[geise6738]

Sorry if this is a redundant topic but I switched to Q16 about 2 months ago and jetted up according to what was recomended by VP. Went from 97 jets to 98 and 2 sizes on the air bleeds. My O2 meter said I was about 13:1 air fuel.
My engine is a 614 with big duke heads and a single 1440cfm blp carborator. This is in a 1800 lb dragster that we are running in top dragster in the Pacific Northwest.
Last race we were at I switched over to a set of merge collectors from the standard collectors with a 5" outlet on them, I was told that was way to big. Now the problem I am having is that my a/f meter is reading around 15:1. I jetted up to 99 and it didnt change anything. I called blp and they said that I need to go up to jets with a .140 oriface in them which is much larger that the .125 in the 99 jets.
I just wantd to get everybodys opinion on this big change and see if it makes since that the collectors scavange that much better that I now need a ton more fuel or is there something else going on? Has anybody else needed this much jet with Q16?


Thanks for your help
Clint

 

[ATVracer]

How close is the O2 bung to the end of the exhaust now?

My O2 will read lean if I dont put a 1' extension after the headers.

 

[AutoRoc]

Yep...same here. has to be In the exhaust stream really good, not at the end of it..and also..Make sure your Evac bung is well after the O2 sensor. That made mine read almost 2 numbers high until I plugged it up.

I went up 4 jet sizes and seen an ET/MPH increase. from 84's to 88's.

 

[Jagtec1]

Are any carb modifications required to run Q-16, or just jetting changes? I run an older 1050 Dominator # 9375. I'd like to try it out this fall in some good cool air to see what it does

Sorry, didn't mean to hijack.

 

[geise6738]

My O2 sensor is about the same distance from the end that it was with the old collectors, about 7"-8". I placed it right where the 4 pipes merge into one.

 

[buschmec]

we had to go 6 jets from torco no2, what mid air bleeds are you running.

 

[RacinMan37]

i have heard of o2 sensors going bad and reading funny like that... might be something to check, might have gotten damaged when you were switching it up. The new merge collectors also create more backpressure maybe there is something funny going on in the pipe, fuel puddling then burning off??? have any egts?

 

[598nos]

READ THE PLUGS 1st! 02 may be off, the plugs will tell you the true story. and then compare all.

 

[Ron Clevenger]

READ THE PLUGS 1st! 02 may be off, the plugs will tell you the true story. and then compare all.

Good suggestion, the plugs are a witness to the combustion event. Learn how to read them and they will tell the story.

Blessings...........Ron.

 

[Doughboy692]

I just started changing over to Q16 from MS109 (highly oxygenated as well). I tested yesterday at the track and I can tell you that I kept adding fuel injector pulse width to add more fuel after every pass and it kept getting faster. just like VP claims you have to make a sizeable jump in the amount of fuel you are feeding the engine. If I had added this much on any fuel I have used before the engine would have been so pig rich it might not have even been runnable. I am going to the chassis dyno this week to try and speed up the process of getting dialed in on this fuel but I have alread picked up a couple of tenths over MS109 and I know there is more once I get it fully dialed in. So far it seems to be making the additonal power they claim that it will.

 

[donho]

My o2 on my wideband used to be perfect. When i ran the car with open headers and just little extensions, the wideband showed 18-1!!!!

Plugs look great. car runs great. i think the o2 needs a very long extension or a exhaust to work properly

 

[abbottracingheads]

Q16 takes a lot more than two jet sizes. Keep jetting up till you find rich. I have a 565 that I run in Texas Pro Stock. One carb, 1400 cfm, .154 drill size jets. It likes about 1250 egt in the eighth. The plugs do not read right. Keep jetting up and let the time slip tell you what you want to know. The int. bleeds and idle bleeds can be shrunk a little also.