So I've yet to install my wide band O2 sensor and gauge ( a bit of being lazy, not wanting to lay under the car, and not wanting to destroy the Jethot coating) so I've been trying a bunch of different needles in my carb. I have a write up from Keith Calver on the initial jet height to get the car to start and run of .060 to .075. My car starts and runs pretty well but doing plug chops to check the fueling it's running a bit rich. My question is; short of raising the jet height until it won't start/run has anyone measured the jet height from the bridge for the minimum height, I'm at .060 now.
Some specs: A+ 1293, unknown cam, definitely not stock, good compression across all cylinders, valves adjusted, new HIF 44 carb with a BCE needle, new 65D dizzy, new plugs gapped to .032, new wires, the correct .9ohm coil according to AC Dodd , static timing set to 10 degress (vacuum disconnected) idle set to 1000 rpm, advance of 35 degrees @ 4000 rpm. Also running 94 octane non-ethanol unleaded.
Curious, why aren't you running a vacuum advance?
Quote from: 94touring on May 07, 2024, 08:35:38 PMCurious, why aren't you running a vacuum advance?
I'am. I edited the wording to "vacuum disconnected" I set the static timing to 10 degrees without the vacuum attached, most of the British guys recommend that as a starting point. With the somewhat lumpy cam this engine has, the Haynes recommendation of 8 degrees and 900 rpm idle doesn't work.
You also get tons of guys that "just turn the distributor until in runs right" I found a pretty stable idle with it set like this.
Gotcha. 35 degrees all in is probably too much but you'd really need to dyno it to see. Mine stopped making power around 32 degrees. Running 94 octane will at least help keep it from detonating depending on if it likes that timing in conjunction with what compression ratio and cam you're running.
As far as jet height goes....install the damn wideband lol. Till then you're guessing.
Perhaps a slightly leaner needle? All of the needles have basically the same idle stages. it would be the mid-range and WOT stages that you may want different. It can be a bit time consuming to find needle options that give what you may want. Finding the desired needle through a supplier becomes the next challenge.
I use the "MintyLamb" site to sometimes visually compare needle profiles.
http://www.mintylamb.co.uk/suneedle/ (http://www.mintylamb.co.uk/suneedle/)
I run a BDL (currently) or BDK needle in my car with similar specs......but Dan's right - if you put the meter in you'll know exactly where you're at. And I agree with Michael, mid range and WOT are where you want the mix just right. A little rich at idle doesn't hurt anything.
I'm not sure the jet height is critical, mostly you want to know where you're at on mixture and set the jet height to get what you're after. Needle size is more important. Jet adjustments are just to fine tune the mixture.
Figuring that with all of the needles I have they won't do much until I can get good data, so I started down the path of getting the AFR gauge installed. Something to do on a dreary day off.
Welded in the bung, got the exhaust reinstalled, and cut a hole for the gauge. I just need to wire the power in and get tuning.
Thats a fancy bung! Show quality bung work :grin:
I need to get this done on mine, I highly doubt mine will look that good though. Where is the best place on the exhaust to weld the bung in? After the Y pipe I assume but does it matter how far past? I know you are supposed to mount it so that it is pointed up a bit to keep moisture out of the sensor.
Quote from: 94touring on May 08, 2024, 08:14:42 PMThats a fancy bung! Show quality bung work :grin:
That's because my stainless welding skills aren't what you'd call pro. Making sure I had good penetration and full coverage created a lot of weld, best to grind it down so it didn't look like one of those Youtube vids where "my friend fixed my exhaust" :great:
Quote from: cstudep on May 08, 2024, 08:29:00 PMI need to get this done on mine, I highly doubt mine will look that good though. Where is the best place on the exhaust to weld the bung in? After the Y pipe I assume but does it matter how far past? I know you are supposed to mount it so that it is pointed up a bit to keep moisture out of the sensor.
Not much choice on my car I put it where it would fit under the car after the "y" collector which ends up just after the shifter. It's about half way from the "y" and the center resonator.
Placement is not critical as to length, so anywhere after the Y pipe is good, but closer is better. You want it pointing downward, not up - so that any moisture can drain out. But, there's not a lot of room under there, so it goes where it will fit.
I like the metal dash, I'm going to do something like that with my hot rod.....
I noticed the double gauge, this late model car should already have a temp gauge, doesn't it?
Actually Dave the sensor should be facing upwards, typically between 3 and 9 oclock. It's to keep moisture out of the sensor and fouling it.
Quote from: MiniDave on May 09, 2024, 07:54:16 AMPlacement is not critical as to length, so anywhere after the Y pipe is good, but closer is better. You want it pointing downward, not up - so that any moisture can drain out. But, there's not a lot of room under there, so it goes where it will fit.
I like the metal dash, I'm going to do something like that with my hot rod.....
I noticed the double gauge, this late model car should already have a temp gauge, doesn't it?
The SS dash is 14 gauge SS sheet laminated over a marine plywood base, the 3 clock has a binnacle to house the stock cluster. I bought it from a guy in Florida probably 10 years ago.
