Rebuilding a Harry Pellow (Maestro) engine

[alan hall]

What pushrods are you using, I don't recognize them? Also when you say the rocker stand was short by .050 do you mean that the iron bridge had been machined for some reason at the mounting pads?
Thanks

[Jbrooks]

Alan

I don't think the rocker stand had been shaved, it looks stock, but on glass with depth stick on a dial caliper its shorter that the others. I will bring it home and put it on a surface plate with a hight gauge and get a real measurement, then put some Prussian Blue on it to see if it is parallel. The distance between the head bolt interface surface, and the top of the No#1 rocker pin is short. Mismatched parts sometimes do that.

The pushrod are later C type. The white dots are to monitor rotation while cranking to build oil pressure.

[neilbardsley]

Thank you for sharing John.

I'm a bit surprised that one of Harry engine's had a 58 v 62 head volumne?

[Jbrooks]

Neil
I have seen worse. No crack repairs, could be in part new seats, but they are balanced out now.

We figured out the dead cylinder, not a carb, a wire. Like everyone says, with most zenith carburator problems, they are mostly, always electrical. Got a good 30 minutes run time on the engine at 2.6-2.8K RPMs, did not toss any cam lobes. Another 20 min, then readjust the valves, tweak, re synchronize carbs. Review all the tune-up data and get her ready to install.

I also found a "color tune spark plug" in my stuff. Probably put it in verify the idle mixture and try to get a photo. Have not used it in 50 years, but once upon a time they were "the thing" for re-jet setting and getting the burn clean. It's almost impossible to use on a 356 installed. Since the engine is out why not?

[Jbrooks]

All done, ready to put back in. We put the "Color Tune" in each hole to check the combustion mixture. I have not used this in 50 years, but it still works. First photo is when the flash was on so you can see the installation. Second is the Bunsen Blue color of the stochiometric mixture

Above installed, just a clear spark plug


Idle. No3


Idle No4


This is No1 with the idle jet 1-3/4 from bottom. The tach RPM peaked, but it is still rich, back off 1/8 turn and the blue comes in. After doing this to all four, the idle RPM went up from 750 to 835. So we rebalanced the carbs and went back to 750 idle. It's a smooth idler, and revs quickly.
Thanks for looking, should be back on the road this week.

[neilbardsley]

I have a colourtune. I have given up using it. I couldn't see the flame with the mirror and I kept shocking myself trying to adjust it. Pity because it's a good idea.

[Jbrooks]

Neil

I agree it's a pain when the engine is installed. A fiber optic inspection camera probe works pretty well if you have one of the little hand held ones. I took these with my phone, I forgot I had one until I stumbled on it, I used it to do SU carbs on british cars, it's about the only way to adjust the idle mixture on Jags and MGs.

I have not done a 356 with it in 50 years, but I must admit it works well and the idle mixture is probably perfect.

[Jbrooks]

Done, installed, on the road gain. No leaks, seeps or drips. Starts on the first revolution, runs well and quiet.




Sorry for the washed out photo, the sun came out from somewhere.

Thanks for following, this one is in the bag.

[admin]

Thanks, really enjoyed following your rebuild. I wish those last photos where videos as I'd love to hear it run and perform.
Kind Regards,
Karl

[Jbrooks]

XL
Maybe in a few weeks, the photo was at 2 miles. Want to bring it up slowly, after a couple oil changes, and valve adjustments, I will get Tom to power through the gears on a video.

62B next on deck


Cleaning up and inventory, just had to take a photo

[Phil Planck]

I bet Tom is a happy driver again. Thanks for sharing the rebuild.

[jjeffries]

What an excellent thread...I've forwarded it to two 912-owning buddies. Very educational even for a guy like me with no 4 cylinder Porsche's to his name...love the photo of the tools used. Thanks very much for documenting and sharing. John in CT.

[Jbrooks]

Well guys, stuff happens...... At about 300 miles, it started puffing a little blue smoke after idling at a stop sign. Rings were still seating so we decided to watch and see if it got better. But it RAN well and TOM took it for a 400 mile trip over the mountains. A good hard climb and return should seat the rings. A little over 900 miles now and never saw 5K RPM. Well he's back and it still smokes. No#2 plug oil fouled the others are clean..



Did a leak down and bore-scope looked OK except NO# 2 had a couple scratches and a strange brown stain spot at the bottom of the piston. Leak down also was also acting strange. At #2 piston TDC there was no leaks , no pressure loss at all. But move the crank 5 degrees either way, it would drop to 30% loss, hiss from the filler, put it back to TDC it would go back to full pressure, go past 5 deg back to ring leak.



So this morning we pulled the engine, rechecked the leak down and looked in the holes some more. Pulled off the head to get a better perspective of the scratch. CRAP looks like a broken ring. Pulled the #2 cylinder and piston, 2nd compression ring and oil rings broken. Not sure why yet but the bits were caught between the skirt and the 2nd ring grove and beat the side of the piston. If the compression ring was at the top it held pressure, but when it got to the divot in the cylinder it leaks.
Divot in the cylinder wall is where the 2nd compression ring tops out, top ring would seal above that.



Side of the piston where the rings failed, the missing section is about the size of your little finger nail as deep as the groove. Top ring is fine, the other two broken, missing about 8mm of 2nd compression and 12 mm of oil rings.




Now The Good News!!! I called Lenard at Shasta yesterday afternoon when it failed the leak down, he has set of rings, they were on the way in 30 minutes. We were not sure yet if the rings were bad but, so the rings are here. Called him back this morning with the scored cylinder and bad piston, replacements were on the way within the hour. Customer Service is still alive and well in Nevada.

Thanks for watching. More to follow.
PS. Not sure about the brown stain on the piston top, but it wipes off.

[Jbrooks]

Plugs, and fouling
Here is no# 1 and 2 yesterday when we did the leak down test. I cleaned them with a wire brush and swapped cylinders with them.
One is a little rich the other is oil fouled, this is about 900 miles since overhaul.



This morning pulled all four, they are in the cylinder location order. 3-4 are perfect, 1-2 still showing a little fouled, but #2 is shinny. This is 25 miles after cleaning yesterday afternoon. Cyl 3-4 are since overhaul.

[Jack Staggs]

What type of ring compressor did you use? I wish I could see what the rings looked like before they were removed from the piston.