View original topic: Preping my buggy's spare engine
MrGoodtunes Sat Nov 14, 2020 5:23 pm

This will be a long slow process because buggy's current 1585cc dual port engine is running totally fine. I'm very happy with it; but it's been in since June 1992, and has gone close to 100,000 miles. Meanwhile, her spare engine has been sitting still under a tarp in the garage; has been used only as a source for a few parts. (For example, I borrow'd a valve rocker adjuster when my main motor needed one due to mushrooming.)

First order of business: Bringing her out from where stash'd for 28.5 years.

Next, a little clean-up with the shop vac. Anxious to see if the crank will turn; but before trying that, I wanna inspect what position she's been left in. Popping the distributor cap, I find the rotor was about 1/4 of the way from #2 toward #1. So, I think this means...

#2 would have just fired, and was in early part of power stroke,
#1 would fire next, so was in early part of compression stroke,
#4 would have been in early part of intake stroke, and
#3 would have been in early part of exhaust stroke.

Pop'd off the left valve cover, and did a happy dance 'cuz #4's intake valve spring and #3's exhaust valve spring were depress'd, verifying what I thought. Yey! So, the right cylinder bank chambers were seal'd off by closed valves; while left bank chambers were somewhat open to whatever (humidity, critters, etc.) as I had left the engine with no headers, didn't even stuff a paper towel wad into carb flange opening of intake manifold. My bad. It'll be interesting to compare what's inside of cylinders #3 & 4 to what's inside cylinders #1 & 2.

MrGoodtunes Fri Nov 20, 2020 5:00 pm

The crank TURNS !!!

Since cyl#3 was the one most likely to be rusty (was left with exhaust valve open and no header) and since it was in the early part of an exhaust stroke, I didn't want to turn the crank forward and possibly push rings into rustyness. So I put my torque wrench on the flywheel gland nut. And then, well before getting up to 10 foot-pounds, the crank lurch'd over an inch (as measured on outer rim of crank pulley) ~20.

Cobbled a skateboard scooter under the charcoal grille base I used as a sort of wheel burrow when stashing this engine. (Both items pick'd from neighbor's trash.) Now I can move it so easily, it's a joy!

Cylinder #3 had none of the rust I was worried about; just some oil soak'd carbon deposits. Both (#3 & 4) pistons had an awful lot of caked carbon. Not bad tho, considering how long it sat in this position. It was surprising to see so much oil, 'cuz I had drain'd the oil when stashing the engine over 28 years ago.

My next step is to pull out the slightly used set of 85.5mm pistons and cylinders I stash'd 30 years ago. They were left in a cardboard box at the bottom of a stack of plastic crates near the garage door where rain has been known to blow in.

calebmelvin Sat Dec 05, 2020 9:51 pm

Doesn't look too bad for almost 30 years of sitting!

oprn Sun Dec 06, 2020 6:34 am

Looking fine. I'm guessing it's a 1500 SP. Dressed up and oiled up it would have run as is with a small risk of carbon getting stuck under an exhaust valve.

I just sold my '69 Bus that had not run in 31 years to a fellow from the next Province. All he had to do to the engine before the 14 hour drive home was replace the dried out fuel pump diaphragm and a rusted out muffler.

MrGoodtunes Sun Dec 13, 2020 3:20 pm

oprn wrote: ... guessing it's a 1500 SP ... Correct.

oprn wrote: ... Dressed up and oiled up it would have run as is with a small risk of carbon getting stuck under an exhaust valve.
Or, between sparkplug electrodes. When this engine came out of the buggy in 1992, it had Bosch Platinum plugs. They have a super tiny little center electrode. (Platinum is expensive.) Any little bitty piece of carbon could easily cover the entirety of that center electrode. I do recall the experience of running on 3 cylinders occasionally, typically following a short freeway sprint, especially on off ramps. Found an unused box of 4 new Platin plugs. I won't be using them. I did find a use for one that came out of the single port head; namely, I dremmel cut a groove across its threads for chasing grit out from the sparkplug threads of the dual port head I found stash'd (since 1991 when I traded 2 used singleport heads for 1 new dualport with minor issues). The dualport took awhile to clean up 29 years of garage funk, remove the gooey protective coating that had harden'd a little, free it's valves which were stuck tight, and replace the valve springs 'cuz they were way rusty.

