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My original problem was an off-idle stumble. After unlocking the distributor and another fuel issue tweek, that has disappeared. What hasn't disappeared or what I'm trying to figure out now is why it's so under powered at a low rpm vs high. Hence the sperate thread because, being very new to this, I thought they were two separate issues. Sorry if starting a new thread messes things up. I'm just trying to figure stuff out best I can. I'm not going to stop asking questions either just because one person says "this is all that can be done". I've learned to many times there's more than one way to skin a cat, and I love hearing different people's ideas and learning how everything works. Please and honestly, give me a little bit of slack, I'm trying to learn something I've never done before.

When you say "The torque converter is just set up so that the truck has to be really wound up and into the cam before it starts loading the drive line." Isn't this exactly what I'm experiencing with a lack of power until high rpm? Is it I have to get the RPM up to a specific amount before the TC cuts in and delivers power to the drive line? Im not very familiar with torque converters, but if this is an issue, would no amount of engine demodification I do make a huge impact on the ability to make a slow take-off speed until I also change back to stoke the TC?

(1986 Ford F-150, 300 I6, Rebuilt Engine, Heavy Cam, HEI Distributor, Offenhauser Intake, Headers, Motocraft 2150 2 barrel Carburetor. No electronics/emissions control, c4 automatic transmission) Restoring a previously owned Ford F150 that was being turned into a race truck. When I go to accelerate from a stop I get very little power/almost none until I hit 1700-2000 rpm and then the thing takes off. This means I can never ease into acceleration. Its always all or nothing. It accelerates great but I dont want everyone to think Im on some starting line at every stoplight. What is the primary cause of this? Is it timing and the module in the HEI distributor? Or is it entirely the heavy cam with a large degree and heavy overlap? I also believe the torque converter was replaced with a different one and a shift kit was put into the automatic transmission, but am unsure how that might effect drivability. I've messed with all the carburetor settings and dont think any of those effect this issue.

Unfortunately I don't have the area or the knowledge to replace the camshaft... Don't even have an engine hoist. Is there a way to mitigate the off idle hesitation. I mentioned I read about drilling a small hole in the butterfly as an option. Thoughts? Also what would be the best timing for a cam such as mine

The measurement I got on the cam lobe was 1.708 height 1.465 width for a ratio of .243. The box again had this info: Adv Dur 268,268 Dur @ .050 219,219 Lobe Sep 110 deg Valve lift .456, .456 So if the measurement I took doesn't match the box info then the new cam was installed and the old cam is what was put back in the box ( IE what i measured) If that is the case, is the new cam (the one that is installed using the box numbers) considered a "Heavy Cam"? Also back to the hesitation off idle/engine stalling situation I am having. So if I do have a heavy cam, then from what Im reading it pulls less vacuum at idle. This means you really have to back-out the idle set screws and push in the curb idle screw to get a good idle (Which is exactly what I've had to do to get it to idle). From my reading this means the transfer slot is open to manifold all the time and you don't get that smooth transfer from idle to low rpm. I still not sure why this means its a "Rich Bog/Hesitation" but it does seem that too much fuel and not enough air is getting into the system at off idle conditions. (and yes I have checked my accelerator pumps, they are good and quick to squirt) The solution I've read about is drilling a small hole in the throttle plates (1/8" or less) to allow more air flow but still let your plates be mostly closed over that transfer slot. Since I've had this problem with two different carburetors, each needing the idle screws set extremely high, would it be safe to say that I am not getting enough air and this is the cause of my bog/hesitation and not the timing? Should I drill these holes?

This is the cam that came in the box, obviously not the one that's installed. My calipers say a love is 1-22/32 wide

It's coming directly off a switch that's run back to the main solenoid in 10 gauge wire. No relay. That probably isn't it because it wouldn't be intermittent or increasing as driving went on. Plus the wire isn't hot/warm to the touch so it's not drawing to much current. I think your right about the distributor being the problem. And too much advance. But when I try to turn it below 30 degrees it starts to stumble really bad at idle and any lower and it just dies. Pity if the distributor is bad. Looked pretty new. What did I do when I opened it up that made it be stable at 14-16 degrees to now not getting lower than 30???

