Complete & Utter Newbie Looks for Direction

[6PAK72]

You're right - rear wheels.

Best I can guess, we're at 2000lbs even. Book spec was 2350, and we've pulled a lot of weight off even keeping the stock frame and body panels and full interior.

Any Stromberg guys out there? We had a really interesting dyno chart - the air/fuel ratio leans out to about 10.5:1 right in the middle of the torque curve - 3400rpm to 4000rpm - then comes back up to 12.8 from 4000 to 4800, then goes rich about 14:1 from 4800 to 5800.

It's running B2E needles and Grose jets, and the dyno guy was really good, got us up about 8hp, but could not get the lean spot out. He suggested we have a jetting problem.

Ideas?

[breakaway500]

Umm.. 10.5-1 is rich. 12.8 is nice and 14 is heading lean. I would look at the plugs and get a reading off them. A bit old school,but it has always worked for me. If those old Strombergs are oil filled,you may want to run thinner oil.It lets the slides lift sooner. Those numbers aren't scary anyways,although the 4800-5800 is a bit on the lean side...I would like to see some exhaust temps as well.An advance curve would be nice too. I used to set up a LOT of carbs. I do miss them..a little but I LOVE fuel injection!

[chaos4NH]

Umm.. 10.5-1 is rich. 12.8 is nice and 14 is heading lean. I would look at the plugs and get a reading off them. A bit old school,but it has always worked for me. If those old Strombergs are oil filled,you may want to run thinner oil.It lets the slides lift sooner. Those numbers aren't scary anyways,although the 4800-5800 is a bit on the lean side...I would like to see some exhaust temps as well.An advance curve would be nice too. I used to set up a LOT of carbs. I do miss them..a little but I LOVE fuel injection!

Thanks for the reality check Mark! I read those numbers the same as you, but thought something had errr, perhaps changed in the last couple of years.

[6PAK72]

I guess I reversed them - still getting used to the ratio - fuel to air/air to fuel.

I know the numbers are correct, as I have the plot in front of me. At least the cam quits precisely where Dick Good said it would, and there's no bumps/dips in the curve.

I've got Marvel Mystery Oil in the carbs - I was using Moss's oil and they back-ordered.

Someone also suggested 20-weight, or sewing-machine oil.

Guess I'll work through these this season.

[6PAK72]

Exhaust temps before balancing:

Front manifold: 530f

Rear manifold: 488f

Exhaust temps after balancing:

Front manifold: 515f

Rear manifold: 515f

Temps checked at idle, about 3" from head, 5 readings each averaged.

[breakaway500]

Temps look good. I have used ATF in the carbs with success,which is about a 5wt oil. Marvel Mystery oil is quite thin,if I remember correctly.Hmm...time for sleep...

[DanB]

If you're rich in the middle (10.5 is a bit rich) and lean up top (14:1 is a bit lean), then you want slightly smaller main fuel jets and more significantly smaller air corrector jets.

Maybe one size smaller on the main fuel jets and three sizes smaller on the air correctors.

edit:
ER, waitaminute I thought you had Webers...

Strombergs? I dunno...

Nemmine...