Ok guys, here we go again. I went and bought new cylinders from CycleFab, with fitted pistons and valves. I had my head surfaces checked on a friends CNC Mill, they were warped, it took .020" to get them flat. Put her together and it felt like no compression when I kicked her. I put a quality compression gauge and 22 PSI. I squirted a little Corrosion X in and 26 PSI.Double checked the valve clearances and perfect. Now, with milled heads and new cylinders with fitted pistons, my PSI should be up there a little more. Only answer would be a HUGE ring gap, or possibly the cylinder decks didn't get machined enough? She's on the lift begging to get tore down, but I may be missing the obvious????
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Steve -
Oh, annealed copper head gaskets.Steve -
Throttle wide open for the test?Robbie Knight Amca #2736Comment
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Yes, wide openSteveComment
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Clutch not slipping?Robbie Knight Amca #2736Comment
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Any chance the cam timing is off?
TomComment
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Rings on upside down? Valves seating properly?Last edited by HDSmitty; 03-12-2020, 10:58 AM.Comment
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I'm checking all of that today, ThanksSteveComment
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So I just heard that some of Cyclefabs ULH guides aren't concentric with the seats. Really? Holy Sh*t! I heard this guy was great. Ok, leak down test this weekend! Everything else checks out. Lifter clearances, clutch fully engaged. I took my OEM cylinders off after starting her because it was .060" over and the valve seats were so deep that I had to make special 7/16" wrenches to fit down in the lifter blocks to adjust them.SteveComment
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I would be careful here as Paul uses Kibbelwhite valves and guides for those. May not be a problem from him but them. He has them made up specifically for him and to his specs. so would think that if there is a problem it would be with all of them. I know several folks who have his cylinders and that was never a problem for them. Might have had other small issue but not that. I have had him do several motors for me over the years and while I can't recommend him right now due to delays in getting work out I would say he has spent more time and money figuring out HD flat head than anyone I know. I am sure if you find he is at fault he will make it right. Good luck!
Tom (Rollo) Hardy
AMCA #12766Comment
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Not to defend anybody, Folks,...
But you can cut a seat 'true' to a 'concentric' guide,
Mark it for indexing, press it out,
Press it back in indexed,...
And it still won't be perfectly concentric to the seat.
....Cotten
PS: Place any guide in question upon a mandrel (such as NEWAY seat cutting pilots), and put it between v-blocks for inspection with a decent indicator.Last edited by T. Cotten; 03-13-2020, 09:57 AM.AMCA #776
Dumpster Diver's Motto: Seek,... and Ye Shall Find!Comment
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Thanks Tom, but wouldn't seat to guide concentricity be due to cutting the seats, which falls into CycleFabs lap, not Kibblewhite? Just a question.Originally posted by Rollo View PostSteveComment
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I am not a machinist so I can't answer your question but maybe Cotton's response sheds some light on it. I know a number for folks that have those set ups from Paul and didn't seem to have those issues and are running them fine. I would think that you would cut the seats first then drive in the guides but again I am not an expert machinist so.... Good luck figuring it out.
Tom (Rollo) Hardy
AMCA 12766Comment
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I think its the other way 'round, Tom!Originally posted by Rollo View Post
The guide is pressed-in first, so the seat can be cut concentric to however it goes in.
(That's one reason why so many veterans are sunk so deep: Too many guides have been arbitrarily replaced.
And an over-sized guide is rarely-if-ever going to follow the bore perfectly, because the bore aint' perfect if it needs it.)
....CottenLast edited by T. Cotten; 03-13-2020, 11:43 AM.AMCA #776
Dumpster Diver's Motto: Seek,... and Ye Shall Find!Comment
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