Carb jetts and bad dyno
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Carb jetts and bad dyno
Ok I got my motors back from the dyno shop 97 squared in the carbs . But wouldnt idle.So the question is if I lower the primary to maintain idle and increase the secondary side I shouldnt have a lean condition .At 87 squared it idles like a champ. Also can I pull power off the starter selenoid in front of the motor for my electric fuel pump ?
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Re: Carb jetts and bad dyno
The pump should be powered from the battery through the appropriate fuse or breaker along with a relay and oil pressure switch.
#3
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Re: Carb jetts and bad dyno
if the motor was jetted on the dyno, then leave the mains alone. They should be good (or at least close, since your boat exhaust will change it a touch from the dyno headers).
If you cannot get a good idle by playing with the mix screws, then check and make sure your power valve is "low" enough. They may be staying open.
If you cannot get a good idle by playing with the mix screws, then check and make sure your power valve is "low" enough. They may be staying open.
#4
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Re: Carb jetts and bad dyno
Originally Posted by mcollinstn
if the motor was jetted on the dyno, then leave the mains alone. They should be good (or at least close, since your boat exhaust will change it a touch from the dyno headers).
If you cannot get a good idle by playing with the mix screws, then check and make sure your power valve is "low" enough. They may be staying open.
If you cannot get a good idle by playing with the mix screws, then check and make sure your power valve is "low" enough. They may be staying open.
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Re: Carb jetts and bad dyno
I know ive been harping on these carbs for a while , A couple locals have the same and or bigger set ups and run 10 jetts smaller. 97 squared seems so exteme for a 540 and a dominator . The stock jetts are 87 squared and thats what they run. And they run over 600 cubic inch motors. Although what you say makes sense. Sounds like I might try a 4.5 power valve. The boat ran fine from 1200 rpms on but the idle screws were only one turn out. I will check the floats again . I checked idle screws last night.
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Re: Carb jetts and bad dyno
Check ignition timing. Modified engines with larger than stock cams need more initial timing. If you have a MSD set up, you limit the total advance with a bushing so you can use more initial. If you have Merc ignition, use the V6 module. It provides less total timing so you can use more initial.
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Re: Carb jetts and bad dyno
I have the v6 module . The boat ran great but in gear at idle its crap and in neutral it was crap. It only idled at abt 1200. But with 87 jetts it idled great but that was a 10 jett size change.