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1981 straight six manual 4x4 project

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Ford F834

Re: 1981 straight six manual 4x4 project

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PetesPonies wrote

Running a quart of transmission fluid mixed with your oil will clean the lifters. I woulds drive it about 50 miles, then drain.

I actually thought about doing that before I drained it this time, but he I'm a little chicken to do it right before a long trip after what happened to David. I didn't want to break a bunch of crap loose and clog the screen. If it keeps it up I might do it when I get back and can drive it around close to home.

SHORT BED 4-DOOR DIESEL: 1986 F350 4x4 under construction-- 7.3 IDIT ZF5+GVOD

STRAIGHT SIX 4X4: 1981 F150 2wd to 4x4-- 300 I6 close ratio diesel T19, hydroboost brakes, Saginaw steering

BIG F: 1995 F-Superduty under construction— converting to 6.9L IDI diesel ZF5+DNE2

Gary Lewis

Re: 1981 straight six manual 4x4 project

Administrator

On the heater, pull the blower motor and look in there. That's where lots of stuff goes, and the mice can get to it if the blend door is open/broken. Plus, it is easy to get to in order to clean out.

As for the oil, I agree about not doing the clean-out on a long trip. But 45 psi at idle is a lot. So, it looks like the engine is in good shape, although you don't know about how dirty things are. Best to play it safe.

And I like the wheels and tires. Big Blue's are wide enough that they can't really sit in like yours w/o rubbing on many turns, but yours fit nicely. And those E's should be good for where you are going.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

1986F150Six

Re: 1981 straight six manual 4x4 project

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In reply to this post by Ford F834

Ford F834 wrote

"I checked the speedometer ~before the bigger wheels and I was only 2-3 mph slow, and 1 mile on the odometer was 1.1 actual miles. This will obviously be worse with the bigger wheels, but still useable for the time being".

Based on your posted numbers, the odometer is off [low] by 10%. The gas mileage will be low by 10% as well.

"The truck still runs rich and stinky. I have not filled the tank yet, but it's looking like my mpg may be really terrible. I'm actually thinking of stealing the carburetor off of the 1968 to see if it changes. I tried leaning out the carb that is on it and it didn't like that very much".

My initial 2 tanks returned 11 and 9 mpg. Perhaps your sending unit is whacko and drops in a very nonlinear fashion. What vacuum does the engine pull @ idle? Have you tried advancing the timing? Have you felt the hubs after driving to make sure the brakes are not dragging?

Ford F834

Re: 1981 straight six manual 4x4 project

Administrator

David,

I will report an approximate mpg when I fill the tank. Right now there are a lot of unknowns. The sending unit is new, but it does float around a bit and seemed to be reading low when I initially filled the tank.

I don't happen to have a vacuum gauge, so I don't know what it is pulling at idle. I'm drawing the distributor advance from a port on the passenger side of the carburetor base.

I need to time it again with the timing light. After I deleted the vacuum booster it ran like crap. I reset the timing by ear, but it would bog and almost die when I would goose the throttle, so I backed off on it until I got decent response throughout. That's where it still sits, but I don't know where that is in degrees...

I really feel like this carburetor may have problems. Sometimes it runs extremely smooth, other times it stutters and stumbles quite a bit, and it is way harder to start than it should be (unless hot, then it fires at the touch of the key). I know the carb on my 1968 isn't perfect (just a junkyard take-off) but that truck has run pretty well for me so I may swap it on and see if anything changes.

Gary Lewis

Re: 1981 straight six manual 4x4 project

Administrator

I think I'd swap the carbs if you know the other one is good. Can't hurt.

Gary, AKA "Gary fellow": Profile

Ford F834

Re: 1981 straight six manual 4x4 project

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In reply to this post by Ford F834

I filled the tank today and using the odometer correction factor that I got from the GPS it looks like I ran 12.5 mpg. That's not as horrible as I feared but nowhere near where I want it either. Granted most of that was short trips, start stop driving and a lot of warm up idling, so I'm not discouraged. We will see what it does with the other carb and timing with the light.

I've been driving it around while preparing for our road trip and the more I drive it the more I like the gearing. The start out gear is just fine, I just have to slip the clutch a bit more than I'm used to on my other trucks. The closer ratios of the diesel T-19 are just what the doctor ordered for the straight six. I thought the taller tires would make it worse, but if anything they handle better. I just love this whole set up.

While cleaning and moving furniture in our camper I managed to break the large front window... doh! Even with six glass shops right in town no one could cut a piece of SS on short notice... really? I had to beg one guy to do it for me this morning (Saturday) so that I can get this show on the road! Luckily I have some flexibility in my vacation schedule so we still have plenty of time.

Gary Lewis

Re: 1981 straight six manual 4x4 project

Administrator

Glad you got the window fixed. Bummer!

But, 12.5 MPG on gas that may have been sitting around and in start/stop driving isn't terrible. And the other carb may help it.

As for the gearing, glad it is working. However, do you think you'll need to change the diff's? Or will starting in 4lo with the trailer do it for you?