The 3 clock cluster does have a temp gauge it works, kind of... I did the dual temp/oil pressure gauge for a more accurate representation of the actual temp, it's plumbed into the head at the corner where older cars have the heater output so it sits in the water jacket.
Quote from: 94touring on May 09, 2024, 08:01:48 AMActually Dave the sensor should be facing upwards, typically between 3 and 9 oclock. It's to keep moisture out of the sensor and fouling it.
I think we are probably all talking the same thing, just from different end of it. When I said pointing up I was referencing it via the tail end with the plug, so it would be pointing up. Pretty sure you are saying the same thing since the 3-9 you mentioned is what I was remembering when I mentioned it. I think when Dave says it should point down, he is referencing it from the other end of it, so the sensor end would point down into the pipe so it can drain, which would mean the tail end would be pointing up like we want it LOL.
Ha, well so long as the bung is on the top side between 3 and 9 or 9 and 3 depending which way the clock is turning
Ri
Quote from: cstudep on May 09, 2024, 06:31:03 PMQuote from: 94touring on May 09, 2024, 08:01:48 AMActually Dave the sensor should be facing upwards, typically between 3 and 9 oclock. It's to keep moisture out of the sensor and fouling it.
I think we are probably all talking the same thing, just from different end of it. When I said pointing up I was referencing it via the tail end with the plug, so it would be pointing up. Pretty sure you are saying the same thing since the 3-9 you mentioned is what I was remembering when I mentioned it. I think when Dave says it should point down, he is referencing it from the other end of it, so the sensor end would point down into the pipe so it can drain, which would mean the tail end would be pointing up like we want it LOL.
Right, that's what I meant.....end that goes in the pipe faces downward :great:
The other up!
So I've got the bung in the exhaust and the gauge wired in. My question is what should I be looking for in regards to the numbers?
I know the ideal number is 14.7-1 what kind of numbers should I try for at idle, 2k, 3k, 4k, 5k?
I figure most of the time I'm driving between 2500 - 4000 should I be shooting for 14.7 - 1 in that rev range?
Idle 14+/- a little depending what it likes.
Cruise with vacuum advance 16-17
Wide open throttle 13. Keep it out of the 14s at full throttle.
Right, doesn't it depend on load too? IOW, if you're pulling a hill or on onramp even if you're not WOT, it should be richer? not 10-1 or anything.....
Also, in my experience these gauges are not instantaneous - there's a certain amount of delay between what you do with your foot and what readings you get.
What you can expect to see, for example, cruising at 16:1 at light throttle, get to a hill and need more throttle. Depending on how much throttle you need the air fuel will be between 16:1 and 13:1.
Based on the needle you mentioned at the start of this thread and the two needles Dave recommended, I plotted them in the "MintyLamb" site (screenshot attached below).
If the picture of the guage active is at idle, then you are way rich. I would recommend starting with a needle change to a BDL needle and see what you get.
Quote from: MPlayle on May 16, 2024, 10:25:36 AMBased on the needle you mentioned at the start of this thread and the two needles Dave recommended, I plotted them in the "MintyLamb" site (screenshot attached below).
If the picture of the guage active is at idle, then you are way rich. I would recommend starting with a needle change to a BDL needle and see what you get.
The picture of the gauge was during the first time I powered it up. It was heating up and calibrating.
When I actually ran the car after warm up it was 13:1 at idle but way to rich anywhere else. Before I put in the AFR I tried a BDL it was too lean based on the plugs and hesitation.
I think I have a long road in front of me getting the correct fueling but I think the BDL will be a good one to try and modify.
I agree with starting with the BDL needle and adjusting from there. You may be able to sort the lean seeming issue on the BDL with richening the jet setting slightly. The gauge will tell you for certain.
Quote from: MPlayle on May 16, 2024, 10:25:36 AMBased on the needle you mentioned at the start of this thread and the two needles Dave recommended, I plotted them in the "MintyLamb" site (screenshot attached below).
How does one read those charts? In the chart is the BCE overall richer or leaner than the BDL?
Thanks.
Yes, BCE is overall richer than BDL.
The charts are read left to right, bottom to top. The lower left is the idle station. WOT is at the top right.
The station numbers are along the bottom with the pointy end as #16.
Lean is at the bottom, rich at the top.
On the MintyLamb site, enter the needle to be graphed in the "Search Needles" box. To remove a needle from the graph, click on the colored needle name above the graph.
Thanks for clarifying. I must have been reading the old Minty Lamb chart wrong. I put several needles I've tried into new chart and the way my current needle behaves checks out on the chart as it's a BDK which is lean down low & likely explains the light throttle hesitation/stumble I have.
I too need to get my O2 sensor installed. But I've been saying that for several years now!
So here are my numbers after modifying a BDL needle with 1000 grit paper and metal polish in the my lathe.
Idle @ 1000 rpms 10 degrees advance 13.3 - 14.2 pretty steady idle now.
