Never made it to Ocean City the other week. The flathead started running like crap when I pulled the Model A out of the garage to take down to fill it with gas. Good thing I made up that towbar. LOL, it paid for itself already. It was running bad the second I fired it up. I have close to 1000 miles on the engine since I put the hot rod on the road and it has always run like a top. Really took me by surprise. I hadn’t done a thing to it since I drove it last- not even different gas (that was why I took it out in the first place). It sounds very weak at idle and doesn’t have any power. Stumbles when you try to accelerate. If you stall it when you try to accelerate, it won’t restart. Just cranks without firing. If you let it sit about for about 10 minutes, it fires up like nothing was ever wrong. I know it’s not the fuel pump since I gravity feed the engine, and I still have half a tank of gas so that’s not the problem either. I haven’t verified fuel to the carbs, but I just changed the sediment bowl filter and have a filter in the tank, so I doubt the delivery line is clogged. I had noticed some fuel leakage around the rear carb and have had a couple backfires, so I figured I might have blown a power valve. Just got a couple from Charlie Price (machined to fit the 94) and it didn’t make any difference. I’m thinking the next step is to swap out the Harman Collins dual coil distributor or at least make sure the points and spring loaded rotor contact look OK. Ideas?
if you are running more then one carb. one of them is most likely leaking fuel because of float sticking.... that will cuase the problem you are describing.
I bet the gas has gone bad. Does the gas smell like fresh gas or old nasty varnish? How does it run when you squirt carb cleaner into the carb?
Condensors are easy to swap too. I'm running the 50 year old Mallorys that came with my HC dual coil. I had an electrical friend check them befroe I put the setup on a few months ago and they were fine, but maybe they crapped out once I started to use them.
Got some time to work on the flathead today. Took the tops off the carbs and the floats didn't have any leaks and the inlet valves weren't sticking. Smelled the gas and it seemed fine. I checked the fuel filter again and it looked pretty dirty for only having about 5 miles on it. I unhooked the line to one of the carbs and the gas was barely dribbling out. I took the filter out of the sediment bowl and had a noticeably greater flow to the carb. I replaced the filter and figured I'd go for test drive. The car was much better but still seemed like it was hesitating. I pulled it up on the interstate and she cut out. I undid the line to one of the carbs and it wasn't getting any gas. I pulled out the filter and had a nice stream of gas to the carbs. Not sure why the flatty was happy with the gravity feed setup for close to a thousand miles, but I guess I'll just stick in a fuel pump. I have everything set up for the stock model A firewall mounted sediment bowl, so I'm going to use one of the early pumps. Anyone happen to know which fuel pump rod I need with an Edelbrock Super? I'm thinking I need the longer 8 7/8" rod.
Running gravity requires that the gas tank cap have an open hole in it. Did the hole get blocked uP Traderjack
Good thought. I did check that and the hole was clear. Even had about 3/4 tank of gas. I used to be able to run below a quarter tank and never had a problem.
Is there a chance you did what I did when I was building my '36 Sedan? That is, I let the gas tank sit around unsealed and mud daubers made a home there. When I began the shake down runs, it would run fine then suddenly stop. It would not restart right away, but if I let it sit for a while it would crank and go. Fixed this by getting a fuel filter, one of those with the removable cannister with the filter inside. It has taken a couple of years, but when I now check it in the spring, I no longer see any bug parts.
I believe long pushrod...never got around to measuring the different manifold heights that dictate choice, but VERY roughly short manifold is about 1" high from bottom to flange for pump stand, tall one about 2". Once you notice that, you can tell from 20 feet. Someone on Ahooga posted a good cleanout method...run car on a Moon tank or whatever temporarily, hook up an electric pump to stock tank to cycle half a tank of gas and carb cleaner endlessly through a big filter with replaceable element. Put a couple of killer magnets on the bottom of the anti-fire strainer thing under the cap, so you can easily fish out rust as needed.
Definitely have some type of gas delivery situation. As the motor got some miles on it the rings sealed a little better and HP came up a little as did the gas demand. This may explain why it was running fine the first 1000 miles. just my thoughts and then wouldn't hurt to check out the ignition again.
Good thought 36tbird, but the car has been running and the tank was closed and full of gas. Bruce, thanks for the info on the push rod. I did alot of searching and couldn't find an answer. Here is a picture of the back of my block- only looks like about an inch to me- maybe I need the short one? Also appreciate the tip on the magnets and adding carb cleaner to the tank. I spent ALOT of time trying to get all the crap out of the tank- Filled it with vinegar, pressure washed it through the filler and sending unit holes, recirculated the gas in it through a filter for days- STILL getting loads of crap out of it. I finally broke down and stuck one of the 30-31 style valve filters in the tank and added the paper type element in the sediment bowl. I've had to change the filter every hundred miles or I don't have enough head to feed the carbs, but it's working. The carbs were spotless when I had the tops off. I'm giving up on the gravity feed and sticking in a fuel pump. I'll update the thread once I get it in.
I think short... 2 things: HC is notorious for cracks in the special plastic bits--carry a normal crab with wires! an engine with almost clogged filter will fill up while off, then run perfectly normally for maybe 30 seconds until bowl gets low enough to matter.
Thanks for the quick reply on the pump rod, Bruce. I keep a normal crab distributor in the trunk for emergencies. I definitely have a fuel delivery problem and am sick and tired of fighting the gravity feed tank, so I'm going to stick in the fuel pump. I just rebuilt the HC, but will lay an eyeball on it while I'm waiting on the pump rod and rebuild kit
Two and half years I’ve been fighting the flathead. Every time I think I’ve got it beat, it doesn’t turn out to be the problem. When I was over at JackandDueces shop before Christmas he suggested I try disconnecting the condensers. The flathead wouldn’t run without them but I swapped in a new pair and it has been running like a sewing machine ever since- actually hasn’t run this good since I was gravity feeding it with a milk jug before I even got the car on the road! Since the Harman Collins dual coil basically fires the engine like two four bangers, I looked for a condenser for a 4 cylinder application that was small enough to hide under the Mallory’s with a long lead to go from the bracket all the way down to where they tie in on the sides of the distributor body. Chevy Luv pickup works like they were made to go there (NAPA #G583). As always it has been a calamity of errors. First the dirt in the stock cowl tank kept biting me in the ass and before I ever really sorted that out I compounded the problem with the condensers when I replaced the stock crab distributor with the HC dual coil. The filter I was using above turned out to be a restriction with the stock gravity feed, so I went to a true sediment bowl filter (62 LeSabre, NAPA # FIL 3039). 2000 miles on the car I finally have most of the dirt out of the tank but in desperation I broke down and put on a mechanical pump. I could t at least get it to run with a new set of plugs every couple hundred miles but the flatty still ran like it was missing about a hundred cubic inch and was hard as hell to start when she’d sat for a couple days. I had completely discounted the old Mallory condensers as being the problem since -they tested out “in spec,” at 33 & 34 microfared. The old Mallory’s might be OK if they weren’t bolted a bracket bolted to the vacuum break adjuster screwed to the distributor body, bolted to the block with a connection at either end of the wire that connects them to the points-that’s a lot of mechanical joints to have to find ground through. Guess they just weren’t good enough to run an engine. I left them on for looks.
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