DragRaceResults.Com    Bracket Talk    Bracket Talk Forum  Hop To Forum Categories  Tech Talk - by Abruzzi    4-7 swap cams and air/fuel meters
Go
New
Find
Notify
Tools
Reply
  
4-7 swap cams and air/fuel meters
 Login/Join
 
DRR Trophy
posted
In the past with normal small chevy 18436572 firing order always used #5 as place for oxygen sensor but with 4-7 swap its 18736542 so I was thinking #4 as to be leanest hole any thoughts?


The difference between ignorance and stupidity. Ignorance is lack of knowledge. Stupidity is the inability to learn. Don't be stupid
 
Posts: 412 | Location: des moines iowa | Registered: January 10, 2020Reply With QuoteReport This Post
DRR Pro
posted Hide Post
If one O2 sensor, I’d say in the collector would be best. That would provide an average of the bank at WOT.

Using EFI they recommend collector location with 15” of pipe behind sensor if wanting accurate readings at lower rpm (idle).
 
Posts: 2484 | Location: 53056 | Registered: December 30, 2009Reply With QuoteReport This Post
DRR Pro
posted Hide Post
quote:
Originally posted by markemark:
If one O2 sensor, I’d say in the collector would be best. That would provide an average of the bank at WOT.

Using EFI they recommend collector location with 15” of pipe behind sensor if wanting accurate readings at lower rpm (idle).


I agree with M & M.

My previous set-up on our motor had the 4-7 swap cam. I checked the plugs here & there, never paid attention to find the leanest cylinder. That combo stayed in the car for 13 years. Anyway, we reconfigured the motor for a ProCharger & EFI. I needed to put in an O2 sensor & we placed it in the left collector. The cam is the standard firing order now & the #7 cylinder is the leanest. We tune to that that cylinder.

2BKING Wink


1980 Camaro
Taking the Best Working Small Tire Shyt Box & making it Greater Than Before!
3000 lbs.
Pump Gas 436
 
Posts: 2580 | Location: NV. | Registered: October 20, 2006Reply With QuoteReport This Post
DRR Top Comp
Picture of Curly1
posted Hide Post
I run 8 O2 sensors on my small blocks. The O2 is same on all. Now number 5 may be hotter (EGT) but can not say any difference on the O2.

I threw all my EGT stuff away years ago it was not reliable information or repeatable.


https://postimg.cc/gallery/np3zpruo/
"Dunning-Kruger Effect"
-a type of Cognitive bias where people with little expertise or ability assume they have superior expertise or ability. This overestimation occurs as a result of the fact that they do not have enough knowledge to know they don't have enough knowledge.

Before you argue with someone ask yourself, "Is this person mentally mature enough to grasp the concept of a different perspective?" If not there is no point to argue.

4X NE2 CHAMPION. 2020 TDRA NE2 Champion
 
Posts: 4042 | Location: United States of Texas | Registered: April 02, 2011Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
Had sensor in #5 at collector just before dump into open area always read steady there at WOT question was should it be moved to similar spot because of firing order change -as in 4-2


The difference between ignorance and stupidity. Ignorance is lack of knowledge. Stupidity is the inability to learn. Don't be stupid
 
Posts: 412 | Location: des moines iowa | Registered: January 10, 2020Reply With QuoteReport This Post
DRR Top Comp
posted Hide Post
One of the theory's surrounding the 4-7 swap is "smoothing out" the firing impulses and improving the traditional thought of #5 being lean(er).
IMHO, assuming it does improve that issue, I wouldn't bother moving your WB sensor to a different tube. If you are going to do anything I would move it down into the collector more to get a broader reading of more cylinders.


.
Dave



F J B

 
Posts: 4476 | Location: Earth | Registered: February 08, 2006Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
All great advise thats the third vote for put it in collector ****her down changing several things on race car at once -cam- car itself-its a little heavier- header collectors so just looking for advise-thanks


The difference between ignorance and stupidity. Ignorance is lack of knowledge. Stupidity is the inability to learn. Don't be stupid
 
Posts: 412 | Location: des moines iowa | Registered: January 10, 2020Reply With QuoteReport This Post



DRR Pro
posted Hide Post
quote:
Originally posted by vetman:
Had sensor in #5 at collector just before dump into open area always read steady there at WOT question was should it be moved to similar spot because of firing order change -as in 4-2


This is what I followed from my Holley EFI instructions:

"Locate a position for the oxygen sensor as close to the engine as possible. The oxygen sensor should be mounted at a point
where it can read a good average of all the cylinders on one bank. This would be slightly after all the cylinders merge. If you
have long tube headers, mount the sensor approximately 1-10” after the collector. You must have at least 18” of exhaust pipe
after the sensor. Verify that the Oxygen sensor is tight in the bung, if the gasket is not seated properly on the O2 sensor exhaust
leaks and poor engine operation will occur."

My O2 is on top of the left collector on about a 45* angle & about 6" after the primary tubes end. I have about 22" of pipe (muffler) after the sensor.

IMO, I would follow the same basic instructions & have a bung installed in the left & right bank. Just swap the sensor & plug the bank not being used.

2BKING Smile


1980 Camaro
Taking the Best Working Small Tire Shyt Box & making it Greater Than Before!
3000 lbs.
Pump Gas 436
 
Posts: 2580 | Location: NV. | Registered: October 20, 2006Reply With QuoteReport This Post
DRR Pro
posted Hide Post
^^^^^^^^^This X2. If you’re not wanting/ needing accurate O2 readings at idle, you do not need a pipe extension after the sensor if in collector. It will read properly at WOT without extension.
 
Posts: 2484 | Location: 53056 | Registered: December 30, 2009Reply With QuoteReport This Post
  Powered by Social Strata  
 

DragRaceResults.Com    Bracket Talk    Bracket Talk Forum  Hop To Forum Categories  Tech Talk - by Abruzzi    4-7 swap cams and air/fuel meters

© DragRaceResults.com 2024