3.0L Rebuild at 250k miles

['76 911S 3.0]

I've been working on tearing down my 3.0L in my '76 S, the chassis has a touch over 365k on it and the engine has just over 250k...initial reason for the teardown was a large oil leak on the top of the engine but has slowly progressed into more the further I get into it.

Some pictures:
The Beginning:


Bumpers Removed:





Fan Removed:


Engine Out:


Engine on Stand:

['76 911S 3.0]

Intake Removed:


Shroud Removed:


Found some standing water in the intake port on cyl 1:


Beginning of Timing Component Removal:


Timing Components and Valve Covers:


Case Components:


One Bank of Heads Removed:

['76 911S 3.0]

Broken Divlar Head Stud:





2nd Bank of Heads: Something found its way in there and did some damage...exhaust valve is burnt as well

[NEWFIE 69 911E]

Watching with interest!

['76 911S 3.0]

Curious if anybody knows if these RUF 98mm short skirt pistons will work with the 3.0l? I have Nikasil Mahle P&C's but I found a stress crack on one of the pistons...



98mm pistons

I understand I will need to have the rods resized and the cylinders bored and replated...

['76 911S 3.0]

It's been a while since I've updated this but some progress has been made in the past few months...After being unable to source a replacement 3.0 piston, I bit the bullet and purchased a set of 98mm 9.5:1 JE Pistons and matching cylinders from EBS Racing. Don at EBS is great and their work is top notch.










Head studs were replaced with new all steel studs and a set of 964 camshafts were purchased. Cylinder heads are disassembled and off to Randy at Aasco Motorsports in Anaheim for a complete rebuild.



After break-in, the engine will be on the dyno at 911 Design in Montclaire for some power figures.

[Robbbyg]

Great stuff,
and great to see big miles on your engine
And better to know that its going to do even more!

[304065]

I would split the case and do bearings after 250k.

[GT2BH]

Great work! Just curious as to why you decided not to split the case.. I am doing mine at 115k and decided to split the case and found a rod bearing that was on the edge of giving out

['76 911S 3.0]

I've battled back and forth with splitting the case. The car has been in my family since 1978 and we know the entire history of the car and the engine. There has never been any metal in the oil, no abnormal noises, and never revved above 4000 rpm but maybe a handful of times. The case does not leak a drop of oil and my grandfather (retired Porsche Racing mechanic) rebuilt the engine in 1983. I had him take a look at the engine after teardown and he deemed it not necessary. But then again you can't know without tearing down completely and inspecting.

I must admit, I've had a few sleepless nights contemplating the idea of splitting the case and as the engine sits now, it's not too much work to get it back down to the case and split it. My biggest concern is the intermediate shaft bearings (which I have new ones). I'm still contemplating at this point.

There are plans for turbo down the road, Carrillo rods are in the future for this engine. When these are installed (perhaps a year from now when funds become available again), the case will be split and bearings replaced on the bottom end.

[Sigurd]

This is similar to a build I am currently doing.

Will you have twin spark? What, if anything, will you use between cylinder and head?

[304065]

Originally Posted by '76 911S 3.0

I've battled back and forth with splitting the case. The car has been in my family since 1978 and we know the entire history of the car and the engine. There has never been any metal in the oil, no abnormal noises, and never revved above 4000 rpm but maybe a handful of times. The case does not leak a drop of oil and my grandfather (retired Porsche Racing mechanic) rebuilt the engine in 1983. I had him take a look at the engine after teardown and he deemed it not necessary. But then again you can't know without tearing down completely and inspecting.

I must admit, I've had a few sleepless nights contemplating the idea of splitting the case and as the engine sits now, it's not too much work to get it back down to the case and split it. My biggest concern is the intermediate shaft bearings (which I have new ones). I'm still contemplating at this point.

There are plans for turbo down the road, Carrillo rods are in the future for this engine. When these are installed (perhaps a year from now when funds become available again), the case will be split and bearings replaced on the bottom end.

The intermediate bearings are probably trashed. Has nothing to do with your use of the engine, they just go. Split the case and reassemble probably adds about 10 hours to the job. You can go with ARP rod bolts so you don't waste a set of Torque-to-Yield, same with bearings.

['76 911S 3.0]

Sigurd,

No twin spark. The 9.5:1 compression will not require twin plugging. As far as the cylinder-to-head surface, no gasket is needed. The mating surface on the cylinders is slightly tapered for sealing purposes.

What are the specs on your build?

['76 911S 3.0]

Originally Posted by 304065

The intermediate bearings are probably trashed. Has nothing to do with your use of the engine, they just go. Split the case and reassemble probably adds about 10 hours to the job. You can go with ARP rod bolts so you don't waste a set of Torque-to-Yield, same with bearings.

Yea I'm really leaning towards splitting the case now...I have a week or more to wait for the heads to get back to me. This would be the time to do it. Thanks for the insight.

[Sigurd]

Originally Posted by '76 911S 3.0

Sigurd,

No twin spark. The 9.5:1 compression will not require twin plugging. As far as the cylinder-to-head surface, no gasket is needed. The mating surface on the cylinders is slightly tapered for sealing purposes.

What are the specs on your build?

Thank you for the info on the cylinders being tapered. I was not aware of this.

I have 98 mm EBS cylinders with JE pistons. I am, however, planning to have distributor and twin spark. I have been waiting since Easter for the machine shop to start working on the heads. I am in no hurry, but I am looking forward to continue the build. I have 964 cams available.

I am also planning to use a PMO efi setup but I have not decided on what computer to use.

['76 911S 3.0]

Sigurd,

There are many different options available for EFI on your engine. I work for the company that designed and built all of the electronics systems and engine management systems for the Singer Porsche builds. If you have any questions or need help with your setup, feel free to PM me and we can talk.

Update:

I have decided to split the case, inspect, and replace all the bearings. The replacement bearings will be sent to WPC in Torrance, CA for their "coating" process and should be returned within a week or so. Thanks for all the advice so far guys.

[zelrik911]

I am watching with interest.
Thanks for sharing

Peter 78 3.0 SC

PS: I gather the Singer EMS is a Propriety development?

['76 911S 3.0]

Thanks Peter.

PS: I can't get into the details on the project, sorry.

['76 911S 3.0]

Cylinder Heads ready to have seats cut and new valvetrain installed.

['76 911S 3.0]

Finally got to splitting the case last night. Found some issues that would have been catastrophic had they not been found. Thanks again everyone for convincing me to split the case.

#3 rod bearing was within hundreds of miles of failure, IM shaft thrust bearing was on it's last leg as well.

I've purchased GT3 main and rod bearings and am having the crank mic'd and polished as well as the rods refurbished and ARP rod bolts installed. IM shaft will be refinished and I've found some pitting on the Aluminum IM shaft gear so I'm most likely replacing that as well.

I still need to crack open the oil pump and inspect for wear as I fear that bearing material made its way in there.

Case Split:



Crank Removed:



Crank on Flywheel:



Cylinder Heads Finished:



ARP Rod Bolts: