196 Flathead Carb Issues

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   I need some pro tips here.
I'm redoing a 1958 196 flathead auto back from the dead and the motor's all rebuilt and running nicely with 250 miles, no mechanical issues, perfect compression. But I can't get rid of the stutter on takeoff (tip in) and it's making me nuts. It acts like there's no accelerator pump. The car runs great from 5 mph up but waiting at a stoplight and moving into the intersection is fearsome. It WILL stall. And start right up with a little pedal.
It was a mess when I got it so I don't have a "before" to compare the carb to. For all I know it's been messed with and has the wrong jets or something. I've done 2 proper carb rebuilds with kits, dip and a compressor. The float, needle/seat and diaphragm/ball are new, aluminum ball has been seated and reseated. Everything is set up as shown in the manual. I've tried fuel pressure from 3psi to 10psi and several float levels. I've swapped needle and seats. In park or neutral it idles perfectly - really nicely - and responds well to the accelerator but going into gear pulls the rpms down more than I like and shakes the engine unless I crank the idle up well past where you would have it for a manual trans. The tailpipe and plugs are a little rich but there's been a lot of idling. It starts instantly - reach in the window and hit the key - and idles immediately without the choke, but it's been warm here (mid-90s.) The accelerator pump checked with a flashlight while running seems to be doing it's thing, although as a Weber guy I still think it's weird there's no squirter nozzle, just the dump tube. My bet is I have some kind of too-rich issue combined with a wonky accelerator/idle circuit.

The auto trans seems OK and has a new diaphragm on the modulator so no vacuum leak there. I've tried adjusting the modulator pressure in case the trans/converter is grabbing. Trans seems fine once the carb has caught. The wiper vacuum is blocked off. Engine vacuum is 17psi at idle, timing is OK static but I ditched the frozen vacuum advance rig and diddled the mechanical advance for more, so that vacuum's blocked too. For sure it needs more advance somehow.

I have a new Weber 28/36 and adapter on the shelf. Should I send the original carb out to a pro and try to save it, mount and jet the Weber or buy a Chinese Carter YF Ford copy on Fleabay for $71? Or what?

I'm ready for the brake conversion and and some serious driving...and pleased with the motor... but the car is undriveable in traffic.

Help please.

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andyleonard Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Apprentice Joined: Dec/10/2016 Location: 90290 Status: Offline Points: 138	Post Options Post Reply Quote andyleonard Report Post Thanks(0) Quote Reply Topic: 196 Flathead Carb Issues Posted: Aug/16/2017 at 11:09pm
	I need some pro tips here. I'm redoing a 1958 196 flathead auto back from the dead and the motor's all rebuilt and running nicely with 250 miles, no mechanical issues, perfect compression. But I can't get rid of the stutter on takeoff (tip in) and it's making me nuts. It acts like there's no accelerator pump. The car runs great from 5 mph up but waiting at a stoplight and moving into the intersection is fearsome. It WILL stall. And start right up with a little pedal. It was a mess when I got it so I don't have a "before" to compare the carb to. For all I know it's been messed with and has the wrong jets or something. I've done 2 proper carb rebuilds with kits, dip and a compressor. The float, needle/seat and diaphragm/ball are new, aluminum ball has been seated and reseated. Everything is set up as shown in the manual. I've tried fuel pressure from 3psi to 10psi and several float levels. I've swapped needle and seats. In park or neutral it idles perfectly - really nicely - and responds well to the accelerator but going into gear pulls the rpms down more than I like and shakes the engine unless I crank the idle up well past where you would have it for a manual trans. The tailpipe and plugs are a little rich but there's been a lot of idling. It starts instantly - reach in the window and hit the key - and idles immediately without the choke, but it's been warm here (mid-90s.) The accelerator pump checked with a flashlight while running seems to be doing it's thing, although as a Weber guy I still think it's weird there's no squirter nozzle, just the dump tube. My bet is I have some kind of too-rich issue combined with a wonky accelerator/idle circuit. The auto trans seems OK and has a new diaphragm on the modulator so no vacuum leak there. I've tried adjusting the modulator pressure in case the trans/converter is grabbing. Trans seems fine once the carb has caught. The wiper vacuum is blocked off. Engine vacuum is 17psi at idle, timing is OK static but I ditched the frozen vacuum advance rig and diddled the mechanical advance for more, so that vacuum's blocked too. For sure it needs more advance somehow. I have a new Weber 28/36 and adapter on the shelf. Should I send the original carb out to a pro and try to save it, mount and jet the Weber or buy a Chinese Carter YF Ford copy on Fleabay for $71? Or what? I'm ready for the brake conversion and and some serious driving...and pleased with the motor... but the car is undriveable in traffic. Help please.

