Holley 1850 low speed tuning

[Nick_nl]

That could be, I haven't pulled the plug before. The sediment is easy to remove.

[GTO Geoff]

Nick,
The Edel has smaller primaries than the H & will work better & have better response. If the E carb didn't work before, then it sounds like a tuning issue. On every one that I have worked on, the float level was incorrect out of the box; maybe carb got knocked around during shipping. It needs to be checked, should be 7/16". Unlike brand H [ & clones ], you will not need a pile of gaskets or o rings if you are careful.

[GTO Geoff]

my 1979 Edel catalog lists 9 Holley carbs, 660, 750, 830 & 850 cfm.

[Right hand drive]

When your tuning for AFR check the stoichiometric ratio of the fuel with the supplier/manufacturer. Universal gauges just multiply lambda x 14.7 under the assumption everyone will use it with generic gasoline. If your 98 isn’t 14.7:1 then you might be making changes that otherwise wouldn’t. One of the more popular 98 RON fuels in Australia is 14.4:1 stoich. Not the end of the world but 15.2:1 would really be 14.8:1 with a 14.4: stoich. You start thinking different when you start seeing a ‘15’.

Like previously noted, power valve selection and maybe incremental PVCR enlargement could be the answer. You say you have tried the Edelbrock so I don’t see why you would trade one tuning challenge for another, especially when you reported below par performance. Probably the tiny primaries not giving your engine the air it needs to breathe.

[gntkllr]

[57 210]

Nick, that spark looks funky. It looks like it was very rich witch caused it to get sooty; then something in the fuel or in the tank caused that white coating on the plug that covered the plug and the soot. A lean condition would make the plug look white like a new plug. That white looks like some coating of some kind. A lean plug wont have build up on it, it will be just a plain white plug. It looks like it was rich prior to that white stuff.

[rgalajda]

I strive to get 15:1 (or better) AFR when cruising with slightly leaner on acceleration until the point of hard acceleration or WOT with my 454BBC street car. I run a 3310-1 780 holley that I have been able to achieve this with. Previously I ran a Quick fuel carb which had a larger transfer slot making this difficult to get there.

Tuner wrote,

"There is no reason to run an engine at part-load any richer than as lean as it will run without misfire. Of course for each engine just what that AFR may be depends on the particular engine’s characteristics, cam, compression ratio, headers, mufflers, etc. The biggest factors are uniform AFR distribution to the individual cylinders and exhaust reversion through the valve overlap. At part-throttle, distribution is affected by throttle angle and other carb geometry as well as the manifold, manifold heat, fuel distillation curve, etc, etc.

Between about 10% to 20% and 70% to 80% load some engines will run well at part-throttle with 17/1 AFR or leaner and others start to turn bitchy at 15/1.

You need to realize that the leaner the AFR, the larger percentage of oxygen in the exhaust. When running at part-throttle the high intake vacuum is drawing hot exhaust back into the intake manifold. Leaner than stoichiometric the excess oxygen in the exhaust is returning to the cylinder in the reversion gasses and the hot oxygen improves combustion.

Obviously, the leaner it is, the larger the proportion of unburned oxygen in the exhaust will be, and up to a point (unique to each engine) the lean running usually noticeably improves the part-throttle combustion.

Depending on your particular engine’s nature, you will be surprised how much part-throttle torque improves as it is operated progressively leaner on the lean side of stoichiometric. The limit is usually reached when the leanest cylinder misfires.

Because lean part-load mixtures have a slower combustion rate, they require additional spark advance, compared to rich maximum power WOT mixtures.

Correct vacuum advance tuning is as important as carb tuning. If the timing isn’t correct, you can chase the carb tuning into a box where a rich cruising AFR is wasting gas, because, without vacuum advance, a faster-burning richer AFR compensates for retarded timing.

You have to use common sense applied to your particular engine to determine at what amount of load the engine should be switched from the lean economy AFR to the rich power AFR. The power valve opening point and the vacuum advance starting point (fully retarded vacuum amount) should usually be near the same intake vacuum.

A high compression engine that is close to stressing the available octane, such as a 10/1 mild-cam street engine on pump gas, like a muscle car engine in the late ‘60s, may need to be rich and retarded at 9 or 10 inches Hg.

A low compression engine may not need to richen up until much closer to WOT and may tolerate the vacuum advance not fully retarding until as low as 5 or 6 inches Hg.

Because lean mixtures burn slower they require the correct amount of additional timing, compared to rich WOT mixtures. The correct vacuum advance is a key to lean part-throttle tuning."

[Nick_nl]

[57 210]

rgalajda
would you please share your setup for your 3310-1 780. does it have a secondary block or a plate

[rgalajda]