Crossram manifold

[PHAT69AMX]

I am no expert, just doing research, and some things I find, or come across, or see surprise me.
So I ask the community and look forward to the discussion and can only hope to learn more.
No intention to stir things up or dispute...  only discussing...
It is my hope to gather and share some more information about this topic.

Yes, research and direct communication resulted in findings that the plenum floor "wet flow ridges" made out of strips of solder and epoxy as seen in the Prototype version pictured above were done at GM by GM Engineering to equalize "wet flow" distribution, Exhaust Gas Temperatures, and equalize all 8 cylinders on the dyno, so they were found to be needed to accomplish that.

So... the production casting flow ridges are incorrectly oriented, since they are non-symmetrical, when compared to the solder strip / epoxy prototype...  or at least it appears that way to me.  And since the production casting flow ridges are incorrectly oriented compared to those in the prototype then the production version would NOT result in equalized cylinder distribution or at least as it would seem...

I would think the Edelbrock version would be "inferior" since it contains now "wet flow equalized distribution management ridges" ?...  where GM Engineering found that they were needed and incorporated them.

I've yet to find online a picture of a production casting with the wet flow ridges oriented like those solder/epoxy ones shown in the pictured prototype.

[crossboss]

I am no expert, just doing research, and some things I find, or come across, or see surprise me.
So I ask the community and look forward to the discussion and can only hope to learn more.
No intention to stir things up or dispute...  only discussing...
It is my hope to gather and share some more information about this topic.

Yes, research and direct communication resulted in findings that the plenum floor "wet flow ridges" made out of strips of solder and epoxy as seen in the Prototype version pictured above were done at GM by GM Engineering to equalize "wet flow" distribution, Exhaust Gas Temperatures, and equalize all 8 cylinders on the dyno, so they were found to be needed to accomplish that.

So... the production casting flow ridges are incorrectly oriented, since they are non-symmetrical, when compared to the solder strip / epoxy prototype...  or at least it appears that way to me.  And since the production casting flow ridges are incorrectly oriented compared to those in the prototype then the production version would NOT result in equalized cylinder distribution or at least as it would seem...

I would think the Edelbrock version would be "inferior" since it contains now "wet flow equalized distribution management ridges" ?...  where GM Engineering found that they were needed and incorporated them.

I've yet to find online a picture of a production casting with the wet flow ridges oriented like those solder/epoxy ones shown in the pictured prototype.

Phat-
Like yourself, I am no expert on Chevy's Cross-Ram design. Just like I am no expert on a Chrysler 'Rat-Roaster' Cross-Ram. What worked for me on the Boss 302, was by my own 'learning tricks'. Every intake is different, so as the old saying goes: "What works for me, may not for you". My only assertion would be what DID work for the Chevy racers (like Tom McIntyre's) intake. Obviously, Smokey was keen on making odd ball stuff work, and a genius. That said, Chevy's small block canted valve prototype heads were really not much better in achieving the power they desired, yet Ford did have great success with their Boss 302/351 Cleveland designs. My point is not to say whom had a 'better' design, just what worked better on a given engine combo.

[TangoBravo]

The distribution dams were a try-it and see how it works experiment. (These type of manifold distribution corrections were done well into the 1980's at some speed shops I am aware of. Fuel comes out of suspension and needs to be channeled to try to even cylinder a/f ratios!)The dams were done with epoxy and wire (reportedly) on a set of O-dash numbered experimental developmental manifolds (reported to be 4 or 5 of them) They were being sent back and forth and developed ASAP. There was tremendous pressure to get them done fast and some were raced in the developmental configuration. When they were casting the first early production pieces, an error was made configuring the dams in the molds and the dams were reversed front to rear-an apparent last minute lay-up under duress. And undid what they were trying to do. The error was quickly corrected and the regular production manifolds were cast correctly. Wayne Guinns Crossram guide, Mark Donohues "Unfair Advantage" and Smokey Yunicks wonderful autobiography have some great insights to what was going on.

