[4676]

Hello.

First A Little Background on the vehicle in question:

76' Ford F-250 Highboy 4x4

4 Speed Tranny
Divorced NP-205 Transfer Case
Dana 60 Rear Dana 44(?? I am pretty sure) Front Axle
4.56 Gears With Limited Slip In The Rear
Stock Wheels (16.5") With Stock Size Tires

Misc Mods:
2 Generic KC Wanna-Be's Bolted To Front Bumper
Roll Bar With 3 KC Daylighters (one rear facing)
1/4" Steel Rear Bumper With 3/4" Hitch Welded To Frame
Cammo Paint Job Curtesy Of Krylon Spray Bombs
2.25" Exaust With Glass Pack Muffler (No Cat)
SunPro Mechanical Gauage Set Oil Pres/Temp/Amps
SunPro Tach

The Engine:

Original 300 i6
Non Egr
Rebuilt Carter YF 1bbl manual choke(From older model truck?)
6" open element air filter setup.

Now to the problems now that ive gotten all that out of the way:

I bought the truck off a small junkyard who used it to drag cars around with. The truck only has 133k on it and had not been licenced since 1982! When I first got it I had alot of fuel starvation problems which i tracked down to a defective pickup in the gas tank(Perhaps why it had been in a junk yard so long). Anyway I tuned it up new pcv valve, plugs wires etc, carb rebuild, belts hoses.. Replaced a couple broken brake lines(rear brakes where the only ones that worked) Got plates and insurance and tested my luck out on the road. I only paid $100 for the truck(WHAT A DEAL HUH?) Anyway the first 300 miles or so it ran good leaked a little oil but otherwise was strong and didn't smoke. Besides some stearing play and a rattling throw out bearing everything seem ok. One day when I got brave and decided to take it on my 50 mile one way commute to work, It started smoking real bad under the hood. No loss of power or oil pressure I still get 25/30lbs at cruising speeds. Anyway I am getting excesive oil and smoke blowing out my pcv system on the end that is supposed to draw air in. I have a new pcv valve and checked the vacumm port on the intake for clogging and everything was fine. I have to run with the breather element out of the rear of the valve cover to prevent oil from pushing out of all the seals. Which i still get alot of smoke comming out of the rear hole of the valve cover. I Had to run a hose from the hole for the breather element through an anti-freeze jug to catch all the oil that blows out to prevent more underhood mess. Still the engine has not lost power and does not smoke out of the exaust system. Could this possibly be a stuck ring from it putting around in a junk hard for 22 years and me taking it out on the highway? 60mph = about 3100rpm in 4th gear. Also right before this problem started I changed the oil The old oil looked like crap smelled like crap and was very thin. I replaced it with Havoline 20-50 and a new fram filter. I own a 91 f150 2wd with a 300 and 240,000 miles on it and have never had any problem from the engine, its never been overhauled and goes oil change to oil change without using anymore than 1/2 a quart and i change it every 5k and average 500miles a week. This is why I wonder if my problems with this truck can be fixed or do I need a rebuild?? 130k dosen't seem like much for a 300..

Also If I do rebuild this engine how do flat-top pistons and 4bbl intakes with perhaps a 600cfm edelbrock work on a 300? I've never been able to find anyone that has modified a 300 so I don't know if its worth the trouble? I catch a lot of flack from the 302 guys about having a 300 in both my trucks and it sure would be nice to be able to show them up without spending a fortune. Also i thought about swaping a dual exaust manifold setup of an injected 300 Any power gains there? On my 91 f150 I am running true dual exaust with 2" pipes thrush glasspacks, And no cat (No vet testing in my area and my cat...lets just say it fell off) which seems to have added some low-end tourque and improved gas mileage. Sounds kinda funny and makes alot of noise between 2000 and 3500 but it was well worth it. I've also flipped my air box over and cut the bottom out so I can get more air to the filter(Can't find a K&N kit for my funky 2 air tube to one air box filter setup). Can anything else be done to my efi truck to improve performance? Also it has a speed limiter which is very anoying on the interstate anyway to disable this? I have very high gears and a 5 speed and i can get it up to the speed where it cuts off in 3rd!.

Well I am sorry that I have asked so many things in one post but i have so many questions to ask and nobody I know messes with 300's. Any help would be greatly appreceated.

Thanks!

 

[953]

your PCV is working properly right?
it and its hose going to the aircleaner are open, and not stuck correct?

if so, you are having a blow by issue thats causing all the high and mass amounts of crankcase pressure. its to much for the PCV to handle, thuis it is also coming out the inlet.
i would do a cylinder leak down test on all the cylinders after you have run the truck and got it warn and see if you have major leakage on any one cylinder. leakage should not be more than 20%. listen to where the air is escaping to(though, you probably know its goinng into the crankcase, but checks the intake, cooling, and exhaust also.)

