My truck has a very very bad off idle hesitation. Trying to start from a stop sign or red light is near impossiable. The problem is there with two different carbs. Trying to take off it backfires and spudders real bad. Once I can get some rpms in it, (1500-1800) it goes along fine.

I am thinking internal, One of the last things done to it was install new heads. With my bypass surgery last May, I didn't drive the truck last summer or fall so I don't recall how it progressed to where it is now.

Any suggestions? Email is available by clicking my user profile.

thanks

John

 

My truck has been cursed with the throttle application hiccup since I've bought it. Petronix ignition, carb rebuild, tune up, new timing chain all in an effort to get rid of it. NADA. This, coupled with another running issue involving temperature, is causing me to reluctantly give up on the stock 2v carb. I love it's simplicity, but after much discussion with various FE people, these carbs can get failures in the casting that will cause problems. I'm going to try a Edelbrock 4v on it and see how that does. I can't see why, other than a sloppy timing chain, it would be an internal problem. Is your vacuum advance working? Accel pump linkage set to the most aggressive application?

 

I am swapping between a 390 cfm Holly 4 barrel and a 1406 Edelbrock. I used to run a Unilite dist and now have a OEM with a new vac controller. I was told that the vacuum advance would help the gas mileage so I put it on. I may try the Unilite again to see if that eliminates the issue.

The puzzling thing to me is once it builds a few rpms you don't notice it. We have been checking hard for vacuum leaks too.

John

 

hey John dood day to ya.hope this helps,as ya know over the weekend i swaped motors in my 71 well the 429 that had been sittin in my 85 was not run for about 5-6 months,after the swap it run great exept the fact it wouldnt go no where like yours.i checked timing,vacum leak,swaped carbs every thing.last ditch efert i pulled the spark plugs and changed'em now it doesnt pop bang or nothing.i know it sounds dumb that a plug could go bad from just "sitting" but i gess they can

 

Got new plugs installed and it is much improved, but not healed.

I am gonna look for a hotter coil that I have here somewhere and see if that could help. If it doesn't then the next move might be to reinstall the Unilite and it's coil.

There is a very slight movement in the top of the dist. shaft but I can't tell if it is too much or not.

John

 

What is your initial timing set at? My 2100 was rebuilt by Pony Carbs so I knew when I got it back that it would be in perfect condition like the others. That didn't eliminate the poor off idle response of the truck so I knew the carb was not the issue. When I moved the timing up to 12-13 initial advance my hesitation was gone. Changing out the heavy spring for a lighter spring then let the engine take off from there. Many stick to what Ford says about timing but after talking to Jon at Pony I now go with what the engine tells me. The Cougar now runs 16 degrees initial and what a difference that makes to the idle of a moderate camshaft after all these years.

 

Mike, I was not able to read it, I will try again tomorrow when I have more light. I feel certain it is not at Ford suggested.

I swapped in a hotter Petronix Flame Thrower coil and that helped a bunch and as long as I take off gently I don't have problems. If I mash the gas it coughs and spits.

I am beginning to think the distributer is the culprit.

John

 

I don't think you should really pay that much attention to the timing light to start. Put it away and hook up a vacuum gauge instead. Advance the timing and watch the gauge. The 360 hits 19mm Hg and any further with the distributor gains nothing. I then back it down to check the drop off point before bringing it just back to maximum vacuum. Then onto the idle mixture screws for best idle speed. Find that 3 1/2 turns out on my 2100 work the best. Four turns gives a touch higher idle speed but 3 1/2 is better for moving the truck from a dead stop. Remember this is an engine that was ill treated during it's life and I wasn't sure if I could revive it. Has taken 7 months tweaking it but it is now a whole different engine and almost as smooth as the 410 in the big Merc.

 

Do you have a carb spacer plate, either the composition type or an aluminum one? Composition type chip/crack, aluminum ones burn out internally/also can crack from the heat.

 

Bill, Actually there is one of each under the carb. I had been uising a phenolic spacer because of boiling gas, and had to add a metal one because the carb doesn't have a pcv port.

John

 

I spent several hours tightening up the exhaust system on the truck today. Added new hangers, and stopped the bad leaks. Took it out and it still doesn't want to take gas. I am gonna try a different dist. cap and if that doesn't help, I am gonna stuff the Unilite back in it.


John

 

John as dumb as this sounds the manifold may need to be retorqued from all the heat/cool cycles. Just a shot in the dark.

 

Mark you might be right. It hasn't been run much in the last year, since the heads were off.

Do you have those specks?

John

 

Off the top of my head I don't think most Ford intakes go past 25 ft/lbs.

 

Does the fuel pump have the can type fuel filter on it?