[PHAT69AMX]

TangoBravo and others - might you be able to say if these Distribution Dams in this claimed 1967 casting prototype on the left in this picture from the previously posted 2018 Hemmings For Sale Ad are oriented the "correct" way or are they "reversed" ? 

[crossboss]

Boys,
FWIW, and sorry If I go off topic. Here is the Boss 302 'Cross-Boss' lower portion of the cross ram intake. IF you look you can see the 'bumps' I was referring to that are one of the offending problems in the design near the entry of the ports. Removing them and modifying some areas with Devcon made a world of difference. Im sure the Chevy racers did similar 'mods' to correct the flow on their intakes as well.

[PHAT69AMX]

Found this Chevrolet document on GMPartsWiki for 1968.
In the brief Description on this page for the # 3940077 "Engine Conversion Kit", the CrossRam Kit,
it says "( use with 3953867 )"... Might someone know what GM Chevrolet Part Number 3953867 is ?
GMPartsWiki found no results for 3953867... The 3 illustrated Instruction Sheets are Part # 3953866...
Even search GMParts Wiki and failed to find the Part Number for the 6-Cyl Camaro Accelerator Pedal Assembly
that the Instruction Sheets show to use with the 2x4 Crossram Set Up, thinking it was maybe that.

[PHAT69AMX]

Well making the previous post worked like a charm.... 
Chevrolet Part Number 3953867 is for the "Air Cleaner and Plenum Unit"
with the Duct to the Firewall / Cowl, and appears at the top of page 4 of 4
of previously posted Parts List in the very thread... 
But does not show up, is not listed in the Super Stock Heavy Duty Equipment 1971 Catalog 

[PHAT69AMX]

Wow, for sale on eBay Fri July 03, 2020, SBC GM CrossRam Intake & List 4295 Carburetors, Fuel Lines, etc
Claimed NOS 'in the crate' ?  May I ask, does it look legit ?  Just curious... eBay Item # 193534316733

https://www.ebay.com/itm/1968-1969-Camaro-2x4-Crossram-Intake-NEW-Z28-68-69-Cross-Ram-RARE-PARTS-COMPLETE/193534316733?hash=item2d0f8b50bd:g:LpYAAOSweFhe81RS

[WorkinProgress]

Says "new" in the ad, not NOS. Should say reproduction in the crate.

                                           - Warren

[PHAT69AMX]

What might be the GM Part Number ? for the 6-Cylinder Accelerator Pedal Assembly, Gas Pedal Assembly,
that the Part Number 3940077 Crossram Instruction Sheets show to use with the 2x4 Crossram Set Up ?
The 6-Cylinder Gas Pedal Assembly is absent from the 3940077 Parts List, is it not ?

[Jon Mello]

The gas pedal part number you are asking about is 3928326.

[PHAT69AMX]

Thank You John Mello, it if was a snake, it would bit me 

Has anyone ever seen a set-up like this on a CrossRam Intake ?

Anyone have the Instruction Sheets from an out-of-the-box Edelbrock SBC STR-10 CrossRam Intake Manifold?

Anyone have a 1971 Edelbrock Catalog?
If so, anything in there anywhere about Edelbrock Conversion Kit # 2562 ?

A May '68 Hot Rod Mag Article 'Short Stack To Go' is all about the Edelbrock Crossram on a SBC.
15 Dyno pulls making comparisons, with a HP Chart in the article.

For 'Street Use'... ( 2 ) lowly List 1850 600 CFM Vacuum Secondary Carbs...
BUT... 'upfitted' with ( 2 ) Larger Diameter 3-Barrel Vacuum Diaphragm Housings !

1850 600 CFM Main Body has same Venturi & Butterfly Diameters as 3810, 4210, 4295, 4584, 4776, etc
2x 1-1/4" + 2x 1-5/16 Venturi & 4x 1-9/16 'Flies

It is right there in the original Edelbrock AMC STR-11 Crassram Intake Manifold Instructions.
Pair of 1850's were down only 3 HP compared to pair of List 4224 660 Center Squirters !