 

[BRONCOMANIA]

Re: 76 F250 4x4 300-6 Bad Blow-By Rebuild Or v8 Sw

aside from the good points burned bronco pointed out, how do you REALLY know its only 130K on a 76 and not 230 or even 330K?

sounds as if you definitely have a serious blow-by issue and as far as performance with a 300six, its a darn good low end torque engine stock, modifiying it with an offenhauser manifold & a holley 4bbbl along with bigger exhaust will only take away from the low end torque and a 300 will probably never be a high revver, if your`e really looking for more juice, IMO i would swap in a nicely rebuilt 390 4bbl.

 

[1576]

"Built" inline sixes
http://www.fordsix.com

 

[4676]

As far as I can tell the PCV system is working properly. This is what I have. The pcv valve is pushed into the oil fill cap on the front of the valve cover. The inlet where the breather element goes has a hose in it now to keep the oil that blows out from getting all over the engine. The PCV valve is new, the hose from the pcv valve to the intake under the carb is new, I checked the vacuum port on the intake and made sure it wasn't clogged. I haven't done a leak-down test yet because I don't have a leakdown tester. I do have a compression tester but haven't tried it yet. Maybe I can rent one from the local parts store. The truck hasn't been on the road since 1983 1982 was the last year that it was licenced, thats why I am pretty sure on the mileage plus the title showed 128k on it when it was sold to the last owner. I would love to do a 460 swap but I would like to get all the other bugs worked out before i even think about it and would be nice to be able to save the engine I have till then. If I could get the blow-by problem fixed and could get a little more uumph out of it I would keep it. I am happy with the power of my injected 6 i have in my other truck but compared it feels like it has half the power. Just seems like a 300 cubic inch engine could do with more than 190cfm carb. Maybe a 2bbl? at least then maybe I could pass someone. Carb seems like a govenenor to me.

 

[953]

i would personally do a v8 swap, since im not a fan of small engines(on road driven)
is this truck worth dumping $$ into? is it in fair to good condition with minimal rust? if you like it, i would say rebuild which ever motor you want to and dump it in it.

 

[4676]

Good condition? haha

If i had a digital camera I'd post a few pics of it. The drivetrain is in good condition (other than engine) the body.... well it sucks.. but the cab is descent I've fixed all the holes, doghouse, and bed all beat up. Looks don't really bother me. What good is a show truck 4x4? I want something I can go anywhere I want to go with and not have to worry about a scratch or dent or breaking something that is why I went f-250 the dana axles and np-205 t-case and granny 4 speed are probably about as tough as you can get.
About 4 years ago I had to sell my last 4x4 due to lack of funds. This is my 3rd 4x4 truck my last one was a 78 f-250 XLT Lariat with a 4" lift 36" TSL's 4.11 gears. Engine was a 460 out of an early 70's lincoln had the dove II heads. Bored .40 with flat-top keith black pistons, Clevite 77 bearings, Melling high volume oil pump, Heads where ported and polished, Crane 292 cam, double roller timing chain, Performer Intake, 750 Edelbrock carb with electric choke, full length hooker headers, 3" duals with 1 chamber flowmasters. Tranny was a c/6 rebuilt by a local shop with a hurst shift hit, TCI cooler. The truck was hunter green metallic. Chrome bumpers, chrome roll bar, KC's... I miss the old truck...Alot of money sunk in that one. I was single, lived at home, no bills, dumped all my money and time into it. The sucker would scream but I was always paranoid of dents and scratches. Fuel economy wasn't even that bad I averaged 12/14mpg! If you can't do something with a 460 it can't be done! I kick my self for selling it!!.(I kick him for selling it too!!!!!---his wife) Now that I've started over I am more interested in building a truck that will take a beating. Now I am on a limited budget so if I could save the 300 for now that would be great! I could take care of a few other problems. Like finding 16" wheels (i have a good set of 16" mud tires) and rebuilding(if possible) or replacing the power asisst steering control valve(I guess thats what its called not to familure with that system) Its got alot of play in it (the valve). Maybe there is a way to convert to regular power stearing? Or is it more cost efective to repair this? I've located another valve used for $75

 

[4676]

I've come across a 2wd 73 f-100 with a 390 for $100 body is SHOT! but motor runs descent. Needs a tune-up looks like its been sitting for about 5 years. Also its got an auto probably c6? I've always heard that the FE engine where gas hogs and didn't give much power for the gas they suck. I had a 68 ltd 2 door with a 428 and it was pretty strong but i was lucky to get 5mpg! This truck is not a daily driver but I would like to at least get 10mpg! Does a 4bbl swap make a 390 a little more fuel friendly? also does anyone know the tourque/hp specs on a 73 390? I also know where I can get a complete 400 out of an 82 f350 that dropped a valve for $150. Would I be better off with rebuilding a 400? I know they really wake up with a 4bbl intake and a diffrent cam. Also would I have to change less stuff to go 390 or 400? or would it be about the same eaither way? I know a 302 or 351w would bolt up to my bell-housing but I really don't like 302's They are a great car engine but I think a 300 is better in a truck. I had a 351w in a 2wd I used to own and I wasn't real impressed with it. Had more power than a 302 but it drank gas like a 460.

