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Discussion Starter · #1 · (Edited)
I just pulled the heads off my 73 1200 to get them twin plugged and noticed that there are two different size valve guides in one of the heads (Rear). The odd one out has Rowe 80" AMPCO-45 written on it. It is a little shorter (50.2 mm) and a touch wider (15.3 mm top seal end - 15.8 mm bottom port end) than the other three stock ones (53.58 mm x 14.42). Does anyone know if this is for a later 80 ci shovel or has someone put an evo guide in it?? I'll obviously have to find out exactly what the Ampco ones are out of as all will have to be replaced with the wider guides unless I get the head rewelded and remachined to fit a std guide. The top of the ampco guide sits approx 13 mm off the head in situ as opposed to approx 17.5mm for the std guide. Any help would be appreciated. Gus
 

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the shovel used 3 different valve guides over the years the odd one sounds like it was for 79-80 if the lower headside is the same .562 std as the others where the factory was installing valve seals. in 81 they upsized the the lower part to the same size as the top {seal end} .625
 

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Discussion Starter · #3 ·
The bottom port end is measuring up as .60 top seal end is .625. You said the port end should be the same as the std earlier ones, but they measure up as .567.....
 

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The 80' guides for a Shovel went through alot of experimentation , not all good. The shorter guides were shorter and fatter and loosened in the heads and leaked oil into the guides at ahigher rate than the older sealless guides. They were aluminum heads and I believe yours are iron so they can maybe tolerate the larger diameter. Lakeshore HD did a nice job of welding up my rear exhaust guide hole several years ago. Dagonman does excellent work welding also.
 

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unfortunatly i can't identify the one odd guide without seeing it but it is probobly a kibblewhite or rowe unit could be one of the odd extra oversize for bad guide holes
 

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In my experience with shovels and pans the best route is with cast iron guides and black nitrided valves.
A mix of stuff is an indication of a patch job or two.
S&S sells a .060 oversize repair guide in the later large style.
HD experienced severe valve problems in the late 70s when the reduction of leaded fuel happened, ended up using cast iron guides, seals and Nitan black nitrided valves in 1981. That is still the most durable combo for today.
They even tried evacuators " hoses from the cylinder bases to the tappet guides" in an effort to get the oil out of the rocker boxes. They finaly used a restrictive oraface in the top end oil fitting on the crankcase.
Seem just like yesterday. Damn I am gettin old!
 
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