456 HP vs 459 at 6k on a SBC 350 in the 'Short Stack To Go' Article Dyno Chart.
The Holley List 4224 660's are the same VENTURI as 1850, 3810, 4210. 4295, 4584, 4776,
BUT the 660's have 4x larger 1-11/16" Diameter Butterflies...  thus the additional 60 CFM.
A 660 Main Body is nothing more than an 1850 Body with a 1/16" 45 deg chamfer at the bottom.

Wonder what it says in the Chevrolet Version of the Edelbrock CrossRam Intake Manifold Instructions?

Anyone ever done or seen such a thing ?...
Black & White photoshop pic requires some modified Linkage, but looks really cool imho.

3-Barrel Pods and Parts are non-existent basically, but 3x2 can still be had.
3-Barrel Pods have a 4-Screw Lid, 3x2 Tri-Power Vacuum Diaphragm Pods have a 'better' 6-Screw Lid.T
They say all 3 types of Diaphragm Pods have the same 3-Screw to Main Body Mounting deal... I wonder...

The Throttle Shaft End Piece is different though for all 3 types, each one is it's own,
Standard Pod, 3-Barrel Pod (4-Screw Lid), and 3x2 Pod (6-Screw Lid),
each one has it's own Specific different Throttle Shaft End Piece afaik.

Larger Diaphragm Diameter, same vacuum signal, larger surface area, more opening force...

The fact that Holley used (2) Larger Diameter Vacuum Secondary Housings on the 3x2 Tri-Power set-ups
goes along with the 'idea' of also using them on (2) 1850 600 cfm 4-barrels on the crossram for the same reason, I guess.

[PHAT69AMX]

Here typed up as text is the information
from posted Holley Black Book images for the
Holley List 4210, 4295, & 4584 Carburetors
with the corresponding Part Numbers for each listed item
as found in the referenced Holley 34-1 Typical View.
Yet to determine the meaning of (ld), (llg), (llh), & (XIII) .015".
Did my best to be accurate and correct, but not guaranteed.
Please advise of any errors found, Thank You


4210 Holley List - 585 CFM 1:1 MECH SEC SINGLE PUMPER DUAL INLET
----
R-4210A, AAS (OBS.), T.V. 34-1 (Typical View)
1968 CAMARO, 302 ENG. 2 x 4 BBL.
(ld), (llg), (llh), (VI) No. 2 (Pump Cam Position), (XIII) .015".
Gasket 4-319, Renew  3-422, Master ?
( 12) 5R-155     THROTTLE STOP SCREW
( 27) 5R-635     THROTTLE PLATE SCREW - PRIMARY
( 28) 5R-635     THROTTLE PLATE SCREW - SECONDARY
( 33) 5R-682     PUMP CAM LOCK SCREW
( 34) 5R-691     FUEL PUMP COV. ASSY. SCR. & L. W.
( 61) 8R-1330    FLANGE GASKET
( 62) 9R-109     THROTTLE PLATE - PRIMARY
( 63) 9R-118     THROTTLE PLATE - SECONDARY
( 64) 12R-4089A  THROTTLE BODY & SHAFT ASSY
( 68) 16R-420A   FLOAT & HINGE ASSY - PRIMARY
( 69) 16R-420A   FLOAT & HINGE ASSY - SECONDARY
( 71) 17R-41     FLOAT LEVEL SHAFT
( 72) 6-82       FUEL INLET VALVE & SEAT ASSY ( 188P-135AS )
( 74) 19R-370    FUEL INLET FITTING
( 77) 21R-572-28 PUMP DISCHARGE NOZZLE
( 78) 22R-40-69  MAIN JET - PRIMARY ( 22BP-40-69 )
( 79) 22R-40-71  MAIN JET - SECONDARY ( 22BP-40-70 )
( 83) 6.5        POWER VALVE ASSY - PRIMARY ( 25R-591A-65AS )
(101) 34R-4743A  MAIN METERING BODY & PLUGS ASSY - PRIMARY
(102) 34R-5806A  MAIN METERING BODY & PLUGS ASSY - SECONDARY
(103) 85M-4036   FUEL PUMP COVER ASSY
(104) 34R-5058A  FUEL BOWL & PLUG ASSY - PRIMARY
(105) 34R-5753   FUEL BOWL & PLUG ASSY - SECONDARY
(120) 38R-782    PUMP LEVER ADJ. SCREW SPRING
(124) 38R-1216   FLOAT SPRING - PRIAMRY & SECONDARY
(135) 41R-218    PUMP CAM ( WHITE )
(165) 59R-37     METERING BODY VENT BAFFLE
(166) 59R-79?    FLOAT SHAFT RETAINER BRACKET
(168) 63R-782    DIAPHRAM LEVER ASSY ( SEC SHAFT END PIECE )
(169) 63R-740    PUMP OPERATING LEVER
(176) 37R-257    ? NOT IN LIST OF 34-1 TYPICAL VIEW DRAWING

