1981 straight six manual 4x4 project

The reason for the different timing, manual vs. automatic transmission. A lot of vehicles were that way for years so they wouldn't spark knock if they were lugged down in gear.

85lebaront2 wrote

The reason for the different timing, manual vs. automatic transmission. A lot of vehicles were that way for years so they wouldn't spark knock if they were lugged down in gear.

Thanks. At least I know why it was done, but wow it ran like garbage at 6*. Gary, even though I set it at 10* it was actually sounding better the higher I went (to a point). I might try giving it a little more. I can bring the timing light in case the altitude changes cause knocking but if it is safe to run it that high I will give it a try.

For operation mouse I think I'm going to have to remove the AC condenser and heater cores, blow them out with compressed air and wash them under running water. Then vacuum and wipe out the housing boxes with bleach water. I already washed out the upper ducts but I might do it again just to be thorough. My suspicion is that there is still mouse pee and feces in the fins of the AC and heater cores and that is where most of the smell is coming from. Whatever it is I have to find it. It is disgusting and unsanitary. Hantavirus comes to mind... I will probably get another blower motor to replace the eaten one, but not before the trip. I just don't have time and it seems to be working okay.

Well, I better get back to it, thanks guys for the info and advice! 🙂

I believe you said it is a 1986 carburetor, does it still have any of the feedback carburetor stuff hooked up and if so is it functional?

Since you have a 1981 truck, it should still be Duraspark and just time it where it runs best.

Bill - I think it is a '68 carb.

Jonathan - If it doesn't knock/detonate it'll be safe.  And your ears are much younger than mine so you'll probably hear if it pings, which is earlier than true knocking/detonation.  But, as you go down in elevation the actual cylinder pressure goes up since there are more air molecules in each intake stroke.  And higher cylinder pressure brings in pinging and then detonation earlier.

Here's an interesting read regarding detonation, engine timing, combustion chamber design, etc: http://www.contactmagazine.com/Issue54/EngineBasics.html

As for Operation Mouse, that sounds like a good plan.  Somewhere there's residue that is causing the smell, and your plan should solve that problem.

Thanks Gary, luckily I still pass my hearing tests with flying colors so I should know if it starts to ping.

The carb is a junkyard take-off of unknown origin. I had to file the holes in the base to make it fit the '68. But it's an early one, no bowl vent...

My ears aren't what they used to be, as Scott is the one that heard Big Blue pinging when we went after Huck.  I was able to hear the detonation, just not the pinging.  But a slug of 91 octane on top of the 87 helped that a lot.

As for the carb, I didn't realize Carter made a side-draft carb.  

You know how those damn Y series Carters are, can't make up their minds, you have YF, YFA, YH and YS that I know of, maybe they made a YU?

Thanks Gary, my phone app fixes the photo orientation, but assigns the same file name to all saves in the camera roll. When I upload to Nabble it just inserts the first photo with that file name over and over... I need to download more apps and find one that does not do that but I have not gotten around to it. When I shoot pictures specifically for the forum I try to remember to always shoot in landscape so that does not happen 🙄. I know, I know, it's lazy... just like that carburetor.

Operation mouse seems to be a success. Most of the offending material was urine soaked dirt packed into the fins of the AC condenser. Both AC and heater cores were removed, blasted out with compressed air and soaked in 10% bleach water all afternoon. The thick foam on the heat/AC door had to be scraped off. Too gross. I know the thick side was probably put there to insulate the heat from the heater core while using the AC, but it had to go. I can glue more foam there later and/or do the hot water shut off mod if it's a problem. Everything was scrubbed with bleach water and the odor seems to be gone. I get a faint whif here and there (probably from all the foam doors and foam seals in the housings) but I trust it will disappear with use.







I removed the sintered steel exhaust flange gasket and replaced it with a conventional one. I just could not get the steel one to seal correctly.



I emailed David about where he runs his timing, and tried his advice. I believe mine may behave a little differently because I am still running DSII ignition. I tried advancing it from 10* and it did not ping. However, it idled rougher and did not seem as good as it did at 10*. I also tried hooking the distributor to manifold vacuum and that was pretty much disastrous. It ran rough as guts and did not like the extra vacuum at all. Granted, I was not expecting to mirror David's settings as I am at 3,200' elevation and my set up is very different. At the end of the day I couldn't improve upon the results of 10* and Venturi port vacuum advance, so that's what I put it back to. My dad was amazed, he said that was the best running straight six he had ever heard.

