The dot thickens...

The dot thickens...

Joined: January 1st, 1970, 12:00 am

November 5th, 2008, 3:38 pm #1

I recieved this message on the Wiki this morning from a new member zgreatwhite I don't have answers for him but you guys might.
-blizz

-I have an addition to your table and a note.

Table Addition
My heads are D1AE GA, date code 0G3, 4dot.
They are closed chamber.

Note: 4 vs 4Dot
My understanding of dot usage is in regards to the CHAMBER SIZE.
US 4V CLOSED 61.3-64.3cc 4 cast in corner
US 4V CLOSED 64.6-67.6cc 4 & dot cast in corner

Boss heads have the larger chambers, don't know if they have the 4dot.

This information is a little harder to confirm because it isn't easy to measure for most people, and the difference is only 5% so errors are easily made. However, when choosing pistons for compression, it is very important.

Email with any thoughts. I am currently attempting to build a somewhat streetable 351C for my 73 'tang' to replace my aging, overworked 302. I would be interested in contacting others in SoCal to see what builds have worked for them.

Thanks.

1963 Galaxie 500 SOLD!!!
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Joined: May 2nd, 2001, 1:57 am

November 5th, 2008, 4:00 pm #2

The chambers are as-cast. The measured valumes posted over the years are all over the place, and I have not seen and correlation of size to dot.

But, does this poster have any factory data to back up this conclusion?

zgreatwhite, are you out there?

"That wasn't any farewell slap." -Dick Powell
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Joined: November 6th, 2004, 7:00 am

November 5th, 2008, 11:37 pm #3

I recieved this message on the Wiki this morning from a new member zgreatwhite I don't have answers for him but you guys might.
-blizz

-I have an addition to your table and a note.

Table Addition
My heads are D1AE GA, date code 0G3, 4dot.
They are closed chamber.

Note: 4 vs 4Dot
My understanding of dot usage is in regards to the CHAMBER SIZE.
US 4V CLOSED 61.3-64.3cc 4 cast in corner
US 4V CLOSED 64.6-67.6cc 4 & dot cast in corner

Boss heads have the larger chambers, don't know if they have the 4dot.

This information is a little harder to confirm because it isn't easy to measure for most people, and the difference is only 5% so errors are easily made. However, when choosing pistons for compression, it is very important.

Email with any thoughts. I am currently attempting to build a somewhat streetable 351C for my 73 'tang' to replace my aging, overworked 302. I would be interested in contacting others in SoCal to see what builds have worked for them.

Thanks.

1963 Galaxie 500 SOLD!!!
The dot is used on both open and closed chamber heads starting in 71
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Joined: November 7th, 2008, 6:05 am

April 10th, 2012, 9:42 pm #4

The chambers are as-cast. The measured valumes posted over the years are all over the place, and I have not seen and correlation of size to dot.

But, does this poster have any factory data to back up this conclusion?

zgreatwhite, are you out there?

"That wasn't any farewell slap." -Dick Powell
I was searching for previous posts I had made, and discovered this, so I thought I would respond...4 years later!

I have been unable to find ANY FORD LICENSED DOCUMENTATION such as a service/shop manual detailing combustion chamber volume as well as camshaft information for a 351CJ or 351BOSS. People are quoting information, but are never able to produce the Ford printed document. That does not mean they are wrong, it just means there is no manufacturer trace for the source of the information.

I do have a 70 & 71 shop manuals. 70 lists 351 4V and 302 Boss. 71 lists 302HO, 351 4V. No mention of a CJ or BOSS unless it is in a note on the page that I have missed. No mention of mechanical lifters. 302 Boss does indicate 7/16 threaded stud, page 21-04-35 under cylinder head. No mention in 71 manual for 351.

70 Specs
302 Boss, page 21-04-35 lists chamber combustion volume as 61.3-64.3cc.
351 4V, page 21-05-28 lists combustion chamber volume 61.3-64.3cc.

71 Specs
302HO, Page 21-21-34, 61.7-64.7cc
351 4v, page 21-22-28, 64.6-67.6

The specs do not indicate if the spark plug displacement is taken into account. I measured the combustion chamber of my heads without spark plug, cast with the following identifying characteristics:

1. 4dot
2. D1AE
3. GA
4. D Shaped quench head
5. Non machined pedestals

and I got 68cc. If anything, I was probably a little over but not by more than 2cc.

I understand there are errors in manuals/documentation. In fact, my 70 Shop Manual indicated 302 Boss combustion chamber volume as 6.13 - 64.3, so we do need to be careful. But I would sure like to see a shop manual for the 351 Boss.

This site has some nice photos:

http://mustangtek.com/heads/Heads.html

Interestingly, for 351 Boss they list combustion chambers at 75.4 but do not show combustion side of head. Pedestal is lower, and the thread appears 7/16, but it doesn't look as if the pedestal was machined.

Photo of my chamber:


Last edited by zgreatwhite on April 10th, 2012, 9:44 pm, edited 1 time in total.
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Joined: October 1st, 2004, 8:05 pm

April 10th, 2012, 10:48 pm #5

I've already answered a couple of your past posts, and received no thank you or acknowledgement from you.

There is tons of Ford literature to provide answers to your questions. Not just the engine Manuals, but the OHO manual and the OHO Newsletters, and Shelby Performance Parts catalog (the Shelby Parts business was owned by Ford in this period of time), the Ford Muscle Parts catalog (Ford's performance parts program, operated by the Autolite division, prior to the OHO program). A decade later it was the Motorsport Division/SVO that was selling performance parts and producing catalogs.

You'll never find an engine manual for the Boss 351, I've already explained why in a previous post. But the Boss 351 cam specs are identical to the 302 HO cam specs in your 1971 engine manual.

The 351 Cobra Jet cam specs are in the 1972 engine manual, you just have to advance the timing by 4 degrees to arrive at the 1971 specs.

But the Boss 351 & 1971 Cobra Jet cams were sold over the counter by Ford in 1970 via the Muscle Parts program, and guess where those specs can also be found .... in the 1970 Muscle Parts catalog.

Those specs can also be found in Pat Ganahl's book.

As you know the engine manuals lists the combustion chamber volumes with a tolerance of +/- 3cc (approximately). Those figures are nominally (dropping the tenths) 63cc for 1970, 66cc for 1971 for the quench heads and 75cc for 1971 - 1972 open heads and 78cc for the 1973 and 1974 open heads. that stuff is all in the engine manuals. I don't have to look that stuff up though, because I've been using that info for 40 years.

I haven't pulled this crap out of my ass, I have ALL the literature. You can trust this data comes from that literature or you can choose not to. I've tried to helpful, to make it easy on you and others. A whole lot of people trust me as a source for 351C info. But you can be damned sure about one thing, I sure as hell am not going to scan the literature and post it on the net for somebody who doesn't have the courtesy to say thank you. Or somebody who keeps asking the same questions even after I've answered them, as though I'm an idiot to be ignored. Would You?

Have a nice day
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Joined: December 22nd, 2009, 6:12 pm

April 11th, 2012, 1:47 am #6

n/m
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Joined: May 1st, 2011, 7:18 pm

April 11th, 2012, 5:03 am #7

The dot is used on both open and closed chamber heads starting in 71
.





. . .



.

George thanks for all the info you share with us. Maybe a game of join the dot's for those less apreciative.
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