Flathead surging at idle

[Firepower flyer]

Hey guys looking for some trouble shooting help on a surging issue that just started out of no where.I didn't want to just start throwing parts at it without asking on here first.I'll give you some info on what I have.I'm driving my 50 F1 and it runs out really good pulls strong no issues under load or at speed but I pull up to a stop sign and it starts surging..I've been driving this thing back and forth to work not to mention everywhere else I can and it's been great.At first it was pretty mild but tonight on the way home it seemed worst and died.It restarts fine but will start surging again.When I got this truck a few months ago the engine 8 EAB was mildly stuck from sitting 11 years,I soaked it with diesel and it freed right up.I cleaned the fuel tank spotless with acid and changed out a few fuel filters and everything looks good there.I did not touch the carb 7RT.It looks horrible but ran perfect so I didn't want to mess with it If not needed.I put fresh plugs,points,condenser,cap and rotor,but not wires yet.So if you guys have some suggestions on what to look for first that would be great.
I want to mention I added all of those new parts before the problem started,the only thing that I tried was another new fuel filter just because I had a bunch.
Thanks in advance
Joe

[steve-cook]

possibly the float could be deteriorated allowing the needle to not close off against the seat completely then dumping more fuel into the intake or just some trash caught inbetween the needle and seat.

[APDAVE]

Look for a vaccuum leak if it is while idling. Dave

[ken ct]

I would have the carb gone through OMO. ken ct.

[Cecil/WV]

I'm with Ken, sounds like a carb problem if there are no vacuum leaks.

[flatjack9]

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The float needle is likely sticking causing this surge. Probably has a rubber tip and and is getting sticky from todays fuel. Try to find an old steel needle.

[ken ct]

My rebuilds are fitted with steel needles and leather accelerator pumps,no rubber ones in them.ken ct. Or you can buy 1 of my kits to diys. ken

[Firepower flyer]

Thanks guys!!Thats the input I'm looking for.I wasn't sure to start with ignition or fuel.I do have a bunch of old carb kits,they may have the good parts in them.Can anyone tell me if the kits from a 94 or 97 would have anything that interchanges into my 7RT?I know I have those kits in stock and other models also.Ken if I don't have what I need I will send you a pm and order a kit from you.
Thanks
joe

[flatjack9]

The 7RT is a model of the 94. 97's different.

[ken ct]

Right on flatjack. Old kits usuall have rubber accel. pumps and rubber tipped needles and the wrong # power valve and has a non-compatible diafram with todays gas in it. Only thing good in them would be the gaskets if they havent shrunk. If you want to discuss the possible problems with them PM me. ken ct.

[ken ct]

You could have a slopy link connection on the acce. pump link to the throttle arm. ken ct.

[Tinker]

I had a problem like that from having a few loops in the copperline between the carb and pump. Sure looked cool though.

[oldford2]

The nice thing about dealing with the experts like Ken is that if you are new to rebuilding a carb and have his kit with the "correct" parts, you can always call him and he will walk you through any questions you have. Try that with the "big vendors" and there is no help line. I also recommend that instead of rebuilding, trade in your core to him and you will get a beautiful looking carb that bolts on and goes. I just did that and I am a happy boy.
John

[32Gnu]

Ditto on Ken... My 97 Idled right out of the box...

[ken ct]

Thanks for the plugs guys.Driveing them is what its all about. good luck with what ever you choose to do.There are little tricks that some of us rebuilders do that nobody knows about LOL ken ct.

[tiquer]

Might just be too much fuel pressure? Seems the early carbs only handle about 3 pounds pressure before the fuel by passes the float needle.The stock pump can put out 5-7 pounds. Try a regulator and set it at 2 pounds. Works for me for the last 5 years.???

