Installing new pistons and rings

[Azcrash]

I am about to install new pistons/rings/cylinders, and have been doing a lot of research to make sure I am doing it correctly.

I found some conflicting information, so made a list of what I plan on doing and wanted to run it by you guys to confirm what I am doing is correct:

1. Going to weigh all pistons/rings and make sure they are within 5 grams of each other (to balance them). The packaging for them (mahle brand) says they are already balanced so I assume they should be good already.

2. Place the top ring at 10-11 o clock position. Middle ring to 1-2 o clock position, and the bottom oil ring to 4-5 position.

3. Compress rings and insert into new cylinder, with the arrows on pistons pointing to the front of the car.

4. Put a small amount of aviation permatex gasket on the case to cylinder surface (on each side of the paper gasket).

5. Put in retaining clip on inside end and place cylinder on case studs, with the piston partially showing out the bottom.

6. Connect the piston to rod and put on the snap ring on the other end.

7. Push the cylinder into the case and install the head. Then torque the head bolts down.


Anything I am missing or doing wrong? Thanks as always!!!

[bowserb61]

You've pretty much got it, I would only add a few things.

I put the ring gaps at 12, 4, and 8 o clock so that they are as far away from each other as possible while also keeping all gaps as far away from 6 o clock as possible.

Not sure what engine you're building, but VW issued a bulletin later on saying to skip the paper spigot gasket and just use RTV to seal the cylinder to the case. Not that you can't still use the gasket and permatex if you want, but just be aware that even VW changed their mind on it.

Otherwise, just take your time and make sure you think several steps ahead of yourself so that you don't forget a clip or something dumb. Make sure you use assembly lube or oil any time you fit two moving metal pieces together (wrist pins, cylinder walls, etc.), and make sure you torque your head nuts in the correct order.

It's not difficult, but it's definitely worth taking the time to be careful.

[KTPhil]

Don't forget the little cooling tins on the bottom of the cylinder pairs. And the pushrod tubes, of course! (stretched or new tubes, and new gaskets)

I've read the oil ring gap should be on top, and the two compression ring gaps at 8-9 and 3-4. But they can rotate over time so this may not be as important as is implied.

I always lapped the cylinders into the heads before assembly, followed by a thorough cleaning. And no paper gasket--RTV is fine but not too much; you don't want RTV balls floating in your oil passages, clogging up the works.

[rockerarm]

Hi again.
I hope you address the lower end concerns first prior to continuing with the cylinders/heads.
Correct on the previous posters. Keep the ring gap away from the 6 Oclock position, as this prevents oil from seeping past ring gap when sitting.
There are different oil rings, 2 pc and 3 pc. Many people like the 3pc with the 2 rails and expander. Recognize that the ends of the oil ring expander butt up to each other and not to overlap the ends.
I will put the compression rings around 3-4 Oclock and 8-9 Oclock for the very same reason of the oil seeping past the gap.
The arrows on piston point towards the flywheel.
Use a popular RTV silicone sealer and no paper gasket. Shims are common to adjust for compression ratio.
When cylinders are installed try and measure your deck height with piston at TDC. The min amount is .040" but for daily driver .060 is ideal minimum. Lots of opinions here on deck heights.
You can use the same RTV under the 4 washers in the rocker arm area, to control oil seepage.
I initially will wash the new cylinders in hot water/Comet cleanser/rag to remove honing grit. Then oil cylinder walls lightly with oil. Paint fin area with BBQ paint. Will also clean and paint the new pushrod tubes.
Hope this helps, Bill.

[Azcrash]

Ok, I weighed all 4 Pistons, and they came in with the following weight in grams:

560
559
554
553

Is it true that they should only be 5 grams within each other? And is that for all 4 or by side? If it was by side, I could match up the two lower weights and higher weights, and be within a gram of each other. But between the 4 lowest and highest weights, there is a 7 gram difference

[KTPhil]

Lowest to highest.

[Zwitterkafer]

The pistons do not balance "by side". It doesn't take much work to get them down to within a gram of each other, just make sure you know where it's safe to remove a little material. Obviously, weight of rods and piston pins factor into balancing as well.
Suggestion: After installing all 4 cylinders & the deflector plates, install both heads in the same operation. First make sure that the head nuts all spin easily on their studs, without rust or thread damage that can affect torque readings. Tighten the first head hand tight, the other a little more, then alternate between the two as you incrementally approach the final torque values. Use the factory tightening sequences. Recheck the torques the next day before completing assembly.
_________________
"Criticism comes easier than Craftsmanship"
- Zeuxius, 400 BC

[gt1953]

Something an engine builder once told me was to rest the engine between torque cycles. Not sure why but he had his reasons. Like mentioned do check again the next day. Take your time and do it right once.
_________________
Volkswagen: We tune what we drive.
Numbers Matching VW's are getting harder to find. Source out the most Stock vehicle and keep that way. You will be glad you did.

72 type 1
72 Squareback
({59 Euro bug, 62, 63, 67, 68, 69, 73 type ones 68 & 69 type two, 68 Ghia all sold})

[Cusser]

Check the repair manual; I seem to remember oil ring gap straight up (12), the compression ring gaps at 4 and 8 positions.

I assume that your connecting rods are balanced if you're concerned about piston weights/balance. Obviously check piston weights with their own wrist pins, consider weighing wrist pins separately and moving those to better match the total weights if they vary.
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[Azcrash]

The wrist pins were all the same weight, so no luck on being able to distribute the weight better by swapping pins.

Is it really that big of a deal to just go as is and deal with the 7 gram variance? This is just going to be a driver, not racing or performance.

I have not taken out the connecting rods, so those are part of the weight calculation as well? Hmm if it is a big concern to distribute weight, I will take them off and weigh with pistons.

[Cusser]

I "think" I took my pistons in to my work to weigh them, last time I did this on mine (back in 1986). Or maybe I'm thinking of my B2200 pistons in 2011...

Anyway, I know that previous to that I just took manufacturer's word and installed the pistons without weighing them, never had any issues.

Up to you if you want to lighten the two heavier pistons a little to get closer to the two lighter ones; it sounds like you already have a way to weigh them....
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[Dr OnHolliday]

Personally, I'd get the piston weights much closer.

2nd - why aren't you putting new rod bearings in?

3rd - how are the valves? Now's the time for new exhaust valves...
_________________
1965 Type 1 sunroof Baja / about 70k miles on self-rebuilt '74 1600 and counting / SP heads and aftermarket valve keepers / non-doghouse shroud with external cooler and filter / 1.5 qt extended sump / Weber 32/36 DFAV progressive carb / 009 dist with Pertronix / 1.25 ratio rockers and ball adjusters / 1.5" stainless steel J-pipes and carbon steel baja exhaust

[Azcrash]

Ok I installed new rod bearings per your guys recommendation.

3 of the rods turn great, but the 4th is stiff. If I loosen up the nuts it spins freely but it won't take the 23 ft lbs torque.

What would be causing a new set of bearings to function worse than the old set?

[HRVW]

For a whatever thingy try the TIGHT rod on another journal.....some times that will work......also

Tap the small end of the rod (lightly) with a small hammer or mallet before trying to torque the nuts. I did that on all of my builds when in the trade.

[Baggs]

[Snowbro]

When I built mine, I got all my pistons and wrist pins within 1 gram. I didn't take any material off of the pistons, just the inside of the wrist pins

[Helfen]