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BigBlue 94 02-24-2018 09:02 PM

300-6 performance engine build
I noticed a leaking head gasket a week ago on my 85 bronco. Had a few spots that were boiling coolant out. So I've been discussing it in this thread. I got the engine out today, so the build thread can begin!

So after removing everything from the 300, and unbolting the mounts from the crossmember, I was ready to pull her out. Hood had to come off too, lol I kinda like the visor look.

This shows just how BIG the six really is. It would not come out of the engine bay straight. It's hitting on the firewall and the radiator. Had to take the radiator out, and spin the engine to get it out.

Managed to get her mounted to my new HF engine stand.

Most of the bores have vertical scars in them, but they aren't real bad. Number one cylinder looks pretty clean. Pistons come up to about .031" in the hole(using a depth micrometer), as best measured without knowing exact TDC. I do have most all the correct measuring tools for this stuff though.

My goals for this engine is around 300 hp and 400 ft/lbs. Going to have the head worked over with larger valves, a good port and polish, and roller rockers. Shooting for a 9.5:1 compression ratio. New pistons, cam, and timing gears as well.

Already have a Clifford single plane intake and split 3 into 1 headers. Running a QFT 450 4bbl slayer carb currently, and as it's brand new I'm hoping to reuse it. Backing it up will be the factory NP435 transmission, np208 transfer case, and locked 4.56 gears on 37" tires.

I've been reading builds over at a couple more 300-i6 specific sites as well, and they are far more detailed than I'll get here. If you have questions feel free to ask, as long as we don't get off on some weird tangent.

BigBlue 94 02-25-2018 09:04 AM


Originally Posted by dash_cam (Post 6991481)
"got a leaking gasket. Probably should pull the engine, rebuild it, and put in performance upgrades."

I like where your head is at.

Well when i pulled the head off first, i noticed some decent scarring in the cylinders, and since I have zero idea how many miles it's had since the last rebuild in 2002, I figured it's time to pull it. Cylinders 5 and 6 were also burning oil by the looks of the chambers.

BigBlue 94 02-25-2018 10:02 AM

Here you can see some of the vertical scars

And I finally get to grab a good pic of the modified oil pan. Looks like it adds about a quart of capacity. Was done by the P.O.

BigBlue 94 02-25-2018 10:34 AM

That's the plan! I thought this engine had about 15k on it, but maybe it's 115k, or more. That's the bad thing about the old odometers, you never know how many miles are on it. If it's worn again at .040 over, did they rebuild it twice? Or did they run the snot out of it for 400k+, then rebuild It? These things are 300k between rebuilds normally.

Oh well, at least I'll know what I have when it's done.

I ran into a problem when it came time to bolt the engine to the stand. The original bellhousing bolts weren't long enough to bolt through the mounts. And they are an odd size, so I couldn't use my supply of bolts. I ended up remembering @AbandonedBronco saying the head bolts were the same thread as the bellhousing bolts. So I grabbed a bunch of washers and nuts to space them out, because they were over an inch too long. Worked like a charm!

BigBlue 94 02-25-2018 11:15 AM


Originally Posted by Rusty in Wis (Post 6992105)
We are all here to help you spend your money :popc1:
Is there a stoker kit available for the 300

Not any more, though it can still be done with the right amount of money. The 300 is technically a stroked 240 anyways... it cant be stroked too far, due to the factory stroke being 4 inches already. Thats near what a 408 stroker has. Both use a 6.2" long connecting rod. As it sits, im at about 306 cubic inches. There is a guy named the frenchtown flyer, who drags a 314 cubic inch six, at almost 14:1 compression, but he has one of the experimental crossflow heads (intake and exhaust ports on opposite sides of the head, like a v8). I think he's at about 600 hp.

Parts availability for the 300 is pretty much limited to cams and intakes. I'm most likely going to run 351w pistons, though 390 FE pistons are a viable, albeit heavier option. The 351w pistons will require putting a bushing in the wrist pin hole of my rods. The 390s wouldn't, but they are a significantly heavier piston from what I've read. Pistons for the 300 are all low compression, and not what I want for this build.

