300 finally died. Motor is out.... what now?

[Gnant]

Hey all! So I started getting a knock in the 300 (right after an oil change) and pulled the motor over the weekend. Significant play in the bottom crank bearing of Cylinder 1. Completely worn through the hardened surface. Also a burnt valve on the same cylinder. No idea if they are related but nonetheless time to rebuild.

Just as an FYI, a machine shop will be doing all block work, so I will have the crank ground, everything planed, etc...

Where I need help is in a balance of performing reasonable upgrades vs. unnecessary ones. For example, is getting an RV cam worth it? I think yes but maybe someone has gotten one and it didn't make any difference worth while. The carb is a single barrel so is it worth upgrading that and the intake? I am not looking to make a race truck and it is paired with a 3 speed manual so highway speeds are impossible without winding the snot out of it. (Silly question, but how do I get a 4th gear!!!!)

The truck is a 65, but I am pretty sure the motor is from the early 80's. Any and all thoughts are welcome and appreciated.



Cylinder 1 crank bearing


Burnt Valve

[chris401]

My wrecking yard findings tell me that most inline 6 with 3 speed manual trucks came with a 3.70:1 rear axle. If this is your case your turning around 2700 rpm at 70 mph. I've read online that you can swap around parts with a 240 and bump up your compression. Seems it took some machining to make it work. In my 20 years as a mechanic I can probably count on my hands how many 300 sixes that had problems. A number of that were just exhaust manifolds. Good engines

[SteveCanup]

I currently have a '64 F-100, but 20 years ago I owned a '66 with the 300. That is a great engine. Mine did the same and I purchased a new long-block assembly locally. It was the same on the highway as these old trucks are geared for "farm work" and 1960's speed limits. Two ways to help with the rpm's: upgrade to a T-5 (or an auto with overdrive) and replace the rear-end gearing with something higher. I just updated the 3-speed in my '64 with a T-5 and improved the driveability on the interstate immensely. It also increased my gas mileage by at least 5 mpg. I am in the process of obtaining a 3.0 "chunk" for the rear-end (it's currently a 3.70). I used an rpm calculator that I found on the internet and plugged in the tire size in inches, final drive of the T-5 and the rear-end gearing to find the desired rpm for 70 mph. If the engine is an early '80's you shouldn't have much problem installing a newer 5 speed. I bought mine for $100 and spent another $200 for miscellaneous to install it.

Just my 2 cents worth....Hope that it helps.

[Gnant]

Thanks for the advice on the T-5. Is that a straight swap? My truck is a long bed if that matters.

I think I am going to leave the single barrel manual choke carb and intake. Pretty sure its a Carter YF. That will be an easy rebuild. I kept the exhaust and intake together and will have it surfaced as a completed set. Something I had never seen before is the butterfly flap operated by a weighted spring in the exhaust. What is that?

The all metal timing gears on the motor are in great shape and I am tempted to reuse them vs getting new ones that seem to be plastic. I know in practice this isn't a good idea but my gut tells me I am better off with the ones in there than "new" ones. If this is an egregious mistake, please tell me.

Regarding ignition, just a small change to a Pertronix is all I think I am going to do there. A new distributor isn't that much either.

Is there any justification for a high volume oil pump?

A few years back I replaced all the lifters, rockers, and pushrods. I didn't properly break them in with the old cam and this I think was the start of the demise of my motor. The head has studs and I am looking for advice on whether I replace them. If so, with what? The reason I ask is because I fought to keep the valves adjusted and in the end couldn't adjust a few anymore as I ran out of thread. Hence my suspicion the cam was extremely worn. Or I was just doing it wrong which is always possible.

And speaking of the cam, if I am not looking to gain power in a higher RPM range, do I just keep it stock? It seems changing cam durations is like pulling on a string. So many other considerations to take into account when you do that. So if there is a cam upgrade that doesn't require me changing the octane of the fuel or curving my distributor I would like to go that route.

