I just don't know what to do anymore. I've had this 240 in my 69 F100 for coming up on three years (Wow, didn't realize how long it'd been.), and it's not been too much trouble, just a few scares here and there. The thing is, while it runs okay, it's still a damn dog. I pretty much expect that, it's no 300 or FE. I might as well just get down to my dilemma.

It idles rough, or at least now it does, but it's been popping and banging in the exhaust at lights for a while, moreso when it's warmed up. I suspect(ed) unburned fuel. (edit: Haha, duh. I should read what I'm typing. I should note, too, that I didn't have much of any gas smell out the pipe.) I finally got off my butt and checked timing and idle tonight, found it idling at 1200, but couldn't comfortably knock it down much lower than 750-800. Timing was pretty close, and what little messing didn't help or hurt any. It's also recently had a tune-up, which really helped; you know, something about running all six cylinders again after a year and deciding there was a carbon trace from 4 to 1. I also finally locked down an exhaust leak due to broken off smog plugs in the head.

Secondly, I've got a clatter I can't pinpoint. I checked all across the valve cover and found nothing, checked at the timing gears for strike two, and struck out at the water pump and alternator. I swear it sounds exactly like a diesel in a very mild sense. I'd call it a rod bearing for lack of explanation, but it's not knocking, just clattering. This noise also seems louder on the passenger side, which baffles me beyond anything else, too. And in case it's relevant, I did adjust the valves, but I'm pretty sure it was right. It made stranger noises before I ever started any of this work.

As a final kicker, the 78 F250 I'm ripping apart has a perfectly running, fairly clean 300 with around 142k on the clock. It's so perfect running, it's what concerned me about the 240. Taller tires, lower ratio rear, same tranny, and I swear it still had power on tap.

But you know what? I'd rather sell that 300 for the cash to put into building a 410 out of the FE in the garage. I'd rather keep an okay running motor in the truck over ripping it out for something that'll only be ripped out again.

I'm so confused. HELP!

 

Sounds as if your dwell angle/points could use some adjustment... and probably a carburetor tune or overhaul may be a likely need as well. The clattering is probably pinging caused by preignition or excess fuel being drawn in by the cylinders or excessive carbon buildup inside the engine. I'm sure others should have some input on what you may want to do to correct it, but those three areas would be a likely start. Not sure if your timing gears are worn, that may cause issues as well - but I think if they were, you could hear it via stethoscope or screwdriver method. Hope this helps

 

Oh, hey, probably also should have mentioned I did an electronic conversion to a Crane Cams box coming up on two years ago. May be necessary to mess with the trigger wheel a little, as I suppose this can still affect how well it sparks if the optic sensor is calling for spark in a poor spot.

I don't think it's pinging, as it doesn't get worse under acceleration, it seems to go away. Road noise and exhaust might only be drowning it out. Also doubt much in the way of carb adjustment(brand new a year ago, toasted the other via an e85 and regular blend, I figure, but I was trying to be a cheapskate), though I could be wrong, it doesn't smell much like a rich mixture, but something has to be igniting out the exhaust, so it screws with my reasoning.

 

Yeah, might want to check your trigger and see if it's in specs. I can't remember, does the Crane distributor put out a square wave (like points) or? Could be a hair off, and if your timing isn't set where the engine is 'happy', well, you know. Backfiring and what you described is usually related to a timing or carb issue, though, as far as I can remember or think of. When was the last time you checked / replaced the fuel filter? Something's gotta be amiss, kind of difficult to think of the possibilities. The clattering could be - which side is your starter on? Could be starter, exhaust, suspension, all kinds of things that could be loose - if it's not pinging.

 

I'd put the trigger wheel to a spec if it was anything more than guessing and checking. It's an optical trigger setup, so yes, square wave, digital, binary, or however else you'd like to term it. I'll probably set it to TDC and see where the open spots line up in comparison, but I'll have to remember the pickup isn't lined up with cylinder 1. I'll probably see about the idle mix screws, too, because another detail I left out was a slightly low vacuum signal around 14-15 inches until I hit 1500 to 2000 RPM. On a note of the clattering, your suggestion has led me to possibly look into listening to the starter and bellhousing. If nothing else, I'll have a listen at the pan for giggles.

 

Ok. Not sure if there is much adjustment on the trigger, but another possibility that came up as I was thinking about it is that the trigger is having other issues. Always possible, never know. Do you still have the documentation that came with the kit? I'd look long and hard through that or try and find info online. Of course, the bad thing about it is IIRC, Crane has shut their doors, so I don't know if you'd be able to get replacement parts Idle mix / speed is probably a good idea to check and double-check. Is that vacuum @ idle? Check for vacuum leaks. That will also cause the higher idle and sputtering and all sorts of fun. If you have absolutely no leaks, you may wish to try setting the timing via vacuum gauge method as well as doing a compression test. Also, what's the oil pressure @ idle, etc.? I'm starting to think about what all could contribute to your problem(s). Yeah, might want to take a listen at the starter, bellhousing, and even pan. If you hear anything @ the pan, that would lead me to think about bearings and loose main and rod caps.... but lower-than-normal oil pressure would also point @ other issues, too - oil pump, bearings, worn camshaft, etc.

 

How about a vacuum leak at the power brake booster? Had one of those, and couldn't get a good idle, was all over the place. Does the exhaust manifold have a heat riser valve? If so, they can clatter until their spring heats up enough. It couldn't hurt to check that the carb is tied down on the intake as they have a habit of coming loose on some 6's.

As far as the 300 swap, I'd do the swap. You might find you like it so much that you'll be selling the FE. It's a days work, I'd bet, and you get to enjoy it all the time until you sell the FE or get it built. Heck, sell the 240.
tom

 

I suppose I could check for a vacuum leak, no power brakes yet, but it certainly wouldn't hurt. I at least don't have that open vacuum port like I used to, and man did that make it tough in traffic. One foot on the brake and gas at the same time. You're also saying your idle was all over the place, mine is just rough and stays around a 750-800 range. As far as the heat riser valve, I'll check, but I get this clatter when warmed up, and what I'm pretty sure is piston slap on occasion when cold.

Money is a big part of what talks in that swap, and I've had little enough interest in the 300 that I doubt any interest in the 240 that's worn out. And beside that, Tim Taylor sez, "More power!"

 

I guess it all depends on what your intended use of that '69 F-100 is. I'd personally stick with the 240 or 300, but that's just me. If you're thinking piston slap, and that is the case, I'd swap to the 300 and sell the 240 as is or rebuild that 240 and sell the 300. You could probably even do better doing a TBI/CFI setup as far as power, economy, etc. All depends on what you want, though. I'm guessing your FE in the garage is a 390?

 

Have you ever seen the videos on Youtube for the F2000? To a lesser extent, that's what I'm after. I'm only thinking piston slap in the first minute or two of the truck being started on colder days; it's a completely different noise. And unfortunately, no, it's a 360 or I'd be high on getting it going. Planning on a 410, when and if I ever get my tax refund.