When looking for aftermarket heads, you won't find a single one. You can weld v8 heads together, but to be done right, youd have to chop up 6 Cleveland heads and weld them together to get the correct bore spacing. Oddly, the closest head to working with only two cuts is the Chevy Nascar R07 head. Another option is to cut up two 300 heads lengthwise, and mate the thick valve top to the thick chamber bottom. Sealing is handled by an o-ring. This allows for taller air runners. Third is a custom billet head, without coolant passages, for around 10 grand. Fourth is the crossflow head I mentioned earlier, and you'd be better off looking for a unicorn. None of these are valid options for me, so I'll be working the factory U-port head over as best as it can be.

BigBlue 94 02-25-2018 12:12 PM

Found this lil guy behind an engine mount.

Guess its warranty would be voided, seems someone overheated it at some time.

BigBlue 94 02-25-2018 12:33 PM

Now that the engine is out, it gave me a good chance to find my DSII ignition box... and I can't. It's not in the engine compartment. The red wire that leads to the distributor comes from in the cab somewhere... how the hell is this possible? Only thing under the dash is the factory eec with only a few wires running to it. I havent traced the wires fully yet. I do have the little stamped steel box next to the battery, but not the cast aluminum one with ridges that I'm accustomed to seeing.

BigBlue 94 02-25-2018 12:35 PM


Originally Posted by dash_cam (Post 6992265)
what is that? and what about it tells you it overheated?

It's a tag used by engine builders who warranty their work. If you overheat the engine, the center will burn out, leaving the little hole you can see in the middle. If it's burnt away, the warranty is void, and you can't blame them for your negligence.

BigBlue 94 02-25-2018 12:38 PM


Originally Posted by Rusty in Wis (Post 6992281)

For 1400, something has to be wrong. Just the manifold and carbs is 1400+

The fact it has zero engine spec other than "A real stonker kit" is kinda worrisome.

BigBlue 94 02-25-2018 03:00 PM

Got a hold of my neighbor who has an old 1970 ish ford van (haven't seen it in a long time, could be a early to mid sixties even) and it has a six cylinder in it. He said I could take whatever i wanted from it, for free. Hoping its got a 240 in it, and if so, I'll be snagging the whole engine. The 240 head will boost my compression ratio about .5. Crossing my fingers

BigBlue 94 02-26-2018 07:54 PM

My search for a 240 head begins here.

My quarry, a July of 74 Econoline 100 with a supposed 6 cylinder. Been there sitting since about 1985.

Horse sh1t doesn't clean out of my tires very well...

Like I said earlier, it's basically a shed, and animal house.

Well, there is a six cylinder there, buried in animal bedding and feces of at least 4 different animals.

Made some progress, and was able to remove the carb and air cleaner, both stock. Oh and some of the crap.

Found this tag. I'm 99.99% sure I've found a 240. You can see the "240" in the upper right corner

I got 10 intake/exhaust manifold bolts out, all the head bolts out, and the valve cover off. The manifolds are stuck like glue, and since I can't get to the exhaust collector to unbolt it, I couldn't get the head off, yet. I ran out of daylight, but there's always tomorrow!

BigBlue 94 02-26-2018 09:34 PM


Originally Posted by Rusty in Wis (Post 6994121)
Now that's nasty..

Yeah, pretty "lived in" lol. My dumb ass forgot the respirator, so I didn't want to get too crazy, just breathing through a t-shirt. There were some crazy big turds in there. Like big cat poops or something. There were also a number of bones in the nest

I immediately showered when I got home

BigBlue 94 02-27-2018 07:49 AM


Originally Posted by Rusty in Wis (Post 6994273)
I was reading your other thread. Don't fall into the long/high duration trap 300. It will run like SHIT and the reversion will make the carb impossible to tune

Yeah, I kind thought about that, and will be going with a moderate cam. A 270 duration with .480 lift is probably as big as I'll go.

BigBlue 94 02-27-2018 12:01 PM


Originally Posted by Rusty in Wis (Post 6994913)
Did you guys find this thread.

Yeah, I actually found that just this morning. Looking to be very promising. But we Sixers have been told all that before, starting in 07 with the classic inlines head. It got into the casting phase, then fizzled out. Plus, if it's anything like the edelbrock jeep 4.0l head, it'll be 3k plus. That's not a light investment.

