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Call G&H and ask them what they can do for you. Is your camshaft and your head still good? Pull the cam out and look at the bearing areas if you haven't already. May need a new sprocket and chain too... wrap a new chain around your old sprocket and if the new chain doesn't lie down real nice all the way around the old sprocket its junk.

Did you scrub the cylinder in hot, soapy water after honing it? Really work at it scrubbing and scrubbing...?

 

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Did you scrub the cylinder in hot, soapy water after honing it? Really work at it scrubbing and scrubbing...?

I cleaned it up in my parts cleaner....figured that would be just as good....?

Nope, not much difference than if you didn't clean it out at all. After machining and honing the bore is loaded with grit. The amount of grit in there that the bore holds can amaze you... You have to use HOT, Soapy water and scrub until you can't stand it anymore. Then rinse, dry with cloth and test your work with a clean white paper towel or cotton cloth with a bit of fresh motor oil on it. Rub the oil in really good then look at your wipe. If that wipe is not PERFECTLY clean you gotta mix up some more fresh HOT, Soapy water and scrub it some more! Oil it well once it is clean.

The amount of grit in there that the bore can hold after machining can truly amaze you... Failure to get it all out = early or immediate topend failure. This cannot be underestimated...

 

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I have too. Methanol fueled racing motors were my forte... My niche (and love) was design engineering. I thoroughly enjoyed beating up on my competition on the race tracks! I did the design and build of small, lightweight V-8s that would produce massive torque figures on the dyno. I was/am a humble and quiet pioneer. I put motors on the race tracks that made over 1000 ft lbs of torque at the crankshaft from as little as 441 cubes and a single 4-bbl carburetor, per sanctioning rules. As far as I know, today, some of my torque production figures still stand unmatched, per cube.

I explained the importance of cleaning out freshly machined bores and what can happen if you don't. If your wipe came out clean after washing, you got it all, so please disregard my warnings above. Being a forum environment here, it is difficult to assess one's skills and knowledge, so I always end up over-explaining things. I hope you'll forgive me.

 

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@SlammedRanger,

Nah, not at all... I figured I may have come across a bit too blunt cause many times I do! Rarely do I ever intend to unless I say so up front... I appreciate someone who challenges something I say or do or has a better idea!!! My partner was like that, a great friend, a smart guy with a lot of knowledge and a lot of experience... He was a great driver, very skilled and a deep thinker concerning the physics of things. We used each other to bounce ideas off. Without him and our long brainstorming sessions (and constructive argument!) neither of us could have ever achieved our goals. Hit me with all your best shots I always say... Please don't hesitate to empty your clip on me whenever you feel like it!

 

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You said earlier that the motor turns over freely for a bit then gets tight. You mentioned the chain getting tight all the way around the sprockets when the motor became tight. Did you put a new chain in the motor recently? On the old sprockets? At this point I would want to know whether the oil pump is working or not too... maybe you can get to it? Any chance you put the oil filter in backwards?

 

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I just re-read this thread and you mentioned having the side cover off to clean screens etc. Was there a reason for that? Crankcase have junk in it? Someone sink the motor? When you put the side cover back on, did anything get left out of there or did anything fall out of place (an o-ring, washer, oil pipe etc) as you were working? For some reason I have a sneaking suspicion that your motor wasn't getting any oil pressure...

 

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That piston hasn't been in there very long... and its getting chewed up. A few questions if I may...?

Was the top end under the rocker cover looking like it was getting lots of clean oil when you took it apart this time? Any discoloration on the cam or rockers from friction or heat? Any scratches on the cam lobes?

Is there any discoloration of the steel connecting rod at either end of it where it meets the wrist pin and lower bearing? No signs of high heat there?

How much wear is their left in the timing chain? Push the tensioner against the guide where it belongs and note the gap distance between the tensioner and cylinder.

Can you take a photo of the piston from the side so that we can see the ring set? Also a photo of the piston crown and combustion chamber?

Measure the piston-to-cylinder clearance and tell us what it is. Slide feeler gauges carefully between the piston skirt at its largest point (90 degrees from the end of the wrist pin) and the cylinder bore, while the piston is halfway down its normal stroke distance from the top. Start with a narrow feeler gauge and work your way up to thicker sizes until the fit feels snug and looks tight.

