duel 4 bbls on crossram

[Geri]

the STR crossram, places the carbs staggered facing forward.
when the factory crossrams were made the carb jetting was unsquare with forward facing jets larger than the rearward jets on both primaries and secondaries.
beings the forward facing carbs have 4 jets farther away from the runner was there/should there be a consideration as to jetting similar to factory cross rams?

 

[Endangered Species]

I'm not expert.. but the larger jets are always in the Primary because you need the fuel while the car is accelerating. It doesn't have anything to do with how the carbs are positioned. You can fine tune with the secondary.

 

[dvw]

Are you talking Eddy/Carter or Holley? Eddy/Carter are always bigger front jet due to metering rod restriction. Without O2 sensors in every cylinder it comes down to plug reading after a clean cut and coast. A lot of time and spark plugs. I'd start with stock jetting + 5% and go from there.
Doug

 

[Geri]

Are you talking Eddy/Carter or Holley? Eddy/Carter are always bigger front jet due to metering rod restriction. Without O2 sensors in every cylinder it comes down to plug reading after a clean cut and coast. A lot of time and spark plugs. I'd start with stock jetting + 5% and go from there.
Doug

I'm going to use Holley 600CFM vacuum secondary carbs. thanks

 

[Geri]

I'm not expert.. but the larger jets are always in the Primary because you need the fuel while the car is accelerating. It doesn't have anything to do with how the carbs are positioned. You can fine tune with the secondary.

I'm going to disagree with you on this. on the factory SS wedge cross rams, the front side of the Carter carbs(sitting sideways) were always jetted different from the rear side-toward firewall side. because of acceleration the gas in the fuel bowls would be pushed toward the firewall,all forward side jets were smaller than aft side of the carbs, even the primaries and secondaries had different size jets depending on forward or aft side of the carbs. I have purchased a few factory max wedge crossrams the former owner said did not perform, every one the owner thought they found an issue and jetted all primaries the same and all secondaries the same (primary and secondary jets not the same size). by using the factory jet charts I could take a car stumbling to run a high 13 deep into the 12's just by jetting carbs correctly, carbs are not made to sit sideways so jetting per fore and aft has to be considered.
the hollys on this STR manifold sit conventionally forward but beings they are staggered side by side, the outside jets might need to be considered, but I am fairly clueless on the holley performance massage and I'm trying to account for all this.
this is also why the Holly carbs for the superstock hemi's are marked left side and right side- put them on wrong side performance suffers.

 

[dvw]

I ran my 63 Dodge wire a factory stage 1 crossram with 3705s. Recomded Direct Connection jetting. One jet was very small as I remember (.068?). Then I ran it with Eddy carbs (same throttle bore and venturi size) with out of the box jetting. Then ran within s few hundredths of each other.
Doug

 

[Geri]

I ran my 63 Dodge wire a factory stage 1 crossram with 3705s. Recomded Direct Connection jetting. One jet was very small as I remember (.068?). Then I ran it with Eddy carbs (same throttle bore and venturi size) with out of the box jetting. Then ran within s few hundredths of each other.
Doug

thats good if it worked for you. the fact remains I have purchased 3 max wedge manifolds with the 3705 carbs, all had been "square jetted- same size jet on all primaries and same size on all secondaries- all were dogs. the last set I bought in 1994 the seller a person I knew well complained of poor performance. I put them in my '62 Dodge SS clone and like he said- they were dogs. I got out my Mopar performance book and rejetted per factory specs and it was a different animal. (not a dog) with correct jetting none of the 4 jets in the carbs are the same size, I no longer remember the jet size, at the time I had the "must have" Carter trackpak of jets and metering rods. I can only relate what I found throughout the years using these parts going back to the '63 SS426 plymouth I bought new.(wish I had it now). even removing the 5/16"? vacuum hose from back of manifold to valve cover reduced performance, I never expected that , tried that once and put it right back on.

