Technical section T/A details

[pbf777]

Scott, Do you have any comment on the exhaust flow on 68 hypo 289 heads? Which I read or was told flowed better than the other Exhaust ports because of the D shape.     

     Not sure which "Scott" you might be referencing but: those '68 heads present the "D", sorta shape, only because the secondary air injection boss is crowding the exhaust port runner; which also is positioned on the high pressure side of the port, so 'no' they do not flow better; that is out of the box.   

    But, that same initial detriment does provide greater material thickness on that wall, that over the earlier head castings without, which can be utilized as a benefit in the porting endeavor if chosen to do so; but then you do sorta end up with a bit of crook in the runner.   

    The only significantly different/better S.B.F. exhaust port executions provided for by any of the O.E.M. iron castings, that I recall, is that of the C6FE & T.P.; all the rest your just squinting to hard and splitting hairs for a conviction of any real merit.   

     Scott.

[JohnSlack]

Pictures of original TA carburetors which I believe are 525C. F. M which John Slack now owns. It also shows the special linkage.
Scott, Do you have any comment on the exhaust flow on 68 hypo 289 heads? Which I read or was told flowed better than the other Exhaust ports because of the D shape.

       Roy

Roy,

I believe that those carburetors are in the 495 to 525 CFM arena. I am very happy to own them and as you know they will be finding their home on the BOSS 302 standard flange Holley T/A intake in my 1969 BOSS 302. I digress, Harold Droste reworked those carburetors at Holley for FoMoCo to use in the 1968 T/A Tunnelport program according to my conversations with Randy Gillis. Randy was very interested in the Harold Droste carburetors and similar carburetors were used at Lemans. Those carburetor had Droste serial numbers that fell on both sides of carburetors the Randy had in his possesion and had run on his big Tunnelport engine. The Carburetors have 1.250" primary and secondary venturis with 1.495" primary and secondary throttle bores. The cam slots in the linkage were custom ground by Droste to give a softer secondary opening phase. They are very nice carburetors. the only truly vintage downside is the air horns were milled off at some point. Randy said that he had found several of those carburetors complete and in pieces at the Pomona and Long Beach swap meets over the years



John

[gt350shelb]

the list numbers on the  carbs on my intake are 4224 s
from holley web site :



Barrels   4
Booster   Straight
Brand      Holley
CFM   660
Choke   None
Emission Code   3
Finish   Gold Dichromate
Fuel   Gasoline
Fuel Inlet   Single
Material   Zinc
Model   4160
Primary Main Jet   76
Primary Pump Nozzle Size   25
Product Type   Carburetor
Secondaries   Mechanical
Secondary Pump Nozzle Size   25
Supercharged Application   No
Throttle Bore   1.688 inch
Vacuum Ports   1 timed (spark) port, 1 full, and 1 PCV port
UPC   090127000588
Part Number   0-4224

[JohnSlack]

the list numbers on the  carbs on my intake are 4224 s
from holley web site :



Barrels   4
Booster   Straight
Brand      Holley
CFM   660
Choke   None
Emission Code   3
Finish   Gold Dichromate
Fuel   Gasoline
Fuel Inlet   Single
Material   Zinc
Model   4160
Primary Main Jet   76
Primary Pump Nozzle Size   25
Product Type   Carburetor
Secondaries   Mechanical
Secondary Pump Nozzle Size   25
Supercharged Application   No
Throttle Bore   1.688 inch
Vacuum Ports   1 timed (spark) port, 1 full, and 1 PCV port
UPC   090127000588
Part Number   0-4224

https://www.saacforum.com/index.php?action=dlattach;topic=24980.0;attach=119015;image

The huge difference that the Droste carburetors have over the standard 4224 Holley 660 center squirter is the phased progressive linkage on the secondary side. This allows the secondaries to be brought in slowly instead of 1:1 bringing them in like a drag car. You get some low RPM drivability with this feature. People can modify the slot in the 660, However if you look at the pictures you can see that the opposite side of the cam slot for the roller to react to has a bump to close the secondaries as well. This feature is important, especially on a road race car.


