Longevity of 103's?

[MegaRookie]

I will post pics of my heads and the plates.

Thnx! I'm very curious!

Mark

[E_bug]

Sorry tonwake up this post but I think it's relevant. What are the specs for 103mm cylinders?
I have a basketcase motor with 103s srp pistons and those extra stud holes on the cyl liners.
Is it 103,050mm 103,150? I want to do cylinder bore measurements but dont know where to find the inspection specs. (Out of round, tapper etc)
Also whats a good piston ring end gap for a type 4 with 103mm n/a at a hot climate ?

Thanks

[wreck]

"I did a 103 recently with JE forged pistons , it has Deutz cylinders and they were bored for .006" clearance . I have another 4.004" inch bore engine that runs cheap SBC Hyper pistons that was set up with .0015 " clearance that has not had any issues , I'm in Brisbane that has 35C summer days . Not quite as hot as what you can get up to in Summer . Both engines run cool . 120C CHT measured at the spark plug boss.
I checked the JE ring gap with the spec sheet but can't remember what it was . I'm sure it was in line with most gap calculators . sorry can't help you with the ovality /taper specs .

[E_bug]

Thanks for the info . I am trying to find the wear limits of the 103s . What would be concidered unusable .

[E_bug]

So I measured stuff to make my own conclusions.. .

I have 0,060mm taper
I have 0,12 piston to cylinder wall clearence
I have piston ring end gap 0,85mm top ring and 1mm second ring.

I am tempted to fix the taper with a light hone at the bottom and give it a try. What do you all think?

[Type 4 Unleashed]

I wouldn't try to fix the taper, I would give it a light hone and run it.

I've ran as much as .010" piston to cyl clearance, and was manufacturer recommendation, .005" is generally what is used for Forged pistons.

Your ring gaps are larger than I like to run, most ring manufactures recommend .004 N/A and .006 with power adders times Bore. If your concerned about the heat then split the difference between N/A and Power Adders. Just go with some file to fit rings and go manufactures clearance recommendation, and add a little more for your heat concern.

[E_bug]

Thank you very much for the Advice Richard

I have a tripod honing stone setup.. Its hard to find the ball hone at this side of the world I was using back in New Jersey! I will follow your advice with the light hone.
I would like to see what piston ring gap would be with new rings . The used ones seem like they where filed with a wood file .

Oval measurements are Top 0,010mm
Mid 0,030mm
Bottom 0,010mm Would you call 0,020mm in the center barell shape cylinder?

Off to get new rings !!
I sprayed the piston skirts with molykote D321 for kicks and giggles..

[E_bug]

Just wondering.

What would be the best chepo engine package for deutz 912 100mm cylinders and cheap chevy off the self piston setup?
Machining costs are not a hassle at this side of the atlantic.
Keep in mind using the 71mm stock crank.

[wreck]

Spend a morning ringing around anyone local that rebuilds Deutz engines , i.e. tractor or diesel engines . See if you can get used ones for scrape value . they are work hardened and will last longer . I then would look through summits online shop for 4 inch small block V8 pistons with a compression height of close to 1.4 inches 35-36mm , if you work out the head CC's maybe also look for dished pistons to get the comp ratio you want to run . if you're running the standard rods get them re bushed to suit the pistons pin . .927 inch I think .
My engines both have a 0.045 thou deck height . made up of .005 deck and a .040 copper head gasket that is annealed .

Richard do you know of any big mile engines that are running EMW qa'd QSC nikasel barrels ? you never hear of any reports good or bad .

[Type 4 Unleashed]

I don't think there are really any cheapo packages, but if you have 100mm deutz cyl's then 100mm Porsche pistons would be an option, I believe the Turbo pistons are 100mm with 22mm pins, and are easier to work with than the 23.5mm Chevy pins. And you can always adjust pin height with rod length, for instance if your pin height is to short use a slightly longer rod, to set piston deck height.

As to the EMW qa'd QSC nikasil barrels, a bunch have gone to Europe, and the thing is, you only hear about things if they are bad, there will always be someone complaining when stuff doesn't work right, I will try to remember next week to ask specifically about them.

[E_bug]

Great ideas guys. New 100mm liners go for 100euro each with a piston in oem form. I will try to source indian or chinese knockoffs.

I want to just use a mass produced piston , do any nessessary boring honing to the linner to fit it and use stock 71 crank. The heads on this motor where cut for the 103s and have big valves on them. 38 and 44 if i measured correct. There are signs of a dropped valve damage on the cylinder head deck and they are rebuild. (Single spring.. Maybe thats why the valve hit and broke.)
On the cam gear i could see 86c is that a web cam?

[wreck]

What about honing your cylinders to suit these pistons .

https://www.summitracing.com/int/parts/ ... /overview/

4.06 inch or 103.124mm , The valve seat may have come loose due to overheating . What sort of cooling system does it have ? and I'd say you'd be correct with the Web 86C . I'm running a scat c55 which is very similar in a 2.6 lt in a Ghia , below 3000rpm on light throttle it drives like a 1600 ,once over 3k it really starts to boogie . What are you putting the engine in ?

[Steve Arndt]

911 turbo pistons have 23mm pins IIRC.

[E_bug]

Its going on my 1971 Beetle.

[E_bug]

The more I look around for these linners the cheaper they get.. New KS 912 Linners 41 euros + tax..