Holley/Weber Jetting Update

[BIGREDRASA]

I've just added some additional info to the jetting chart.
http://fordsix.com/forum/viewtopic.php?f=1&t=49901&p=379855#p379855

I haven't driven Charlie much in the past year; but on the times I went on the Interstate, where our Speed limit is 75 MPH, I had trouble going the limit whenever I came to any slight hill (not very steep along the Platte River Road). Even at 65, I couldn't maintain my speed uphill without flooring it. I checked my plugs after a trip, and they looked powdery white, usually a sign of overheating or running lean. Since I'm actually running quite cool after rerouting my heater hoses, suspicion fall on either too much timing or too-lean jetting. It seemed logical that the headers and larger, less restricted exhaust would tend to lean the mixture out. My jetting seemed to be on the lean side, anyway, at : 130 Primary and 140 Secondary.

After referring to the chart, which some members were kind enough to provide me with AFRs. I saw Jamyers has been running 142/160, I swapped out my main jets to 140 and 171. (I had a 171 lying around.) If the weather permits, I'll take alittle road trip tomorrow and check for seat of the pants results. If the OldsTimers' Disease permits, I'll pull the plugs on Sunday.

 

[Ronbo]

Tony, I'm running a DGES 38/38 just breaking 20mpg. If you look at some of my earlier posts you'll see the drama I went through with carbs. Using the rod linkage tends to tear up the throttle shaft bores if you are not careful and subsequently, performance goes down hill. I swapped to a cable set up with the DGES and had a heck of a time setting it up because they are so darned finicky! ANY vacuum leak, and I mean ANY, you will never get it tuned right. My brake booster had blown out and caused a vacuum issue, to get the car to run right I stepped up to 65 idle jets. When I figured it out and replaced the booster I was able to drop back down to 50 idle jets and +4 mpg! I have a brand new Carter sitting on the bench but I kind of like the DGES so I'm going to stay with it for awhile. I'm guessing the 5200s are the same, vacuum dependent. The DGES is running off those idle jets until 2500 rpms. DGEV? Don't know.

Oh yeah, I started with a rebuilt 5200 from Stovebolt. That was the one the bores wore out on and gave me grief. It was ok when it was good but when it failed I couldn't pull 45 mph uphill on a new rebuilt engine. Check for vacuum leaks.

Ron

 

[BIGREDRASA]

I took it out for a short spin yesterday. Held my foot to the floor in 2nd. Saw 4500 RPM and 75 MPH. Thought she was gonna blow. Took a run at hill, and she was gradually accelerating past 75 in 3rd. Had to be careful, as the speed limit was 55, dropping to 45 in 500 yards. Haven't checked the plugs, but I'm going on a 180 mile round trip this PM, on the Interstate. 8) It's low 80s and bright sunshine right now!

I'll tweak the advance curve on the DS II tomorrow or Monday.

 

[aribert]

Thanks for the jetting update. I'm surprised that your (new) larger jets are still a bit on the small side. Is your idle speed adjust screw set to less than 2 turns of engagement of the main bore cam? I put a DGV5A on my Falcon this past winter and I am still dialing it in (currently waiting on some jets to arrive in the mail).

So how will you be tweaking the adv curve - I assume changing springs? How do you know which direction you want to make the changes in or when you want it to advance or drop out? My Weber does not have a vacume port and when I add the DS1 later this year or next winter I suspect that the adv curv will need to be adjusted to suit the vehicle.