'74 911

catspaw · 12-02-2005, 03:24 AM

I recently bought my first Porsche, '74 911. After reading many threads and tech articles it seems only a matter of time before the 2.7 starts to self destruct. The motor runs fine now
, 78,000 mi.,upgrades include, chain tensioners, pop-off valve, Carrera valve covers, no oil leaks, runs fine, no issues at this point. My question is should I look for a motor to rebuild or do these 2.7's have a longer life span than I am lead to believe. If looking for a rebuildable core is the way to go what year engines should I be looking for and would my 2.7 be worth anything if it's still in good shape? Thanks.

Rex Walter · 12-02-2005, 03:53 AM

Catspaw,

I got 160,000 miles out of mine before I discovered that a couple of head studs were starting to pull. It would have gone farther if I had done more to prevent this (external oil cooler, checking head nut torque,....). At 78,000 miles, I would say you are in good shape. Some like to replace the 2.7 with a larger motor - but I vote for keeping the original motor. A replacement motor may also need a rebuild. There are several Professional shops that can rebuild your motor for only a little bit more than what it would cost you to do it yourself - if that is the way you decide to go.

Hang in there - do your maintainance - enjoy the car for another 5 to 10 years (depending on how much you drive it), then worry about an engine rebuild.

Rex

IROC · IROC's Garage

I think one of the major keys to 2.7 liter engine longevity is keeping the oil temp down. IMHO, I would strive to keep the oil temps less than 200F for street driving (even lower would be nice). My old 2.7 rarely exceeded 180F on the street and lasted for a long time with steel head studs and no inserts in the case, etc.

Congrats on the car. The '74s have alot going for them.

Mike

widgeon13 · 12-02-2005, 04:09 AM

Find a good 3.0 motor from an older SC and have it installed along with SSI heat exchangers and backdated 74 or earlier exhaust. You can do it for half the cost of a good 2.7 rebuild and the car will scream as well as be very reliable. Get in contact w/ Dan Jacobs at Hairy Dog Garrrge near Oxford Airport, I think near Southington CT and he will do a great job for you. He did it for me and I loved the results. I have placed the link below.
This is what I did with my 74 911 and I really enjoyed the car until I took the stupid pills and sold it, but I did get a good price for it.

http://www.hairydoggrrrage.com/[img]

PM me if you have any questions. I had the car for 13 years and did a lot of other mods, suspension, oil cooler and front valence. really fun car, you just have to watch out for rust on the 74's before they were not galvanized steel.

Doug&Julie · 12-02-2005, 04:22 AM

If I recall correctly, the '74s don't have those evil thermal reactors, which caused a lot of the heat related problems with the 2.7. So, the '74 cars tend to be a little more reliable.

I'd say right now just enjoy the car. If you're worried, keep an eye on it and start saving for a rebuild or replacement motor. In the meantime, "if it ain't broke, don't fix it".

Enjoy that car!

catspaw · 12-02-2005, 04:47 AM

Thanks to all. This site is great someone has alway been there done that before. The car's not a daily driver, weekend toy if it's not raining. It needs some cosmetics but the tub seems clean, it was originally a Calif. car. It is also my understanding that '74's don't have thermal reactors (what ever they are).

Doug&Julie · 12-02-2005, 04:50 AM

Again, if I recall correctly....thermal reactors were a "quick fix" by Porsche to try to meet US emission laws in the mid 70s. They were designed to create heat to burn off excess exhaust/emissions. Unfortunately, they were placed right under the heads...spreading that heat into the valves and other "fragile" parts. I think they sucked power, too.

Somebody correct me if I'm wrong...

widgeon13 · 12-02-2005, 05:03 AM

no thermal reactors but they did have magnesium case which I believe has different heat expansion chacteristics than the case bolts and head studs so the bolts can loosen up and consequently the case will leak oil. Regardless of what you do to the car, you will never recover your total invest cost (unless you got a real bargain) but you can have a high fun quotient with it and given the right mods it can be a very competitive DE car or club racing machine. You can rebuild a 2.7 but it will not have the reliability of a solid 3.0 and if you don't get the right party to do the rebuild, it can be a very expensive lesson to learn. In CT you shouldn't have to worry about emissions since you car is now exempt and I don't see that changing. I still maintain a residence in CT so I speak from experience. Get the Bruce Anderson 911 Performance Handbook, it has much good advice on the 3.0 mods.

IROC · IROC's Garage

If and when it becomes necessary to replace or rebuild the 2.7, economics will most likely drive you to finding a replacement engine rather than rebuilding the 2.7 (that's why I have a 3.2 in my car now).

Until then, Doug summed it up nicely - "don't fix it if it ain't broke"

Mike

overman · 12-02-2005, 06:34 AM

catspaw... enjoy your car, keep it serviced and drive the hell out of it!! If it ain't broke don't worry about it!!

overman · 12-02-2005, 06:41 AM

Here's a plug for the 2.7's just for interest...

Had my 2.7L upgraded last year... Webers, JE's, Web Cams, HD return springs, head work, SSi's and sport exhaust... the engine screams! Dyno'ed 190hp at the rear wheels. I love this engine... lot's of torque all the way to the rev limiter, it's a blast to drive. This engine starts, runs and behaves very well... as far as drivability, the only difference is less gas mileage when compared with my stock CIS 3.0L SC. The 2.7L will smoke the 3.0L!!

