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There is a tremendous amount of mis-information seen in auctions for cross-ram intake manifolds to fit Small-Block Chevrolet engines. This guide is intended to cover cross-ram manifolds that have removable top plates that the carburetor(s) mount to. I do not intend to cover cross-rams that do not have removable top plates such as the Offenhauser 5590, Edelbrock XC-8, Weiand 7291, and similar.
There are four similar but NOT IDENTICAL cross-ram intake manifolds that are often sold on eBay that fit the small block Chevy. In addition to those four, there are some exceedingly rare units which almost never go up for auction. One such manifold will be covered later.
There are four similar but NOT IDENTICAL cross-ram intake manifolds that are often sold on eBay that fit the small block Chevy. In addition to those four, there are some exceedingly rare units which almost never go up for auction. One such manifold will be covered later.
A. The original General Motors manifold. It has a Winters Foundry emblem (a snowflake) cast into it. Original units are rare and insanely expensive--I've seen asking prices well into the 5-figure range for complete units with carbs, linkage, etc. They were a dealer-installed option on Camaro Z-28 cars in the late '60's, and of course they were available over-the-parts-counter. I recently saw at a GM Performance Parts display that there are GM-authorized reproductions which are still plenty expensive--on the order of $7000 for a complete kit with carbs, linkage, air cleaner, etc. The key is to look for the Winters Foundry snowflake. This is the ONLY ONLY ONLY cross-ram manifold supplied by GM for use on the DZ 302, Z-28 Camaros. NO OTHER CROSS RAM IS ORIGINAL--despite what the auction claims. Smokey Yunick did some development work on this manifold.
B. The Offenhauser--a close copy of the GM manifold, including the mixture distribution tabs cast into the plenum area. The bare manifold with a top is available BRAND NEW from vendors for $500 and down., but be aware that a linkage kit to use with the dual-four-barrel carb plate will add about a hundred dollars to the price of the base and top plate. Some vendors are clearly "trolling for idiots" and making huge profits. This manifold , two top plates, and the dual-four linkage kit are still available new, as of 17 March 08. The most common top is the dual-four. Offy made a triple-Weber-carb top plate, a single four top plate to fit Holley 4150 and Q-Jet, and a single four top plate to fit Holley Dominator. The Weber top plate and linkage is discontinued. The single-four Q-jet/4150/4160 top plate may now be discontinued, too. Be aware that this manifold with the dual-carb top plate is a good, but NOT PERFECT copy of the GM piece. There is no Winters Foundry snowflake, and there are other detail differences. Because it's still in production, prices are reasonable--IF YOU SHOP AROUND--and the top plates and manifold base are available separately. Each piece includes a gasket. Offenhauser does not seem to have a web site--good luck contacting them directly.
Offenhauser part numbers are: Base--5893 Single four top for 4150/Q-jet--5901 (possibly discontinued) Single four for Dominator-- 5948 Dual-quad top--5903 Linkage kit for dual-quad--5902 3-Weber-top--5899 (no longer available) 3-Weber linkage kit--5900 (no longer available)
This is a strictly aftermarket manifold--GM DID NOT sell this piece.
C The Edelbrock Street Tunnel Ram (STR-10) looks superficially similar to the GM and it's clone, the Offy. Big differences are the thermostat location and the shape of the top plate's corners--the STR is more rounded/streamlined. This is a dual-four manifold. It has been out of production for many years.
This is a strictly aftermarket manifold--GM DID NOT sell this piece.
D The Smokey Yunick-designed Smoke (or Smokey) Ram SY-1. This one is the most different from the others--it was designed from the beginning to use a single four-barrel carb. The SY-1 has been out of production for many years. It was cast and sold by Edelbrock. Smokey said this was a particularly good manifold for small-displacement, high RPM engines. This manifold was written about in the November 2002 issue of Car Craft. They found excellent midrange power, when installed on their test engine using a Holley 750 carb. The SY-1 added 23 ft/lbs of torque at 4,600 rpm, but subtracted 17 horsepower from the peak reading as compared to the Victor manifold it replaced. (They did not say how much carb tuning was done, and they didn't list the engine displacement.) The manufacture and sale of this manifold caused some hard feelings between Smokey and Edelbrock, according to Smokey's autobiography. I have heard--but not verified--that Edelbrock issued a "mixture distribution fix" for this manifold, with instructions on where to weld-in some tabs or dams on the plenum floor to even-out the fuel distribution. I have seen manifolds that claim to be reworked in this manner; but I don't have a copy of the actual instructions to verify the work was done right.