[Firepower flyer]

I'm not sure why it would develop a fuel pressure problem all of a sudden after running good.I have some other questions regarding excessive cranking when hot after sitting awhile.I have to hold it to the floor and it will finally start?I did pull the carb off tonight.Ken it does appear to have excessive play in the acce plunger link,again not sure if that would cause it to surge,I would think that would make a stumble off line which it had a small amount of.Another concern I have is when I pulled the top choke horn off it appears that most if not all the fuel in the float area and accelarator pump well was almost empty.Would that indicate a bad or blown power valve?I checked my kits all of my 97 kits have leather pumps and steel tips needles,but my 94 kits have black or blue rubber pumps not sure about the needles in those I didn't tear them open yet.I may try a quicky rebuild until I pull it of the road when the snow flys,then order a good kit from Ken,or send it in if I can't get it.
Joe

[tiquer]

Originally Posted by Firepower flyer

I'm not sure why it would develop a fuel pressure problem all of a sudden after running good.I have some other questions regarding excessive cranking when hot after sitting awhile.I have to hold it to the floor and it will finally start?I did pull the carb off tonight.Ken it does appear to have excessive play in the acce plunger link,again not sure if that would cause it to surge,I would think that would make a stumble off line which it had a small amount of.Another concern I have is when I pulled the top choke horn off it appears that most if not all the fuel in the float area and accelarator pump well was almost empty.Would that indicate a bad or blown power valve?I checked my kits all of my 97 kits have leather pumps and steel tips needles,but my 94 kits have black or blue rubber pumps not sure about the needles in those I didn't tear them open yet.I may try a quicky rebuild until I pull it of the road when the snow flys,then order a good kit from Ken,or send it in if I can't get it.
Joe

The engine is flooding , points to fuel getting past the float level check valve. Not a new flathead problem. Been happening since 1932.

[flatjack9]

Originally Posted by Firepower flyer

I'm not sure why it would develop a fuel pressure problem all of a sudden after running good.I have some other questions regarding excessive cranking when hot after sitting awhile.I have to hold it to the floor and it will finally start?I did pull the carb off tonight.Ken it does appear to have excessive play in the acce plunger link,again not sure if that would cause it to surge,I would think that would make a stumble off line which it had a small amount of.Another concern I have is when I pulled the top choke horn off it appears that most if not all the fuel in the float area and accelarator pump well was almost empty.Would that indicate a bad or blown power valve?I checked my kits all of my 97 kits have leather pumps and steel tips needles,but my 94 kits have black or blue rubber pumps not sure about the needles in those I didn't tear them open yet.I may try a quicky rebuild until I pull it of the road when the snow flys,then order a good kit from Ken,or send it in if I can't get it.
Joe

The hard starting is a common problem when hot. When you shut the engine off, the heat will boil the fuel out of the carb in to the intake manifold. So when you try to start it, there is a an excessively rich mixture. Hence you must floor the accelerator to get enough air in to the engine to fire the mixture. There are insulating gaskets that are available which will help this problem. I know Dick Spadaro has them in stock. I doubt fuel pressure has anything to do with your problem. Change your inlet needle. Even if you only have a rubber tipped one, it should work for a little bit and may show you the solution to your problem.

[Firepower flyer]

Originally Posted by flatjack9

The hard starting is a common problem when hot. When you shut the engine off, the heat will boil the fuel out of the carb in to the intake manifold. So when you try to start it, there is a an excessively rich mixture. Hence you must floor the accelerator to get enough air in to the engine to fire the mixture. There are insulating gaskets that are available which will help this problem. I know Dick Spadaro has them in stock. I doubt fuel pressure has anything to do with your problem. Change your inlet needle. Even if you only have a rubber tipped one, it should work for a little bit and may show you the solution to your problem.

Jack I was thinking that but in these cooler fall temps I checked coolant temp with a mechanical therometer and a digital and shes only running a 170* is that hot enough to boil the gas out?It didn't seem that bad when I first got it running,like it got worse the more I used it?I think I will go thru the carb and see what happens.
Thanks for the help
Joe