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Posted by: mate914 Jan 17 2020, 10:44 AM

My father and I are starting the process of restoring a 9146 that he picked up 15 years ago. We are about to dive into the motor rebuild and I have a few questions, a few as in 1000 or so. We have both done a lot of research and are confident enough to be dangerous. He is keeping the numbers matching motor to sit on a shelf. We will be building off of a 69 magnesium case. We plan on going with the short stroke crank and either 86 or 90 mm J&E pistons and cylinders. Engine will have 40 weber carbs with chokes sized accordingly. Camshaft will be ordered specifically for engine.
Can any of the informed engine builders advise whether this is a good set up or not? Car will be a garage queen and occasionally autocross and driver’s ed. He is looking for 150+ horsepower.
Thank Matt

Posted by: brant Jan 17 2020, 10:49 AM

The 69 mag case is the weakest of all of the cases and as a result is not a good choice for high HP
the stock motor was at least 110hp... and can easily be jetted and tuned to 135hp

if your looking for 150hp you will likely be fine
you won't need big pistons though
the case spigots will not likely support those big pistons

you would be better off with a 7R case if you intend to have a High RPM or larger bore/piston motor

the factory found a Need to update to a 7R case when they went with 90mm pistons

additionally I don't think the 69 case has the piston squirters you would need with larger displacement

the small spigot 73.5 case is a 7R that was made for half of year

its the strongest of the small spigot cases... but you ideally would look for a large spigot case for those large cylinders. Aluminum cases cost more, but require much less machine work to bring back to correct specs (may not cost more once you add the machining)

Posted by: roblav1 Jan 17 2020, 10:54 AM

That's the last case I'd spend money on.

Posted by: Johny Blackstain Jan 17 2020, 10:57 AM

Slightly off topic... when did they stop making mag cases for street use?

Posted by: mate914 Jan 17 2020, 11:00 AM

OK, how about making it a 2.2 S? Engine will be sent to Ollies for machining and prep work. Oil squirter’s will be installed if they need to be, dowel pins will be installed.

Posted by: brant Jan 17 2020, 11:06 AM

the cases were

early aluminum, small spigot motors 1965 -1968

then magnesium small spigot 1969 1973.5

magnesium large spigot motors 1974-1977

then aluminum cases came back with large spigots in 1978
(1977 on the euro only 3.0 cars)

oh... and the turbos were the later aluminum cases also in 1975-1976

Posted by: brant Jan 17 2020, 11:16 AM

Matt,

I failed to add that this sounds like a very cool project !
I restored a 914 with my dad and will always treasure him, the experience, and the car...


hey motors are super expensive to build.
why not use the correct number matching block
build it above stock HP... the same machining and the same cost exactly as the 1969 case-builder...

it will look stock from the engine bay
you can achieve the 150hp you want
and you only have to pay to build one motor instead of eventually 2

plus the one motor you spend the money on is going to be much more valuable to the car and much more valuable than an old 69 motor that has little value when you pull the car (a big $ looser eventually)

where the number matching motor becomes a money maker... in that the huge investment you spent on building it will all come back to you in the sale or eventual sale

Posted by: mate914 Jan 17 2020, 11:46 AM

I agree with the logic in value of the original 9146 engine. My father on the other hand thinks that that case should be saved. He wants a motor that he can run hard in the six and if it donates it won’t break his heart. We looked around for other engines, but then you have 4K invested in something that still needs just about the same machining.
It’s a tough decision, is the 69 magnesium case so lousy that you would spend 4000 on something else?

Posted by: mate914 Jan 17 2020, 11:47 AM

The $4000 that I’m referencing is about the average 2.7 in our area obviously that would need rebuilt

Posted by: brant Jan 17 2020, 11:56 AM

I know my builder was really disappointed with me when I brought my 73.5 mag case in for maching and rebuilding.

he told me the machining work would cost more than if I had rebuild my prior 66 aluminum race motor that wouldn't need the maching
(I did it to save 20lbs in a race car)

the maching difference was thousands...
I think it depends on the evaluation of the actual case condition of the one you are trying to use.

maybe send the 69 case out and have it evaluated?
a good, trust worthy, builder can answer the dollar and cent question based on your exact parts and your exact situation


both of your examples... the 69T and the 914/6 case... have steel cylinders.
bad for shedding heat and normally the first things that is junked to build hp over stock...

so either of those starting points will require new Pistons and also new Cylinders
not cheap....


but these are the details that keep people up at night
a biral or other cylinder on a different motor might be reusable saving thousands..
so its hard to really say which is cheaper..
depends a lot, on which parts you put into it.
but because of the steel cylinders your going to need more parts than others already

and thus the reason the "affordable" cores often cost just as much as an aluminum 3.0 when all is said and done.

Posted by: mepstein Jan 17 2020, 12:00 PM

If you build it right, you should be able to run it hard and not damage the engine. That’s what these engines were designed for. Letting them sit is just as abusive to the engine.

Below is a mag case that was sitting for years. Not worth putting the money into fixing it.


Attached thumbnail(s)

Posted by: mate914 Jan 17 2020, 12:05 PM

Are you saying that this happens to all the magnesium cases while they sit? Did those deteriorating holes underneath the bearings happen with the bearings installed, or the races dry?

Posted by: brant Jan 17 2020, 12:07 PM

maybe show this thread to your dad..

a good motor build.. even when trying to maintain costs...
is still going to end up at 10K


10K into a 1969 case becomes a crappy/cheap/undesireable core 10 years down the road... one that you sell for 3k

10 into the correct matching number block for the 914/6
after rebuild, will add 20K to the value of the car

you are not likely to blow or hurt either motor once rebuilt
or if you miss a shift... yes you can hurt either motor
but both will put out good hp and run a long life...