This is the DUI HEI Distributor opened up. Looks fine to me, but I'm open to any input

The manifold is an Offenhauser dual port 240/300 cfm. I have a phenolic spacer/2-4 port adapter that is open, so the dual port thing shouldn't much matter. The box that has the cam in it says comp cam part# 66-248-4, grind# f66 268h-10, gross valve lift .456 duration at .006 tappet lift 268 valve timing open @.006 int 28, btdc 60 exh 68. (The cam looks new too me, so it might have never been installed, but it could be the old one too) The original carburetor was a Holley 4160. I replaced it with a Motocraft 2150. I have the same stumble off idle issue with both carburetors, which is what led me to thinking this is a timing issue. Ever since I cracked open the distributor and unstuck the centrifugal weights, I have not been able to get the timing back down under 32 degrees without killing the engine. It seems happy around 36-40 degrees and will idle @800rpm (dropping to 600 when in gear) and an idle vacuum of 20. Tried turning over the engine before kicking the start and that seems to help with the hard starting. Thanks for that tip! Anyways I took it out for another drive after setting it to sound decent and somewhat steady (still fluctuates a bit). Good acceleration, good feel for about 2 minutes (like always) and then it starts to stumble when coming off an idle. This stumble gets worse when you push the accelerator, and to keep from killing it you have to completely take your foot off. It also progressively gets worse doing this off idle stumble more and more over the course of minutes. Finally the stumble will get to the point it kills the engine entirely. You then have to wait a couple minutes to restart the engine. I also noticed that a small oil leak at what I think is the rear seal, seems to get worse after driving it like this. Maybe the engine oil pressure is going up above a threshold when its running poorly, because the leak doesn't seem to happen all the time.

Okay Im starting to piece together what the previous owner did/wanted. He locked out the distributor because he put a large cam in and was looking to make a track vehicle. Thats why when I set timing to something the engine is happy with it idles at 1000+ rpm, and has nearly 36 degrees of advance. Plus i need the idle set screws almost 5-6 turns out to idle without stalling. My question is, I need a work truck, something reliable at low speeds with good torque and reliable start. If he put a large cam in it, can I ever get back that good low end power and reliable start? I dont have a way to remove the engine and replace the cam, so it would all have to be done in my front driveway, whatever that is. Some people have mentioned an MSD system to retard the timing during start. Can a MSD system like this be hooked up to a DUI HEI distributor? The other option was modding some type of pin control in the distributor. And then am I only ever going to have power at 3000rpm and up? I really love the truck, and love the idea of a no computer, simple reliable, 300 I6, but if I need a shop to make it so then I probably just need to sell it and get something else.

When I got the truck there was a camshaft in a new box in the back. I cant tell if it was the old original one, or the one he wanted to put in. How can I determine what cam shaft is in the engine now?

Okay I did my timing again and found out that I was getting no mechanical advance. The timing would sit at whatever i set it at which was around 14-16 degrees. When I hooked up the vacuum advance I would get it to advance a bit when I reved the engine. So I took apart the HEI distributor, and kinda just moved everything around. It felt like the weights might be sticking so I moved them a couple times and put it all back together. After that I was getting mechanical advance and thought I must of done something to unstuck it... Now that I have done this it still runs... odd. First thing I noticed is if I disconnect the vacuum advance line and plug it, the engine will die a couple seconds later. The other thing is Im still getting hesitation at certain times that acts like its about to die and then self corrects. It seems to happen while im cruising down a street without giving it any gas, and then I go to give it just a little and it bucks/hesitates and then corrects and goes. Any ideas what I should do next?

Thanks, I went ahead and posted in the new user form. As far as the HEI module and retarding the initial timing for starting the engine, thanks for pointing this out. I wasn't even aware you could do that. For what parts I already have on hand, could I put a solenoid on the vacuum advance line and have it closed (IE no vacuum reading) during startup to stop those initial 10-12 degrees of advancement that's puts on the distributor, and would this be enough to ease startup? After startup I could turn on the solenoid and open it to full vacuum reading as it normally would be if hooked up without it in line. Thoughts?

Yes sir, read and understood. Glad to be a part of this place!

Hi, got a 1986 Ford f150. Trying to get it up and running. Hope this place can help.