360 stalling on downhill stops
Thread Starter
|
5th Wheeling
Joined: Nov 2020
Posts: 48
Likes: 0
360 stalling on downhill stops
Last year I rebuilt the Motorcraft 2100 2-bbl on my '68 360 automatic. Starts easy and runs like a top ever since EXCEPT when I come to a stop heading downhill. The engine shudders and I have to throw it into neutral to prevent stalling. Then it recovers and is fine idling on the downhill. Coming to a stop on the level or heading uphill presents no problem. Any ideas what could be the cause? Float level? Does not seem to be related to engine being cold or warm.
One thing I did not fix is the slow-return-to-idle diaphragm thingamajig part of the throttle linkage . The diaphragm seems to have failed so is not providing any damping so based on reading around the Forum I disconnected that part of the linkage as apparently not vital. Maybe it is vital after all or ?
Thanks in advance for any advice!
One thing I did not fix is the slow-return-to-idle diaphragm thingamajig part of the throttle linkage . The diaphragm seems to have failed so is not providing any damping so based on reading around the Forum I disconnected that part of the linkage as apparently not vital. Maybe it is vital after all or ?
Thanks in advance for any advice!
FTE Legend
Joined: Nov 2015
Posts: 30,915
Likes: 4,123
From: Angier, NC
First place I would look is the float level.
Did this happen right after the carb rebuild or some time after?
Also may want to check timing and adjust the carb mixture too.
It may need that dash pot but I believe it is for smog more than anything.
If the throttle was to close fast you will the unburnt gas level go way up where if it closes slowly it only goes up a little till the throttle is closed all the way.
Dave ----
Did this happen right after the carb rebuild or some time after?
Also may want to check timing and adjust the carb mixture too.
It may need that dash pot but I believe it is for smog more than anything.
If the throttle was to close fast you will the unburnt gas level go way up where if it closes slowly it only goes up a little till the throttle is closed all the way.
Dave ----
Cargo Master
Joined: Dec 2015
Posts: 2,253
Likes: 345
When I put my rebuilt 360 in my 70 f250, I switched back to my autolite 2100. I didnt have the dash pot on it. The truck wanted to almost stall every time I would let off the throttle. I would put it on before fixing parts that might not even be out of adjustment.
Thread Starter
|
5th Wheeling
Joined: Nov 2020
Posts: 48
Likes: 0
Thanks all for the input. I don't recall when I noticed the stalling. Probably not immediately or I would have tackled it then and there. I can pull the float bowl cover and adjust the level with the carb in the truck as I recall so I may as well check that.. In regard to the dashpot I checked t for damping action and there is nothing there so I assume the diaphragm is shot as it provides no resistance at all to throttle closing. I will need to get a new one to try it.
I also read somewhere it could be a vacuum leak involving the power brake booster, occuring only when the brakes are appllied. Interesting but that should happen on level and uphill stops too. I'll have try some fast stops going uphill to rule that out.
I also read somewhere it could be a vacuum leak involving the power brake booster, occuring only when the brakes are appllied. Interesting but that should happen on level and uphill stops too. I'll have try some fast stops going uphill to rule that out.
FTE Legend
Joined: Nov 2015
Posts: 30,915
Likes: 4,123
From: Angier, NC
A vacuum leak raises the RPM not lower it to stall.
Also if the booster leaked just idling in park and press the pedal the RPM will change.
Also sometimes you hear a hiss when pressed.
Dave ----
Also if the booster leaked just idling in park and press the pedal the RPM will change.
Also sometimes you hear a hiss when pressed.
Dave ----
Hotshot
Joined: Mar 2013
Posts: 14,255
Likes: 199
From: Phoenix, Az.
I think the float level is too low. Not enough gas over the jets on down hills for gas level to be very far up the venturis. Raising or lowering the float level changes the air/fuel mixture a bit. Higher float level raises the fuel level heading up to the venturis. Thus a richer mixture. And then vice versa.
Thread
Thread Starter
Forum
Replies
Last Post
Sergio Reta
1967 - 1972 F-100 & Larger F-Series Trucks
8
Apr 26, 2016 09:43 PM
jax72sportcustom
1967 - 1972 F-100 & Larger F-Series Trucks
6
Sep 11, 2012 05:21 PM
Esmith215
1973 - 1979 F-100 & Larger F-Series Trucks
4
Dec 8, 2007 04:21 AM
Project71
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
38
Jun 20, 2007 08:11 PM
greghoffmann
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
1
Aug 27, 2000 10:17 AM
