Build engine
06-29-2022, 11:50 PM
#21
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.8 bar of vacuum = 24" of mercury.
That's a LOT of vacuum. I would think 18-20" of mercury would be all you'd see at a 750-800rpm idle.
10 psi of fuel pressure? What is the box pressure? Usually, you'll have a little positive pressure in the carb box even at idle. If you are running "box pressure" to your fuel pressure regulator (you should be), then you want to see about 7 psi PLUS box pressure. If you have 4 psi of box pressure then you want to see 11 psi of fuel line pressure. If you have 10 psi in the box (at higher speeds of course) then you want to see 17 psi of fuel line pressure. By the way, you can't run a fuel pump that doesn't have a built in regulator (unless it has a boost reference port).
You mention a problem with higher rpm problems. What is your fuel pressure at max speed, and what if your boost pressure at that speed.
That's a LOT of vacuum. I would think 18-20" of mercury would be all you'd see at a 750-800rpm idle.
10 psi of fuel pressure? What is the box pressure? Usually, you'll have a little positive pressure in the carb box even at idle. If you are running "box pressure" to your fuel pressure regulator (you should be), then you want to see about 7 psi PLUS box pressure. If you have 4 psi of box pressure then you want to see 11 psi of fuel line pressure. If you have 10 psi in the box (at higher speeds of course) then you want to see 17 psi of fuel line pressure. By the way, you can't run a fuel pump that doesn't have a built in regulator (unless it has a boost reference port).
You mention a problem with higher rpm problems. What is your fuel pressure at max speed, and what if your boost pressure at that speed.
06-30-2022, 06:06 AM
#22
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I have to convert bar to inHg (vacuum) and Psi (boost) In meantime, is your boost gauge plumbed to intake manifold ? Ie: under throttle blades of carb ? Fuel pump reference line to the carb box ?
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Wally (06-30-2022)
06-30-2022, 06:44 AM
#23
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good morningSB...regarding the convertiom 0.6 bar vacum is around 17 in.hg..my boost guage is conected to the manifold...not under the trotle blades i conected it direct on the manifold.and yes fuel pump to the box...
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SB (06-30-2022)
06-30-2022, 06:47 AM
#24
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17”hg at idle indicates good chance your engine has a stock camshaft. Ie: very mild.
And just checked, .4 bar = 5.8psi boost. That’s fine as many kits are set up for 6psi. I wouldn’t change pulleys for more boost until you get it tuned correctly. How are your a/f ratios ? Plugs ?
And just checked, .4 bar = 5.8psi boost. That’s fine as many kits are set up for 6psi. I wouldn’t change pulleys for more boost until you get it tuned correctly. How are your a/f ratios ? Plugs ?
Last edited by SB; 06-30-2022 at 06:52 AM.
06-30-2022, 07:05 AM
#25
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17”hg at idle indicates good chance your engine has a stock camshaft. Ie: very mild.
And just checked, .4 bar = 5.8psi boost. That’s fine as many kits are set up for 6psi. I wouldn’t change pulleys for more boost until you get it tuned correctly. How are your a/f ratios ? Plugs ?
And just checked, .4 bar = 5.8psi boost. That’s fine as many kits are set up for 6psi. I wouldn’t change pulleys for more boost until you get it tuned correctly. How are your a/f ratios ? Plugs ?
06-30-2022, 07:09 AM
#26
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my a/f guage did not com i don't know why..i'll take foto of spark plugs tomorow and send to you...europa is under a heat wave it is 38 celsius in the shade(very hot on the sun..burns skin) so in the morning im doing compresion test and preaload like you told me(E.O.I.C)...then i'll get back to you...
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SB (06-30-2022)
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