Dellorto DHLA40E Fuel Level
Posted: Mon Feb 22, 2016 4:45 pm
Can anyone tell me what depth of fuel should be lying in the float chamber with the cover removed? I have adjusted the float height in accordance with their weight (10 grams).
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Float height (fuel level) is a foundational setting for the rest of the jetting, and it should be set accurately. "Give or take a mm" is a pretty generous tolerance for the fuel level, and you should make an effort to zero in on 27mm fuel level, or a correct float level.William2 wrote:I measured the depth with a vernier caliper and got a reading in each float bowl of about 27mm give or take a mm.
Jetting is more precise than, "more or less as per the book", but going with what you've written so far, I don't see anything that threatens to melt a piston. If you're tuning for performance rather than emissions, then the 180 Main Air Corrector is probably too large. Larger is leaner, and 180 is probably one or two steps too lean. I'd put my money on 170 for now.William2 wrote:I am assuming that if the jetting is more or less as per the book then I shouldn't worry about causing any damage to the valves and pistons, etc.
It's best that you avoid any more short runs, and wait to start the engine until you can devote some time to it.William2 wrote:I kept my fingers crossed and with full choke applied I turned the key! After a bit of cranking she fired into life and seemed to run quite evenly but I only ran it for a few seconds gradually pushing the choke knob in.
So initial results look promising but the carbs will need balancing, etc. I read somewhere that on a rebuilt engine it is best to run it at fast idle until it is fully warmed up as I guess I shouldn't rev it too much until it is fully run in, although I will need to apply some revs to check that the distributor is advancing correctly.
William,William2 wrote:Measured the fuel level several times adjusting the 10gram floats to get the required 27mm depth of fuel.
Matt is correct that the richer Main Jets will offset the slightly leaner 180 Main Air Correctors. The same can be said for the 170 Air Correctors. The difference is a matter of degree. The 170 Air Correctors are more correct for the 120 main jets, and 180 Air Correctors will result in a slightly lean mixture. You're not going to burn valves or pistons, but you're also not going to get the power you could have.William2 wrote:Phoned Eurocarb to order some 170 air corrector jets but the chap I spoke to said that as the main jets were slightly larger (120 as opposed to 115) this would offset the slightly weaker 180 air correctors.
You seem reluctant to do the proper run-in at 2200 rpm for half an hour.William2 wrote:I ran the engine today for about 15 minutes and checked oil pressure and coolant temperatures all the time. All looking good. Also checked the timing with the engine running at about 1200 rpm and it is reading 10/12 degrees BTDC.
Have you balanced the carbs yet? The carbs must be balanced before attempting to do any other tuning. Otherwise you're just wasting effort.William2 wrote:The tick over is rather lumpy though and the carbs are popping a bit. If I puIl the choke out a small amount the popping ceases. I assume this suggests that the idle mixture is too lean. I haven't as yet tried unscrewing the idle mixture screws further than 3 1/2 turns. Also I am running the engine with the air trumpets fitted but not the air box/filter system. The Eurocarb chap said that I should connect all the air filter system up as this would also have some affect. Regards, William.
William,William2 wrote:(Snip)...
Eurocarb said that I should make sure that all the air filter system is in place before attempting to get the idling correct as this will affect it.
Initially I just need to get it running well enough to get it through am MOT and drive it 1 mile to the garage!