If you were going for 180 hp or more, I wouldn't try it with the stock block or the 69

but if your going for 140hp... it makes no sense to put 10K into that 69 block

Posted by: mate914 Jan 17 2020, 12:10 PM

this is the factory motor.....

Posted by: brant Jan 17 2020, 12:13 PM

yeah.. but if its number matching to the chassis..
it ads value to the finished product
and anything can be repaired….

its just not worth repairing things that don't have the matching COA/ engine numbers

mag can be welded and machined

Posted by: mb911 Jan 17 2020, 12:15 PM

I have a 73.5 case 7r with 2.4 steel cylinders with nikisal plating done by millennium then S pistons coated both top and skirts.. Using solex cams.. I expect to be north of 150hp very easily.. In fact the parts package came from supertec and Henry said it would a great combo..

I have not driven the car yet but have run the engine and it runs nicely.

Posted by: brant Jan 17 2020, 12:19 PM

killer combo!
and I would expect 170hp or more

(I don't have that case... but wanted to build the same motor for a street car)

you should pick up some 2.2 E or S pistons... bump it another half compression point with the long stroke... up to 180-190

Posted by: TomE Jan 17 2020, 12:42 PM

This is Tom, father of mate914
. Everyone I spoke to or have read said put the original 6 engine on a shelf. Cover it in oil and put it up because the engine with the car will add a lot of bucks to a resale. The 69T engine and the 914-6 engine is the same engine? That is why we are looking at the 2.0T. With that said we are in no big hurry to do anything. We are just weighing our options at this time.

Posted by: mepstein Jan 17 2020, 12:46 PM

It might be toast regardless of what you do to it. When mag gets to the point that it crumbles away, there isn't any way to fix it. It's a fairly reactive metal. We have mag minilites that you can break apart by hand.

That's one reason why aluminum case engines are going up in price (especially early 2.0) and mag isn't.

Posted by: mepstein Jan 17 2020, 12:49 PM

It will add money to resale to have the number matching case but less sitting by the car than running in the car. I would talk to a good machine shop to see if the case can be saved. It won't get better with age, even covered with oil.

Posted by: brant Jan 17 2020, 12:50 PM

the 69 911 engine
and the 70 914/6 engine

are really the same engines with the same performance.

only one is very un-desirable to 911 guys
and even though it will still cost 10K to build it will be worth less than the cost of building...


the numbers matching case, isn't valuable EXCEPT it has the numbers to match your car... it also cost 10K to build... but it adds the full value of the rebuild back to the cars value... instead of detracting from it.

Posted by: Mark Henry Jan 17 2020, 01:56 PM

I'd put the original 6 engine on a shelf, build a 3.0 SC engine, euro piston, cams and use the weber carbs you have 3.0 tuned. Often a 3.0 and up core just needs the top end and head studs done.
Or add JE pistons and better/bigger cams, friend did this and got over 200hp easy.

Posted by: sixnotfour Jan 17 2020, 03:41 PM

76 or later , 2.7 4rib oil pump,oil bypass done...

here is a numbers matching i did.. had a spun main bearing


Attached image(s)

Posted by: mate914 Jan 17 2020, 05:13 PM

Can I please ask who did your case repair?
Matt

Posted by: mate914 Jan 17 2020, 05:18 PM

The original six case we have has been opened up to 84mm pistons. I no longer have the original six heads,we have K1819g now. So if I go with 84 or 86 mm pistons will I need oil squirter‘s?

Posted by: sixnotfour Jan 17 2020, 10:46 PM

dont F with it.. get a 2.4 solid fun ..

the og 6 case I did it..not cheep..

2.4 9.5 E or solex cams ...solid combo..autocross legend,,affordable...

2.7 add 1k for case inserts , spingot resize, cylinder sealing surface machine...

Posted by: Mate914@gmail.com Jan 18 2020, 07:28 AM

Thank you for your help.... it is very much appreciated.
We have been looking for a 2.4-2.7 case for some time now. Unless he can find one reasonably, we will be using original case. The previous owner replaced heads and opened up the case spigot(sp) to except 84mm p&c.
What would you guys do about piston and cylinders? 84mm replacement P&c or 86mm?
Would like to stay under $2000 for P&C, have any good sources?

thanks, Matt

Posted by: Superhawk996 Jan 18 2020, 07:41 AM

Garland has a 2.7L long block on this site if you want a 2.7 7R mag case.

http://www.914world.com/bbs2/index.php?showtopic=341519

2.7L cases pop up with regularity. Most hated cases in Porsche history IMHO (right or wrong). Oops now I've gone and done it!

Almost anything can be fixed. Don't sweat the original case, it can be fixed. Talk to Ollies directly. Yes, it will cost money. If you can't afford the money to fix (and update) an old mag case, I'd question why you're playing with sixes in the first place. FYI - I had to have the same heart to heart with myself over a 2.4L 7R case. I'm not interested in chasing HP and 3.x Litre engines. Period correct vintage engine is what I wanted for me!

Do what suits you!

FYI -- If the orignal six case has been opened up to accomodate larger pistons then technically you don't have an original case anymore. Depending on next buyer's personal preferences for a 9/14/6 they may want to take it back to 2.0L bone stock and then they would be in a world of hurt having to weld the spigots and remachine to get back to orginal. Can be done with $, but technically not original which could affect the value of keeping it in the 1st place other than for the matching numbers element.

Sounds like you have some hard decisions to make -- I don't envy that. Good luck with whatever you decide.

Posted by: TomE Jan 18 2020, 10:57 AM

This car is not being rebuilt for the resale value. Yes it kind of sucks the case was opened up but what I paid for the car it was a steal anyway. The car in no way is going to be 100 percent original. Matt and I can get a better deal on a 2.7R locally than the one for sale on 914world.