Engine Rebuild

[Eric McKinley]

I have a question I am hoping that I can get some direction on.

It is in relation to the rebuild time of a 912 engine in man hours.

Assume that all machine work is completed, everything is now at the correct tolerances, carbs have been rebuilt, new cam, crank is ground to correct tolerance, all tinware is painted.

I solely mean, a rough estimate in time to put it back together correctly and bench test.

I understand this can be a difficult one but just a ball park given the details I have supplied.

Thank you in advance.

[C J Murray]

40 hours plus, apart and together. Most of the time is putting it together.

[David Jones]

Depends on the experience of the person doing the rebuild Eric. I could do it in 20 hours or less as could many people but for someone who has never built one before it could be 100 hours. There are things involved that could result in requiring parts that would be ready and on the shelf for someone like Vic but for me I may not have the right end float shims or the cam drive maybe needs to be a + or - size. Little things can stop you dead because until you do the assembly you do not know what will not mesh.
Not what you want to hear I am sure but that is my perspective.

[C J Murray]

If parts have been sourced from various different engines add significantly more time.

[David Jones]

I once built a formula Vee engine overnight at Blackhawk race track.Broke one engine Friday and another on Saturday and built another one out of the remains of the other two in the back of my VW bus overnight. It ran and I finished mid pack on Sunday. I was younger and did not know I should not have been able to do it.

[Dave Wildrick]

I was younger and did not know I should not have been able to do it.

Kind of like the old saw about bumblebees technically not being able to fly, but doing it anyhow because they don't know any better.
For a chuckle, see: http://www.todayifoundout.com/index.php ... f-physics/

[Eric McKinley]

Many Thanks for the replies.

Let’s assume that all machine work has been completed, the engine is in good shape and all parts are new, cam shaft SX1, Shasta P&C, new aluminium oil cooler, aluminium sump plate, you get the idea.

Again let’s assume the person doing the build has a lot of experience in stripping, measuring and building 356 and 912 engines and has all tooling and everything to hand.

What would the average timescale be to rebuild.

I apologise for trying to be so precise, just trying to pin this down.

[C J Murray]

There is quite a bit more to it than bolting it together. When the cars were new and if factory parts were used you could pretty much disassemble and assemble just replacing parts. Not now, after machining and using no-standard parts there are many things to be checked or the job goes sour.

You can spend quite a bit of time just cleaning everything properly. Putting the tin back on is time consuming and even more so if the tin came from other engines. You have to set the compression ratio and check many other clearances.

Are you being shocked by an estimate or the cost of a completed job? What did they do and how many hours did they charge?

[David Jones]

Does anyone have access to the standard work sheet for the 60's for a Porsche repair shop? I have no doubt there is a time set for re-assembling an engine. In practical terms I still think if you gave me all the parts as you said and then I think I could do it in 20 hours and the engine would be ready to run. Now add on 4 hours to prepare it and do a break in run.
I would think Vic could do it in half that time.
By the way the last time I took an engine apart it took 4 hours. It was dirty and some parts wanted to stay with their partners after 30 years.

[Chuck Allard]

I redid the brown 356A Peking to Paris 912 engine a couple years ago in 17 1/2 hours across two days to replace the crank and bearings before the car was shipped off for the race due to a flywheel to crank problem that I probably caused. It was a tin to tin rebuild and run in on my test stand before going back in the car. All the tolerances and compression ration had already been configured by me a few weeks earlier on the same engine and end play was the only fiddle. The initial build took longer.
I recall that Tim Berardelli and I did a long block or two back in the early '80s in a day for our race car. We were much younger (and luckier) then. Now I think 40 hours is about right to diagnose and take apart some greasy questionable engine and rebuild it excluding machinist and parts supplier time.

[Eric McKinley]

Mainly trying to do my homework with regards to the engine before getting it rebuilt.

I have been collecting parts for the engine for a number of years, and I am close to getting it rebuilt in the near future.

[Ashley James]

If everything is machined by subcontractors you know and there are no hitches, I’d agree with David that a leisurely twenty hours would cover it. Might be less.

The problems come with not having the right seals, shims or washers, a torque wrench big enough for the crank nut, misunderstanding instructions and having to orders bits. Delays might add a week or more.

[Neil Bardsley]

I don't understand this then. If an engine build takes about 40 hours. Lets say 50 for round numbers. the labour is $100 an hour equals = $5000. Lets say all is well you only have new bearing set, and a crank grind = $1000? Another $500 for gaskets, sealant, bolts etc so. The average build isn't $6500? You could throw in an AA piston cylinder set for $1000 and still have change?

[C J Murray]

Machine work is $2000 or more. Parts are at least $2000. Need a crank and rods, add $4000+ for the best. $10-14k is common.

[Dave Wildrick]

? You could throw in an AA piston cylinder set for $1000 and still have change?

An AA P/C set is still about $400. That's their cheapest big bore kit with cast iron cylinders. http://www2.cip1.com/ProductDetails.asp ... C-C10-5217
I've been running one since 2010 in my 65C coupe w/no issues for over 30,000 miles.