Gary, AKA "Gary fellow": Profile

Ford F834

Re: 1981 straight six manual 4x4 project

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Gary Lewis wrote

As for the gearing, glad it is working. However, do you think you'll need to change the diff's? Or will starting in 4lo with the trailer do it for you?

I think 4Lo starts for towing will work for me... but I will report back after I actually tow with it that way. I can either get it rolling in 1st Lo and jump to 1st Hi, or I can shift 1-4 Lo then jump to 2 Hi for a nice close 7-speed gear set. I'll be shifting like a semi driver but I won't have to rev much past the torque peak... ever.

I don't really want to change diffs if possible, as that will hurt the overdrive end of things and I'm liking where the shift points fall as-is. I'd have to go down to at least 4.10's to make 1st a stout towing gear.

If this set up does not do it for me then I might consider a ZF-5 and give up the close ratios... but the long term plan is to tow with the diesel, not the straight six. As long as it's manageable I will probably leave it alone, or *maybe add an overdrive if I feel it crying for one. I can't say this enough... i ~really like the way the truck drives and handles just the way it is. It has exceeded my expectations and the 4Lo starts are just for towing heavy. 1st gear final ratio is 12.06:1 so I just need the TC Lo range to save the clutch and avoid lugging. I'm used to 12.63:1 2nd gear starts in my 4.10 trucks with T-18's, and only rarely needed 1st/Lo. This truck drives around town beautifully and the tach reads 1,000-1,200 most of the time 🙂

PetesPonies

Re: 1981 straight six manual 4x4 project

The YF, if that is what you have . . has a design element I don't like. The accelerator pump is such that if the diaphragm rips( and they all do eventually) not only does the acceleration circuit not work, but now the carb will be overly rich. This is because fuel will actually drip into the venturi area from a rip in the diaphragm. If you ever have a rich problem, it's something to check for sure.

Pete's Ponies
Mustang RUSToration & Performance

1982 F100 Flareside
1983 Bronco

Gary Lewis

Re: 1981 straight six manual 4x4 project

Administrator

Jonathan - You have a plan and I'll bet it'll work. When you get the diesel going you won't need to start in low range, so don't gear for towing.

Pete - The old leather skirts on the accelerator pump pistons do tend to crack. Even the synthetic one on Big Blue's Eddy was bad when I got it. So, that is a good place to look.

Gary, AKA "Gary fellow": Profile

Ford F834

Re: 1981 straight six manual 4x4 project

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In reply to this post by PetesPonies

PetesPonies wrote

The YF, if that is what you have . . has a design element I don't like. The accelerator pump is such that if the diaphragm rips( and they all do eventually) not only does the acceleration circuit not work, but now the carb will be overly rich. This is because fuel will actually drip into the venturi area from a rip in the diaphragm. If you ever have a rich problem, it's something to check for sure.

Thanks. I do have a YF and that is a good tip. The carb is a fresh Napa rebuild that came with my parts truck but that means nothing to me. I've been round and round with rebuilds and usually the core got turned because it was worn out too badly for a rebuild kit to do any good. I owned a '72 Comet for about two years and went through 21 (yes, twenty-one) parts house warranty carburetors. Some sprayed gas all over the engine right out of the box in the parts house parking lot. Had to go back in for my old one just to not be stranded. So my faith in rebuilds is not there. I'm going to try the one from my 1968, and if I'm not happy then I will try to get one from a company in Canada that David suggested. They actually bush the shafts and rebuild them to last. If that does not work then it's aftermarket intake time and bye bye one barrel (but I hope not).

Gary Lewis

Re: 1981 straight six manual 4x4 project

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I vote for this. (Dad used to say "Misery loves company".

)

Gary, AKA "Gary fellow": Profile

Ford F834

Re: 1981 straight six manual 4x4 project

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You have a point. I tend to want to stay as simple and mechanical as possible, but those parts are readily available and probably cheaper than a fancy aftermarket intake + carb. I just hope I can get a good working YF and run it... at least for now.

Gary Lewis

Re: 1981 straight six manual 4x4 project

Administrator

You are going where, which is at what altitude? (282') And you work where, which is at what altitude? (7000') And you are going with me to the North Rim at 8000'. You expect your carb to automagically adjust for that?

It is one thing for folks like David who lives at 548' and sometimes drives to Skiatook where it is a whole 646' above sea level. But, where you drive has got to change the air fuel ratio significantly. So, my suggestion would be to start acquiring the parts as you frequent the salvages. Then, when I get proficient at this......

Seriously though, we got lucky that Ford EFI'd the 302 during the Bullnose era. And then they continued to use the same high-pressure pump on all of the vehicles, from the 300 to the 460. So, we can use the 302's fuel system and sending units, and both the EFI and our gauges will work.

