Hello all,
I am going to swap my 460 7.5 out of my 1985 F250 4x4 with a 300 4.9 (carbarated).
My question for the good people here is whats the best year or years for a donor engine. I plan to de~smog the 300 before putting it in. I have noticed the engines have the air provisions in the intake or the head. Which version would be easier to defeat the air smog provisions and other smoggy stuff?
Thanks for your time in advance, Jon

 

There are far smarter minds here than I on this subject, but I am replacing my tired 4.9 in my '85 F150 4x4 with a used efi 4.9 from a '88. I will keep the efi exhaust with the Walker 45166 pipe & have a Offy C manifold/2100 carb to put for intake. On the Walker pipe, remember to hole saw the rear connecting pipe and plug the O2 port.

As for the engine factory pollution controls, all I see with mine are the intake inserts (not sure correct term) in the head, and the big one in the rear efi exhaust manifold. For the head, you need to remove the air injection (I sawzalled mine off the top, then took the screwed in parts individually). I had read here that others used 1/2-20 set screws as the plug. That doesn't work on my particular engine. Mine were threaded 9/16-18 - which is a hard thread to find locally. I ended up ordering 6 set screws from Fastenal via my local store. The link below has them for $6.56 ea, but my local store sold them for $5.25 (times 6). You could probably get by with 1/2" length versions, but I opted for the slightly longer ones.

9/16"-18 x 3/4" Black Oxide Alloy Steel Cup Point Socket Set Screw | Fastenal

So, 6 of those will take care of the head.

On the exhaust, if the fitting doesn't come out of there easily - which most don't - then you have a couple of options.

> Soak with a penetrant like PB Blaster (what I used) and use an impact. Hopefully it will come out. It didn't work for me - see below.

> Take it to a machine shop. Usually it's a small fee for them to remove it and either have the right plug, or you can take it to the hardware store afterwards and match it up. I don't have a machine shop convenient to me, so didn't do this either.

> I cut off the tube extension from the manifold, repeatedly soaked in PB Blaster, used an impact, all w/no success. So, I drilled it out with a 21/32 drill (reduced shank), then tapped it for 3/4-11 and am putting a bolt threaded into the frozen fitting already there.

There are some things to know about which head is best, but used efi engines are all over the place so that's what I got.

Oh, and a efi engine will require you to either mount an electric fuel pump for a carb, or I believe you can cut out where the old mechanical pump went. I'm sure someone will correct me if I'm wrong there - or add to what I've written above.

Good luck! Wow, that's going to be a big change. You'll need the trans too, yes?

 

Thanks still looking for a suitable 300 inline in my area. Thanks again for your help.

 

If you can find a engine/tranny combo that may be best for your situation.

You can use the efi exhaust like I said above, but on the intake new offys + carb can set you back $500 pretty quick. Not as much power but easier to find used and much cheaper should be a stock 1bbl intake w/carb. I see them somewhat regular on craigslist here. That would get you running at least.

Oh, yes, also the distributor would need to be changed to a Duraspark II. They are used ones out there, but getting a reman unit isn't that expensive either. Just search for an earlier model - like '82 - and you should be OK. You'll need the control module too, just get the one that matches it. You can also use HEI modules - there are some threads on that here too if you search, but the stock ones work great and plug right in.

Good luck!

 

Thanks fljab!

 

I've heard that there was an issue with the block material in the 80/81 engines. But I have no proof of this either way. I've never had any issue with one. And the 65/66 300 have a different main thrust bearing design.

But there really isn't a bad year. I like to mix and match the best parts to build mine. The main thing I look for is a good standard bore block( I prefer carbed engines ) . I like the carbed 300 head ( before pedestal mount rockers, early 80's or older ) or a 240 head. I like the late 70's - early 80's DSII distributor, 87+ efi exhaust manifolds and serpentine accessory drive parts.

