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300 carb heads

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brandoncw
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300 carb heads

Post #1 by brandoncw » Mon Sep 24, 2018 3:10 pm

Ok, ive been surfing the web, and i swored there was a difference in the 300 ci carb heads depending on the year. I was originally going to go with a 85ish cylinder head, but i found a good foundation for a 300 head off a 76 pickup for $125 + shipping. Better than the rebuilt heads that im going to rip apart and throw the valves and retainers away in and have the seats cut bigger. If there is no difference then im going to jump on it.

If it is different, will it work with my build. for those of you that arent following, im gathering all my big ticket parts for my Turbo 300 build. Going to use throttle body EFI. I have not ordered pistons yet as due to insufficient funds and since i have not gotten my cylinder head to get the final comb chamber CCs to determine my dish size.
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pmuller9
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Re: 300 carb heads

Post #2 by pmuller9 » Mon Sep 24, 2018 5:41 pm

The 85 and 86 carb heads use a pedestal mount rocker arm the same as the 87 and later EFI heads that bolt down using a 5/16" bolt.

The pre 85 heads use a 3/8" stud mount rocker. The stock pressed in studs are removed and the heads are drilled and tapped for a 7/16" base screw in stud. The upper end of the stud can be 3/8" or 7/16" depending on the choice of rocker arm.
These heads also have a 5/16" pushrod guide slot and do not require guide plates

The 85 and 86 heads have a round hole for the pushrods and require pushrod guide plates if they are converted to stud mount rockers.
https://www.dropbox.com/s/ibs9tk4i0rbue ... 6.JPG?dl=0

It is best if the adjustable guide plates are welded so they don't turn when you tighten the stud.
https://www.dropbox.com/s/hw9cogn2posft ... 2.JPG?dl=0
https://www.dropbox.com/s/raics8rx0g9rx ... 5.JPG?dl=0

Both style carb heads have around a 76cc combustion chamber.

brandoncw
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Re: 300 carb heads

Post #3 by brandoncw » Mon Sep 24, 2018 5:55 pm

pmuller9 wrote:The 85 and 86 carb heads use a pedestal mount rocker arm the same as the 87 and later EFI heads that bolt down using a 5/16" bolt.

The pre 85 heads use a 3/8" stud mount rocker. The stock pressed in studs are removed and the heads are drilled and tapped for a 7/16" base screw in stud. The upper end of the stud can be 3/8" or 7/16" depending on the choice of rocker arm.
These heads also have a 5/16" pushrod guide slot and do not require guide plates

The 85 and 86 heads have a round hole for the pushrods and require pushrod guide plates if they are converted to stud mount rockers.
https://www.dropbox.com/s/ibs9tk4i0rbue ... 6.JPG?dl=0

It is best if the adjustable guide plates are welded so they don't turn when you tighten the stud.
https://www.dropbox.com/s/hw9cogn2posft ... 2.JPG?dl=0
https://www.dropbox.com/s/raics8rx0g9rx ... 5.JPG?dl=0

Both style carb heads have around a 76cc combustion chamber.


great info thanks. so its easier to use the pre 85 carb head?
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pmuller9
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Re: 300 carb heads

Post #4 by pmuller9 » Mon Sep 24, 2018 6:06 pm

brandoncw wrote:great info thanks. so its easier to use the pre 85 carb head?


Yes if you want a stud mount rocker arm that gives you a wide variety of rockers to choose from.

The only off the shelf pedestal mount roller rocker for the 85 86 head where you wouldn't need guide plates is the Scorpion 1.73 ratio rockers.
Just bolt them on. In your case with a low lift cam profile the 1.73 ratio rocker would be beneficial.
https://www.summitracing.com/parts/scc- ... /make/ford
You may have to shim the Scorpion rockers to get the correct geometry but not a big deal.

brandoncw
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Re: 300 carb heads

Post #5 by brandoncw » Mon Sep 24, 2018 7:29 pm

pmuller9 wrote:
brandoncw wrote:great info thanks. so its easier to use the pre 85 carb head?


Yes if you want a stud mount rocker arm that gives you a wide variety of rockers to choose from.

The only off the shelf pedestal mount roller rocker for the 85 86 head where you wouldn't need guide plates is the Scorpion 1.73 ratio rockers.
Just bolt them on. In your case with a low lift cam profile the 1.73 ratio rocker would be beneficial.
https://www.summitracing.com/parts/scc- ... /make/ford
You may have to shim the Scorpion rockers to get the correct geometry but not a big deal.