======================================

4295 Holley List - 585 CFM PROGRESSIVE MECH SEC DOUBLE PUMPER DUAL INLET
----
R-4295A, AAS (OBS.) T.V. 34-1 (Typical View)
1969 CAMARO, 302 ENG. 2 x 4 BBL. Dual Pump
(ld), (llg), (llh), (VI) No. 2 (Pump Cam Position), (XIII) .015".
Gasket 4-226, Renew 3-488, Master 85R-3287
( 12) 5R-155     THROTTLE STOP SCREW
( 27) 5R-635     THROTTLE PLATE SCREW - PRIMARY
( 28) 5R-635     THROTTLE PLATE SCREW - SECONDARY
( 33) 5R-682     PUMP CAM LOCK SCREW
( 34) 5R-691     FUEL PUMP COV. ASSY. SCR. & L. W.
( 61) 8R-1330    FLANGE GASKET
( 62) 9R-109     THROTTLE PLATE - PRIMARY
( 63) 9R-118     THROTTLE PLATE - SECONDARY
( 64) 12R-4247A  THROTTLE BODY & SHAFT ASSY
( 68) 16R-420A   FLOAT & HINGE ASSY - PRIMARY
( 69) 16R-420A   FLOAT & HINGE ASSY - SECONDARY
( 71) 17R-41     FLOAT LEVEL SHAFT
( 72) 6-71       FUEL INLET VALVE & SEAT ASSY ( 188P-135AS )
( 74) 19R-370    FUEL INLET FITTING
( 77) 21R-572-25 PUMP DISCHARGE NOZZLE
( 78) 22R-40-69  MAIN JET - PRIMARY ?
( 79) 22R-40-71  MAIN JET - SECONDARY ?
( 83) 6.5        POWER VALVE ASSY - PRIMARY ( 25R-591A-65AS )
(101) 34R-5882A  MAIN METERING BODY & PLUGS ASSY - PRIMARY
(102) 34R-5885A  MAIN METERING BODY & PLUGS ASSY - SECONDARY
(103) 85M-4036   FUEL PUMP COVER ASSY
(104) 34R-5893A  FUEL BOWL & PLUG ASSY - PRIMARY
(105) 34R-5887A  FUEL BOWL & PLUG ASSY - SECONDARY
(118) 38R-569    PUMP DIAPHRAM RETURN SPRING ( 38R-1375 )
(120) 38R-782    PUMP LEVER ADJ. SCREW SPRING
(124) 38R-1216   FLOAT SPRING - PRIAMRY & SECONDARY
(135) 41R-218    PUMP CAM ( WHITE )
(166) 59R-79     FLOAT SHAFT RETAINER BRACKET
(168) 63R-822    DIAPHRAM LEVER ASSY ( SEC SHAFT END PIECE )
(169) 63R-740    PUMP OPERATING LEVER
(176) 37R-257    ? NOT IN LIST OF 34-1 TYPICAL VIEW DRAWING
*(118).          ? PUMP DIAPHRAM RETURN SPRING ( 38R-1375 )