The engine is so quiet and smooth that I am now hearing other noises that were masked before. There is still a lifter tick but it seems that it may be getting less. What is more obvious is a knock that sounds exactly like a diesel. This was worrisome at first, but I am 99.99% sure it is the transmission input shaft and associated gear noise. I went under the truck to retighten the exhaust flange after warm up and it was definitely loudest right at the front of the transmission and bellhousing area. As I drive the truck I hear way more gear whine than engine noise. I'm sure it's always been there but I couldn't hear it hooked up to that rowdy diesel. Plus I have no carpet in the '81 so the noise comes right through the tunnel cover. I guess if I'm straining to hear the engine over some subtle gear box noises that is a good thing.

One more day of truck stuff and packing... I'm almost "there". I've practiced my T-case low range shifts and I'm liking the 1-4 Lo then double clutch and continue in 2 Hi. That will get a mountain rolling with no high revving or beating on the clutch. The close ratio trans is going to be awesome for towing!

Apps are cheap, but I use Photoshop Express on my phone.

Yikes!  That A/C system was GROSS!  I'm glad you took everything apart and cleaned it, for your health's sake.  And, I'll bet I know how filthy you felt when doing all of that as Huck was also that bad.  Just working on him initially would almost cause me to retch.

As for the engine timing, if it works then it must be right.  And you can't really use David's numbers as his system is quite different than yours.  Different centrifugal advance and different vacuum advance, as well as a different carb that is quite lean, and that makes a difference is how much timing it'll accept.  So the only way to tune it is as you've done - play with it until it works best.  And, by the way, you really don't know for sure that your timing marks are correct unless you check the damper's mark against TDC.  So, you may have more than you think, but what you have works, regardless of what it is.  Well done!

On the noise, sometimes the pilot bearing causes noise - either in the pilot bearing itself or, more often, the input bearing on the transmission.  A worn pilot bearing allows the input shaft to be positioned slightly differently each time the clutch is used.  So if the noise is different after using the clutch then it might be due to a worn pilot bearing/bushing.

And I'm glad you are getting the shift out of low range down.  As you said, you should be able to move a mountain, and once you get that mountain rolling the close-ratio tranny will let you keep it moving smoothly.  

As most of you probably know, I took the ’81 to Death Valley over the holidays. I pulled our 1960 Streamline travel trailer, then unhitched and did some back country exploring. It was a really neat trip, and I am thinking I will share some of that via an off-topic travelogue thread for those who are interested while keeping the truck related issues here…
 
I wish I could say that my journey was problem-free, but unfortunately I had my share of misadventures.
 
Electrical gremlins. Lots of gremlins. Before I left I had low battery/bad battery symptoms. I had the charging system tested and was told it was all good but the battery was weak. I bought a new one (group 24-F), charged the other one and tossed it in the bed as a “spare”. Glad I did that because after a long trek out to the Racetrack playa my headlights went dim and the engine stalled just seconds after I found a safe place to pull over. New battery was dead as a rock. I put in my spare battery and swapped out the voltage regulator and drove the remaining 57 miles back to camp. The ammeter was acting crazy, showing nothing, then pegging to “C” or the half way hatch to “C” while revving. I’ve never seen more than a twitch out of these gauges.


 
The next day I checked the alternator wiring and the main “batt” lead had crispy insulation, but it was not freshly melted, it had been that way for a while. I didn’t like the look of the wire or terminal so I spliced in a new piece from my toolbox. This seemed to stabilize the gauge, but it still does not seem to charge at idle. After coming to a stop then revving up, the ammeter shows a strong charge. I think the alternator is about done. Mine has a two prong plug-in, but I’m not crazy about the quality of those connectors. I may replace it with one that has regular threaded lugs on the back.
 
Less than 30 miles from home I lost my emergency flashers. Still have flashing turn signals but no emergency flashers. I also lost my brake lights. I was the slowest thing on the road and didn’t use brakes much but obviously that needs fixed. I replaced the high beam foot switch but I was still having my headlights cut out when using the high beams. The tach died before I left, but after messing with the alternator it started working again… about 90% of the time anyway.
 


Besides electrical gremlins my other major issue was engine stalling and cutting out after getting a tank of bad gas in Furnace Creek. After seven more partial fill-ups from other sources it finally went away, but it was quite unnerving especially since I was not 100% sure that it was “just” bad fuel. But I had two spare carburetors with me and 10 gallons of known good gas in cans so I kept going…
 
One morning we were headed to Beaty for fuel and I smelled antifreeze. There must have been a heater core shut off installed at one time that was replaced with a barbed union. A plastic barbed union that decided to collapse. Fortunately the primary hose was long enough to reach the heater core when routed over the air cleaner snorkel. I lost about 2 gallons of coolant but I had spare coolant and water.
 
