mixture distribution
Thread Starter
Registered User
Joined: Oct 1999
Posts: 356
From: Oakland City, IN
mixture distribution
maybe this doesn't belong here.. dunno.. Put it where it's appropriate if thats the case..
Anyhow, I'm switching to a carbed 383 LT1 setup, and I'm wondering if mounting the carb on the intake sideways will have a negative effect on mixture distribution. Reason for this is fitment mainly. Everything will "line up" better if I can mount the thing transverse. This is on a single plane Vic Jr. CNC.
Thoughts?
Anyhow, I'm switching to a carbed 383 LT1 setup, and I'm wondering if mounting the carb on the intake sideways will have a negative effect on mixture distribution. Reason for this is fitment mainly. Everything will "line up" better if I can mount the thing transverse. This is on a single plane Vic Jr. CNC.
Thoughts?
Registered User
Joined: Oct 2002
Posts: 2,931
From: Upstate NY
Re: mixture distribution
You mean rotating it 90 degrees looking down on it, right?
That puts the primaries near one bank and the secondaries near the other. Because the manifold wasn't designed for that kind of flow, I suspect mixture distribution might be compromised at anything less than wide open throttle.
Just my thoughts.
That puts the primaries near one bank and the secondaries near the other. Because the manifold wasn't designed for that kind of flow, I suspect mixture distribution might be compromised at anything less than wide open throttle.
Just my thoughts.
Moderator
Joined: Dec 1969
Posts: 10,745
From: Buffalo, New York
Re: mixture distribution
Originally Posted by OldSStroker
You mean rotating it 90 degrees looking down on it, right?
That puts the primaries near one bank and the secondaries near the other. Because the manifold wasn't designed for that kind of flow, I suspect mixture distribution might be compromised at anything less than wide open throttle.
Just my thoughts.
That puts the primaries near one bank and the secondaries near the other. Because the manifold wasn't designed for that kind of flow, I suspect mixture distribution might be compromised at anything less than wide open throttle.
Just my thoughts.
Oopsie, you're right. when I wrote "square bore" I was thinking of square bore "double pumper" type race carbs which open all 4 at the same time. When I think of carbs, that's what is the default mode.
Rich
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Joined: Sep 2002
Posts: 655
Re: mixture distribution
I'm going to agree based on the trial and error I've had with jetting combos.
My setup incorporates a single plane intake with a square bore Holley which
sits in the "normal' position (floats front to back).
When I'm swapping jets and checking plugs, I can see a noticeable variance
between the front and rear plugs (#1, #2 and #7, #8).
IE: Replace all of the plugs. Do a wide open pass and shut down.
I find that with jetting for street use (conservative primary jetting) amplifies
this imbalance.
Wish there was a method to have a jetting combo that works well on the street
and the track!
My setup incorporates a single plane intake with a square bore Holley which
sits in the "normal' position (floats front to back).
When I'm swapping jets and checking plugs, I can see a noticeable variance
between the front and rear plugs (#1, #2 and #7, #8).
IE: Replace all of the plugs. Do a wide open pass and shut down.
I find that with jetting for street use (conservative primary jetting) amplifies
this imbalance.
Wish there was a method to have a jetting combo that works well on the street
and the track!
Last edited by Zero_to_69; Aug 28, 2005 at 03:31 PM.
Banned
Joined: May 2003
Posts: 6,661
From: LA (lower Alabama)
Re: mixture distribution
Originally Posted by Zero_to_69
I'm going to agree based on the tiral and error I've had with jetting combos.
My setup incorporates a single plane intake with a square bore Holley which
sits in the "normal' position (floats front to back).
When I'm swapping jets and checking plugs, I can see a noticeable variance
between the front and rear plugs (#1, #2 and #7, #8).
IE: Replace all of the plugs. Do a wide open pass and shut down.
I find that with jetting for street use (conservative primary jetting) amplifies
this imbalance.
Wish there was a method to have a jetting combo that works well on the street
and the track!
My setup incorporates a single plane intake with a square bore Holley which
sits in the "normal' position (floats front to back).
When I'm swapping jets and checking plugs, I can see a noticeable variance
between the front and rear plugs (#1, #2 and #7, #8).
IE: Replace all of the plugs. Do a wide open pass and shut down.
I find that with jetting for street use (conservative primary jetting) amplifies
this imbalance.
Wish there was a method to have a jetting combo that works well on the street
and the track!
The imbalance I have seen is the front is lean and the rear is rich. Is this your case?
It can be fixed with plentum mods and runner end mods in the plentum.It takes someone who knows what they are doing to do it right.
Thread Starter
Registered User
Joined: Oct 1999
Posts: 356
From: Oakland City, IN
Re: mixture distribution
Sounds like sheetmetal modding is going to be much easier than making it work sideways. There really is nothing easy on these cars is there?
Thanks for the input fellas.
Dave C.
Thanks for the input fellas.
Dave C.
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