I tried this one in the classics forum to no avail....Guys, I'm curious if anyone knows any of the details about the changes FORD made to their 300-6 heads from 75ish to 85ish. I know this is more of a 6'er forum, but some of you old timers know this stuff real well. Specifically, I've been told FORD made some changes to the combutions chamber side of the head to help meet tightening emissions requirements during these years. I know about the introduction of the air manifold that threaded in into holes along the P-side. Any specifics on the head changes would be great. No, I'm not into the 240 just the 300. Curious - were they trying to lower compression by increasing the cylinder bore ends on the head (valve area) to better the combustion?

 

i know rotators were employed on the exhaust valves, some where in the late 70s, rotators were to prevent valves from burning.


John M Floyd

 

I'm not sure this is germane, but here goes:

A couple of months ago I bought a "mule" '87 EFI head for dissection and experimentation.

The '87 head has some very nice, very up-to-date, heart-shaped, high-swirl combustion chambers. What their CC is, I've no idea yet, but again, in spite of some extra work, I think the late head's chambers make up for it.

The huge bugaboo in these heads is the typical Ford "who cares" exhaust side, made much worse by that air-injection nozzle boss cast into the roof of the exhaust port. What I'm going to do to fix that is move the air injectors to the header primaries just downstream from the flange.

The air injector enters from the top of the cylilnder head, pointing downward at about a 45-degree angle, aimed directly at the top of the valve head, opposing flow. Worse, the boss terminates in an angle 90-degrees to the tip of the air injector, and, in a cast-in diminishing cylindrical wedge shape, really screws up roof flow. The solution here is to drill out and tap completely through the entire length of the injector hole, into the port roof, then screw grade 1 or 2 ("butter") bolts in from the top of the head, tack weld the hex, making sure the bolt is long enough to fill that wedge-shape completely. Then port the head including grinding down and blending in that horrible boss and the bolt's protrusion.

Gasket-matching told me that there is plenty of meat in the port walls, and I plan on sectioning that head so I know exactly how much thickness is there; I'll photograph and write the whole mess up here over the next few months.

Eddie

 

What year did Ford begin taping those air injuection holes into the head? I know '79's didn't have them. I'm thinking around '82, can anyone confirm this?

 

I meant to turn you on to this link-- <http: //www3.ns.sympatico.ca/mt.flemm.mac/fordpage/trucks.html>

Evan has a couple of pics of combustion chambers--a '66 240 and an '82. The '82 doesn't have air injection ('course--neither does the '66).

John Stark, who used to build engines for Clifford, told me that a '79 or earlier head was cheaper to equip with roller rockers as there was one less machining step involved because they had pedestal-mounted ball-fulcrum rockers vs. '80-up with rail rockers (no valve rotators, either).

Eddie

 

Air tubes started with the EFI..i believe...but i know i didnt have em in my '86 head (last year for carb.) Hoped i helped...and Eddie....man, you got too much time on your hands...haha....you know your stuff......

Dan "Mudinford" MacDonald

Rather be pushing a Ford than driving a Chevy.

Like A Rock......In Water!

 

My '86 doesn't have them either. I did see in LMC though, an "air pipe manifold" for '76 and '79-79. Is this the same thing or not?

------------------
1986 F-150 4x4 300 I6 NP435

 

Hobbies, Dan, hobbies!

I'm an inveterate tinkerer, and one of my main hobbies just happens to be maintaining and upgrading my '91, and learning everything I can about it.

Not real useful, but...a hobby.

My interest in the smog head came about when a drag-race 300 guy told me to "stay away from the EFI head; the exhaust ports are useless".

Sound like a line in the sand to me, and when I saw those up-to-date combustion chambers...

Eddie

 

My local machine shop (auto) told me that the newer EFI heads were more prone to cracks because of the increased metal removal from the casting (machining). The reason why I ask is that same shop has a rebuilt head sitting on the shelf (no thermactor holes) but he's not sure what year it came off of. He informed me that just like the various smog system changes in the mid/late '70s to early/mid 80's the heads were altered somewhat to help with meeting emission requirements. My '79 300-6 still has to meet CA SMOG requirements. I have seen carburated 300's with the injection holes on the head.

 

[font size="1" color="#FF0000"]LAST EDITED ON 20-Jul-01 AT 01:18&nbsp;PM (EST)[/font][p]AH-HA!

Thanks for that "crack" tip; I'm not a crackhead, but that '87 mule head I WAS fooling with sure is--it has no less than six cracks in five exhaust seats!

I believe I'll use a non-air-injected open-chamber head for my buildup and take a chance on increased NoX due to a higher surface-to-volume ratio--I know where there are half a dozen 300's that came out of propane-fueled airport Econolines.

Thanx! (I just found the worm in the apple)

Eddie

 

That's odd, my 84 head has the ball-fulcrum rockers, same as the 66 240.... The only 85 and 86's I've been around do have the rail rockers(same as a 79 and later V8.)
Evan MacDonald
82 F100 FlareSide 2wd
HD 300-6 9.5:1 CR
Clifford 270H cam
Hedman Hedder
SBC valved 66 240 head
Headlight Relays - Delanty Style
NP435(6.69 low)
3.55 Geared ARB'd 9"
31x10.50/15 Cooper Discoverer LT's

 

Interesting, all the myths, lies, half-truths and miscommunications!

Isn't that '84 head an HD? I wonder if that could make a difference in rocker type (?) I don't see how it could, as the 460s in 1-tons have rail rockers.

Eddie

 

Yup, it is a HD, but other than the valves, it is identical to the 82 head that I have. Those other 2 were definatley HD's by my HD identification standards, and they have the post 79 Windsor V8 style rockers. One of them only has 71000 miles on it, maybe I'll have to see if it's still there....
Evan MacDonald
82 F100 FlareSide 2wd
HD 300-6 9.5:1 CR
Clifford 270H cam
Hedman Hedder
SBC valved 66 240 head
Headlight Relays - Delanty Style
NP435(6.69 low)
3.55 Geared ARB'd 9"
31x10.50/15 Cooper Discoverer LT's