DohertyCM · DohertyCM's Garage

I have a 74 911. Get the large oil cooler for the fender well
do the oil system upgrade (cost about 10 dollars) outlined
in bruce andersons book to increase your oil pressure.
and make sure you have an 11 blade fan. These are, in my book necessary upgrades. I love mine and constantly woop the 3.0 guys on the track. A blast to drive.
The other standard upgrades are needed for the motor but the ones I listed are extra.
I am looking at an engine overhaul but it is about that time.
And Im doing it because I want that "warm and fuzzy" because I have never torn down the engine, nor do I know its complete history. Its not smoking nor has it lost power.

Dont let the 2.7 head stud thing scare you. If you get them fixed right you will never have a problem with them again. The 74 had the stronger 7R case.

JP911 · JP911's Garage

If you've got a leak free 2.7 that's running well, then don't worry about it. It's true that the 2.7 doesn't have the longevity of the 3.0 or 3.2, but it revs faster and can be a real blast to drive. I've been driving the snot out of mine and it just wants more. It was rebuilt some point in the past, but I'm not sure when. I have an engine waiting in the wings based on a 3.0 but I'm still having fun with my 2.7. The advice about the external cooler is sound and made a huge difference in my oil temps.

jtkkz · 12-02-2005, 09:30 AM

132,000 miles on mine, still seems to run strong.

wowzer911 · 12-02-2005, 10:08 AM

You had to start something, didn't you

widgeon13 · 10:17 AM

I enjoyed my 74 911 with the 2.7 engine but thought the 3.0 offered long term reliability and the most cost effective way to get more power so that is why I went the 3.0 route. ( I did it at 125,000 miles and had the usual oil leaks as well) I don't believe one way offers significant advantage over the other. I also agree with some of the other comments that if you have a solid 2.7 that is leak free, just drive it and worry about it when the signs start to appear.

What puzzles me is that the stock 2.7 CIS produced 150 HP and with mods it appears 190HP is possible at the rear wheels. Bruce Anderson's book says that with those same mods you only achieve 210 - 220 HP out of the 3.0. The carbs, as I have been advised really don't give any additional HP but do improve low end throttle response.

My setup produced 220+ HP at the rear wheels and I believe cost me less than half of what it would have cost for a quality rebuild on my 2.7. I opted to go for the 220HP in a 2300 lbs car vs the 190HP. As I mentioned earlier, after taking the (Da) stupid pills I sold it anyway. After going through withdrawal for 6 months, I bought an 84 Carrera so the process starts all over again. I enjoyed the 74 and I'm enjoying the 84 as well so the important thing is that it's yours and have fun with it, life is good.

PatrickB · PatrickB's Garage

Good God man, drive it and have fun with it until it needs to be rebuilt! Do you have an extra $10k burning a hole in your pocket?

Key is, as Mike said, keeping the overall engine temps down. Your way ahead of the game by not having to suffer the effects of smog equipment. If you want an effective upgrade for your '74, add an external oil cooler to aid in keeping oil temps down... Money well spent!

Check with Alexander911 on this board. He has close to 300k miles on his unopened 2.7. He does burn a bit of oil, but the motor still runs great and makes a ton of power!!

wowzer911 · 12-02-2005, 02:22 PM

widgeon13

How do you like those Boxter wheels? I've been toying with that idea for a while. How's the handling?

widgeon13 · 12-02-2005, 02:45 PM

wowzer911, How much snow are you getting up there. I come up to Chaumont once and a while in the summer, fly up from Piseco.

The Boxster wheels worked out well for me but I did have to run spacers on the back because of the way I routed my oil lines, not thick spacers but I think they might have been 1/2 inch. As I said I sold the car so have no longer got the details on what exactly they were. The wheels were 7X16 and I had 205/55X16 all around. I have run track wheels and tires on 15 inch rims where I had 225/50 in the back and 205/50 in front. That worked well also. Never had any rubbing on the rear fenders and did not have to roll the lips. It was a great car and I was really sorry once it was gone but I found a nice 84 Carrera on the west coast and have recently had it deliverd to CT.

I thought the Boxster wheels looked good on the silver car and if I recall they were reasonably priced. I didn't want to hassle with trying to fit something else under the narrow fenders and the 16's seemed to fill out the wheel openings for street application. Not certain they would look as good with another color however I did see them on Aubergine and that was when I had the idea of putting them on my car. Let me know if you have any other ???.

PRE-H20 · PRE-H20's Garage

like patrick said, "Good God man, drive it and have fun with it until it needs to be rebuilt!"

and yes i have almost 300k on my unopened 2.7, ive TRIED to take care of it, maintain it, keep it clean, give it the good gas, change its blood often, and most importantly like JP911, i have driven the SNOT out of it and its given me the love of almost 300k miles in return....... soooo at 78k you havent even broken it in in my book! hehehehe.

jon,...... a quick word with you please...... hummmm you say you have been driving the snot out of your engine, the one im gonna buy from you?????.............................. GOOD! dont deny that thing the last rev's with you.... hehehe! cuz when i get to it............... hehehehehe...................