2000-3500 accelerating 14.1 - 15.2
Steady state 50 mph/3000 rpm 14.4 - 15.2
Steady state 70 mph/4000 rpm 15.5 - 15.8
Accelerating on the highway from 70 mph leans it out to 16+
Other notables LZX 2085 damper with 20/50 oil (this was recommended by AC Dodd), MED stub stack w/ITG MED foam filter, BP6ES plugs
I started with the jet height at .075 but have since brought it up but I didn't remove the vacuum chamber to remeasure it.
What are the wide open throttle numbers?
Quote from: 94touring on May 22, 2024, 09:03:51 PMWhat are the wide open throttle numbers?
I'll check as I drive it more.
I kind of wish I had mounted the gauge on the dash up higher in front of me so I don't need to look down when driving.
When you say accelerating, approximately how much throttle? Is it hesitating at 16+ when you're at 70mph+? Or is it a momentary lean spike?
Quote from: 94touring on May 23, 2024, 11:27:53 AMWhen you say accelerating, approximately how much throttle? Is it hesitating at 16+ when you're at 70mph+? Or is it a momentary lean spike?
So I drove it after work with some secondary roads and highway.
If you you just pin it in 4th at 70 it spikes lean and stumbles, I'm just not sure you would actually drive the car like that. If you accelerate "normal" to pass it leans to 16 or so but doesn't feel like it has a flat spot. It probably could be a little richer on the top to help that a little.
Most everywhere else it drives pretty good. I didn't have time to do a plug chop during the highway run to get a look at the plugs.
I have another BDL I could mod to see if I can get it better and save this modded BDL as a reference.
There's no point looking at the plugs, you have a wideband. I need rough throttle positions and the numbers to give advice. If you're full throttle and 16:1, you'll melt pistons eventually. Take it out in 3rd gear on a long straight road and at full throttle starting around 2k rpms, run it up to whatever your redline is and see how lean it is. Myself personally I let off the throttle tuning once I hit 14s at full throttle. Drive back to the shop and adjust/file needles, make jet changes, or redo fuel cells on the cars with programmable fuel injection.
You'll have 16 stations (can't remember if it's 1/16 or 1/8" incriminates) starting around station 10 is your WOT (wide open throttle) stations. Work slowly by removing material from 10 gradually tapering down towards 16. The last 3 or so stations do nothing. Remove until you get yourself around 13:1 at full throttle through your entire rpm range. Depending on your heads and cam, you may expect to see rich dips at lower rpms, about 3k rpms for myself it dips to around 11:1, but then works it's way back to 13:1. Once you get your WOT air fuels in a safe mixture of 13:1, you can play with spring rates to dial in cruise air fuel. Ideally you can get that 16:1 maximum fuel economy at light throttle cruise. Use a lighter spring to get a leaner cruise. Use a thicker dash pot oil to richen the mixture in the transition from light throttle to full throttle if you have lean spikes and hesitation.
Quote from: 94touring on May 24, 2024, 12:27:14 PMYou'll have 16 stations (can't remember if it's 1/16 or 1/8" incriminates) starting around station 10 is your WOT (wide open throttle) stations. Work slowly by removing material from 10 gradually tapering down towards 16. The last 3 or so stations do nothing. Remove until you get yourself around 13:1 at full throttle through your entire rpm range. Depending on your heads and cam, you may expect to see rich dips at lower rpms, about 3k rpms for myself it dips to around 11:1, but then works it's way back to 13:1. Once you get your WOT air fuels in a safe mixture of 13:1, you can play with spring rates to dial in cruise air fuel. Ideally you can get that 16:1 maximum fuel economy at light throttle cruise. Use a lighter spring to get a leaner cruise. Use a thicker dash pot oil to richen the mixture in the transition from light throttle to full throttle if you have lean spikes and hesitation.
I'll work on the #10 to 16 sections of the needle. The book I have says it's 1/8" stations, I'll mark it all out before I spin it in the lathe an let you know how I make out. I plan on measuring the stations and recording them before I reinstall it so I have a new baseline needle.
So this is what I've come up with modifying my existing BDL needle. I made a holder for the needle to hold it straight in a collet. Sanded off a little with 1000 grit and polished it with metal polish.
Position Before After
9 735 730
10 725 715
11 705 700
12 695 680
13 650 640
14 630 620
15 595 590
The jet height is .0445
I didn't get to drive it a lot but on hard acceleration from 70 in 4th I saw a momentary 16 spike and then it richened up to high 13's to briefly low 15's. Generally speeds around 30-50 I was around 14 to 15. In lower gears on acceleration it would dip into the 12-13's. What kind of numbers should I be looking for at idle when the car is warmed up? Right now I'm still at low 13's to 14 at idle. I'm a little concerned it will richen it too much at idle if I change the jet height too much.
I also realized it's a bit of a problem looking at the gauge, tach, and driving. It does have data logging, I may consider setting that up later.
I'm amazed at how such a small amount off the needle can make such a big difference.
13-14s at idle is perfectly fine. It's whatever the leanest you can get at idle and it still idle ok. Sounds like you're getting closer. Lean spikes on initial throttle are to be expected. Just keep working at it a little at a time till you can maintain that 13 target at WOT.