 

Hi Ted good information there thanks. Do you by chance know how long the early style main thrust bearing was used?
A good standard bore block is what i am lacking the 1980 block is at .40 over now and the 1966 looks good but i bought a cheep bore gage and i am not too sure that it is accurate. So i will wate on the word from the shop when i get it magnfluxed and hot tanked.

 

The early thrust bearing was used through 66. Then 67 went to the newer design. It's not a big deal, you just have to make sure to get the right bearings for it.

I've got this little problem. I like to buy 240's and 300's that are listed for sale in my area for $50-$100. When someone list them for that little they are just forcing me to buy them!! So right now I've got a small hoard of 240/300's. I lucked out and a few of them are standard bore. But it did give me a small shelving unit full of 240 heads.

Well good luck on your 66 block! Hopefully you get good news from your machine shop.

 

Hi Ted, ok i will closely pay attention to the bearing. Thanks good advice i would have possibly overlooked that.
I am sorry to hear of your problem. Lol. Would love to help you out with that problem.
I had looked for a 300 engine/s for almost a year and a half before I found the 2 i have now.
I wished my problems were like that. Lol.
Thanks again for the information.

 

I've heard this too. If I remember correctly, it had something to do with improper amounts of nickel in the metal or something that made them too soft. (Details are VERY fuzzy).

When I went to rebuild the engine in my '81, it had already been previously rebuilt and bored 30 over. It had worn out so much that they couldn't rebuild it again without going past 60 over and the block had to be scrapped.

So, either it is what you are saying and that there is an issue with block material, or my Bronco would have to have some 500,000 - 750,000 miles on it to wear a 300 out twice. Or both. Who knows.

 

Thanks AbandonedBronco. Have torn down the 1966 mercury but i am not sure if its not a 240. I have heard that both the 240 and the 300 are the same block if that is the case i wounder how far could a 240 block be board out?
The 1980 300 is perty ruff. Wont know how i stand till a trip to the mech shop.

 

The 240 and 300 use the same block, the 240 has a different crank, rods, and pistons. If the head's off just turn the crank until a piston is at BDC and measure the distance to the top of the deck - 3.5" for a 240 and ~4" for a 300. Either way, you only want to bore it as little as possible.

A 1985 chassis uses a rear sump oil pan, I'd try to find an engine that has the right oil pan to start with.

And fwiw, a 460 runs circles around a 300. For all the time and money you'll spend building a 300 and buying performance parts, changing the bell housing and engine perches, etc. you could build a 460 that will make almost double the HP even a strongly built 300 would make. What's the motivation for the change? Don't get me wrong, I like the 300 in my Bronco and F150 but in a big heavy truck like yours I'd stick with the 460.

 

Stroke:

240 = 3.18"
300 = 3.98"

Yeah, the 460 can make more power. You're talking about an engine that is almost 150% it's size.
I love the 300. Plenty of power for what I want, plus the gas mileage is great. But, I admit the power of a built 460 sure would be fun.

 

The whole 460 - 300 debate really comes down on what you want it to do. Without adding forced induction to the 300 it's not going to make the torque the 460 will. And doing heavy towing/hauling the 300 probably won't get better mileage either, because it will have to work harder then the 460 would.

But a mildly modified 300 will have no problem doing the work in a F250 4x4. Especially with a manual transmission and the right gearing.

The main benefit of the 300 over the 460 is it's lighter, easier to work on and fewer parts to fail.

The easier to work on part, is the main reason I'm going to be swapping one in place of a 351W in my E350 extended Club Wagon. That and the 300 is my favorite engine. I'll be hauling/towing some heavy loads with it when it's finished. And the van is no light weight.

 

Hello BaronVonAutomatc, Thanks for the time and advice. So let me ask this. So could someone have a 240 block and boar it to a 300 and then boar the same block .40 additional?
The block in question is a 1966 and it is now dissemble at the moment. It appears to have 240 heads kidney bean shaped combustion chambers.
Would you by chance know the rod length of a 240 and a 300?
Oh yes i am building this engine that's working range will bee from idle and 3500 rpm.