BigBlue 94 02-27-2018 12:08 PM

I'm liking this cam at the moment. Single duration should keep my low end up in the powerband, and still breathe well at 5000 rpm. Decent duration at .050 should also help with torque.

Schneider Racing Cams
135H Ford 240-300 Hydraulic Lifter Camshaft

Your Price: $184.99

Part Number: 13919
Grind Number: 135H
Intake Duration (gross): 270
Exhaust Duration (gross): 270
Intake Duration (.050): 214
Exhaust Duration (.050): 214
Intake Valve Lift*: .472"
Exhaust Valve Lift*: .472"
Lobe Separation: 110
Intake Valve Lash: .000"
Exhaust Valve Lash: .000"
RPM Range:
*Based on 1.6 Rocker Arm Ratio

BigBlue 94 02-27-2018 01:54 PM

AB, yeah I know 300 is lofty, but it's achievable. I read a thread that achieved 300/400 using the mellow Melling camshaft. I'm hoping with the 240 head I can get to 10:1 and I'll run a bit bigger cam, maybe custom. I had a good read earlier about split duration cams, and Rusty's link above looks interesting. This thing isn't a dd so I wanna go a bit more "wild".

And yeah the van is nasty, with a heap of gross on top. Going in with a tyvek suit and respirator today after work. I was so pumped to see a 240 in it. There's a bit of crumbly rust on the rockers, but it's not bad. Hopefully the block is good too, for a spare. And I got me one of those "powered by ford" valve covers!! Grabbed the carb for anyone here wanting one. It's a motorcraft/Carter, but that's all I know.

BigBlue 94 02-27-2018 02:54 PM

Definitely not intruding. I'm only 29 so I have much to learn. I enjoy relevant information. I have lots of decisions to actually make regarding pistons, and have been reading some about quench and squish.

AB, the split long tubes I have are great. Seal easily, and are very easy to remove. But i get your point, and wont razz ya like they did in your build thread haha! Every situation is different. Don't forget that I have the Clifford open plenum intake as opposed to your dual port. Mine likes to breath up in the rpms

BigBlue 94 02-27-2018 03:33 PM

Yeah the Clifford has 2 side ports and 3 bottom ports into the warming chamber, which is about 12" long under the carb and supply runners. Ill snap a pic of the bottom for ya later. Its quite a hefty piece.

Im certainly no pro, but I'd think that the dual port would be bested by the open plenum on your engine, especially with your head flowing those crazy cfms. You could always have it flow tested.

Building the rest of the exhaust IS the expensive and hard part about using long tubes. My y-pipe is very goofy, and I had to make some funny turns to make it work, and stay above the trans crossmember. The only point my exhaust is below the frame is at the tailpipe, when it drops to exit out behind the rear tire. It's 2.5" into a single 3" with high flow cat and borla xr1 muffler. Lol, my engine will have no problem evacuating exhaust, especially with a third collector in the y-pipe.

ARP studs will be used on heads, main caps, and rod caps.

Fel-pro 1024 gasket will be used as well.

BigBlue 94 02-28-2018 09:14 AM

So my 74 Econoline journey continued yesterday.

These guys were hungry, and wanted out the gate. One of em got a little "smart" with me.

Its a little ways back in the holler

I was real close in my guestimate, it was last tagged in 86

All suited up and ready for battle

I managed to get the collector bolts out and pulled the head off. My heart sank... D shaped combustion chambers. I'm looking for kidney shapes. I didn't look it over very well, or look for casting numbers. The chambers do look pretty small though. Either way, ive got a spare head.

The van was parked because of a hole in the number 6 cylinder. Oddly it's got solid flat top pistons in it, without any valve reliefs. I covered the block with a piece of headliner and went home with the head. Lol it had a Frantz oil cleaner on it, you know, the ones that filter with a roll of toilet paper.

I did score a Full set of FORD letters from the grille, and "ORD" off the back doors. Got a Econoline emblem to match one I already have, two dog dish ford hubcaps, and two 1930s v8 baby moon hubcabs, that dont match exactly.

BigBlue 94 02-28-2018 09:18 AM

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