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19672	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Aug/17/2017 at 7:10am
	The auto trans might need a bit more idle speed than a manual would. Manual is set at 550 rpm in the TSM (I have a 63 American TSM handy), 500 for the auto. TSM doesn't say specifically, but I would set that 500 rpm with the engine in gear holding the brake. If you set it in neutral the engine will bog to below 500 rpm in gear, and that may be your problem... unless of course you've set idle speed with the car in gear... The TSM often leaves out things like that, since it should be common knowledge to an experienced mechanic of the time. Yes, the engine will like more advance than the factory dizzy allows! This is specifically for the 196 OHV, but might help: http://195.6ohv.com/Distributor/index.html Personally, I think I'd try the Weber. You have everything you need, and state that you're familiar with tuning Webers. I'd only try the knock-off YF if you really want to keep it stock appearing. Another option is the later model L-head Carter RBS carb. Don't know if it came into use in 62 or 63, but was used through the end of L-head use (65). 61 and earlier L-heads used the YF.
	Frank Swygert

andyleonard Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Apprentice Joined: Dec/10/2016 Location: 90290 Status: Offline Points: 138	Post Options Post Reply Quote andyleonard Report Post Thanks(0) Quote Reply Posted: Aug/17/2017 at 9:30am
	Thanks farna. Yep, that's how I diddled the mechanical advance. I'm convinced it still needs more advance though. Maybe I can convert something. I put a MBZ electronic distributor in an old Maserati once. Still runs fine. And the idle was set in gear. When you go back to park, idle's at maybe 1200 and you get a thump going back into gear. So the idle setting's either wonky or the trans is pulling too much power at idle. I hate to give up on the YF as it's so (allegedly) simple and in keeping with the minimalist design of the car....but it's kicking my rump. Maybe I can borrow a known-good carb for an hour and rule out ignition and trans issues before I junk the original YF.

vinny Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Jan/05/2012 Location: Calgary Status: Offline Points: 2837	Post Options Post Reply Quote vinny Report Post Thanks(0) Quote Reply Posted: Aug/17/2017 at 10:19pm
	I was sure I had a carb problem in my old truck because when taking off it would cough and spit through the oil bath air cleaner and then take a while to clear it self. A carb kit didn't help but installing an HEI totally cured it.

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19672	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Aug/18/2017 at 6:46am
	If you look at that 195.6 site of TomJ's you will find where he used an EDIS system on his OHV. That will definitely take away the minimalist approach, but give you all the timing control you'd ever want or need. Converting anything will take some cutting and welding (or good epoxy on the housing), but if you do let us know! A Pertronix would help some, but still wouldn't give more advance. You could have a torque converter going bad. I'd pull the valve body and give it a through cleaning first though. A sticky valve could be an issue.
	Frank Swygert

andyleonard Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Apprentice Joined: Dec/10/2016 Location: 90290 Status: Offline Points: 138	Post Options Post Reply Quote andyleonard Report Post Thanks(0) Quote Reply Posted: Aug/18/2017 at 10:30am
	I found a rebuilt YF on Fleabay for $40 and it's on the way. If that doesn't get it, we'll attack the ignition. And save the trans for last. You'd think if it were the ignition it would also be breaking down under full throttle or steep hills but it's OK. Be nice to find a hot HEI distributor with the coil in the cap from a Chevy or something, cut and machine the snout and install the Rambler drive gear and go. Any attempts at this anywhere? Does this Delco distributor show up in Studebakers or Plymouths like the YF and some other parts? Maybe those guys are ahead of us on this.

rocklandrambler Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Feb/09/2013 Location: Nanuet, NY Status: Offline Points: 3953	Post Options Post Reply Quote rocklandrambler Report Post Thanks(0) Quote Reply Posted: Aug/18/2017 at 10:50am
	IIRC, the flathead dizzy doesn't have a drive gear. I believe it's a slot fit.
	Past AMC's 1974 Hornet X (new) 1975 Gremlin X (new) 1964 Classic 660 Cross Country 1965 American 440-H

andyleonard Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Apprentice Joined: Dec/10/2016 Location: 90290 Status: Offline Points: 138	Post Options Post Reply Quote andyleonard Report Post Thanks(0) Quote Reply Posted: Aug/18/2017 at 11:21am
	Yep. Does the distributor from any other AMC product fit the 196 flathead? Anyone?

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19672	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Aug/20/2017 at 11:21am
	No. The dizzy for the flat-head six is unique to it. Wouldn't be hard to mod a shaft -- it's an offset slot drive so it only goes in one way. The gear is on the oil pump. When rebuilding you don't worry about timing the oil pump. Just install it and install the distributor the only way it will fit, then place the plug wires accordingly. So it's a bit of a hassle when rebuilding, but after that it's real easy to pull the dizzy to change and adjust the points. Hard to get to it low in the engine bay at that angle to change points with dizzy in. I only tried that once, then figured out it was easy to get it out (with the cap off) and put it back in.
	Frank Swygert

andyleonard Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Apprentice Joined: Dec/10/2016 Location: 90290 Status: Offline Points: 138	Post Options Post Reply Quote andyleonard Report Post Thanks(0) Quote Reply Posted: Aug/20/2017 at 1:12pm
	So nipping the shaft end off an old distributor and welding it onto the shaft of an HEI with appropriate housing diameter and reach is a good $55 solution, yes? ohh. What about rotation direction? Does rotation direction matter? Stock vacuum advance is external and turns the entire distributor if necessary. Edited by andyleonard - Aug/20/2017 at 1:15pm