| Carb Jets [message #63835] |
Wed, 11 November 2009 10:41  |
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Well I got my new box of tuning parts from holley, and was able to pretty much tune out the accelerator pump bog I was gitting right off idle, basically the pump shot wasnt enough to get the job done so holley supplies a set of cams to change the duration and volume of the pump shot. one screw and about 3 minutes is all it takes.
then I decided to see if I could lean out my jetting to improve cruise milage, so I purchased 2 sets of jets, the stock size was 65, so I thought it would be a good idea to drop it 5 to 10 numbers, so I ordered a 60 and 55 jet. one thing about the holley, the jets can also be changed in about 5 minutes, but you will usually spill a couple ounces of fuel removing the fuel bowl, paper towels are a must here!
so I put in the 55s first, put it back together and start'er up, motor runs fine until I take it for a test drive, way too lean and no power! unvelievable how much difference a couple thousands of an inch make! so im like F this and put in 60s, it ran better but still no cigar, but at least it didnt stall, problem was now to get power I had to press the accelerator pedal to the floor to get the PV to open then we were off. so im thinking the leanest I should go should be a 63 jet, which is 2 down from stock. it seems the holley came pretty close outta the box, for best power, so it seems my lack of carb experience (im a fuel injection guy) has tought me that in carbs, less is actually still less!
I know most here are actually Q-jet types but I assume some have had exp with the holley units, the carb runs great stock, just looking for that extra 1-2 mpg outta her. so any advice as o jet size? although granted I am running watered down CA fuel which is notorious for giving you 10-15% less mileage but costs more, so maybe im already at the sweet spot for the fuel....
73 Canyon Lands, (a.k.a. The Yellow Submarine) West Los Angeles CA
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| Re: Carb Jets [message #63963 is a reply to message #63955] |
Wed, 11 November 2009 23:22  |
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yeah the best such system is an innovate motorsports wide band O2 sensor and controller, I use one in my 88 turbo mustang. I plan to eventually build an EFI setup for my coach. EFI tuning is so much easier, just flip open the laptom, plug in the serial cable and bring up my tuning software, and now with EEC emulators actual tuning on the fly with motor running is possible! carbs may be "simple" but not having to open the fuel system to tune it is sooo nice...
| rgleas wrote on Wed, 11 November 2009 22:01 |
The best way I have found for tuning for milage is with an oxygen sensor. Sevetral of the hot rod companies make a setup that mounts on the dask with a series of lights to indicate what the fuel mixture is. This is good to have since there are several different adjustments you have to make idle, power valve, and main jet size. Holley usually sends these carbs out from the factory on the rich side. When I was hot rodding I ran different jets in all four to make up for distribtion variations in the intake. Since our rpms with thes engines are not as high they should not be that much of a problem. There is a book available on holley carburators that is very helpful.
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73 Canyon Lands, (a.k.a. The Yellow Submarine) West Los Angeles CA
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