360 LA installing Promaxx Aluminum heads

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74Scooter said:
OK.. got the rod swap and escaped for a 20 minute ride mixed in town and highway.

Setup and results:

74 Primary jet
went from 60-50 rod to 58-50
Green spring
Idle about the same 13's and occasional 14.
A hair more rich on highway and around town.. more 13's fewer 14's. Fixed cruising & low speed tip in. Not as "smooth" by seat of pants.. might actually mean it's running better though.

60-50 rod was like a marble on a glass plate smooth on highway but went slightly too lean off cruise and in low throttle situations infrequently. If I had a long highway trip I might just toss it back in.

Not going to pull a plug right now as it's near 100 today and garage with hot car is... hot. :p

I'll get a plug pulled tonight after the sun goes down.
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Can you take logs of the AFR?
 
Pulled #1.. think this tune is a keeper.

I put the 60-50 back in and gave it a lil more juice on the curb idle for low speed/throttle situations & it seems to have done the trick. No more light throttle leaning so far. Looking at the plug I could probably back the curb idle screws out another 1/4 turn.. AFR reads 12.5-13 at idle. I'm not seeing it that fat on the plug and she idles great. Seeing 11-12 AFR around town leaning on the throttle part load.. 13-14 AFR on the highway. Heat range looking good too.. just 2 threads. Timing mark showing up now as well. I could probably add another degree for mileage and crap pump gas.. but I'll stick with the safe play where it is. Almost forgot.. AFR is still saying WOT at high 10 & 11's.

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74Scooter said:
Pulled #1.. think this tune is a keeper.

I put the 60-50 back in and gave it a lil more juice on the curb idle for low speed/throttle situations & it seems to have done the trick. No more light throttle leaning so far. Looking at the plug I could probably back the curb idle screws out another 1/4 turn.. AFR reads 12.5-13 at idle. I'm not seeing it that fat on the plug and she idles great. Seeing 11-12 AFR around town leaning on the throttle part load.. 13-14 AFR on the highway. Heat range looking good too.. just 2 threads. Timing mark showing up now as well. I could probably add another degree for mileage and crap pump gas.. but I'll stick with the safe play where it is. Almost forgot.. AFR is still saying WOT at high 10 & 11's.

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Cut the shell off that one and measure the fuel ring. If it’s over .100 wide the A/F meter is correct and it’s rich. That ring should be .060-.080 wide and no more than .100 wide.

How pig rich do you think it would be if you turned the plug brown???

Edit: I keep forgetting to ask if your distributor is locked out. If it’s not it must have a very short, fast curve.
 
Rat Bastid said:
Cut the shell off that one and measure the fuel ring. If it’s over .100 wide the A/F meter is correct and it’s rich. That ring should be .060-.080 wide and no more than .100 wide.

How pig rich do you think it would be if you turned the plug brown???

Edit: I keep forgetting to ask if your distributor is locked out. If it’s not it must have a very short, fast curve.
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Cut will have to wait till I get back.. but on the list for sure. Only able to WOT about 1/8 mile at a time.. don't need the local Johnny's on my tail... lol.

Dizzy is not locked out. IIRC the springs are pretty light.. all in fast.
 
Go up another jet size. Put some colour on those plugs.
 
I think that plug looks great. So far. Interested to see the fuel ring also. But I’d bet it’s .120 or more up the porcelain. You’re giving away power if it’s that rich (10, 11:1). And on a pump gas street car I like where the timing mark is now. Your willingness to test and tune is refreshing to see. Keep at it.
 
One thing on the AFR that just dawned on me last night. I installed the gauge over a year ago and we have moved since. Our house is now up at 5k feet. Definitely going to calibrate the sensor when I get home next week.
 
Am I right in assuming that if you are testing at 5000 feet your set up is going to be leaner than mine at close to sea level?
 
qkcuda said:
Am I right in assuming that if you are testing at 5000 feet your set up is going to be leaner than mine at close to sea level?
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Rich or lean is a ratio, not a volume measure. If you have tune for sea level and take it to 5000 feet, I think it would now be rich because each unit of air has less oxygen so there is more fuel in the mix. At least that's how my addled brain interprets it.
 
qkcuda said:
Am I right in assuming that if you are testing at 5000 feet your set up is going to be leaner than mine at close to sea level?
Click to expand...

Yes. Less air so if you tune the AFR correctly at 5k you will be a bit lean at sea level.
 
Thanks just looking for a starting point for myself based on your testing.
 
Are you able to tell me what the factory primary jets and metering rods are? The full kit here is around $150.00 Canadian. Since I figure I just need to lean out the primaries, I may just order leaner jets and rods.
 
qkcuda said:
Are you able to tell me what the factory primary jets and metering rods are? The full kit here is around $150.00 Canadian. Since I figure I just need to lean out the primaries, I may just order leaner jets and rods.
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Home tomorrow.. I'll get you the numbers.
 
qkcuda said:
Are you able to tell me what the factory primary jets and metering rods are? The full kit here is around $150.00 Canadian. Since I figure I just need to lean out the primaries, I may just order leaner jets and rods.
Click to expand...

Ya.. full kit is over $100 US as well.. but I was glad to have the whole shebang when dialing it in. Checked my notes: Stock jets are 80 for primary and secondary. Stock metering rod is .060 x .052.

GL!
 
Thanks for checking that for me. I'll figure out what I need from there.
 
I re-calibrated the O2 sensor this morning and tooled the heap around town.. got some gas. Numbers did not move even a little as far as I can tell. Wondering if the sensor is just FUBAR at this point. But it is consistent across the band... always shows fatter than the plugs show and exhaust smells like. Running fantastic at this point. I'm going to leave it as is for the rest of the week... too much knob dickin I'll likely screw the pooch somehow and never get the tune back to where it is right now. If the plugs come out in a few days looking like they do now.... I'm gonna call it done and get to work getting the new fiberglass hood fitted.

To be continued...
 
74Scooter said:
I re-calibrated the O2 sensor this morning and tooled the heap around town.. got some gas. Numbers did not move even a little as far as I can tell. Wondering if the sensor is just FUBAR at this point. But it is consistent across the band... always shows fatter than the plugs show and exhaust smells like. Running fantastic at this point. I'm going to leave it as is for the rest of the week... too much knob dickin I'll likely screw the pooch somehow and never get the tune back to where it is right now. If the plugs come out in a few days looking like they do now.... I'm gonna call it done and get to work getting the new fiberglass hood fitted.

To be continued...
Click to expand...


A lean miss will make the O2 read fat. That’s why you have to trust the plugs first.

The question is where do you smell the exhaust? Idle? Cruise? In transition?

An A/F meter is a tool. It has limitations like all tools. You are finding a limitation right now. A lean miss will read fat.
 
Just got back from picking up a new fuel pump for the Fairlane at Summit. Got the heap out on the highway and had some lean stumbles cruising at near no throttle situations.. basically whenever I saw a 15 appear on the wideband. Had this last week and I thought fattening the curb idle a hair fixed it... nyet. I'll pop the .058-.050 back in this afternoon when it cools off. That .002 rod actually fixes the lean situation but the engine is less "smooth" on the highway, but still runs fine minus the lean surge. Don't think I'll be able to get much closer than that. We'll see.
 

Why would I pop in a larger jet? I'm only off a RCH and still have smaller metering rods I can fatten it up a bit with. The only "color" I get on the plugs with a larger jet is black....
 
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