Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties VL valves in UL?

VL valves in UL?

Post Sun Nov 19, 2006 9:26 pm

Posts: 74
Location: Wichita, KS
I have a set of VL (#165 - 30) valves in hand. I am building a ground up UL motor. I do not have a set of UL valves to measure or mic. Anyone know actuall demensional differences ( I assume overall length) as to why I cannot use VLs. New motor will be running lightened valve train so stems will be turned. Thanks. Would also ask if anyone knows where to get stronger valve springs.

Post Mon Nov 20, 2006 11:21 am

Too short.

Post Mon Nov 20, 2006 7:58 pm
don User avatar

Posts: 575
Location: Spokane WA USA
I get about .315" longer on UL vs VL Stock H-D valves.
Have You read this? ... ock+valves

Post Mon Nov 20, 2006 11:36 pm

Posts: 630
Location: belgium
Iff you use the longer K tappet adjusting screw, they do the job just fine.
Have a U that has done already 15000m like this , no problems!

Post Mon Nov 27, 2006 3:40 pm

Posts: 74
Location: Wichita, KS
Thanks Panic, you were right on. Just picked up a pair of UL's and set them beside the VL's.

Post Mon Nov 27, 2006 6:23 pm

Happy now?
Last edited by panic on Wed Dec 06, 2006 3:22 pm, edited 1 time in total.

Post Tue Nov 28, 2006 8:58 am

Posts: 74
Location: Wichita, KS
Reducing stem diameter and tapering the guides (reducing transfer area) are suggestons in the 80 Power book, why would you now offer that they are not good ideas because of heat transfer. You also raise the next question I have which is Can the exhaust port be welded and downsized? I understand that optimum flow needs an exhaust valve 75% of the intake size. Victory's info says you can o/s the intake but do not o/s the exhaust, they're already to big.

Post Wed Dec 06, 2006 12:13 pm
The VL valves are about 1/4" shorter than the UL ones and you should be able to take that up with the adjusters. I've made VL/UL valve springs for racing with one less turn of wire which are about 15% stiffer than stock.

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