Careful, don't drop anything... fragile stuff.

Thanks,

 

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Hang on.... I just got back to this thread a few minutes ago.... I think I know some stuff but I gotta go get the service manual downloaded and read it... be back later.

 

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Alright, lets have a conversation. Those photos raise more questions (in my mind) than they answer. But I did see a couple clues worth investigating further.... more on those later...

I just read through three chapters (Head/Valve, Cylinder/Piston, Lubrication) of the service manual familiarizing myself with the motor, so I could talk about this. Again raising more questions than answers, since I haven't gotten enough information yet to point any fingers at anything and say "there... thats the problem". :-(

So I'm just gonna bounce stuff off ya and see what sticks and what comes back... and end with a recommendation.

A possible (or most likely) explanation for why the motor seized up while cranking it during a compression test is, because you may not have had it at TDC on the compression stroke when you took the valve cover off, then put it back on for the compression test? The cam or decompressor plunger or something may have moved up out of place slightly when the cover came off, causing a bind when you tightened the cover back up and cranked it over. My money is on the plunger popping out, but from here everything I say is speculation cause I can't look at any of the motor parts. The TDC procedure for valve cover removal is covered in chapter 8:

Now, what about that upper connecting rod discoloration? It looks like the wrist pin (either this new wrist pin or the old one, can't see this new one well enough in the photo) and the upper end of the rod has gotten pretty darn HOT at one time! It is discolored for what looks like about 1.25 inches or more down the rod beam, and the entire pin area is burned. Is that new wrist pin discolored from heat too? That don't look good... but the bottom of the rod looks like it hasn't overheated. I can't tell from the photos whether its been getting enough oil or not...

Answering your question about the side movement of the piston on the wrist pin... that is normal at the top of the rod. Thrust movement of the rod is controlled at the bottom of the rod where it connects to the crank throw. Any excessive slop at the bottom is a big problem, but not at the top. The bore holds the piston centered over the rod, not the rod itself.

Is the oil ring a one-piece ring or a three piece ring, that you assembled? If you assembled it, are the scraper rails fit into the expander right, rather than one of them put in alongside the expander? Is the oil ring free to move in the piston land or is it stuck? Does it seem to fit snugly in the bore? I have several more questions about that oil ring that can't be answered through a forum, so I'll leave it up to you to insure that it is good and that it is installed right and that it fits and that it works...

You mentioned the ring gaps being lined up in one of the photos... don't worry about that while the piston is out of the cylinder... The cylinder itself doesn't look very good to me. I see wear at the top of the bore and other clues that indicate to me that it should be mic'ed and if not in spec, bored to the next oversize as appropriate.

Now for some general commentary... The photos don't give me enough information... in some of the photos the cam lobes look a bit ugly, but in others not bad at all. Same goes for the rockers... didn't learn anything from them. Cam journals and the head look alright so its your call... was it getting enough oil up on top? Are the cam and rockers still good?

Also, in some photos I see fine black particles in the oil film on the parts. It looks like it could be grit from parts rapidly wearing and burning up from lack of oil, or it could be from old motor oil that was left in there for a few years too many... Your call.

I come away from all those photos with one nagging question... that seemed to be a common theme in most of those pics. It looks to me like there is a lot of grit in that motor. What that grit is composed of, or the source(s) of, I have no clue from here. Some of it is fine enough to be leaving stains... while some are particles. It looks like stuff is getting chewed up pretty quickly.

I'm not there to put eyeballs on it all and figure out what is going on... I know nothing about its history (and neither do you), so my best recommendation has to be this:

Pull the motor out of the frame and split the cases. Clean every part up in solvent so you can inspect it and proceed to make a list of things that need to be replaced/fixed/refurbed. Disassemble the head too, it probably needs valve seals at a minimum... Read the service manual until you understand it all, then put it all back together clean and right with appropriate lubes and sealants.

Hang in there...

 

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Just a reminder while you are going through the oiling system... include the passage up through the jug and check out the head as well. The service manual shows dowels and locations... sometimes they can fall out. Passages can get plugged by RTV as well if the previous owner ever used it.