converting my 350 cid merc. 320 efi's to carbs. what jet sizes?
08-18-2016, 06:42 PM
#12
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When I had pro system build me a custom carb, I took it out of the box and said "this isn't a marine carb". Patrick looked at me and said, "it will run better as it is, here are some j tubes, but I would recommend running it as it is". So that is what I did. My current carbs are not marine specific and I have no intention to ever buy a marine specific carb. With that said, I wouldn't worry about the fact that it's not marine.
Last edited by endeavour32; 08-19-2016 at 07:17 AM.
08-18-2016, 11:51 PM
#14
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Couldn't find a throttle position sensor and after reading some stories of motors that suddenly leaned out and melted I figured it was time. Jets that came in the carb were 68 front and 74 back. I bumped them up to 71 and 76. We'll see what happens.
08-19-2016, 07:21 AM
#15
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I'm sure you could get some good money for your EFI even if it;s got a bad sensor. That was a really high tech set up back in the day. IMO it took them almost 20 years to put something that good on the BBC.
I'm not commenting on your carb jetting. SB is your man for carbs, and he really knows small blocks.
I'm not commenting on your carb jetting. SB is your man for carbs, and he really knows small blocks.
08-19-2016, 07:37 AM
#16
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When I had pro system build me a custom carb, I took it out of the box and said "this isn't a marine carb". Patrick looked at me and said, "it will run better as it is, here are some j tubes, but I would recommend running it as it is". So that is what I did. My current carbs are not marine specific and I have no intention to ever buy a marine specific carb. With that said, I wouldn't worry about the fact that it's not marine.
http://www.jegs.com/i/Quick-Fuel/793/M-650/10002/-1
08-30-2016, 07:26 PM
#19
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[QUOTE=28cigarettess;4476627]Anybody know what jets they are running in their small blocks to give me a Baseline?[/QUOTE
You could up both front and rear a couple jet sizes however I would imagine you'll be back to near out of the box or under a size or two. Just do some simple plug reading and you'll be fine.
You could up both front and rear a couple jet sizes however I would imagine you'll be back to near out of the box or under a size or two. Just do some simple plug reading and you'll be fine.
08-30-2016, 08:04 PM
#20
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All different carbs are different.
Ever notice that most 600 +'s have jet sizes in the 60's
many 700+'s have jet sizes in the 70's
many 800+'s have jet sizes in the 80's.
Anyway, one 600 is not another, one 750 is not another...amongst all the different builders, manufacturers, and even same manufacturers. Different boosters, different sizing throttle blade vs bore vs venturi, different metering block passage sies, different air bleed sies and etc...........
That said,
The QFT I showed has 71, 78 jets stock. Primary 6.5"PV
A 650 vac BG Sea Demon I just cleaned out today has 74/84 in them . Primary 6.5 PV . I tuned it many years ago on pretty decent 350.
Ever notice that most 600 +'s have jet sizes in the 60's
many 700+'s have jet sizes in the 70's
many 800+'s have jet sizes in the 80's.
Anyway, one 600 is not another, one 750 is not another...amongst all the different builders, manufacturers, and even same manufacturers. Different boosters, different sizing throttle blade vs bore vs venturi, different metering block passage sies, different air bleed sies and etc...........
That said,
The QFT I showed has 71, 78 jets stock. Primary 6.5"PV
A 650 vac BG Sea Demon I just cleaned out today has 74/84 in them . Primary 6.5 PV . I tuned it many years ago on pretty decent 350.
