83 mm p/c

[vavenom]

where can I find a set of 83 mm p/c and is this doable for my 64 T1 40 horse check the topic out for more info, need input thanks
http://www.shoptalkforums.com/viewtopic.php?t=43207

[Marc]

For a 1200cc 40hp, your options are limited. You might be able to find some 83mm slip in pistons, headers, and a 2bbl intake, but it may be cheaper to drop in a 1600. If it is all original, I'd rebuild it stock and keep it that way.

There's a whole lot of things that can be done beyond just pistons & cylinders, but if you want to keep it basically stock appearing that means retaining the 40HP heads - with their tiny ports & valves it's just silly to build the engine any bigger than the 1385cc you'll get from 83mm pistons. There were once 80 and 82mm bigbore-40 sets made too (1287/1352cc), you might find a set of any of the three sitting around collecting dust somewhere. A set of NPR 83s went on eBay just last month. Just make sure that they are for the 40HP engine with 20mm wristpins, stock 1500s were 83mm bore also but those pistons/cylinders won't work on your 40HP. Just bolting these on will raise your compression ratio by almost a full point, so you may have to go up a grade in gasoline if you don't shim the barrels or open up the chambers to control the CR.
One other small improvement - if you still have the original early 40HP rockers they're 1:1 - the `65-up 1.1:1 assemblies will bolt right on.
If those heads have 125K on them they're overdue for a valve job and new exhaust valves before they go back on. Many stock 40HPs have gone 200-250K without breaking a valve (their more-common demise is a thrown rod from running low on oil too many times due to all of the oil leaks that develop on an engine that old) but I wouldn't risk it on a bigbore.

[vavenom]

Marc, Thanks again for a response, The 83 mm sounds like what I want to do, I already only run premium so thats no problem, sounds like I'll just redo the stock heads as long as they check out ok, maybe a mild port and polish just to match things up and up gradwe the rockers to the 65 and up models. I would like to keep the stock look for now and have it as a spare when I do another engine. Thanks

[RoWaMe]

Got CB Performance's new catalog last month; the 83mm 40 hp big-bores are listed in there. Although I trust Marc's opinion and experience, you should know that you can install the 69mm crank from a 1500/1600 engine right into the 40hp case without any modifications. But the big ends of the 40hp rods are too wide for the 69 crank; they need to be machined an even amount on both sides to fit. With the 83mm P/C and 69 crank, you'll have a 1500 engine. I have not done this conversion work but do have it planned for a future 40hp; will try to get the P/C at local swap meets- have been looking for 3 yrs but no go. A fella had such an engine at a local VW meet yesterday, with an Engle 100 cam, small dual carbs, stock heads and a header. Said the engine runs just fine.

[Marc]

....you can install the 69mm crank from a 1500/1600 engine right into the 40hp case without any modifications. But the big ends of the 40hp rods are too wide for the 69 crank; they need to be machined an even amount on both sides to fit. With the 83mm P/C and 69 crank, you'll have a 1500 engine. I have not done this conversion work but do have it planned for a future 40hp....

I have built such an engine, and I can attest that it will give good mileage and low-end power but isn't good for more than about 15/30/45mph in 1st/2nd/3rd, and is far more trouble to build than it's worth except as a conversation piece. There's a little matter of the extra 5mm of stroke needing at least 2.5mm (~.100") of barrel spacers, or opening the 40HP case up to accept the longer standard 1500 barrels; also the intake manifold will need to be "stretched" by about ¼" and the sheetmetal won't quite reach, so it's not undetectible to the experienced eye. Neither the 1600 or 40HP exhaust will fit just right, although the 1600 comes close. Along with the requisite rod machining, it adds up to a lot of effort to make a smallvalve engine with weak rods. I'd build a "real" 1600SP for daily driving (with cam bearings!) and a "correct-appearing" 40HP for carshow points before I'd bother to build another "1500 the hard way".

[PEPPE]

i also have built the 69 stroked 1200, it is needed to modify also the skirt of pistons because it hits the crank (very time consuming).
i usuallky build (2 per month) tuned 1200. I use modified 1600 barrels, that i machine with a specific fixture for the lathe.
the rods are modified with special thin 22mm bushings and it all fits well, with no need to modify piston skirt, beacuse i mantain the stock 64mm crank.

the whole modification of rods and 1600 cylinders including purchasing of parts is cheaper than 83mm barrels kit and CC is 1470 (85.5x64). it is MY stock rebuild for 1200 with a little more power than original, and people is happy with the results. I use this on old buses, buggy 1200 with larger tyres and daily driven beetles (that in italy vw sold untils 1986).
torque increase is noticeable and also maximum speed is better.
one my friend with a short transaxle (4.375x0.93 4th), 195/60r15, 1470cc engine, 34 pict 3 with adapter for 1200 manifold, 4in 1 bugpack with quiet pack, alfa electronic distributor reached 150kmh

[RoWaMe]

Peppe- interesting work. Since you have a fixture for the 1600 cylinders or can even do the work yourself, I can see that it certainly could be less money than purchasing the 83mm kit. On your later Euro Beetles with 1200 engines, what size valves are in the heads? Over here in the USA, the 1200 engine was only offered on Beetles from the '61 thru the '65 model year, and had "tiny" valves, something like 31mm intake and 30mm exhaust. For the 1966 we had the 1300 engine (77x69), then the 1500 (83x69) in '67's. If your 1200 engines have larger valves than on our old 1200's, then you'd get a bit more of a performance potential.

[Marc]

I believe the Euro 1200 has the same size valves as the ones we got (31.5x30) which means it's possible to stuff a 1300 or FI-1600 33mm valve in there. The thing I find the most worrisome about Peppe's "mini-1835SP" is the rod strength, although he says he's never had one break. That 150KPH run works out to 5260RPM, so apparently he's getting enough air in there once it spools up!

[PEPPE]

i have seen one that a mechanic built some years ago.
he used 1776 cylinders machined down, magnum 044 heads, single centermount 40 dellorto.
it had always 1200 rods with modified 22mm bushings from 1600 rods
that worked with no rod damage. i also was worried by that.

that gave me the input to experiment myself, and so looking for a smaller bushing, a correct fixture to safely machine barrels (and straight). my results are good.
often i use engle 100 cam but i prefer to make them "torquey" and installing stock cams that give a better service to the valve train.
the only problem that gave me this kind of engine is a broken valve spring.
it was a stock one shimmed 1.5mm.
recently i started installing new ones. before i used selected ones just to be cheap, but i discovered that new ones are better. (((((

when i have i use 33mm intake valves from 1600 cracked heads in slighty opened up valve seats. valves in europe heads are 32x30mm