* = The following INDEX NUMBERS differ from the NUMERICAL LISTING SECTION.
( note from bottom of page of Holley Black Book )
=============================

4584 Holley List - 570 CFM 1:1 MECH SEC SINGLE PUMPER DUAL INLET
----
R-4584AAS (OBS.) T.V. (Typical View) 34-1
1970 HURST SUPER AMX. 390 ENG. CROSS RAM 2 x 4 BBL.
(ld), (llg), (llh), (VI) No. 2 (Pump Cam Position), (XIII) .015".
Gasket 4-319, Renew 3-422, Master ? (Black Diamond Symbol)
( 12) 5R-155     THROTTLE STOP SCREW
( 27) 5R-635     THROTTLE PLATE SCREW - PRIMARY
( 28) 5R-635     THROTTLE PLATE SCREW - SECONDARY
( 30) 5R-854     PUMP DISCHARGE NOZZLE SCREW
( 33) 5R-682     PUMP CAM LOCK SCREW
( 34) 5R-691     FUEL PUMP COV. ASSY. SCR. & L. W.
( 61) 8R-1330    FLANGE GASKET
( 62) 9R-102     THROTTLE PLATE - PRIMARY
( 63) 9R-118     THROTTLE PLATE - SECONDARY
( 64) 12R-4089A  THROTTLE BODY & SHAFT ASSY
( 68) 16R-420A   FLOAT & HINGE ASSY - PRIMARY
( 69) 16R-420A   FLOAT & HINGE ASSY - SECONDARY
( 71) 17R-41     FLOAT LEVEL SHAFT
( 74) 19R-370    FUEL INLET FITTING
( 77) 21R-572-28 PUMP DISCHARGE NOZZLE
( 78) 22R-40-71  MAIN JET - PRIMARY ( 22BP-40-71 )
( 79) 22R-40-77  MAIN JET - SECONDARY ( 22BP-40-77 )
( 83) 6.5        POWER VALVE ASSY - PRIMARY ( 25R-591A-65AS )
(101) 34R-4743A  MAIN METERING BODY & PLUGS ASSY - PRIMARY
(102) 34R-5806A  MAIN METERING BODY & PLUGS ASSY - SECONDARY
(103) 85M-4036   FUEL PUMP COVER ASSY
(104) 34R-5058A  FUEL BOWL & PLUG ASSY - PRIMARY
(105) 34R-5753   FUEL BOWL & PLUG ASSY - SECONDARY
(120) 38R-782    PUMP LEVER ADJ. SCREW SPRING
(124) 38R-1216   FLOAT SPRING - PRIAMRY & SECONDARY
(135) 41R-218    PUMP CAM ( WHITE )
(165) 57R-37     METERING BODY VENT BAFFLE
(166) 59R-79     FLOAT SHAFT RETAINER BRACKET
(169) 63R-740    PUMP OPERATING LEVER
(176) 37R-257    ? NOT IN LIST OF 34-1 TYPICAL VIEW DRAWING
*(30).           ? PUMP DISCHARGE NOZZLE SCREW

* = The following INDEX NUMBERS differ from the NUMERICAL LISTING SECTION.
( note from bottom of page of Holley Black Book )
===========================

[GMAD_Van Nuys]

One of my favorite road tests was Car & Driver's Tunnel Port Mustang vs a 1968 Z28 Camaro:

https://www.caranddriver.com/reviews/comparison-test/a15142639/1968-tunnel-port-ford-mustang-vs-chevrolet-camaro-z-28-archived-comparison/

[Roybalgene]

Hello is it possible to talk to you about this cross ram I'm curious if you're up in Canada thank you oh, this is really important if you get a chance I'd appreciate it to talk to you