Gary, AKA "Gary fellow": Profile

PetesPonies

Re: 1981 straight six manual 4x4 project

I just had the YF on my '71, try and leave me stranded the other day. It was something that had gotten into the seat and the needle wouldn't close enough. Not sure what it was, couldn't identify it. Not rust, was silver, but not metal. I added another filter and dared it to do it again :)

Pete's Ponies
Mustang RUSToration & Performance

1982 F100 Flareside
1983 Bronco

Ford F834

Re: 1981 straight six manual 4x4 project

Administrator

In reply to this post by Gary Lewis

I've used my trucks from Phoenix (a few hundred feet elevation) up to snow bowl on the San Francisco peaks (9,000'). I'm sure the singular carb setting isn't ideal, but I didn't notice any huge problems with performance or mpg. If I'm hauling heavy at altitude I do notice some pinging with the 240, but haven't noticed it with the 300's that I've had (different CR?). I know EFI keeps things more optimal, I'm just not sure if I'd find the juice to be worth the squeeze. Maybe if I drove an EFI I'd never want to go back, but my main beef with carbs has been the perpetual slight stutter and stumble no matter what you do to tune them.

I noticed the effects of altitude more with the diesel because I could ~see it 🙄

Gary Lewis

Re: 1981 straight six manual 4x4 project

Administrator

I've driven from here to the South Rim (7000' for the others), towing, with a carb and didn't have a problem, although the engine was seriously down on power. But once when headed up Pike's Peak with my '72 F250 I lost enough power that we had to drop the motorcycle trailer we were towing in order to make the climb.

The rule of thumb is to go 2% leaner per 1500' of elevation change. With us at 750' and the North Rim at 8000' or more a carb would be about 10% too rich. If the tune was lean to start with you might not have a problem, but if spot-on then the extra 10% probably would be very noticeable - both in power and in the exhaust.

Gary, AKA "Gary fellow": Profile

Nothing Special

Re: 1981 straight six manual 4x4 project

I took my '85 F-250HD up to about 14,000 feet from my 750' home elevation. As I recall there was an idle mix adjustment on the stock 2 bbl which I tweaked to get it to start, but I really didn't have any trouble other than that. Not saying it was running right, I'm sure it was extremely rich (no cats on that truck so I didn't need to worry about that), and we just had the truck loaded with 2 people and a weeks worth of camping gear, so not much load. But you can get by with a lot for a short time if you need to.

Bob
Sorry, no '80 - '86 Ford trucks
"Oswald": 1997 F-250HD crew cab short box, 460, E4OD, 4.10 gears
"Pluto": 1971 Bronco, 302, NV3550 5 speed, Atlas 4.3:1 transfer case, 33" tires
"the motorhome": 2015 E-450-based 28' class C motorhome, 6.8L V-10
"the Dodge": 2007 Dodge 2500, 6.7L Cummins

Ford F834

Re: 1981 straight six manual 4x4 project

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In reply to this post by Ford F834

Woah! What a difference a carb can make...

I put on the carb from my 1968 truck and that was definitely the problem, or at least a problem. It idled way lower and the timing was drastically different (over advanced) compared with the old one.

I put the timing light on it and set it to 6* which is what the emissions sticker specified. The truck didn't like 6* very much. I bumped it up to 10* which was the other possible spec listed in the Chilton manual and it liked that much better. I don't know why some got 6* and some got 10* but I'm going with what works.

It still has a brief hesitation when I goose the throttle, but I don't have a vacuum gauge to check the carb ports. I tried a couple different ones with no change. I might try manifold vacuum if I can get the right adapter, but I don't usually drive by stabbing the throttle anyway.

After the carb change and timing, the truck runs smoother, and has way better response especially at higher rpm's.Before it sounded really awful at around 2,500... now it roars over 3,000 with ease and sounds healthy. It feels stronger while driving too, with better torque and pull throughout the rpm range.

After all the funny business I checked the cap and rotor and they were a bit toasted. I swapped in the cap, rotor, and wires from the '68. I checked the plugs also, and they seemed good. All were gapped pretty close to .042 and looked like this:

I traced and fixed a broken wire to the driver side low beam headlight, and pulled the blower motor to look for mouse activity. They have obviously been in there, although there was not much nest evidence. Tomorrow I will open the whole thing up and take care of business.

Because of the issues with the camper it's looking like we will head out Wednesday. I'm glad to have gotten the tune up stuff done though, and I'm hoping for better mpg results.

The speedometer is reading a bit lower than before the bigger tires. It's pretty close up through ~30ish, but 55 on the dial=60. On the odometer 1 mile = 1.165 actual miles. If I'm 16.5% low, I wonder if I could make a metric speedometer read as miles by going ~UP in driven gear tooth count? It might be one way to get it numerically correct even if the units are wrong

Gary Lewis

Re: 1981 straight six manual 4x4 project

Administrator

I'll bet the carb makes a big difference in MPG if it made that much difference in power and driveability.

On the timing, if it can handle 12 or even 14 degrees without kicking back on starting or pinging I'd give it a try.

As for the speedo, that is exactly the way Big Blue's is - I have to add 5 MPH to whatever it shows. I need to see what I can do about that, but it didn't work very well at all when I got it, and lubing the cable made it nice and steady - but wrong.

The blower's squirrel cage doesn't look very good, and that may cause a balance problem. Anyway, if there was no nest are you going to have to clean the ducts out with a cleaner to get the smell out?

Gary, AKA "Gary fellow": Profile

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