So I got 1 dualport head ready for use along the way, before I even un-stash'd the 85.5mm pistons and cylinders set that I was on my way toward. Cylinders turn'd out to be awfully rusty.

Looking into my old MPGs log book, these cylinders were in my buggy from June 1981 thru August 1990 (different H case engine from the one recently un-stash'd). They've gone approximately 125,000 miles on leaded gasoline, which probably explains the white stuff on piston top surface. None of that white stuff on the unstash'd engine, which was running early unleaded gas.

After cleaning up a couple of the 1600 cylinders, I'm not sure I'll be using them, even tho I found an unused set of rings I had forgotten about. A couple of things have me worried. First, there are these longitudinal scratches (gouges?) that are deeper than honing could remove. And second, at least one cylinder is a little out of round; about 0.004" between piston and cylinder one way and 0.005 or maybe even 0.006 the other. The wider measurement is in direction of the piston pin ends, where the worst worn piston has a wear pattern that looks like the outline of some continent on a map.

I've been careful to keep each piston with the cylinder it originally came in, as I was told some manufacturers match slightly over-size pistons with slightly over-size cylinders, etc. But now that they're all worn in their own ways, maybe it's better to mix and match them for the same reason we rotate tires? And then there's the over-riding primary question, which is complicated by the fact I already have a set of rings for them: Should I re-use these cylinders at all?

calebmelvin Sun Dec 13, 2020 6:36 pm

It might be worth it to find a good set and start fresh with those pistons. It could be a lot of time to get them to work, and even then might not.

oprn Mon Dec 14, 2020 4:04 am

Your 1500s might be better if you can still get rings. The performance difference will not be that great. Four HP according to VW.

MrGoodtunes Sun Jan 17, 2021 7:42 am

More careful checking of piston to cylinder gap shows that the out of round issue is almost entirely due to piston wear in the area near ends of wrist pins. I won't be using those pistons or cylinders, other than for mockup and comparison. Have no desire to go back to the 1500s either. Looking into replacement P&C sets, I got interested in Moresa. They're an original equipment supplier for the Mexican Beetle. And the price is pretty reasonable ~$175 USD per set at Amazon (free shipping). But what's most special about them is the side design in the area of wrist pin ends, where my old set shows excessive wear.

There's a problem, tho. For whatever reason (maybe due to low octane Mexican fuel?) the piston height from pin to crown is a bit short, and/or cylinders are a bit long, because...

vintagecarleds wrote: The problem I have run into Moresa P&C kits is I always get too much deck height, right around .081-.091"
Using .081 in CB Performance's engine calculator page indicates 6.8:1 compression ratio, and .091 indicates only 6.7! If it weren't for this, I'd've already bought the Moresa set. Arrgh! I'm looking to have something more like stock compression ratio was in late 60s and early 70s, 7.5, according to my Clymer Productions reference:

Comp Disp HP ModelYr
7.0:1 1200 40 1961-65
7.3:1 1300 50 1966
7.5:1 1500 53 1967-69
7.5:1 1600 57 1970
7.5:1 1600 60 1971
7.3:1 1600 60 1972-74

MrGoodtunes Thu Jan 28, 2021 3:07 pm

While the Mexican piston design appears to bring oil where I have experienced excessive wear (at wrist pin ends), I am not interested in their low compression ratio (and wish to avoid the expense of machining). So I went ahead and purchased a set of AA Performance standard P&Cs. They arrived via FedEx with a couple broken cooling fins on one cylinder:

Pistons compare very closely with the used set, which was purchased 1981:

Best I can measure, they result in 0.069 to 0.070" deck height. This will give me 7.0:1 compression ratio (unless I can find a way to have 20~30 thousandths shaved off cylinder height, and get 7.3~7.4 CR).

oprn Fri Jan 29, 2021 4:52 pm

Cylinders must be longer than stock.

MrGoodtunes Sat Jan 30, 2021 7:49 am

oprn wrote: Cylinders must be longer than stock.
But Opee, when I moctup the 1980s P&C on this spare engine, I got 0.068 ~ 0.069" deck height. Were those cylinders also longer than stock? Or, maybe my rods are too short. IDK but it seems aftermarket "standard" P&Cs are possibly trying to find a median between the pre- and post-smog emission control standards, with a bias toward the latter.

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