B20 DHLA 40C problems solved almost.

Dellorto, Weber, trycka eller suga?
Miksa89
Ganska mycket laddtryck
Inlägg: 57
Blev medlem: tis feb 11, 2020 6:06 pm

Re: B20 DHLA 40C problems.

Inlägg av Miksa89 »

Thunderbo1t skrev: sön dec 19, 2021 6:35 pm Fuel pressure should never affect AFR when using a carburetor, if it does, for example, the fuel pressure is wrong, or fuel delivery is restricted, or needle valves leaking for some reason, worn, vibrations etc.
Float level affects AFR a little.

Okey,maybe my problem is too high fuel pressure that makes flooding little when running causing the funky spot between 2000-2500rpm? No dripping at idle or when engine not running.

Need to try tomorrow again if there is really difference in afr between 0.15 vs 0.18.

Does electric pump output l/h output stay same with high or low pressure?
Thunderbo1t
Forumsberoende
Inlägg: 1038
Blev medlem: mån okt 31, 2011 5:29 pm
Ort: Ljusdal

Re: B20 DHLA 40C problems.

Inlägg av Thunderbo1t »

I dont think pump output will be an issue. Can you replicate the problem reving in neutral?
Miksa89
Ganska mycket laddtryck
Inlägg: 57
Blev medlem: tis feb 11, 2020 6:06 pm

Re: B20 DHLA 40C problems.

Inlägg av Miksa89 »

Thunderbo1t skrev: mån dec 20, 2021 12:54 am I dont think pump output will be an issue. Can you replicate the problem reving in neutral?
Tried again with 0.15bar fuel pressure.
Maybe was flooding little bit before because afr is now 13-14 just off idle,before it was 12-13 at veryvery light throttle. And idle is little leaner now than before.
Wot afr is 12-13,same as before.
Maybe very little difference in funky spot or not.

Or temperature makes the difference,before was 0c and today almost -15c.

Yes i can replicate it when neutral and not moving.
Need to try take video tomorrow,i think many peopple can tell right away whats causing it :D Better take video outside of car or engine bay or afr meter?
Miksa89
Ganska mycket laddtryck
Inlägg: 57
Blev medlem: tis feb 11, 2020 6:06 pm

Re: B20 DHLA 40C problems.

Inlägg av Miksa89 »

Played with the advance today but no real succes here.

Heres video where the problem occurs.
https://youtube.com/shorts/3uHVNUr1Elw?feature=share

Flooring 2000rpm @ 2. gear just to make problem more visible.

When hitting WOT over 3000rpm no problem but lower revs things get funky.
Miksa89
Ganska mycket laddtryck
Inlägg: 57
Blev medlem: tis feb 11, 2020 6:06 pm

Re: B20 DHLA 40C problems.

Inlägg av Miksa89 »

Anyone have experience with VCS siamese header? 2. and 3. is siamese like original cast manifold. Maybe thats not the right piece in my puzzle to try solve my reversion problem?
Thunderbo1t
Forumsberoende
Inlägg: 1038
Blev medlem: mån okt 31, 2011 5:29 pm
Ort: Ljusdal

Re: B20 DHLA 40C problems.

Inlägg av Thunderbo1t »

If you look in to the carb throats when this problem happens, does it show something strange in any of the throats?
Could the siamese header design cause this? Sure is tight LSA.
I have only run R-cam with 4-1 header, and that was just coincidence.
Someone with experience should know what this problem is by hearing it?
Miksa89
Ganska mycket laddtryck
Inlägg: 57
Blev medlem: tis feb 11, 2020 6:06 pm

Re: B20 DHLA 40C problems.

Inlägg av Miksa89 »

Thunderbo1t skrev: tor dec 30, 2021 10:00 pm If you look in to the carb throats when this problem happens, does it show something strange in any of the throats?
Could the siamese header design cause this? Sure is tight LSA.
I have only run R-cam with 4-1 header, and that was just coincidence.
Someone with experience should know what this problem is by hearing it?

Hard to say because when neutral and revving problem is waaayy smaller versus Wot @ 2000rpm 2. gear and hard to take video,maybe i can try replicate it when neutral and see what happening there.