 

[BRONCOMANIA]

Re: 76 F250 4x4 300-6 Bad Blow-By Rebuild Or v8 Sw

My brother had a 75 F250 explorer (not the suv) pickup with a 390 equipped with a factory holley 4bbl, C-6 and 4:10 gears. with 33" tires it would smoke em all the way down the block and get---- 10mpg.
at the same time i had a 79 F150 with a mildly built 302, 68 quench cmbr heads, edelbrock intake & 4bbl carb, mild cam, dual exh, etc C-5 auto and 3.55 gears---10mpg.
my 86 EFI5.0 bronco, in the summer with a/c on and heavy footed as i am----10mpg.
most everyone i talk to with a 5.8W in a truck?
----10mpg.

most 460s----9mpg....

sure a 352-360FE is an anchor motor, but i think 390s can be built well, and i believe is a better motor than 460s, i wont mention the other FEs 427, 428s as there way too hard to find

i also hear many out there having a hard time dealing with detonation/pinging on 460s even at stock compression ratios due to poor combustion chamber design.

keep in mind im thinking of best power for the dollar , sure a 460 can be built to be a real powerhouse no doubt, with enough cash.....

 

[Guest]

not sure what the weather is like up there. cold? is so the 20-50 Wt oil ya put in the old truck could be way to thick causing the same troubles. with the engine conpartment being so big on these old trucks and the small size ofv the 300 they tend to keep cooler with all the air flow around the motor. this won't allow the 50wt oil to thin out enough. try a oil change with a lower Wt like 10w-30 or 5w-30 to see if it'll settle down on the blow-by. down here the 50wt even at times seems to thin out to much by our heat. 20-50 seems a little to thick on a truck/motor that cools fast in colder temps.

 

[4676]

Re: 76 F250 4x4 300-6 Bad Blow-By Rebuild Or v8 Sw

My 351w was in a 72 f-100 2wd with 3.73 gears and a 4 speed. Engine was out of a 77 ltd with a 2bbl carb. Maybe low compression heads and 2bbl carb effected it I dunno.. I could never get better than 10 mpg and that was realy babying it, where I got 12/14 with my 460 in a 4x4 with 4.11's and 36" tires. I always just figured since the 460 was so much stronger you didnt have to stand on it to pull a hill. I have seen older model 351's that had alot more power so I am assuming when the Emissions Police started cracking down on everyone in the early 70's performance and efficiancy went' out the window. I had a good friend with a 70 f100 with the original 302 and it would run circles around my 351w. It seems like 72/73 is where the performance took a back seat. I had a 79 f150 with a 302 and an automatic and it wouldn't even chirp a tire if you floored it from a dead stop. I've seen 460's that had enough tourque to rip a house apart and the 80's models feel like the old 351's. I guess its all in the heads and pistons. Some years bigger combustion chambers dropped compression other years dished pistons. Don't get me wrong and think I am bashing 302's! By all means they are good engines! I just think that there tourque comes in at higher rpm's than what a 300 does.

 

[4676]

The oil is somthing I will check into. I run 15/40 all year in my 91 f150, mainly because I am the 2nd owner and the guy I bought it from always ran 15/40. It seems to have done it good I have 240k on it, and drive it daily. I change my oil every 5k and never have to add any between oil changes. Usualy when I go to change it I am a little less than 1/2 quart low! On this truck however I use 20/50 because off some valve train rattle and a few oil leaks. I thought it might quiet it down a little. But it seems like the first 20 miles or so after I changed it is when I started having problems. It was still averaging 70+ outside when I changed it. I was thinking that maybe the fact that the oil hadn't been changed in years had somthing to do with it. Maybe I knocked some sludge loose in there?? I've tried adding STP oil treatment, And some smoke-be-gone when that didn't work. Could an oil return passage be clogged? I had the valve cover off to adjust the valved and noticed there was ALOT! of oil collecting in the top of the head. Oddly enough with all the blow-by I am not burning any oil. Are the oil return passaged on a 300 acsessable through the side cover?

 

[tanbuddy]

I would change the oil, and the pvc and breather and see if it clears up. I know in PA now they are emission testing all vehicles with smog stuff, which means anything newer than a 73. it sucks
My 85 300 only has 140K and it has a lot of blowby, I just dont worry about it b/c it still pulls like hell.

 

[4676]

I have already changed the PCV valve and breather but I will try an oil change to lighter oil. Thankfuly around here they have never had emission testing, in fact in louisville KY (not to far away) they have done away with the testing. I am not sure about the regulations on f-250/f-350's but as far as I know they don't have any over a certain GVW I know my 76 has no EGR or Smog equip of any type and looks as though it never did. It seems the laws vary alot from state to state. I know in some places i've heard that vehicles over 20 years old are exempt. Also you can get 11000lb tags and get away with not getting tested(which alot of people I know have done).