Valve float issues on dyno

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lekid
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Re: Valve float issues on dyno

Post by lekid »

Not same fuel on other engine. Quench is 0.080" and 13.0 static compression. Engine wanted 35deg.

Did not miss or breakup until 7100rpm
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Re: Valve float issues on dyno

Post by user-17438 »

So did you check the plugs? Rich up top lean up top? Is it a nitrous carb?
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Re: Valve float issues on dyno

Post by lekid »

We checked the plugs, they looked a little lean but still had some fuel on them
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Re: Valve float issues on dyno

Post by zums »

Ive run that exact seat and open pressure on a 2.08 to 9700 but without knowing weigh its irrelevant, if your checking springs on the engine you need to know what percentage different your hand checker reads verse the bench checker, while you are doing that i would at least take 1 intake spring off and look real good at the locks, retainer, valve stem and spring
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Re: Valve float issues on dyno

Post by CamKing »

If it's a std cam journal size, the base circle has to be below .900". If so, ht's flexing all over the place with those spring pressures.
The other thing I would look at, is if the pushrods are flexing. what diameter and wall thickness are you running?
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Re: Valve float issues on dyno

Post by lekid »

Had a good discussion with Chris Uratchko and he could not agree that it was valve float. He believes that it is the crank trigger sensor causing that issue.

I checked the resistance and Inget 7 ohms. MSD says that it should be between 65-85 ohms. Could that be the problem? That simple?
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Re: Valve float issues on dyno

Post by JoePorting »

IMO, the new cam is too big. I'd go back to the old cam, or maybe consider a cam even smaller like around .650/250.
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Re: Valve float issues on dyno

Post by fdicrasto »

I would not trust ANY spring checker until, as previously suggested, it was calibrated to a good bench spring tester. Could you have a broken inner spring? Those valve springs should be adequate for your set up if installed to spec. Also as MT mentioned, need to post the dyno sheet to look over other parameters for a clue as to what could be the issue.
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Re: Valve float issues on dyno

Post by af2 »

JoePorting wrote: Thu Mar 15, 2018 6:38 pm IMO, the new cam is too big. I'd go back to the old cam, or maybe consider a cam even smaller like around .650/250.
Why the drop in lift? Am I missing something?
A set of springs is all that is needed....
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Re: Valve float issues on dyno

Post by af2 »

[quote=lekid post_id=724654 time=1521152032 user_id=12696

I checked the resistance and Inget 7 ohms. MSD says that it should be between 65-85 ohms. Could that be the problem? That simple?
[/quote]

I doubt it but the easiest part change......
GURU is only a name.
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Re: Valve float issues on dyno

Post by JoePorting »

af2 wrote: Thu Mar 15, 2018 7:57 pm
JoePorting wrote: Thu Mar 15, 2018 6:38 pm IMO, the new cam is too big. I'd go back to the old cam, or maybe consider a cam even smaller like around .650/250.
Why the drop in lift? Am I missing something?
A set of springs is all that is needed....
I think a more stable valve train is more important than a few more hp. I'm guessing a smaller cam would actually make more power, or at worse, about the same. Also, a 2.10 valve doesn't flow much more past .600" lift.
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Re: Valve float issues on dyno

Post by user-17438 »

JoePorting wrote: Thu Mar 15, 2018 10:13 pm
af2 wrote: Thu Mar 15, 2018 7:57 pm
JoePorting wrote: Thu Mar 15, 2018 6:38 pm IMO, the new cam is too big. I'd go back to the old cam, or maybe consider a cam even smaller like around .650/250.
Why the drop in lift? Am I missing something?
A set of springs is all that is needed....

I think a more stable valve train is more important than a few more hp. I'm guessing a smaller cam would actually make more power, or at worse, about the same. Also, a 2.10 valve doesn't flow much more past .600" lift.
Are you serious dude?
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Re: Valve float issues on dyno

Post by user-30257 »

CamKing wrote: Thu Mar 15, 2018 2:42 pm If it's a std cam journal size, the base circle has to be below .900". If so, ht's flexing all over the place with those spring pressures.
The other thing I would look at, is if the pushrods are flexing. what diameter and wall thickness are you running?
Or maybe the pushrods are binding somewhere. Have you consulted with the engine builder? Or cyliner head guy?
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Re: Valve float issues on dyno

Post by user-17438 »

lekid wrote: Thu Mar 15, 2018 1:53 pm We checked the plugs, they looked a little lean but still had some fuel on them
Did you add jet? Did you pull timing?
What all did you guys do at the dyno facility?
Could you post everything you tested and tried? So you could help us help you.
Did the dyno operator test it at 300rpm/sec vs 600rpm/sec. If so did it rpm more at the higher test rate?

There are so many things that could make a graph look like that. Yet all the data you should have to verify anything is missing.
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Re: Valve float issues on dyno

Post by Warp Speed »

MTENGINES wrote: Thu Mar 15, 2018 10:21 pm
JoePorting wrote: Thu Mar 15, 2018 10:13 pm
af2 wrote: Thu Mar 15, 2018 7:57 pm

Why the drop in lift? Am I missing something?
A set of springs is all that is needed....

I think a more stable valve train is more important than a few more hp. I'm guessing a smaller cam would actually make more power, or at worse, about the same. Also, a 2.10 valve doesn't flow much more past .600" lift.
Are you serious dude?
I believe he is! Lol
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