[Jerry D]

Spend a little time over at the fordsix.com website. There's so much that can be done with the 300. The weighted spring on the exhaust manifold is there to restrict the exhaust, causing the manifold and engine to warm up quicker. If you keep it, just occasionally check to see that it's free. If it locks up in the closed or partially closed position, it can overheat and crack the exhaust manifold. This was the case on my motor when I bought it used.

The fordsix site has all kinds of tips and tricks. I'm running EFI manifolds, and have Ch#%y rocker arms (from a 250 six as I recall) that have slightly different geometry that provide more lift for your valves. Cheap modification to make. With the Pertronix, I run their flamethrower coil, and use long reach sparkplugs with a larger gap (I think I'm running like .045 or .050. Chris is right on the 240 head. I've not done it myself, but I've read where you can swap it and increase compression. Lastly, I run an Offenhauser DP manifold with a 500 cfm edelbrock, and it's probably too much carb for the set-up I have, but it works. If nothing else, I feel like all these mods have made a bit of a difference, and it looks cooler than stock.

[Gnant]

Spend a little time over at the fordsix.com website. There's so much that can be done with the 300.

So far I have spent more time on the fordsix.com site than I did pulling the motor. I swear I am set in a decision then I read something else. The definition of paralysis by analysis....

I am liking the EFI exhaust idea and a new set is less than $200. The question becomes the y pipe and how to connect them together. I have no cat, the mufflers shot, and the tail pipe should frankly be replaced. So anything is possible.

I also have a 2bl carb from a 360 motor I replaced in another truck. I am also now tempted to upgrade the intake.

Jerry, on the rocker arms you used, did you change out the studs in the head?

[Jerry D]

Regarding the studs, you'll have to read up on that. I believe there are some heads where you have to do that. My engine is a 1969, and the studs were the right size.

You should be able to pull some manifolds at a boneyard for a lot less, if you have one nearby. I see them occasionally on Craigslist, and even on fordsix.com. I was running a 351M prior to going to the six, so I already had dual exhaust, and just had a muffler shop bend some pipe to adapt it to the dual manifolds. Some swear by the efi manifolds, and say they're better than the headers you can occasionally find, though headers have the "cool" factor.

[Gnant]

Thanks for the info. I am not looking for the wow factor and want to keep the look "original" to the uninitiated. A normal person (we are not normal) would have no idea if EFI manifolds were original to the 65. But headers they sure would. The only change I have made under the hood so far is adding a brake booster an master cylinder to replace the single pot it had. Not one person has ever said "Ohhh, that's not original".

Engine is at the shop and they are taking measurements now. Hopefully this motor hasn't been rebuilt before.

[sgettin]

Personnaly I would avoid a high volume oil pump. When rebuilding my 460 (now 521) i was told the high volume oil pump is a bad idea unless you are going more full race with the engine. No experience with the subject just what I was told by some builders at the time.

Good luck.

[Gnant]

sgettin: I have heard the same but like you have no direct experience.

The engine shop says the engine has been rebuilt before, maybe twice, and they will need to bore 80 over and get oversized pistons. So I guess I will have a 5.0 when all is said and done.

This really has me thinking I could (should?) upgrade the intake and carb from the single barrel Carter YF unit. The motor can take a lot more gas than the YF will give it. Also going with an RV cam. Any thoughts are welcome. I do have an old 2 barrel from a 360 motor laying around. It is also a manual choke.

[sgettin]

Me being not the most mechanically adept guy on here I can just offer some general advice. Boring 80 over would scare me a bit because that's near the max on a lot of engines from what I hear. 300's may be different but if it needs bored that far a new block may be something to consider depending on how cheap and available they are in your area, here in the midwest I can get 429/460 stuff easily so I'd guess the 300's are plentiful.
In regards to upgrading your intake and carb etc, depending on your budget, I would look to an after market carb, intake, headers, and mild cam (the usual culprits). I have heard there is a forum on the net dedicated to the Ford 300, that would pbly be an excellent place to get some information. I do know from experience all the upgrades can be great but they have to fit together or "compliment" each other as a system or you're going to be disapointed in how the engine performs. I believe 300's are a torquey engine I'd build it towards it's strength.
Good luck.