This hose routing ended up biting me in the behind. On my way home I noticed it wasn’t idling very smooth. By the time I got in to Kingman it was flat out running like crap and would not idle at all. I managed to get it parked out of the way and have a look. The pressure on the snorkel plus LOTS of back road vibration had worked the four screw loose that join the carburetor base plate to the carburetor bowl assembly. It was just wobbling around and creating a colossal vacuum leak. Fortunately it was a pretty easy fix for a guy who brought extra carburetors with extra screws on hand. Still it was no fun at 11pm and 37*F.


 
So now that I got all that nastiness out of the way, let’s talk a little about how it performed. Fuel consumption was not great, but sure could have been worse. After the carb change, just running about empty I was getting 15mpg. I was hoping for better with the 3.00 gears but I never got a “highway” run either. With the (quite heavy) 28’ camper attached it was getting 10mpg under the worst conditions you could throw at it. High winds and steep uphill grades. I was in 2nd and 3rd gear almost the whole way to Flagstaff. Once the terrain became a mix of uphill downhill I was getting 11-12. Note that this was very slow going. The fastest I went with the camper was 55-60mph  on the dead flat. More often I was sub 50mph in 4th, 35-ish in 3rd, and 25-ish in 2nd. The straight six can do it, but it turned the drive to Death Valley into a 2-day event to get there and all day + all night coming home. While in the park, the fuel consumption was still between 11.5-13.5, but a lot of that was slow, rough, steep back roads. For example the Titus Canyon run is 27 miles long but requires 3+ hours. Much of it is best done in low range on the transfer case. I didn’t expect great mpg numbers out of that kind of driving.
 
I will say that the close ratio diesel T19 is an AWESOME gear set to have with the straight six, and an AWESOME gear set to have for backcountry driving. For towing the gear jumps are much kinder than the wide ratio 3 speed + granny models. After all the worry over the start out gear I found that 1st gear starts were fine most of the time. No low range needed unless it was up a hill or I needed more control.  4th to 3rd is seamless. Jump to 2nd left me wishing for a 2.5, but still not bad at all. And for back country, I found myself loving the four close gears while in low range. I thought they would be redundant since they are all so low but they are totally not. You always have the ideal gear for any speed you want to travel based on what the road roughness will allow. I just love it, and it decides my close ratio vs wide ratio dilemma on my diesel build. In the past I always shrugged off the popping out of gear downhill thing. On this trip it drove me nuts. Combined with the rattling noises it is obvious I will either have to rebuild or find another one. It also does not shift as smooth as I remember, but perhaps it does not like the oil I used this time.


 
Brakes. The hydroboost is fantastic, but I am finding out that the pads and shoes get hot pretty easily. There is a 10 mile 9% downgrade into Panamint Springs from the park Even empty (and ~not towing) my brakes were pretty hot by the bottom. Ditto coming back into the park from Emigrant pass down to Stovepipe Wells. My pads and shoes are carbon fiber semi metallic. Maybe there are better ones? I still had stopping power but I definitely smelled them burning and they were fading some. I checked my rear shoe adjustment just to be sure they were not dragging and all was free.

Seats. After spending many long days in the saddle (both interstate and back roads) I have to give the captain chairs two huge thumbs up, and say it is one of the very best things I have done to the truck. The jury is still out on the seat pan mounting system, but if any of you decide to go that way, you will definitely want the 40/20/40 receivers. The Bronco style don't fit right and shove the belt up into your neck.

This update is already too long, so I will leave it at that. Sorry if my spelling is sub par, I am working with a shattered phone screen.

Welcome back, Jonathan! Your write-up is great... thanks for sharing with us!

1986F150Six wrote

Welcome back, Jonathan! Your write-up is great... thanks for sharing with us!

Thank you David, and thanks for all the information and advice that helped me get the truck to a point where this trip was possible 🙂

I would say your fuel mileage is very decent considering. We always want more, but you were in bad conditions and the engine did fine. Your electrical snafus are frustrating. Your alternator may have worn brushes. They will cause it to charge sometimes and not others. Congrats on making the trip.

A great write up, and the photos are fantastic. Thank you!

Jonathan!  Wow!  Those pics are AWESOME!  Well done.  

As others have said, that MPG is good.  Maybe the 15 isn't what you'd hoped for running light, but it is good and I'll bet can be improved with some ignition tuning.  And 10 pulling that trailer is excellent.

On the electrical problems, I vote for a 3G swap and that you change out a bunch of the wiring at the same time.  That should solve a number of problems.

And on the carb, I've often wondered if the nuts can be loctited on.  So many have prob's with them working loose, so surely there's a simple solution.

