302 Engine Stalls

Engine, ignition, fuel, cooling, exhaust

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KU4WW
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302 Engine Stalls

Post by KU4WW »

Hi guys,

I need some help and/or advice. I have a 1970 F100 Sport Custom with a 302 with Automatic (C4) Transmission. The motor cranks good and does not smoke, knock, ping or use oil. It idles good (when warmed up). The issue is that when I ease down on the gas pedal, the motor will stall. If I press down a littler farther, it seems I can get past the stalling and the motor will rev nicely. If I burp the pedal fast, it doesn't stall and revs up good. When I drop it in gear, the motor will run a little hesitant and as I give it some pedal it stalls the same way. I've driven it down the road recently and it stalls the same way, but if I mash it down more, it seems to get past a point of stalling and runs pretty good, but I'm going to fast by then, lol.

It has an Autolite 2100 D carburetor that I cleaned and put a new kit in. I'm the second owner, as my neighbor bought it new. My dad told me that the motor has been rebuilt. From all indications it has a 351 cam in it. The heads were changed when it was rebuilt apparently. The firing order is that of an H. O. 302. Before I purchased it, the truck had setup (outside) for about 5-6 years. It would not crank then. I've put in new: spark plugs, spark plug wires, points, condenser, rotor cap, distributor cap, distributor breaker plate assembly, fuel filters (the one at the carburetor and the one at the fuel pump), modulator valve, PCV valve, choke pull off valve, fuel sending unit, oil sending unit, fuel line hose, coil, solenoid, battery (used, but strong), etc.

This is what I know about the mechanics of it. I've timed it at 6 degrees with a good warm idle. I don't have a tach. The plugs are gapped at .032". The points are .018". I've adjusted the carburetor as best I (a novice) know how by the specs. It has an automatic choke. It has a dual diaphragm vacuum advance and a dist-o-vac system. When I purchased the truck, the dist-o-vac was bypassed. I tried running the truck as it was intended to be in 1970 with the lines connected to the dist-o-vac and so forth. Of course this was before I put a lot of the new stuff on. In order to finally get the motor running I routed the front hose from the vacuum advance to the carburetor and the back hose to the block at the back of the intake where another hose routes to the transmission. This is the way it was connected when I purchased it. I have sprayed around the carburetor with WD-40 and traced the line to the transmission with WD-40, but I don't detect any vacuum leaks. The lines/hoses look good. Recently, I disconnected the wires to the dist-o-vac box under the dash thinking that for some reason there might be a false reading through the ignition or something. There was no change in the issue, so I connected them back.

I've cleaned out the (rusty) fuel tank and blown out the lines from the tank to the carburetor. I've checked the canister filter several times and detect no trash. The truck has 77,000 miles on it and I don't know how many since the rebuild. I wonder why it was rebuilt. I remember my neighbor driving by at a snails pace many many times in the truck when I was growing up. I know he didn't "raw hide" it. He was very conservative and took care of his stuff. I'm not a mechanic at all, but thanks to fordification.com I've learned a lot. If anyone has any ideas, I would very much appreciate it. Thanks.

Jeff
1970 Ford F-100 Sport Custom 2WD LWB New Lime Green 302 C4 Automatic No AC, No PS, No PB Second Owner Proverbs 3:5-6
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sargentrs
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Re: 302 Engine Stalls

Post by sargentrs »

Unplug that back vacuum line and plug off that port on the vacuum advance and the intake port you had it connected to. You don't need it. Re-time your engine to maximum advance. Cap off the vacuum advance lines and adjust your timing until you reach 35*-38* at 2500 rpm. Do not go over 38* and listen carefully for pinging (pre-detonation). If it starts pinging back off the timing a couple of degrees. Once there tighten the clamp and don't worry about where your initial timing falls. Then hook a vacuum gauge up to an intake manifold port and tune your carb. Adjust your air/fuel mix screws one at a time striving for max vacuum (18-21Hg) at idle. You'll probably increase rpm's doing so. Idle it back down and check your max timing again. Set your timing and then adjust your carb again. Usually takes me about 3 passes before I'm happy. When it's all settled down, connect only the front vacuum line on the vacuum advance and leave the back one plugged. Should check your points dwell with an old fashioned dwell meter. Mine ran best at .019-.021. Take her for a test run and see if it's better.
Randy
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1987 F-150 XLT Lariat, 5.0/C6 auto.
KU4WW
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Re: 302 Engine Stalls

Post by KU4WW »

Thanks sargentrs for the information. I will investigate this and report back on my findings.

Jeff :fr:
1970 Ford F-100 Sport Custom 2WD LWB New Lime Green 302 C4 Automatic No AC, No PS, No PB Second Owner Proverbs 3:5-6
KU4WW
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Re: 302 Engine Stalls

Post by KU4WW »

I installed a new (refurbished) Autoline Carburetor yesterday. The truck runs much better and drives great! A few weeks ago, we discovered a vacuum leak on both sides of the carburetor at the throttle shaft. I considered a new Holley or Edelbrock, but I love the originality (and price) of the Autolite 2100 (Autoline) rebuild. It's warranted for 1 year and I'm pleased! Now I can drive it and concentrate on brakes and other things. Thanks again for the advice.

God's Blessings!
1970 Ford F-100 Sport Custom 2WD LWB New Lime Green 302 C4 Automatic No AC, No PS, No PB Second Owner Proverbs 3:5-6
KU4WW
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Re: 302 Engine Stalls

Post by KU4WW »

It's been a few months since I installed the rebuilt carburetor. The truck still sputtered and quit at times and I've been blaming it on the old gas tank (with rust). I replaced the tank with a new one, with new filters and fuel lines. I was disappointed that the truck still had hesitation and problems as before. Finally!! My buddy Ray and I discovered the culprit. We missed the large vacuum leak at the bottom of the EGR Valve when we installed the carburetor a while back. I had the wrong gasket on it. Duhhhh!

Since July I've put new brake shoes, wheel cylinders, brake lines and wheel bearings on it. I also put a new Edelbrock breather on it. The original oil bathe type was not good as it would pulled down the motor when installed.

Lima Bean is running much much better now. It's been 3 years and 3 months since my dad and I pulled it to our shop from where it had been sitting in a yard for about 5 years. The truck is now mechanically sound and so I can concentrate on cosmetics and others now. Love my Lima Bean!! :fr:
1970 Ford F-100 Sport Custom 2WD LWB New Lime Green 302 C4 Automatic No AC, No PS, No PB Second Owner Proverbs 3:5-6
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colnago
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Re: 302 Engine Stalls

Post by colnago »

Glad to get the update, and glad you found the problem. I'm working with an Edelbrock carb, since that's what came with the truck. I do love stock, though, so I have the occasional thought about going back to an Autolite carb. But if I go back, should I go with a 4BBL, or return to 2BBL? Decisions, decisions ...

Joseph
"Sugar", my 1967 Ford F250 2WD Camper Special, 352FE, Ford iron "T" Intake with 1405 Edelbrock, Duraspark II Ignition, C6 transmission, front disc brake conversion.
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