1973 911T Advice

[YYZporsche]

Hi All, Been looming for years but never engaged. I am not new to Porsche but I have never owned an Air-Cooled before. Had a Cayman S, a 991 4 and a Macan GTS in the past but I recently made an impulse buy (I know, I know), I bought a 1973 911T with a numbers matching engine and transmission. It is a Canadian car and has always remained in Canada. The previous owner in the 80s did some work where they updated the car to look like an SC. In any case the Car came with all the sheet metal and a whole lot of other parts to bring her back to its original glory.

My first goal was to get it started. The engine came with Weber carbs and is missing its MFI components. Cleaned out fuel tank, lines, new fuel etc and did a leak down test. #1:65%; #2:5%; #3:10%; #4:45%; #5:13%; #6:5% Were the results. Both 1 & 4 are leaking at the intake valve and being that I do not know how long the motor sat for, I can only imagine what’s going on over there. I was hoping to just run the engine a bit to burn of any crud etc to see if the valves would seat any better but I am getting this noise that I am unsure of. Likely bad, broken or a stuck valve or even a rod knock?? Link to the video

https://share.icloud.com/photos/0997rTDmpHd5nLISm_5CcHAcQ

I am hoping one of you air cooled guru can guide me on next steps. The preference would definitely be not to do a full rebuild but my gut says otherwise. I have read all the post about the DIY engine build as well as bought Waynes book but it is a little daunting. I am very mechanical, I am an aircraft mechanic by profession but would be the first time attempting a car engine build…. My concern doesn’t come from messing up but rather if I do, I wouldn’t want to hurt a numbers matching motor. Here in Canada a rebuild is around $35k CAD, It’s not so much the money but the learning experience and the ability to say I have build it myself. I have done a fair amount of vehicle restorations in my life but mostly teardowns and build back and running gear, I have historically given engines and body/paint to the professionals.

Add some pictures of the car in how it looks today.

Just looking for advise….and glad to hear from all of you

[PeteKz]

If you are an A&P, you can easily handle an engine rebuild. For a 1973, you have a magnesium case. Those cases typically need machine work to get them true after they have been in service for 100Kmiles or more. You should send that out to a well-qualified specialist machine shop, like Ollie's. The rest of it you can handle. If your rods or crank need to be reconditioned, you can use a local machine shop for those.

However, first get it running reasonably well and drive it a few hundred miles, then recheck the leak down numbers.

[YYZporsche]

Thanks Pete. I’ll need to rebuild the carbs. And I’ll see if I can get her on the road again.

[Henry Schmidt]

Trying to make it run is a waste of time. Take it out, put it on a stand and start by removing the valve covers and doing a simple evaluation. Check the valve adjustment, look at the valve springs and look at the rest of the obvious ancillaries.
Running only risks exploding it and that might completely ruin your matching numbers case. An unknown 911 engine is a time bomb looking to explode. Bite the bullet and spend the time to find out where you are. Just looking at the engine pictures shows us the exhaust is barely attached.
With all the cool "original" body parts, you're looking at something worth the time to do it right.

[YYZporsche]

Thanks Henry. I am leaning to removal as you say, it is a ticking timebomb and I want to make sure everything is right.

[Henry Schmidt]

Originally Posted by YYZporsche

Thanks Henry. I am leaning to removal as you say, it is a ticking timebomb and I want to make sure everything is right.

My thinking is simple. You are a qualified mechanic that said "your gut" is telling you it needs to come apart. Thrust your gut.
That pounding might be something like carbon break-away in one or more cylinders (very common on engines that sit) or something as simple as a huge exhaust leak. Put it on the stand, start rebuilding the carburetors (or send them out) and then remove the exhaust (looks like someone may have started). With the carbs off, the exhaust and valve cover removed you should be able to get a pretty good picture.

[BobbyThomas]

How is everything now?

[YYZporsche]

Haven’t had a chance to pull anything apart yet.