A buddy of mine just got a 85' F150 freebie from his grandfather. Its got a 302 in it as well as a ( Ford metric transmission? ).

It's in need of some serious help here. I'll take some photos of the engine compartment at work tomorrow so you have that whole visual effect and post in my gallery.

Right now its running ruff. We have replaced cap & rotor, plugs & wires, fuel filter and a couple of noticeable dried vacuum hoses and connections. Still need to adjust the timing. Taken timing light in tomorrow. Any other suggestions as to what else to look in to adjusting? We dont want to just let the thing nickle and dime him.

Exhaust system has I'm guessing a smog pump of some sort that which was attached at one time. But has since locked up and just adding extra weight. Midas gave a estiment of $1528.00 to replace like 3 sensors, both cats and a muffler. Another shop down the road says they can put Flowmasters on it for $400.00 with out the cats. Planning on going with the Flows


TailGater_73F100
Savannah, GA

 

Fuel Injected or Carb'd?

I'd look at doing a compression test before going much further with expensive add-ons like exhaust.

The engine needs to be at operating temp, pull ALL spark plugs(and the coil wire so you don't zap yourself) and then install the compression tester into each spark plug hole, hold the fuel all the way down(remove the fuse for the fuel pump) and crank the engine over for about a 3-5 second count. Mark down all compression values per cylinder number. Repeat the process, this time squirting some engine oil into each cylinder, spin the engine to clear excess and spread it around, install the compression tester and mark down the values again.

The first step is called a dry test, the second a wet test.

If the values differe from step one to step two(step two noticeably higher) you have leaky valves. If they only vary slightly, the rings are slightly worn, and/or the valves may be just starting to leak.

You need to compare compression values with the stock rated values, and decide from there.

An average gasoline engine(varies a bit from one to the next) will generally produce about 130-150psi on the gauge.

The main thing you're really looking for is even wear. The highest compression cylinder should not be more than 5lbs higher than the lowest compression cylinder.

Another thing to watch out for. Any cylinder under 100psi will foul spark plugs quickly, and is a good sign the engine needs to be rebuilt.

If that checks out, removing the smog crap and doing a few performance mods is worth a few bucks, as long as you go through the entire truck and make it sound to drive.

 

Great post RR4E...

Id like to add that if it has sat for a long time you may have other issues that are contributing to the poor running issues (bad gas,seals being dry and cracked, etc.)

 

RR4E - I thought the wet test was checking the rings, not the valves? Idea being that the oil helped to fill gaps between the rings and cyclinder bore.


Good Luck,

Lee

 

A manual might be a good idea as these trucks have lots of individual parts to the spark and emissions systems. One wire on the distributor-mounted module (yellow one with a connector clip) must be disconnected in order to set timing, then reconnect it and check for advance. Bad sensors may be the cause of no spark advance.

-Smoky

 

yeah but definatley do a compression test b4 you go any further, make sure your working with usable equipment. If the engine sucketh, then what's the point of setting the timing and all that if it's still gonna suck when you're done. R4E's got a really good system for getting down to the bottom of the engine.

Personally I go by the values that I'm getting on the dry test and a percentage. Anything less then ten percent difference is acceptable for me(i.e. the average is 150 and one is at 155 is ok, but one at 165 is bad), but you may want to check what he's telling you though, seems to be more in depth.

 

Thats AWESOME.....

So Shakespearean of you.......

 

Well he didn't leave the truck up at the shop last night. He decided to drive to house and rode in with another Ford owner. So it looks like it might be a few days before I get to get under the hood.

RR4E: Its a carb with some carzy electric lookin stuff around it and a *** of vacuum lines. What a great post on compression testing. Where would I be able to find the compression values at?

Icicle: It does have a hole in the gas tank just above the 3/4 mark. Have mentioned to replace or repair.

SmokyOlFord: I mentioned that it would be very wise to pick up atleast a haynes manual so we have atleast a shot at it. Thanks for the advice on the timing. BTW I keep a copy in the house and one in my truck.


Thanks for the advise so far. I will keep yall updated.

TailGater_73F100
Savannah, GA

 

There are many things that can attribute a poor running condition.

Whenever I look at a potential "new" to me vehical, I ask the current owner if I may check it over. Things I look at first, compression. Over-all condition of the exterior of the engine(is it caked in oil and dirt?).

I also like to see what the exhaust looks like once the engine is warmed up and have someone punch the throttle a couple of times to check for excessive smoke. Giving it a listen with a stethescope is never a bad idea, and if you really want to go in-depth, grabbing a decent sized sample of the oil that's in it and having it analyzed really goes a long way in finding out what's potentially wrong with it.

There have been more than a few "good deals" I've brought back and parked them where I found them, and continued searching.

 

The wet test won't really help seal the rings. If they are worn excessively or cracked, oil will pass by them very quickly.

If you only notice a slight increase in compression(between 2-5 lbs give or take a bit), this would indicate slightly worn rings. A more noticeable difference in compression(10+) is a good indication that your valves are leaking.

Valves leak mostly due to large amounts of carbon build-up, or from recession into the head, and lastly, if they are bent(but this is also usually indicated by a loud clatter as well).

If you really want to verify the valve situation, an added test would be to attach a hand held vacuum gauge to an un-used vacuum port on the intake manifold, or a vacuum tree. Watch the needle. If it flutters erratically, your valves are definitly leaking. If it has a slow, steady bounce, one cylinder has a leaky valve or a worn cam lobe. If it holds steady things should be good to go. Along with that, adjusting the idle/air mixture screws on the carb to bring the vacuum up to the max available amount is a good idea. Generally I set the carb to 2.5 turns from lightly bottomed out. Start the truck(at operating temp) and then adjust one at a time until the vacuum reaches the highest point, turning the screws in roughly 1/8 to 1/4 turn back inward to avoid a lean-burn condition.

My experience with all of this comes from being a born and raised farm-boy, then going on to be a long haul truck-driver who maintained his own truck as well as a few others in the fleet. I've always worked on my own vehicals.

I also spent a number of years working on motorcycles/sled's/atv's for a living. One shop I worked for did a lot of performance work. We had our own boring bar, milling machine, flow bench for head porting, metal lathe, etc.

 

If it were me, I'd simply phone a Ford dealer, or an engine rebuilder and ask.

Some repair manuals actually have tables with that information. My current Haynes manual does not, but I remember my Chilton's manual for a previous truck having them.

Off the top of my head, a 302 of the 85 vintage would have likely had around 8 or 8.5:1 compression, which should put it in the ballpark of around 140psi stock(could be give or take 10psi)

 

Hop over to the the Windsor forum and you can probably get some exact answers on compression values, I would say with an older truck like this if you get readings in the 120s (dry) your in excellent shape, consistency is the key more so than the number itself (unless its real low).

The crazy looking stuff is EGR and computer related, your truck is actually EEC-IV controlled, even though its carbed.

 

Ford doesn't give PSI specs, they simply state that "The indicated compression pressures are considered normal if the lowest reading cylinder is within 75% of the highest" The shop manual then proceeds to give a chart for quick refrence.

 

Hey was able to get some photo's of it. Have a gander at my gallery

Tailgater_73F100
Savannah, GA

 

25% difference is a bit much if yu asked me, but hey, they get paid the big bucks to say that.