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Engine mysterie 356B normal

Posted: Sun Oct 15, 2017 10:45 am
by Clemens Mutter
I'm on the way of restoration a 356B T5 coupe normal, and I learn'd a lot for that on reading registry's sites ! :)
At the engine now - some mystery's detected at the dismantling:
- the engine case with crank and cam's look's like stock - never rebuild
- only new piston rings ? (STD stamped on them)
- between each cylinder and case 1 copper shim 0,25mm
- deck hight on piston/cylinder almost 0,0mm at all 4
- between each cylinder and cyl.head 1 steel shim 0,30mm (the one on cyl. 2 was broken and a peace of it was gone - blow out there !
- no shims under the cyl.head nuts !
- the cyl.heads looks unchanged but a number (17335) stamped in each one ? (s. pic)
- under the out- and inlet valve springs 4 shims 0,5mm (under outlet cyl. 1 and 3 only 2 of them ?)
- under the rocker arm holder 2 shims 0,5mm
- some red sealant rests under the 4 cyl.head nuts which are not within the rocker arm space !?

I purchased the car in 2008 from Charlston NC, and I don't know anything about its history. It must be in storage at least since 1995. The key fob show's a garage: Greg Godboud in Roebuck SC (Sports Car Speciality Inc.). Does somebody know him, or how to get in contact - for history relevant questions ?
Thank you for any comments and hints !

Re: Engine mysterie 356B normal

Posted: Sun Oct 15, 2017 11:24 am
by Doug McDonnell
Call Protech https://www.protechmotorsports.com They may know of him. A long shot I know but worth a try. There are a few members in the Greenville/Spartanburg area. Maybe one of them will chime in. Good luck but I fear you are looking for a needle in a haystack.

Re: Engine mysterie 356B normal

Posted: Sun Oct 15, 2017 12:03 pm
by David Pateman
Basic to understanding any engine are the 4 numbers found on the case.
The case pairing numbers are the first to be stamped and indicate that the two or three main case parts were made as a set in the machine shop before engine assembly. Most 912 cases do not have the pairing # on the third piece.
The engine build number is used by the engine shop to indicate how many engines they have built; also called an "internal number" or the "case casting number" it is simply a sequential # that is independent of the various engine types.
The engine type number describes the characteristics of the engine from displacement, compression ratio, valve size, and output characteristics. The type # is assigned a serial # series.
The engine serial number is the sequence # of the engine within the engine type.
So knowing that the pairing #'s match will generally mean that the engine serial # is matched with the build & type #'s, and in turn indicates that the main parts have been kept together. After so many years the engine could have been rebuilt many times, and the components changed. However, using the 4 basic numbers you can determine what characteristics to look for.

Re: Engine mysterie 356B normal

Posted: Sun Oct 15, 2017 3:29 pm
by C J Murray
The past history is of no importance now. You can rebuild it to any specification depending on how you intend to use the car. If you want to maintain the appearance of a stock T5 Normal you can still upgrade the performance to Super or C.

Do I see cracks on the heads? Find a good machinist and get some advice regarding the parts that you have.

Re: Engine mysterie 356B normal

Posted: Sun Oct 15, 2017 10:11 pm
by Vic Skirmants
Clemens; there should not be any shims between the cylinders and the head.
Cliff; I think the "crack" you are seeing is the broken steel shim; that should not be there.

Re: Engine mysterie 356B normal

Posted: Mon Oct 16, 2017 8:07 am
by Clemens Mutter
Thank you all for your input !!
@ Doug, I will contact them, see what they know
@ David, all factory numbers are ok, 3 cases have the same number (148), it is a 616/1 engine *P606386. I am asking about the strange number 17355 stamped in each cyl.head (s.picture below). Not a factory number, I think.
@ CJ / Vic, I'm planning to rebuild the engine as a normal, cylinder and pistons were reworked by a specialist here. No cracks in heads, it's the broken steel shim. I was wondering about all that differences of the engine's cylinder / cylinderhead area build situation - compared to the workshop manual !
Thank you all for your inputs !

Re: Engine mysterie 356B normal

Posted: Wed Oct 18, 2017 11:23 am
by Vic Skirmants
The steel shim should not be there. That surface should be bare aluminum.

Re: Engine mysterie 356B normal

Posted: Thu Oct 19, 2017 2:23 pm
by Clemens Mutter
Thanks Vic,
do I need additional copper shims at the cylinder base ?
The deck height with a 0,25mm shim is 0,3mm.
This gives a CR of 7,53 : 1 (Its a normal, 82,5 bore with flat piston :-( )
Do I have to expect any clearance problems valves to pistons with this small deck height ?
Thank you for your input.

Re: Engine mysterie 356B normal

Posted: Wed Oct 31, 2018 3:50 pm
by Dick Weiss
Clemens,

Most likely the heads will need a light fly-cut on the head-to-cylinder seats which should be equally matched w/in 0,012-0,014 & a face cut to retain the 9,00 depth; After the valves are added, the heads should be re-cc'd to match each other w/in 1-cc (10 was the original spec) & re-stamped.
Further, the 22 degree chamber angle might need a cut if the seat width is excessive; Usually a
.003" .005" fly-cut won't need it.

Dick