[unibody madness]

As far as your trans, final gear on both the three speed and four speeds (not counting three speed w/od) are 1:1.
I would not go higher than 3.25 on the rear gear unless someone who has done so can give you the facts on what else they have done to motor, rear tire size ect.
I put a T-5 behind my stock rebuild 292 with 3.50 rear gear and .68 od gear and that is as far as i would take it. I am not sure you would be happy with anything more aggressive than that with the 300.

[Anthony]

dont go over 60 over on a 300.. going 80 over will put you close to the water jackets.. mine is 60 over and I will get another block if that day comes.. I have a cam for more torque and I run the clifford 6=8 with a 500cfm 2bbl. I use my 300 for pulling and hauling and my daily. I run the 86 EFI split exhaust and had a muffler shop run the two pipes into a 2 1/4 in and one 3" out muffler.

[Gnant]

I run the clifford 6=8 with a 500cfm 2bbl

Thanks for that Anthony, I had not heard of the clifford units before.

The machine shop was able to keep the .6 over bore as the cylinders cleaned up really nice. So got lucky. Engine is back and will post some pics tonight. I had them plane the intake and exhaust assembled as one unit and they said it was the most they ever took off. I will use them to break in the engine but will replace the exhaust and intake after. I don't want to be messing with dialing in a carb while concurrently breaking in a motor. Seems better to just put on the one I know works while breaking it in.

EDIT:

Engine back from the shop. I didn't want to go with one color, so went with the old ford blue and gray.


Cleaned up the engine bay

[Gnant]

In dry fitting everything I noticed the ear on the intake is busted. I can get a washer to grab a very small piece but not sure I want to even try it knowing I am breaking it in. I'd hate to be too lean from a leak.

[chris401]

In dry fitting everything I noticed the ear on the intake is busted. I can get a washer to grab a very small piece but not sure I want to even try it knowing I am breaking it in. I'd hate to be too lean from a leak.

If you decide to run it and not repair take a look here: http://ford-mel-engine.com/viewtopic.ph ... 7166#p7166

The MEL engine has hold downs similar to the 300. These are made of steel, maybe you could take something like this and grind a notch in it so that the load is equalized.

[ratrapp]

how did the machine shop not catch that when they were resurfacing it?

[Anthony]

the engine is looking good.. if that ear is broke and not able to grab it you should replace it, but I am sure you know this. the Clifford is an old intake. I ran an Offenhauser C for about 5 years. I ran across the Clifford and the engine builder liked it better. as far as how yours does interstate, lol, I have 76 4x4 under mine and it is a 4 speed granny with 4:10 gears? I believe. I run between 60 and 65 and have had it to Iowa, Kansas, west Tennessee and Mississippi.. hoping to make it to Iowa again in August love my sixes but this is my second build at 60 over and the next build will be a 352 for mine. I already have it and the bell housing to hook right up to my 4 speed. enjoy the build and let us know how things go.. I two toned mine black and grey

[Gnant]

how did the machine shop not catch that when they were resurfacing it?

That is a good question. Equally, I should have caught it too.

This 81 motor is driving me nuts. I am slowly accumulating a pile of new 65 parts that should have been ordered for the newer motor.

Since I owned it, the truck has had an after market temp gauge as the dash cluster didn't work. Part of me feels that it didn't work is because there were no temp or oil sensors for the idiot lights hooked up. It looks like on the diagram they are interconnected. (I do have a new 5v transformer on the way.) So my current frustration is the temp sensor. The hole in the back of the block was just plugged with a broken sensor when I pulled it out. Based on other threads that have said the 65 needs a specific unit, the one I got has a way smaller thread. Hoping someone can chime in as mixing and matching sensors usually creates problems. Is this a situation where my 81 block took a bigger sensor and I need to find an adapter to accommodate the one designed for my cluster? And same goes for the oil sending unit. I have a pressure gauge in the left slot that is oil driven. No sensor.

[Gnant]

the engine is looking good.

Thank you. And glad to see I am not the only one who goes through copious amounts of brake clean. (Assuming that is what's on your cowl) I like the black as well and think the 65 came in black.