The reason I went with the 31 is because of my rear axle ratio, which is a 3.00. From what I've read, you want a slightly smaller one if you have long gears.
As for the cam, it's the one that came in it and is kind of a neon orange. So this symptom is saying it's not getting enough fuel at the start of acceleration still?
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4bbl Holley 390 w/ Offenhauser DP intake. 4 speed Manual w/OD. K&N air filter, EFI manifolds, 2.5" exhaust.
3.00 rear end and 2000 RPMs @ 80mph!
The symptom indicates not enough squirt up front. The orange cam is long in duration but not particularly aggressive like a blue or green cam. Sounds like you need more shot up front which a blue or green cam would provide. Or, go up to a 35 or 37 squirter. That will give you more fuel over the duration but not necessarily what you need up front. Since you have an extra squirter you might try drilling out the squirt holes in small increments rather than buying another pair or two of squirters. Keep in mind that while you can drill larger holes, it would be with the utmost difficulty to drill smaller holes
Best adjust the pump override screw if you change cams. Technically, this should be done too when the idle speed screw is adjusted.
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1983 F150 300 I6, Comp Cam 260h and lifter kit, Port/Polished head, Offy DP Manifold, Holley 4160/1848-1 465 cfm, EFI Exhaust manifolds, Walker Y Pipe to 3-Way Cat, generic Turbo Muffler, Recurved DSII, Mallory HyFire 6a & ACCEL Super Stock Coil, Taylor Spiro Pro Wires, EFI plugs.
Thanks for the guidelines to follow. Fortunately, the speed shop has the entire array of pump cams in a kit for $9. I'll check out the green and blue ones to see if I can get a little more off-idle squirt. After that, I'll look into drilling the jets. Couldn't agree more, figuring out how to drill smaller would prove challenging.
Which is the pump override screw? I don't remember hearing about that in the Holley literature. Is that the #1/#2 position setting?
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4bbl Holley 390 w/ Offenhauser DP intake. 4 speed Manual w/OD. K&N air filter, EFI manifolds, 2.5" exhaust.
3.00 rear end and 2000 RPMs @ 80mph!
The pump override screw and spring is what adjusts the lash between the arm riding on the cam and the accelerator pump lever. It has a nut on each end and a spring in between the nuts. Hold one nut and turn the other until the screw is not touching the lever. Adjust it back until it just touches the lever plus only a very little more to pre-load the lever. Look down the primaries, move the throttle open and you should see an immediate shot of fuel from the squirter as you just start to move the throttle open.
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1983 F150 300 I6, Comp Cam 260h and lifter kit, Port/Polished head, Offy DP Manifold, Holley 4160/1848-1 465 cfm, EFI Exhaust manifolds, Walker Y Pipe to 3-Way Cat, generic Turbo Muffler, Recurved DSII, Mallory HyFire 6a & ACCEL Super Stock Coil, Taylor Spiro Pro Wires, EFI plugs.
Gotcha. I know which part you're talking about now. I had been worried to mess with that part since I couldn't find any documentation on Holley's site as to how to adjust it properly.
I have another question in the mean time. I'm not sure if this is carb related, or something else. Maybe timing? I've never heard engine ping before, so I don't know what it sounds like, but as of right now, when the engine is lugging (like in first gear from a stop, or accelerating from low RPMs), there's a medium pitched dieseling clack coming from the engine for a second or two before it picks up. Whatever it is, it doesn't sound healthy. Ideas?
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4bbl Holley 390 w/ Offenhauser DP intake. 4 speed Manual w/OD. K&N air filter, EFI manifolds, 2.5" exhaust.
3.00 rear end and 2000 RPMs @ 80mph!
Yup...ping. Retard the dizzy in small increments, driven try until it stops. If you get only a very little bit under heavy load like when pulling hard up hill it probably won't hurt.
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1983 F150 300 I6, Comp Cam 260h and lifter kit, Port/Polished head, Offy DP Manifold, Holley 4160/1848-1 465 cfm, EFI Exhaust manifolds, Walker Y Pipe to 3-Way Cat, generic Turbo Muffler, Recurved DSII, Mallory HyFire 6a & ACCEL Super Stock Coil, Taylor Spiro Pro Wires, EFI plugs.
IIRC factory settings were between 6-10 depending on the application but since you are in the modified world now adjustments will have to be made according to what the engine "likes".
Could be a bit of a lean condition too. If your carb came with a 6.5 power valve you might have to step up to a 7.5 or 8.5 but I would try the timing first and get the off idle/low speed stumble corrected too before going to a power valve change.
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1983 F150 300 I6, Comp Cam 260h and lifter kit, Port/Polished head, Offy DP Manifold, Holley 4160/1848-1 465 cfm, EFI Exhaust manifolds, Walker Y Pipe to 3-Way Cat, generic Turbo Muffler, Recurved DSII, Mallory HyFire 6a & ACCEL Super Stock Coil, Taylor Spiro Pro Wires, EFI plugs.
I'll try the timing for now since it's free, and then give some different cams and jets (darn things are $25 a try) in a few. I don't believe a powervalve would make a difference since I've been driving around with a vacuum gauge and this can happen when it's around 15Hg - 10Hg or so.
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4bbl Holley 390 w/ Offenhauser DP intake. 4 speed Manual w/OD. K&N air filter, EFI manifolds, 2.5" exhaust.