This is a strictly aftermarket manifold--GM DID NOT sell this piece. However, GM did support early prototype work, even issuing a part number (5233751) for development purposes and--supposedly--this was to be the 1970 GM-authorized replacement for the dual-carburetor crossram manifold used previously except that GM chose to just drop the program instead. At that point, Edelbrock stepped in to manufacture the manifold independently of GM.
An exceptionally rare crossram is the "Junior Johnson" unit, cast by Winters for Bruce McLaren Motor Racing (BMMR). That is pretty much a three-way pedigree; and the price is as high as the manifold is rare. The Winters snowflake casting mark, the BMMR stamping; and the JR JOHNSON logo all appear on this manifold. My thanks to johnnydaytona6 for permission to display photos of his manifold.
This manifold requires an extra-long distributor; a regular-length distributor won't clear the back of the manifold.
Because Smokey Yunick, and the DZ 302/Z-28 had such good reputations, unethical sellers use those words to keyword spam --drawing attention to merchandise that otherwise has no relation to Smokey or the original GM parts offered on Camaros. Often, auctions for the STR-10 or the Offenhauser are keyword spammed with those words. The worst of these spammers uses hidden text--it's picked up in your eBay searches, but it won't be obvious. You can find hidden text easily using Firefox and Netscape when looking at a web page--please see my other guide for Keyword Spam Busting.
I'm not allowed to link to web pages outside of eBay, but if you do a search on "Camaro Cross-Ram Intake Manifolds" you'll likely find a wonderful article comparing and contrasting three of the four manifolds listed above. (The Smoke Ram is not included--but it's obviously different because it was never offered as a dual-four)
Of possible interest:
You may also care to view my eBay Guide to Chevrolet Small Block Tri-Power ( 3X2 ) Manifolds
If this guide has been helpful, please give me a "Yes" vote by clicking the button below. If you have suggestions for improvement, you can use the "My Messages" feature of eBay to contact me. Click on my user name above, then on "Contact Member". Thanks, all!
Entire contents copyright (C) 2007, 2008 Camino3X2 Feel free to LINK to this guide in your auctions.
B. The Offenhauser--a close copy of the GM manifold, including the mixture distribution tabs cast into the plenum area. The bare manifold with a top is available BRAND NEW from vendors for $500 and down., but be aware that a linkage kit to use with the dual-four-barrel carb plate will add about a hundred dollars to the price of the base and top plate. Some vendors are clearly "trolling for idiots" and making huge profits. This manifold , two top plates, and the dual-four linkage kit are still available new, as of 17 March 08. The most common top is the dual-four. Offy made a triple-Weber-carb top plate, a single four top plate to fit Holley 4150 and Q-Jet, and a single four top plate to fit Holley Dominator. The Weber top plate and linkage is discontinued. The single-four Q-jet/4150/4160 top plate may now be discontinued, too. Be aware that this manifold with the dual-carb top plate is a good, but NOT PERFECT copy of the GM piece. There is no Winters Foundry snowflake, and there are other detail differences. Because it's still in production, prices are reasonable--IF YOU SHOP AROUND--and the top plates and manifold base are available separately. Each piece includes a gasket. Offenhauser does not seem to have a web site--good luck contacting them directly.
Offenhauser part numbers are: Base--5893 Single four top for 4150/Q-jet--5901 (possibly discontinued) Single four for Dominator-- 5948 Dual-quad top--5903 Linkage kit for dual-quad--5902 3-Weber-top--5899 (no longer available) 3-Weber linkage kit--5900 (no longer available)
This is a strictly aftermarket manifold--GM DID NOT sell this piece.
C The Edelbrock Street Tunnel Ram (STR-10) looks superficially similar to the GM and it's clone, the Offy. Big differences are the thermostat location and the shape of the top plate's corners--the STR is more rounded/streamlined. This is a dual-four manifold. It has been out of production for many years.
