Folks, I have a “new to me” 30 Model A Hot Rod. Unfortunately the previous owner did not have a build sheet on the car, so I have to be kinda detective. It has a Flathead, Navarro Heads with a 4-71 blower and 2 Holly 94 carbs with non-progressive linkage. I have to rebuild the carbs due to gaskets leaking. Carbs are not disassembled yet. I’m just wondering what jet sizes to run and should keep a power valve in them. Thanks for any assistance and/or suggestions.
I wouldn't be changing PV or jetting until you've driven it when it gets warm out. Keep in mind that 'leakage' may not be a gasket thing, when you shut the engine off the last few dribbles that come out of the boosters fall on closed throttle blades and some raw fuel will follow the shafts out the carb and look like leakage. Over time it'll look like crap but its a fairly normal thing depending on how loose the bores for the throttle shafts are. That looks like a great little setup.
Maybe look into a temporary wide band sensor to check existing A/F ratio, look at plugs before major jet changes. I can't remember if the 94s need to be (or can) set up for boost. If you need more cfm, check out the Stromberg BIG 97s, and don't have to worry about power valves blowing out.
I like your blown flathead, know your going to enjoy it. We have a turbocharged flathead, and after a lot of trial and error ended up with no. 57 jets, and 5 in.Hg. powervalves, and 1 3/8 float setting . Be sure to run a fuel pressure regulator set at 3 lbs. We run two 94 carbs with a stock choke in the rear carb only. Have fun with your new project!
Damn.... That's a $weet set-up! Whoever put that together, I assure You, Knew how to jet it. Got any pics of the car..?
Agree with oj and big deuce. Most likely the previous owner has it at the least close. Drive it/run it before making any drastic changes. Sensor is a good thought. Cool looking setup! Good luck with it.
If it was a running motor I would not change the jets or the power valve (if it even has power valves). Remember this simple truth, a wheel only works if it is round. No reason to reinvent it. Cool project BTW. I am not Mr Flathead but blown flatties are cool, I don't care what anyone says.
Your model a is one of the best looking A’s I have ever seen. Nice big fat Ascot looking tires on a widened set of spokes. Flatmotor with a blower makes it look “all business”—— pretty decent look for the headers——all adding up to a very cool A model. Flatheads Forever!!!
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