Rough running after engine upgrades.
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,076
Likes: 1,008
compression test may/may not give correct info, tom terrific hat needed. the vacuum gauge will give a heck of a lot more info for sure and it will dynamic under actual operating conditions. leak down is of no value i see here.
http://www.autospeed.com/cms/article...nostics&A=2393
hummm not so fast, the leak down could tell if excessive blow-by is an issue, but then again, would be other tells!
http://www.autospeed.com/cms/article...nostics&A=2393
hummm not so fast, the leak down could tell if excessive blow-by is an issue, but then again, would be other tells!
Last edited by bustert; Apr 30, 2018 at 02:38 PM.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,962
Likes: 8,056
From: poway
compression test may/may not give correct info, tom terrific hat needed. the vacuum gauge will give a heck of a lot more info for sure and it will dynamic under actual operating conditions. leak down is of no value i see here.
http://www.autospeed.com/cms/article...nostics&A=2393
hummm not so fast, the leak down could tell if excessive blow-by is an issue, but then again, would be other tells!
http://www.autospeed.com/cms/article...nostics&A=2393
hummm not so fast, the leak down could tell if excessive blow-by is an issue, but then again, would be other tells!
Do you have typical values for an HD? Since manifold pressure fluctuates drastically on a HD, what do you recommend for a damping orifice?
Grand HDF Member
Joined: May 2014
Posts: 3,860
Likes: 1,185
From: florida
I would try 40 or 42......i have used these in my carb synch tools before,,,sometimes it works, the other thing i have done is to use a small adjustable line clamp to pinch the hose uhtill the guage stabilizes.
M
M
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,076
Likes: 1,008
snubbing the gauge can be helpful but too much will be counter productive, it is not necessarily the numbers but reaction.
run your test at 1k intervals say up to 4k, of course, you will need to cool the engine with a good fan.
run the test while engine is fairly cool and repeat as temps climb, recording them, cell video works well.
for grins and giggles, all of a sudden you lose valve control via a aerated oil in lifter, it has a pattern similar to say a burned valve.
now say, you get excessive c/c pressure (reason i changed my mind on the leak down) when hot, what happens, well the rings are responsible for seal right? but the rings to do well need diff'l pressure to work better. where you have cyl pressure is combustion and exhaust (unless open port/header) and there will be diff'l but on the intake, no so much so what can happen, the blowby is no longer blowby but becomes a potential of intake charge contaminator.
it did not dawn on me till i posted the video and that you have a built in vacuum gauge, so plot the MAP readings.
Between S&S Premium performance lifters and Wood Performance Alpha Directional Roller lifters .....
What would you choose ?
What would you choose ?
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Road Captain
Joined: May 2014
Posts: 648
Likes: 35
From: San Diego
No need for S&S Premiums on your bike. That being said, Ive used both Woods and S&S High performance lifters and both work just fine. S&S lifters were the more affordable.
Outstanding HDF Member
Joined: Feb 2015
Posts: 2,414
Likes: 433
From: Arkansas
Just out of curiosity, when you are making your PR presets are you going to base circle on each cylinder and then allowing the full lockdown BEFORE the adjustment or are you just adjusting and praying that it is well?