

Wayne 962 · Wayne 962's Garage

Okay, sounds like you need to read this first, before you do anything else:

http://www.pelicanparts.com/techarticles/mult_Engine_Rebuild/mult_engine_rebuild-1.htm

-Wayne

rw7810 · rw7810's Garage

Henry - I like what you did with the air deflectors - gold cad plated. Wish I had of thought of that!

PS: What would you see with E cams in a 2.2T, vs. the T cam??

Henry Schmidt · Henry Schmidt's Garage

The performance enhancement of just "E" cams in a stock "T" motor would be minimal. It is true that the performance characteristics of an engine are primarily determined by cams, with the small ports and low compression your improvement would be almost unnoticeable. Boost the compression and "E" cams and you'll see a great improvement. If you are running carbs I believe you'll find far more enjoyment in the Solex cams.
If you're going ta replace the cams anyway, the Solex cam with small bore carb motors never fails.
901 105 110 04 and 109 04

brockb · 05-20-2004, 04:08 PM

Henry, I've been told that my Zenith carbs won't work with E cams and a compression boost. They were rebuilt and bored by motormeister. What are my limitations if I want to keep the original Zeniths?

Thanks for your input.

Henry Schmidt · Henry Schmidt's Garage

The Zenith carbs have 40 mm butterflies just like a Weber. The limitations are only the jetting and venturi size. The jets are the same as 40P11 Solex carbs (356/912) and the stock venturis can be bore to 31.5 mm. When jetting for 2.2 / 2.4 e or s most tuners feel 32 mm is big enough. .020 " won't make much difference. Jets can also be reamed. It also make sense to remove the decel air valve on the side of the Zeniths. A couple of years ago we built a set of 46 mm Zeniths and put the on a time trail 3.2. Still working today.
The Zenith carb is also a newer design than the 40 IDA Weber. Some of the Zenith improvements were incorporated in the PMO carbs.

Wayne 962 · Wayne 962's Garage

Quote:

Originally posted by Henry Schmidt
The performance enhancement of just "E" cams in a stock "T" motor would be minimal.

Also the 'E' cams with the 'T' pistons get really close. Depending upon what machine work you may have had done on the case or the heads, you may experience some piston / valve clearance issues...

-Wayne

brockb · 05-20-2004, 09:49 PM

You gentlemen have been very helpful. Your insight along with a copy of Waynes book has given me a good plan. Step one is to take the car over to Ed Mayo (PCA Tech Guru) and have him diagnose the light knock in the motor as well as other indicators of the true condition of this engine. If a tear down is required I am going to "go for it" and enjoy the experience. I'll keep you posted.

This is a great forum!

dtw · 05-21-2004, 04:55 AM

Just a suggestion - if there is a light knock in the 'lower' engine, I'd say don't drive it another 10 feet. That light knock can turn into a hole in your case so fast it'll make your rod bearing spin. I mean, head spin.

350HP930 · 05-22-2004, 07:04 PM

Quote:

Originally posted by dtw
Just a suggestion - if there is a light knock in the 'lower' engine, I'd say don't drive it another 10 feet. That light knock can turn into a hole in your case so fast it'll make your rod bearing spin. I mean, head spin.

+1

It could be the difference between a crank regrind and a reconditioned rod and finding another crank, rod and engine case.

Wayne 962 · Wayne 962's Garage

Quote:

Originally posted by dtw
Just a suggestion - if there is a light knock in the 'lower' engine, I'd say don't drive it another 10 feet. That light knock can turn into a hole in your case so fast it'll make your rod bearing spin. I mean, head spin.

True, however, these engines can also make lots of strange noises when cold. If the noise happens when warm, I would be concerned. If it goes away when warm, I would keep a close eye on it, but be less concerned.

-Wayne

brockb · 05-23-2004, 08:06 PM

Wayne, no such luck. I increases as it warms up. I am taking it to Ed Mayo for a second opinion. Do I risk driving it 20 miles?

Wayne 962 · Wayne 962's Garage

Quote:

Originally posted by brockb
Wayne, no such luck. I increases as it warms up. I am taking it to Ed Mayo for a second opinion. Do I risk driving it 20 miles?

How long has the knock been going on? If it's been there for the past 1000 miles, it's not likely to blow up on the way over. If it just developed, then I would be concerned...

-Wayne