Sweet, thats just what i wanted to know. Thanks :beer:
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BigBlue94
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Re: 300 carb heads

Post #6 by BigBlue94 » Thu Sep 27, 2018 10:22 am

I was reading awhile back in the 3 aluminum head thread, and either gramps or FTF mentioned that early 300 heads had a slightly smaller chamber size... Maybe 72cc? I cant remember the cut off date, but remember my spare C8TE head being included.

...take with a grain of salt because I am NOT a 300 guru lol.
1985 Bronco. 309ci I6, NP435, 4.56 gears, Detroit locker and tru-trac, 4" lift, and 37" swamper tires. The 309 is 9.75:1 CR with a Schneider 140H cam, 4bbl, roller rockers, larger valves, and headers.

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THE FRENCHTOWN FLYER
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Re: 300 carb heads

Post #7 by THE FRENCHTOWN FLYER » Fri Sep 28, 2018 10:18 am

To my knowledge all carbed 300 heads had a nominal 76 cc head. All 240 heads have a 68 cc head.
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MechRick
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Re: 300 carb heads

Post #8 by MechRick » Fri Sep 28, 2018 3:17 pm

FYI, the stud mount carb heads used cast rockers, that clear the 'Power By Ford' valve cover. Other rockers may interfere with that particular cover. Clearancing the PCV baffles will allow it to fit.

I just thought you should know, and know you do.
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
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http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
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BigBlue94
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Re: 300 carb heads

Post #9 by BigBlue94 » Sat Sep 29, 2018 12:12 pm

THE FRENCHTOWN FLYER wrote:To my knowledge all carbed 300 heads had a nominal 76 cc head. All 240 heads have a 68 cc head.


Page four of the 3 new heads thread.

[quote="WorldChampGramp"]JOSH: Not familiar with the acronym AJE please explain.

Josh et.al:
Elsewhere in this post and in the Forum there are very good discussions on the various Ford heads that were produced between 1965 & 1996 which I like to group into (4) categories.

Early 240 ‘65-67 with 68 CC’s which are like hens teeth to find. Early 300 heads ‘65-71 were in the ’72 CC arena and none of these early 240/300 heads had the thermactor emission “air holes”. Due to Henry Ford’s corporate edict in late 1971 “we are going to concentrate on lowering emissions and are officially disbanding ALL MOTORSPORTS activity within the company Corporate-wide” which effected not only me personally but 100’s of other very dedicated people who had to scramble to find a new job somewhere else in the company or leave the company Ford
[End quote]

Not saying you're wrong, because you have more knowledge than I, but that's where I got the info from.
1985 Bronco. 309ci I6, NP435, 4.56 gears, Detroit locker and tru-trac, 4" lift, and 37" swamper tires. The 309 is 9.75:1 CR with a Schneider 140H cam, 4bbl, roller rockers, larger valves, and headers.

brandoncw
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Re: 300 carb heads

Post #10 by brandoncw » Sat Sep 29, 2018 4:23 pm

pmuller9 wrote:
brandoncw wrote:great info thanks. so its easier to use the pre 85 carb head?


Yes if you want a stud mount rocker arm that gives you a wide variety of rockers to choose from.

The only off the shelf pedestal mount roller rocker for the 85 86 head where you wouldn't need guide plates is the Scorpion 1.73 ratio rockers.
Just bolt them on. In your case with a low lift cam profile the 1.73 ratio rocker would be beneficial.
https://www.summitracing.com/parts/scc- ... /make/ford
You may have to shim the Scorpion rockers to get the correct geometry but not a big deal.


so the 85-86 head is the only carb head that i can use bolt down rocker arms instead of the stud mounts without modification correct?
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BigBlue94
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Re: 300 carb heads

Post #11 by BigBlue94 » Sat Sep 29, 2018 5:27 pm

Correct, and they have to be the Scorpion pedestal mount rockers. Otherwise it's mill and stud time.
1985 Bronco. 309ci I6, NP435, 4.56 gears, Detroit locker and tru-trac, 4" lift, and 37" swamper tires. The 309 is 9.75:1 CR with a Schneider 140H cam, 4bbl, roller rockers, larger valves, and headers.

brandoncw
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Location: Fulton, Missouri

Re: 300 carb heads

Post #12 by brandoncw » Sat Sep 29, 2018 6:17 pm

BigBlue94 wrote:Correct, and they have to be the Scorpion pedestal mount rockers. Otherwise it's mill and stud time.

I just ordered a set of those today
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