Brakes: I have ceramic pads for Dad's truck, but I don't know if they are better/more fade-proof than metallic ones.  Otherwise, I'm not sure what to recommend.

Tranny: Glad the gears worked so well.  Given that, I'm not sure a ZF5 would be the ideal as I think the spacing on those gears is wider than what you have.  However, there are diesel gears for a ZF5, so maybe you could use them and have a ZF built?

Anyway, glad you are home and didn't have too many problems.  And I'm looking forward to the travelogue.

When you run manifold vacuum . .you must make sure you are setting initial timing with the vacuum line unplugged from the advance cannister and plugged so there is no leak. If you then set initial, to say 6 BTDC and afterwards hok the line back up, your idle will go very high. That is normal, adjust your idle speed then. Also, the 300 can be a bit tricky to set initial timing, marks can be confusing on the balancer and engine, etc.

Gary, I had exactly the same thought on the carb. I plan to put new gaskets in it and assemble it with mild thread locker. I don't see any reason why not.

Pete, I didn't try 6*, but I did try 8* with manifold vacuum and it did not like that. But if timing is the key to getting better mpg I will play around with it. First I need a good "highway" run to see where I am at under favorable conditions. I can't complain about 10mpf towing the camper since my 400 CID truck drank that much running around empty.

On the 3G upgrade that is a good idea. I need to shift my focus to the diesel and not do toooo much more with this truck, but the current alternator has to go regardless. If it's not too big a project I "might as well" make it 3G. (That phrase gets me into trouble!)

From what I am reading ceramic have less dust and better performance but semi metallic handle heat better. But only slightly better. Full organic are the ones to watch out for with heat and fade.

There has been discussions about putting the close ratio ZF gears in a small block case but it has never been done to my knowledge. The input shafts are different between the two and there is a lot more to it than just a case swap. At this point it's above my pay grade, but if I rebuild my diesel ZF I will learn more.

One side note is that for back country exploring I really regret not upgrading to a bigger fuel tank. Gas prices in the park were very high, with a lot of distance between everything. Throw in that Furnace Cree gas was bad and my one 19 gallon tank made things complicated and stressful even with the two 5g's in the bed. My diesel is getting a 38 spectra for sure!

Jonathan - As Pete is saying, the order of setting timing is:

Initial: This is usually somewhere between what the factory calls for and where it causes the engine to kick back on starting.  This is what the engine runs on before the mechanical kicks in, which happens  maybe just a bit above idle, and it impacts startup, idle, and off-idle.

Mechanical: Somewhere above idle the mechanical starts adding advance.  Each calibration code is different, but the factory didn't leave a lot of change on the table, so it may not be too bad/slow.  Anyway,
 you usually want all of the mechanical advance you can give it without pinging or detonation.  However,
 if you detect power loss you've gone too far.

Vacuum: Once the other two are set you can connect the vacuum and start working on this - but not before.  If the can has adjustability it will be via an allen wrench inserted via the vacuum port.  And what you are doing is to move the operating window of vacuum up or down in the range.  For instance, if the current window is from 12" to 18" of vacuum, you'll be able to move that 6" range up or down.  And you want as much vacuum as you can get w/o pinging, so you want to take the range down until you experience pinging and take it back up to where it goes away.  And pinging will happen under light throttle and a heavy load/tall gear.

The 3G conversion writeup is here: http://www.garysgaragemahal.com/3g-conversion.html

And I really think I'm going to like that Spectra 38 gallon rear tank on Big Blue.  Just hope I don't get 38 gallons of bad gas though  

What do you mean didn't like it? I have built many engines and tuned them this way, never a one to stand up and say "I don't like this "  :) So what symptoms are you seeing? And when?

Good point Pete! I should be more specific instead of anthropomorphizing. When I hooked my distributor up to manifold vacuum it caused a very rough idle, and greatly reduced power while driving. The idle was much faster (higher rpm) than when hooked to carb vacuum, yet so rough it would barely stay running without some throttle. I am not familiar with the differences between initial timing and mechanical advance and vacuum advance. I've usually just disconnected and plugged the distributor vacuum and set the timing with the light at idle. Obviously I need to educate myself on timing and carb tuning. It seems to run well where I have it, but that is just a subjective feel, I am sure there are gains to be had by using better methods.

Gary, I guess that is one drawback to a large single tank. If you get bad fuel you get a lot of it. However I think one would be equally likely to purchase the same amount of bad fuel in two 19 gallon tanks if so equipped. I do know that it hurt to buy gas at $4.09 per gallon inside the park when Beaty and Amergosa Springs had it for $2.45!