Received PM from person who had similar problems and he said it sounds and looks similar than his reversion problem.
And spoke with guy who had made many folkrace-motors and got dynoservice said it sounds like reversion too.
Miksa89
Ganska mycket laddtryck
Inlägg: 57
Blev medlem: tis feb 11, 2020 6:06 pm

Re: B20 DHLA 40C problems.

Inlägg av Miksa89 »

Things getting better now with 4-2-1 header.

Theres still funkyspot but much smaller and lower rpms and it can be avoided by playing with gas pedal.

Ordered new acc jets because lean stumble now occurs when flooring. And ordered smaller air jets because gets lean(over 14 afr) after 5000rpm now. I think its good sign when engine needs more fuel.

I think theres still something weird going on based on jetting:
36 choke
135 main/140 air,ordered 125 air.
55 idle with .2 holder.
38 acc jet,ordered 45. :whistle:

E: Now with 135main/125 air afr stays 13-14 below 5000rpm and over 5000rpm goes 12.5-13.

Ordered 140 mains to get afr little richer at mid range WOT.

Maybe should try 5. tubes instead 6. tomorrow just for curiosity.

Accpump jets were weber jets but will get right ones tomorrow.
Miksa89
Ganska mycket laddtryck
Inlägg: 57
Blev medlem: tis feb 11, 2020 6:06 pm

Re: B20 DHLA 40C problems.

Inlägg av Miksa89 »

Miksa89 skrev: mån feb 07, 2022 7:34 pm Things getting better now with 4-2-1 header.

Theres still funkyspot but much smaller and lower rpms and it can be avoided by playing with gas pedal.

Ordered new acc jets because lean stumble now occurs when flooring. And ordered smaller air jets because gets lean(over 14 afr) after 5000rpm now. I think its good sign when engine needs more fuel.

I think theres still something weird going on based on jetting:
36 choke
135 main/140 air,ordered 125 air.
55 idle with .2 holder.
38 acc jet,ordered 45. :whistle:

E: Now with 135main/125 air afr stays 13-14 below 5000rpm and over 5000rpm goes 12.5-13.

Ordered 140 mains to get afr little richer at mid range WOT.

Maybe should try 5. tubes instead 6. tomorrow just for curiosity.

Accpump jets were weber jets but will get right ones tomorrow.
Changed pump jets 38 -> 45 but still dies when flooring rapidly from 2500-3000rpm about sec or a half and then gets going. Waiting to get 50 pump jets if it helps.

Can that be caused by too small pump jets only?
When pressing pedal to the metal more gentle that dying cannbe avoided
Miksa89
Ganska mycket laddtryck
Inlägg: 57
Blev medlem: tis feb 11, 2020 6:06 pm

Re: B20 DHLA 40C problems.

Inlägg av Miksa89 »

Miksa89 skrev: sön feb 13, 2022 7:10 am
Miksa89 skrev: mån feb 07, 2022 7:34 pm Things getting better now with 4-2-1 header.

Theres still funkyspot but much smaller and lower rpms and it can be avoided by playing with gas pedal.

Ordered new acc jets because lean stumble now occurs when flooring. And ordered smaller air jets because gets lean(over 14 afr) after 5000rpm now. I think its good sign when engine needs more fuel.

I think theres still something weird going on based on jetting:
36 choke
135 main/140 air,ordered 125 air.
55 idle with .2 holder.
38 acc jet,ordered 45. :whistle:

E: Now with 135main/125 air afr stays 13-14 below 5000rpm and over 5000rpm goes 12.5-13.

Ordered 140 mains to get afr little richer at mid range WOT.

Maybe should try 5. tubes instead 6. tomorrow just for curiosity.

Accpump jets were weber jets but will get right ones tomorrow.
Changed pump jets 38 -> 45 but still dies when flooring rapidly from 2500-3000rpm about sec or a half and then gets going. Waiting to get 50 pump jets if it helps.

Can that be caused by too small pump jets only?
When pressing pedal to the metal more gentle that dying cannbe avoided
No success here.

Tried with 50 pump jets but not real change except too rich few seconds when flooring higher gears...

Maybe problem is caused by misfire and unburned fuel makes AFR look lean?

But what can cause that kinda misfire only when rapidly increasing revs when flooring and shifting?