John

[gt350shelb]

yes i can see how these are more of an on off switch

[shelbydoug]

damn doug did you sleep last night 

Well...depends? There's sleep and then there's sleep.

I'm not sure why even a race car would need that much pump shot. That is really a throttle response "thing".

You know, all this talk of the "drivers" blowing up the TP's at 9,200 is kind of silly.

IF you ever actually witnessed one of those Trans Am races with the team drivers, you might come to the conclusion that it was an attempted mass suicide? 8,000 rpm was NOTHIN'! They drove the cars like the winner was the one who blew the car up first 'cause they were all tryin' their best to go boom.

The key here is that manifold and now what you can flow on today's heads.


As I said, in switching to the T/A intake from the "turd", the idle vacuum dropped and so far, I can't get it to idle down to 750 like before with 15 inches. It wants 1,100. It may be the intake characteristics.
It is kinda' unique?

It came before tunnel rams existed but has tunnel ram characteristics without looking like one?

I'll get it right. It doesn't keep me from sleeping. Don't worry about that. Yea I sleep last night.

[JohnSlack]

damn doug did you sleep last night 

Well...depends? There's sleep and then there's sleep.

I'm not sure why even a race car would need that much pump shot. That is really a throttle response "thing".

You know, all this talk of the "drivers" blowing up the TP's at 9,200 is kind of silly.

IF you ever actually witnessed one of those Trans Am races with the team drivers, you might come to the conclusion that it was an attempted mass suicide? 8,000 rpm was NOTHIN'! They drove the cars like the winner was the one who blew the car up first 'cause they were all tryin' their best to go boom.

The key here is that manifold and now what you can flow on today's heads.


As I said, in switching to the T/A intake from the "turd", the idle vacuum dropped and so far, I can't get it to idle down to 750 like before with 15 inches. It wants 1,100. It may be the intake characteristics.
It is kinda' unique?

It came before tunnel rams existed but has tunnel ram characteristics without looking like one?

I'll get it right. It doesn't keep me from sleeping. Don't worry about that. Yea I sleep last night.

shelbydoug, did I miss the picture of the intake manifold you are talking about? After all I showed you mine before.

The first picture is of the not used 1969 Standard Flange Holley BOSS 302 Intake Dual Plane Intake Manifold - From FoMoCo to Smokey Yunick to Roy Richards to Me - NOS

The second picture is of the latest version of the 1969 BOSS 302 Dual Dominator Intake Independent Runner Intake Manifold From FoMoCo to Shelby American to Wayne Richards to Me to Scott Thomas back to Me - NOS

The third picture is of the 1970 Bud Moore Mini-Plenum for the BOSS 302 From Bud Moore to Rick Kirk to Me - NOS

John

[shelbydoug]

Yours is so little.

Mine is just another C6OA. No biggie.


I don't know why the pictures are posting so large? It's too early to battle with the computer. I'm just letting it win for now.

Sorry. Mine really isn't bigger then yours.

[gt350shelb]

[shelbydoug]

I thought that the C6ZZ manifold had a mistake in the firing order? Instead of an 8, it had a 9?

[gt350shelb]

I thought that the C6ZZ manifold had a mistake in the firing order? Instead of an 8, it had a 9?

there are 2 one has  9 cylinders 

[shelbydoug]

I thought that the C6ZZ manifold had a mistake in the firing order? Instead of an 8, it had a 9?

there are 2 one has  9 cylinders 

Wouldn't Tech disqualify the car?

[Wedgeman]

Has anyone ever tested the horsepower difference between the Trans Am intake & the blue thunder repop on the same engine?

[shelbydoug]

Has anyone ever tested the horsepower difference between the Trans Am intake & the blue thunder repop on the same engine?

I have run them both.

You need to gasket match the high rise. It is torky but doesn't have the same top end of the T/A.

The high rise will run lean on the #3 cylinder under racing conditions and does not have the same WOT power the T/A does.

The T/A responds more to more cam then the high rise. Both are nice manifolds.

I only ran mine with vacuum secondaries. I don't know what the center squirters will do.

[Wedgeman]

Thanks Doug !!