F-134 Performance Report

Update: 140 mains, 200 air correctors, PULLS and PULLS! Hitting my AFR targets, so on 3rd base, headed to home!
Innova 5568 and generic dialback, confirmed 16* of timing (rebuilt/recurved IAY 4401), the engine sounds right, smells right. Verified correct float height. Still a little intermittent spitty when I flog the pedal down, may be the power valve but will spend some more time driving and butt dyno, observing, check vacuum etc.

 

Finally got the Weber 38 dialed in its best yet. Hit the river trail for some butt dyno, these mod's to the F head are definitely worthwhile giving the engine much needed breathing room to stretch its legs a bit more. I'm pretty damn happy, so much so, I may not build the Buick 215 V8......
https://photos.app.goo.gl/MDUwRUEs2iMa3LGT7

 

Using the Weber Secret, below, from my ignition builder:

Schlemmer’s Weber 38 Tuning Secrets Guide

Preface: The below takes into account you’re using a wideband AFR meter to guide you with tuning via the below steps for the various circuit.

1. Set timing for as much as the engine can handle without pinging or getting into the advance curve. I am at 18* with a rebuilt/re-curved specifically for my engine IAY 4401 with .40 gaps on Champion J8C's

2. Working from the bottom to top circuits, start with the idle circuit. You’re looking for about 13.5 AFR. Adjust mixture screws as needed within the Weber suggested guidelines/parameters, determining if a leaner or richer idle jet set for the Primary and Secondary circuits is needed. Repeat the steps.

3. Emulsion tubes: Check emulsion tubes at 850, 1000, 1200, 1400 RPM’s and see the average AFR. Should be in the 13's, and you should see 12-13 at WOT or it will stumble if too rich. You can enlarge a couple of the holes slightly with a jet drill set and it will get you there. You can also use plumbing solder to “plug” holes, hammer flat before use. DO NOT USE ELECTRICAL rated solder!

4. Main jets: set idle to 1800, make note of the AFR, you’re looking for 12.5-13. Adjust main jets as needed to get within this range. Don't use idle settings for the main jets. Drive the truck and watch AFRs from 1800-4000 range.

You may also note that idle air mixture is influenced by air reverting up the tailpipe. Wrapping a big towel around the tailpipe at idle (a helper makes it easier) to choke out air reversion will give you a more accurate reading.

5. For engines that see over continued 4K RPM use, the air correctors job is to add or take fuel away as needed/indicated by the wideband (again as a general guide tool and using road/butt dyno testing or a proper dynometer) Set idle to 4K, make note of the AFR mixture. Larger air corrector stamped numbers are LEANER, smaller stamped numbers are RICHER.

I landed currently at a best yet:

Dropped in 125 mains, the last bit of richness is gone and it climbs hills better than 130 mains though it felt like it had a little more oomph flat out with the 130's. But as with everything, it's a compromise and I need the best MPG as well as performance. . I could probably split the difference with 127 using a jet drill bit, may try that with a second pair of 125's to sacrifice.

I have one lean flat spot, time to test the emulsion tubes to further dial it in, as the wideband indicates it briefly leans out on transition from idle circuit to main circuit.

 

I called Carlos where I purchased the carb, he said to try the 55 idles since easiest to access, midrange flat spot gone. Will spend some time with this tune to see where I am vs previous tuning.