 

[dvw]

Here's what I used. If you notice the small secondary jets on the 3705's are in the outside of the intake. One carb faces in each direction. The 3447s are the same side to side. These were Chrysler dyno jet numbers done in house under controlled conditions. Take for instance the .104/.053 jet/rod vs the .089 jet by itself. The difference in area is only about 3%. So beside the choke side secondary jets being small (cylinders 2/7) not much difference. My car ran 10.1X@132 best. Your issue might be lack of hood scoop. Not the the scoop is that great, but the carbs are very close to the hood. Like I said, not much difference.
Doug
1963 Stage III 426 Super Stock cars with the 3447 Carter carbs:
Main jets: Primary = .098"
Secondary = .082"
Step-up (metering) rods: .068 X .050
For the 1964 426 Max. Wedge cars with the 3705 Carter carbs:
Main jets: Primary = .104"
Secondary = Choke side .063" Throttle side .089"
Step-up (metering) rods: .066" X .053"
Also, on these carbs (the 3705s), the recommended float setting changes from 7/16" to 7/32"

 

[NSS Guy]

That's close to the jetting in my eddy 750's. slightly richer on primary side

 

[POMONAMISSEL]

this run twin 660

holleys on stage 2 intake , stage 3 heads a street version . drove it like a CAR , any n everywhere .

 

[Geri]

Here's what I used. If you notice the small secondary jets on the 3705's are in the outside of the intake. One carb faces in each direction. The 3447s are the same side to side. These were Chrysler dyno jet numbers done in house under controlled conditions. Take for instance the .104/.053 jet/rod vs the .089 jet by itself. The difference in area is only about 3%. So beside the choke side secondary jets being small (cylinders 2/7) not much difference. My car ran 10.1X@132 best. Your issue might be lack of hood scoop. Not the the scoop is that great, but the carbs are very close to the hood. Like I said, not much difference.
Doug
1963 Stage III 426 Super Stock cars with the 3447 Carter carbs:
Main jets: Primary = .098"
Secondary = .082"
Step-up (metering) rods: .068 X .050
For the 1964 426 Max. Wedge cars with the 3705 Carter carbs:
Main jets: Primary = .104"
Secondary = Choke side .063" Throttle side .089"
Step-up (metering) rods: .066" X .053"
Also, on these carbs (the 3705s), the recommended float setting changes from 7/16" to 7/32"



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I double dog dare you to park that car close to me, you'll never see it again.you have been warned. are you saying all primary jets were the same front side/rear side and same with secondaries?
you are far more advanced in them now than we were then. my' '63 had hood scoops albeit not the mopar scoop, they were not available yet if your car didn't come with one, mine was the 415HP,no scoop or alum front end. the day I ordered my car the bulletin came out about the Alum group offer, I ordered it but didn't know they were only available on the 425 HP version. my scoop(s) were the Ford truck air intake on the side cowl that had screen to keep out the rats and mice. they look pretty much like the later scoops on the Pontiac scoop. my '62 clone was never going to get a scoop as they were not available in' 62, I was making it faithful to the year. I even ran the stock exhaust and centrifugal advance duel point distributor.
so with the 3.90 gears and all factory trim and the tired 440 short block I was pleased with the 109 top end, would liked to have ET'd better but? at the next race after the picture, the SS cars were lined up waiting for a run, first run was about 10AM ,at 3PM we ere still waiting fort a second run, cars in other lanes were doing laps, I asked the staging lane director when we'd get another run, he became belligerent and told us to wait in your f**king car till we call you. I got out of the lane,went back to the pits, took it home -then took it apart and sold it, the engine/exhaust went to Seattle Washington , the car now running with a '68 hyPo 383 (stock, went to a friend. really regret that as well, I purchased the '62 all stock,never wrecked, never rusted, no damage ever with a 318, for 2K, after cleaning from underside up-I jacked the car up about 3' off the ground removed everything from the underside and cleaned it with wire brushes and tooth brushes till it was literally spotless, had a painter friend repaint the underside with light gray gloss epoxy, it looked better than the original blue exterior. it had new interior andafter installing the 383 I sold it for 2 K, pretty stupid looking back. I excel in stupid. thanks for the great information and memory jogs.

 

[Geri]

 

[Geri]

I made a third top for the manifold back to the Carters and turned them sideways like original crossrams. threw away the holleys, they each weigh as much as a VW.