This is a strictly aftermarket manifold--GM DID NOT sell this piece.
D The Smokey Yunick-designed Smoke (or Smokey) Ram SY-1. This one is the most different from the others--it was designed from the beginning to use a single four-barrel carb. The SY-1 has been out of production for many years. It was cast and sold by Edelbrock. Smokey said this was a particularly good manifold for small-displacement, high RPM engines. This manifold was written about in the November 2002 issue of Car Craft. They found excellent midrange power, when installed on their test engine using a Holley 750 carb. The SY-1 added 23 ft/lbs of torque at 4,600 rpm, but subtracted 17 horsepower from the peak reading as compared to the Victor manifold it replaced. (They did not say how much carb tuning was done, and they didn't list the engine displacement.) The manufacture and sale of this manifold caused some hard feelings between Smokey and Edelbrock, according to Smokey's autobiography. I have heard--but not verified--that Edelbrock issued a "mixture distribution fix" for this manifold, with instructions on where to weld-in some tabs or dams on the plenum floor to even-out the fuel distribution. I have seen manifolds that claim to be reworked in this manner; but I don't have a copy of the actual instructions to verify the work was done right.
This is a strictly aftermarket manifold--GM DID NOT sell this piece. However, GM did support early prototype work, even issuing a part number (5233751) for development purposes and--supposedly--this was to be the 1970 GM-authorized replacement for the dual-carburetor crossram manifold used previously except that GM chose to just drop the program instead. At that point, Edelbrock stepped in to manufacture the manifold independently of GM.
An exceptionally rare crossram is the "Junior Johnson" unit, cast by Winters for Bruce McLaren Motor Racing (BMMR). That is pretty much a three-way pedigree; and the price is as high as the manifold is rare. The Winters snowflake casting mark, the BMMR stamping; and the JR JOHNSON logo all appear on this manifold. My thanks to johnnydaytona6 for permission to display photos of his manifold.
This manifold requires an extra-long distributor; a regular-length distributor won't clear the back of the manifold.
Because Smokey Yunick, and the DZ 302/Z-28 had such good reputations, unethical sellers use those words to keyword spam --drawing attention to merchandise that otherwise has no relation to Smokey or the original GM parts offered on Camaros. Often, auctions for the STR-10 or the Offenhauser are keyword spammed with those words. The worst of these spammers uses hidden text--it's picked up in your eBay searches, but it won't be obvious. You can find hidden text easily using Firefox and Netscape when looking at a web page--please see my other guide for Keyword Spam Busting.
I'm not allowed to link to web pages outside of eBay, but if you do a search on "Camaro Cross-Ram Intake Manifolds" you'll likely find a wonderful article comparing and contrasting three of the four manifolds listed above. (The Smoke Ram is not included--but it's obviously different because it was never offered as a dual-four)
Of possible interest:
The Accel DFI Super Ram is a fuel injected cross-ram of similar configuration to the above carbureted units, however the throttle body is front-mounted rather than top-mounted.
General Motors installed a "cross ram" manifold on Corvettes for model years '82 and '84 using two one-barrel throttle-body fuel injectors. The manifold base is often sold with a home-made top plate fabricated to hold two four-barrel carbs. This manifold is very poor for performance use; the runners are TINY and will take you the rest of your life to port out to a decent size.
General Motors installed a "cross ram" manifold on Corvettes for model years '82 and '84 using two one-barrel throttle-body fuel injectors. The manifold base is often sold with a home-made top plate fabricated to hold two four-barrel carbs. This manifold is very poor for performance use; the runners are TINY and will take you the rest of your life to port out to a decent size.
You may also care to view my eBay Guide to Chevrolet Small Block Tri-Power ( 3X2 ) Manifolds
If this guide has been helpful, please give me a "Yes" vote by clicking the button below. If you have suggestions for improvement, you can use the "My Messages" feature of eBay to contact me. Click on my user name above, then on "Contact Member". Thanks, all!
Entire contents copyright (C) 2007, 2008 Camino3X2 Feel free to LINK to this guide in your auctions.
Guide created: 08/13/06 (updated 10/01/08)
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