E:Tried without MSD 6AL but didnt work at all.
Misfires like hell when accelerating and afr was between 10-11.5 at low revs versus 12-13.5 with msd.
But MSD back and works fine except that litlle misfire when flooring and afr stays between 12-13.5 :crashed: :crashed:
Miksa89
Ganska mycket laddtryck
Inlägg: 57
Blev medlem: tis feb 11, 2020 6:06 pm

Re: B20 DHLA 40C problems.

Inlägg av Miksa89 »

Miksa89 skrev: mån feb 21, 2022 9:11 am
Miksa89 skrev: sön feb 13, 2022 7:10 am

Changed pump jets 38 -> 45 but still dies when flooring rapidly from 2500-3000rpm about sec or a half and then gets going. Waiting to get 50 pump jets if it helps.

Can that be caused by too small pump jets only?
When pressing pedal to the metal more gentle that dying cannbe avoided
No success here.

Tried with 50 pump jets but not real change except too rich few seconds when flooring higher gears...

Maybe problem is caused by misfire and unburned fuel makes AFR look lean?

But what can cause that kinda misfire only when rapidly increasing revs when flooring and shifting?

E:Tried without MSD 6AL but didnt work at all.
Misfires like hell when accelerating and afr was between 10-11.5 at low revs versus 12-13.5 with msd.
But MSD back and works fine except that litlle misfire when flooring and afr stays between 12-13.5 :crashed: :crashed:
Switched 6. e-tubes to 5. tubes and that cured the flat spot when flooring.
But with 140 main/165 air afr gets over 15 @ 4000-4500rpm and then gets 14 near 6000rpm.
Tried 150 mains and that makes wot afr reasonable but now cruise 2500rpm too rich and rich stumble when flooring....

How i can get mains come in earlier with 6. tubes or idle circuit last longer without getting richer at 2000rpm?

I think 6. tube afr stays more stable at wot compared to 5. witch seiling between 12.5-14 and leanest point at 4500rpm.

Or witch e-tube is like 6. but comes in little earlier?

E: Tried 6. tubes with step larger main. Was 135 and tried with 140 but that makes hole range afr drop to 12-12.5 instead 13-13.5 with 135 main. :doh:
Miksa89
Ganska mycket laddtryck
Inlägg: 57
Blev medlem: tis feb 11, 2020 6:06 pm

Re: B20 DHLA 40C problems.

Inlägg av Miksa89 »

Miksa89 skrev: lör feb 26, 2022 8:54 am
Miksa89 skrev: mån feb 21, 2022 9:11 am

No success here.

Tried with 50 pump jets but not real change except too rich few seconds when flooring higher gears...

Maybe problem is caused by misfire and unburned fuel makes AFR look lean?

But what can cause that kinda misfire only when rapidly increasing revs when flooring and shifting?

E:Tried without MSD 6AL but didnt work at all.
Misfires like hell when accelerating and afr was between 10-11.5 at low revs versus 12-13.5 with msd.
But MSD back and works fine except that litlle misfire when flooring and afr stays between 12-13.5 :crashed: :crashed:
Switched 6. e-tubes to 5. tubes and that cured the flat spot when flooring.
But with 140 main/165 air afr gets over 15 @ 4000-4500rpm and then gets 14 near 6000rpm.
Tried 150 mains and that makes wot afr reasonable but now cruise 2500rpm too rich and rich stumble when flooring....

How i can get mains come in earlier with 6. tubes or idle circuit last longer without getting richer at 2000rpm?

I think 6. tube afr stays more stable at wot compared to 5. witch seiling between 12.5-14 and leanest point at 4500rpm.

Or witch e-tube is like 6. but comes in little earlier?

E: Tried 6. tubes with step larger main. Was 135 and tried with 140 but that makes hole range afr drop to 12-12.5 instead 13-13.5 with 135 main. :doh:
Tried with 11. e-tubes too.
Pretty much like 6. but main 140/165 air afr stays pretty stabil between 12.5-13.5 @ wot.
6. tube also pretty good with 12.5-13.5 afr wot hole range with 135main/125 air.

That flat spot get fixed by adjusting pump rods. Now little bit on the rich side with 45 acc.jets. Need to change back to 38 jets and make litlle tweak with rods if needed.

And little fine tuning with idlejetholders and i think its good as i can get it by myself. 8)

Thans for helping everybody. :thumbright:
Skriv svar