Special Tuning using AF Equipment by Innovative Motorsports

[steveg]

Now all you need are needle height sensors so you can correlate AFR to needle height.

Phase 1 will be to observe AFRs with their EGTs using the factory rich (UN) and standard (UH) needles. Also to see if there's a quantifiable difference between 7/16" and 5/16" float levels.

 

[Patrick67BJ8]

Phase 1 will be to observe AFRs with their EGTs using the factory rich (UN) and standard (UH) needles. Also to see if there's a quantifiable difference between 7/16" and 5/16" float levels.

Will your Phase 1 include idle, cruise and WOT or will that be later?

 

[steveg]

Will your Phase 1 include idle, cruise and WOT or will that be later?

Patrick - to your question, yes to all.

Running the rich needles, what I found with just the AFR gauges was that I'm able to lean the car out more than before and the rich needle stays in the high 12s - mid 13s during all kinds of driving. I'm adding the EGT gauge as the exhaust gas temp needs to be kept below 1300 preferably 1200. This gives a bottom line to experiments with air-fuel ratios.

I'd like to get to 16 mpg around town and 20 highway. I think that's reasonable on my rebuilt engine. I'd also like to document the difference in AFR/EGT with PCV valve vs stock vent tube.

After that's sorted, Phase 2 would be to add richness at the high end if necessary. I'm thinking I need to do some long grades in summer temps to evaluate that.

PS - idle is trivial - the first couple of stations are the same on all the needles. All the books explain all you need to do at idle is have the car keep running.

 

[steveg]

Got my EGT gauge installed. First run. Apologies for the confusion, the AFRs were on the cusp of 11.8/12.0:

 

[steveg]

Had an incident yesterday in which the AFR gauges were useful:

Was driving on the freeway near home when the car started to miss badly; rear AFR oscillated wildly, then flatlined (zero fuel). Got off the freeway under partial power, car started running properly again with good AF ratios. Was thinking, yet again the rear carb dropped the needle.

Then the front AFR flatlined - realized it couldn't be a dropped needle, must be fuel pump issue. At this point the car quit entirely and I pulled over and called for a flatbed. While I was waiting, determined the fuel pump was not running. Tapped on it with a tool and it went on and off. Wiggled the connectors in the engine compartment. Fuel pump came on and drove home.

At this point, am thinking after extolling Facet pumps, have a failure and am going to have to eat some crow when I report it to this forum!

At home I found the two Facet ground wires, which went to the same screw on the chassis, were loose. Fixed that and separated them to two different scews - end-of-story.

A benefit of the AFRs, in addition to tuning, was they showed the problem immediately to be a fuel pump issue.

 

[twas_brillig]

Something that might be of interest: we've got a 1972 BMW 2002 with a slightly modified engine (it hasn't been on the road in the ten years or so that I've owned it) that we're converting to a 'stealth' Simple Digital Systems EFI system, with two gutted Weber DCOEs with SDS injector bungs welded onto their undersides acting as throttle bodies. SDS is a local Calgary outfit that started out with the automotive market but has primarily moved into aircraft engine conversions.
I can't remember if I've maybe mentioned this in a past post, but we'll hopefully have the system (and the car) ready to go by May. The intention is to have it EFI, but such that a casual observer opening the hood will just see an early 70s hot rodded BMW with dual sidedraft Webers.
Prototyping is a son-of-a-gun (euphemism here!) as, with what I've learned thus far, I wouldn't stick the injectors upstream of the butterflies but would install them on spacers between the manifold and the side-draft carb. As is, I've butchered a couple of DCOE bodies that I won't be able to reclaim if we give up on this approach. But if you're as dumb as I am....
I think it would be worth considering going to an EFI system with the injector bosses installed onto the underside of 1 inch (may be necessary to buy 2 inch thick spacers and have them machined own) spacers between the manifold and the Mikuni/Weber/whatever side drafts. Such a conversion would not be inexpensive, and it would conceivably make more sense to check into the Patton Machine carb/EFI adaptors or the EFI throttle bodies modelled on the DCOE aesthetic.
We do have an air/fuel gauge that we'll be mounting permanently on the 2002 through a bung in the exhaust header, but will also be trying to use to tune a pair of down-draft Kadrons on our dune buggy, with bungs mounted on 3 of the 4 collector pipes on the exhaust system, and rotating the muffler assembly around so we can check each cylinder. And, yes, I don't really know I'm doing but will be presumably more knowledgeable and frustrated in a couple of months after the snow is gone.
Good fortune to all of us on this tuning thing; I asked about a probe we could use for the Healey earlier in this thread as the carbs really need to be looked at and blessed, and any useful tools would sure be useful!
Later, Doug

 

[HealeyPassion]

S
I think it would be worth considering going to an EFI system with the injector bosses installed onto the underside of 1 inch (may be necessary to buy 2 inch thick spacers and have them machined own) spacers between the manifold and the Mikuni/Weber/whatever side drafts. Such a conversion would not be inexpensive, and it would conceivably make more sense to check into the Patton Machine carb/EFI adaptors or the EFI throttle bodies modelled on the DCOE aesthetic.
Later, Doug

It seems the thread has taken a turn... so let me address your thought on injectors placement. I've already done this verison, i.e. spacer between carb bodies, gutted but with butterfly, and manifolds. After some development work, it functioned beautifully. I can't speak to the Patton Machine versions as mine was all bespoke. I was very happy with how mine ran... but, be aware that it is not for the faint of heart... takes some time to get all the fuel mapping done properly. The car now lives in Australia.



I'm now working on a new EFI version... there is a thread on that.

Steve

 

[steveg]

Air/Fuel Ratio gauge followup:

My rear AFR gauge has been showing the rear carb to run leaner at low speeds than the front carb in spite of new needles/jets and caliper-equalization of the jet drops. With the jets set to .063" drop, the rear carb would backfire slightly going downhill, showing 1 - 2 points more leanness.

I found the accuracy of visually locating the HD8 needles in the pistons left a lttle to be desired. Measuring with the dial caliper, the rear needle extended .011" farther than the front needle, which evidently accounted for the rear-carb leanness. Resetting the rear needle with the dial caliper to match the front eliminated almost all the mixture difference between the two carbs.

IMO the takeaway from this, for HD8s, would be to use the dial caliper to ensure the same projection of both needles - as well as the jet drops.