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Exhaust upgrade - any adjustments then?

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Old 10-17-2018, 04:10 PM
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Iron_dog
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Default Exhaust upgrade - any adjustments then?
Gents, I'm going to replace stock exhaust with this Kit, do I need to retune the qjet and/or ignition in order to match the increased exhaust flow?
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Old 10-17-2018, 04:18 PM
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MelWff
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a change to the ignition curve from stock will help even without the exhaust kit. I assume you have a 74 or newer, doesnt seem to be in your profile, so a change to the carburetor would also help, primary rods, and secondary jets and rods. A copy of the Cliff Ruggles book would help with that or if you are not going to do it yourself send the carb. to Lars.
Last edited by MelWff; 10-17-2018 at 04:19 PM.
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Old 10-17-2018, 08:06 PM
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Might be a good idea to also buy an air fuel ratio gauge.
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Old 10-17-2018, 09:09 PM
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A free-flowing exhaust with headers will lean out the carb from its stock setup. If you have the stock exhaust manifolds, not much, if any, change is required. If you have headers with the free-flowing exhaust, richen the carb up 2 jet sizes.

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Old 10-18-2018, 04:45 AM
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Originally Posted by MelWff
a change to the ignition curve from stock will help even without the exhaust kit. I assume you have a 74 or newer, doesnt seem to be in your profile, so a change to the carburetor would also help, primary rods, and secondary jets and rods. A copy of the Cliff Ruggles book would help with that or if you are not going to do it yourself send the carb. to Lars.
Yes I've a 74. Already recurved Carb already rebuilt with Lars and Cliff help (very nice job with those guys!).

Originally Posted by lars
A free-flowing exhaust with headers will lean out the carb from its stock setup. If you have the stock exhaust manifolds, not much, if any, change is required. If you have headers with the free-flowing exhaust, richen the carb up 2 jet sizes.

Lars
Lars, thanks that's what I was looking for! Will change also headers with tight tuck Patriot ones... I'm trying to recap what is my current configuration and revert you back, just to hear from you some suggestions...
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Old 10-18-2018, 06:02 AM
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Originally Posted by lars
A free-flowing exhaust with headers will lean out the carb from its stock setup. If you have the stock exhaust manifolds, not much, if any, change is required. If you have headers with the free-flowing exhaust, richen the carb up 2 jet sizes.

Lars
Lars I'm now with jet 76 and rod 43B (stock setup was 75/46E), what do you think?
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Old 10-18-2018, 07:40 AM
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Pictures aren't the best but it looks like the down pipes are small and then expand to the advertised 2-1/2. I'd look into it further....
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Old 10-18-2018, 08:02 AM
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Originally Posted by jim2527
Pictures aren't the best but it looks like the down pipes are small and then expand to the advertised 2-1/2. I'd look into it further....
Look HERE
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Old 10-18-2018, 08:06 AM
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Originally Posted by resdoggie
Might be a good idea to also buy an air fuel ratio gauge.
good point, yes already bought!
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Old 10-18-2018, 11:51 AM
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Originally Posted by Iron_dog
Lars I'm now with jet 76 and rod 43B (stock setup was 75/46E), what do you think?
Impossible to say without a carb number. The jetting in the carb could be anything, which does not provide any baseline for change.
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Old 10-18-2018, 11:54 AM
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Originally Posted by lars
Impossible to say without a carb number. The jetting in the carb could be anything, which does not provide any baseline for change.
Lars
Here it is: Qjet 7044207 with sec rod CH thanks
Last edited by Iron_dog; 10-18-2018 at 11:54 AM.
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Old 10-18-2018, 11:58 AM
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Originally Posted by Iron_dog
Look HERE
The down pipe that connects to the header....looks small.
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Old 10-26-2018, 04:03 PM
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Originally Posted by Iron_dog
Here it is: Qjet 7044207 with sec rod CH thanks
Lars, any advice on my configuration? Thanks
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Old 10-26-2018, 07:24 PM
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Originally Posted by Iron_dog
Here it is: Qjet 7044207 with sec rod CH thanks
I'd set it up with 77/46/CH. Float level at .300". Should run well.

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Old 10-27-2018, 02:53 PM
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Originally Posted by lars
I'd set it up with 77/46/CH. Float level at .300". Should run well.

Lars
Thanks Lars, I've done some maths and your combination (77/46) compared to my current one (76/43) makes metering area +3% in WOT and -3% in IDLE.
Does this makes sense?
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Old 10-27-2018, 05:43 PM
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Originally Posted by Iron_dog
Thanks Lars, I've done some maths and your combination (77/46) compared to my current one (76/43) makes metering area +3% in WOT and -3% in IDLE.
Does this makes sense?
I'll take a stab and say yes..... +3% WOT and -3% idle/cruise
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Old 10-29-2018, 08:24 AM
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Originally Posted by Iron_dog
good point, yes already bought!
Where did you place the gauge?
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Old 11-01-2018, 06:03 PM
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Originally Posted by IvanoMan
Where did you place the gauge?
Still have to think about...
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