3.00 rear end and 2000 RPMs @ 80mph!
OK...I thought you were referring to the Jets and not the Shooter. Might try Summit...they would ship out of Sparks, NV and probably get to you fairly fast.
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1983 F150 300 I6, Comp Cam 260h and lifter kit, Port/Polished head, Offy DP Manifold, Holley 4160/1848-1 465 cfm, EFI Exhaust manifolds, Walker Y Pipe to 3-Way Cat, generic Turbo Muffler, Recurved DSII, Mallory HyFire 6a & ACCEL Super Stock Coil, Taylor Spiro Pro Wires, EFI plugs.
Alright, did my first long distance test run. Things did not go so well. I have my own theories as to why, but I'm curious what others have to say. I have a 3.00 rear end, 30" tires, and a 4 speed with OverDrive transmission. At idle, it pulls 19Hg. Here's just a list of the symptoms, figured that was easier:
* PLENTY of power in third gear and way more than I used to. I could accelerate effortlessly uphill, and could have probably pushed 100mph if I wanted to. At 65mph, the vacuum was at about 11 to 15.
* Gutless in overdrive. I couldn't keep it at speed and when I watching the vacuum gauge, I'd be at 1 - 4hg vacuum in the flats. I drove the whole 120 miles in 3rd gear because I couldn't keep it in overdrive.
* Going downhill, I pulled more vacuum in 3rd gear than in overdrive. 3rd gear at 65 was around 2400 RPMs and OD was around 1500.
* I had more power in overdrive with my 1bbl setup at highway speed than with my 4bbl. I have driven this exact stretch of interstate well over 100 - 200 times. I've done it plenty of times at 75 with my old 1bbl and only had to downshift on about 3 hills.
* I averaged around 13 - 14mpg, my 1bbl averaged 19 - 20. These numbers are at 65mph. At 75 with the 1bbl, I averaged around 16 - 17.
The carb is plenty powerful when opened up. Like I said, I had tons of power (way more than I ever did) in third gear and above 2000 RPMs. But at low RPMs, it's dumping gas and not doing anything. I couldn't even cruise in the flats in overdrive without the powervalve being open. Are my main jets too small? The carb just doesn't seem to have much power at all until the secondaries and powervalve are in use, contributing to my poor mileage.
Also, it pings occassionally when accelerating from an idle. It's at 8* advance right now, would being too far advance, even by 1 - 2 degrees cause such performance?
Thanks for the help, I have to do the return trip tomorrow and would like to at least see if I can make it a little better.
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4bbl Holley 390 w/ Offenhauser DP intake. 4 speed Manual w/OD. K&N air filter, EFI manifolds, 2.5" exhaust.
3.00 rear end and 2000 RPMs @ 80mph!
The OD causes the engine to run well out of the torque amplification range of the engine when the rear end ratio is tall. This is not necessarily a problem of carburetion but one of gear ratio...it's just too high...and your vac gauge is showing that. It's not an uncommon problem. Some have found that going to a shorter geared rear end can actually increase performance and mpg. I myself am not a fan of some OD set ups precisely for the reasons you have stated and would not consider an OD it in my truck with 3.08's without going to something like 3.55's. My daily driver (Big Truck) has 3.55's with an OD 13 speed transmission and when the speed drops much below 60 mph I usually split to the direct range to bring the engine speed back up to an efficient operating speed...the "sweet spot".
The next time you make that trip do not use the OD at all and see what difference there may be. That should put the engine speed up in the 2000+ rpm range where it will run a bit "happier".
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1983 F150 300 I6, Comp Cam 260h and lifter kit, Port/Polished head, Offy DP Manifold, Holley 4160/1848-1 465 cfm, EFI Exhaust manifolds, Walker Y Pipe to 3-Way Cat, generic Turbo Muffler, Recurved DSII, Mallory HyFire 6a & ACCEL Super Stock Coil, Taylor Spiro Pro Wires, EFI plugs.
The OD causes the engine to run well out of the torque amplification range of the engine when the rear end ratio is tall. This is not necessarily a problem of carburetion but one of gear ratio...it's just too high...and your vac gauge is showing that. It's not an uncommon problem. Some have found that going to a shorter geared rear end can actually increase performance and mpg. I myself am not a fan of some OD set ups precisely for the reasons you have stated and would not consider an OD it in my truck with 3.08's without going to something like 3.55's. My daily driver (Big Truck) has 3.55's with an OD 13 speed transmission and when the speed drops much below 60 mph I usually split to the direct range to bring the engine speed back up to an efficient operating speed...the "sweet spot".
The next time you make that trip do not use the OD at all and see what difference there may be. That should put the engine speed up in the 2000+ rpm range where it will run a bit "happier".
Hrm... That makes sense about the OD, but I still think it's something more. I did the whole trip in 3rd at 65, and got around 13mpg. The other reason I think something isn't right is because I had more power in OD with the 1bb than the 4bbl. I mean, I obviously have tuning to do, just curious what it may be. Next on the list is a Air/Fuel meter but am curious what people think until then.
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4bbl Holley 390 w/ Offenhauser DP intake. 4 speed Manual w/OD. K&N air filter, EFI manifolds, 2.5" exhaust.
3.00 rear end and 2000 RPMs @ 80mph!
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