Holly 94 jet recommendation for a flathead running open exhaust?

[G.M.]

Drive it NORMALY and see what kind of gas mileage you get. G.M.

[F1 Flathead]

Originally Posted by flatjack9

I would read that as being just fine. It is much harder to get a good read with todays fuel. How did it run at WOT? 51's should be just right for your area.

flatjack,
It sputters and missfires but inconsistently. Sometimes it pulls pretty steady and hard but other times it missfires badly and won't accelerate past 3000 rpm or so. I will still go ahead and experiment with richer jets. I don't see any reason not too.

[F1 Flathead]

Here's an update on my issue. I bought a set of Holly #53 jets and put them in just in time to drive to the "Sins of Steel" car show yesterday. I noticed no or only slight improvement in performance with the bigger jets. Interestingly, the spark plugs look a little better now, though. They now have a more even "milk chocolate" color. Bottom line is that I still have an issue. I played with the timing on the way home, first advancing and then retarding it. Either direction made it run worse, not better. Next step will be to install new points since I also sprung a hole in my radiator and have to pull it anyway. I also want to try removing my "Helmet style" air cleaner to see what difference that makes. I read somewhere that some of those have very restrictive filter elements. That will be a simple thing to check out.
Dan

[F1 Flathead]

Played with the car last night some. Removing the aircleaner made no difference. New points made no difference. Regapped plugs to .025 (they were more like .030), made no difference. Am going to have to continue swapping parts like rotor and dist caps and such. I hate to spend money and buy aftermarket crap. I really like to keep my old, original Ford stuff but am running out of options. If that doesn't work, I will have to pull the dist. and send it in but I hate to have the car down now. I'm having a blast driving it even though it doesn't run perfectly.

[F1 Flathead]

Tried a different totally different distributor tonight. No difference. Tried one of my spare, known good carbs and it also made little or no difference. Next step is a new new remote coil conversion kit from speedway. I should have that Wednesday. After that, I guess I'll try distributor caps but I'm really starting to think it's sticky valves and/or weak valve springs. I need to try the Marvel Mystery oil trick that one of you suggested. If none of that works, it will be time to do a valve job.
Dan

[DICK SPADARO]

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I have been following your saga but before you go do a lot of work preparing for a valve job, do a leak down test to see if they are really the culprit. The suggestion of a little marvel mystery oil for a top lube isn't bad idea either, in fact its a good idea to run a top lube in any flathead. Since you changed the fuel mixture and this slightly improved the performance you still need to check the condition of the cap contacts and rotor especially if they are old units. A carbon track on the cap contact or some dirt floating around in the distributor will create a random skip too. While you are at it give the plug wires a look over for electrical leaks in the wire loom.

[F1 Flathead]

Originally Posted by DICK SPADARO

I have been following your saga but before you go do a lot of work preparing for a valve job, do a leak down test to see if they are really the culprit. The suggestion of a little marvel mystery oil for a top lube isn't bad idea either, in fact its a good idea to run a top lube in any flathead. Since you changed the fuel mixture and this slightly improved the performance you still need to check the condition of the cap contacts and rotor especially if they are old units. A carbon track on the cap contact or some dirt floating around in the distributor will create a random skip too. While you are at it give the plug wires a look over for electrical leaks in the wire loom.

Dick,
The engine idles very smoothly and has very good compression. If the valves are hanging up, it can only be at high RPM. The plug wires are new but the distributor caps are original Ford stuff so they are definitely suspects. I have taken them off, washed them and inspected them closely but I may be missing a crack or a carbon track. Thanks for the tips.
Dan

[F1 Flathead]

Decided this weekend to tear the heads off and check out the valves and springs. I cranked it over with the intake off and I could definitely see it blowing back through the intake ports on 2 of the cylinders so I at least have two valves not closing tightly. I will tear it all down, clean it up, reface the valves and seats if required, check the valves springs and replace if weak, put it all back together and report.
Dan