243 replies to this topic

[jd lj]

Will do Wayne.

[RallyRed]

Hi James.. if you wanted to bring up a set of the posts that the main throttle bar
( front to back) goes through...for Dellortos...I'd be interested mate.
I can send a pic if you need it.
p.s. I am assuming the posts/bearing is one part?..If not, all I need is the bearings.. ta Col

p.s. PM'd you my mob. if you need to discuss. Ta

Edited by RallyRed, 12 September 2019 - 09:42 AM.

[jd lj]

I'll see you on Sunday with the parts Col.

Unfortunately my car is not going to be there this time.

[RallyRed]

Okey Dokey, ta James

[jd lj]

Here's a link to my latest DCOE WEBER parts. I've made polished stainless steel cold start blanking plates.

https://www.gumtree....teel/1229341976

[natcamp10]

Hi ya James
So got the old girl out today with the new setup and oh my god the is a completely different car , my first real run since modifying. I’ve got no hesitation with tip in point , the only fault I’ve got is a small hunt when coasting just off idle ,I will post some afr readings this week , running the 3.36 diff in the rear keeps it loving the cam rev range , I well chuffed atm
Post back soon 👍

[jd lj]

I'm glad to hear how happy you are with the results, well done. We can probably solve that hunting that you have just off idle with a bit of work.

Once you post some data we'll work through it. It could potentially be due to your 45dcoe152 carbs having the first progression hole further upstream of the throttle plates at idle than what is ideal. So effectively the throttle plates have to open further before the first progression hole is exposed to manifold vacuum and can begin adding more fuel. If you take off one of the progression hole covers you'll see that you have to open the throttles a bit before you can see the top edge of the throttle plates through the first progression hole, ideally the throttle plates should be positioned directly directly below the first progression hole at idle/when the throttles are clised. What's your idle AFR and what idle jets are you using, plus what is your idling manifold vacuum level again (I'm sure that you have answered this already on an early post). Does the hunt off idle reduce if you richen the idling AFR? Try opening the idle mixture screws a bit and take it for a drive and test it out. Hunting or surging is usually due to a lack of fuel.

James D

[natcamp10]

Hi ya James
I’ve got some AFR data I logged today On the lm2 meter
My specs are 06 tubes , 150 main jet, 145 air correctors,f55f8 idle jets 36mm chokes 4.5 AV
My data shows a lean out at rpm 1500-1900 of around 16/17.1
Tip in seems ok at 13.8 3000-4000
I going to recheck my float levels again tomorrow
I’ve got the idle mixture screws out nearly 3 turns
Still runs pretty good tho 👍

[natcamp10]

Hi ya James
I’ve got some AFR data I logged today On the lm2 meter
My specs are 06 tubes , 150 main jet, 145 air correctors,f55f8 idle jets 36mm chokes 4.5 AV
My data shows a lean out at rpm 1500-1900 of around 16/17.1
Tip in seems ok at 13.8 3000-4000
I going to recheck my float levels again tomorrow
I’ve got the idle mixture screws out nearly 3 turns
Still runs pretty good tho 👍

I’m also running all 6 holes on the 06 tubes
I thought maybe blocking one Hole off on the tubes would possible richen it through the rev range ?? Am I thinking about this right ?

[jd lj]

Plugging up a hole on the O6 tubes will lean out the tip in mixture which is usually at about 2500-3000 rpms, this is where most people get a mid range hesitation.

What's the WOT/redline AFR reading?

Once we know what your manifold vacuum level is at idle then we'll know if you need to try a richer idle jet or to modify them to suit. Depending upon the vacuum level Keith has two types of idle jets that may be beneficial.

James D

[natcamp10]

Hi James
Vacuum is 22 hg ,
Wot is 13.8afr
Regards Nathan

[jd lj]

Nathan,
If you cruise at approximately 2500 rpms do you get a slight spluttering, it'd probably be most notable with the windows open and listening to the exhaust note. This can happen with the amount of manifold vacuum that you have. If so we can fix this. On the logworks program this shows as a saw tooth pattern.

[jd lj]

As for the idle jets there's a few options. The std idle jets don't work very efficiently in engines with either a very low or very high manifold vacuum. Engines with a high manifold vacuum such as yours the use of idle jets with a narrow internal bore are more suitable. Note this is the opposite situation to what we delt with for Brian's car earlier in this thread. Using a 55f9 idle jet will richen the progression circuit but has the same internal bore as the f8,it just has a smaller air bleed hole, so that is one option.

The idle jets with the f6 designation have a narrow air bleed hole but potentially the 55f6 could be too rich, so a 50f6 may be another option. I'm sure that I have a set here if you want to try those, if they don't work just send them back.

The final option is the premium option. Keith makes "Hypojets" which are idle jets specifically for engines with high manifold vacuum. They feature a split collar that can be rotated to open or close more air bleed holes. On these jets more air bleed holes open will lean out the idle mixture which can then be adjusted by the idle mixture screws, but as the rpms rise through the progression circuit the extra air bleed holes create a ventruis effect and draw more fuel into the circuit. The mixture strength is then adjusted by using the split collar to open or close more air bleed holes. From memory the H24's are probably the most suitable size, TBC.

Once the idle circuit is sorted we'll then refine the main circuit further as needed.

James D

[natcamp10]

Hi ya James
hypojets it’ is then 👍 I will order a set .
I’ve got a spare sets of 50f8 /55f8 idle jets ,Can I modify These at all ?? I’ve got jet drills and solder
Regards
Nathan

[natcamp10]

Hi ya James
H24 hypojets it’ is then 👍 I will order a set .

I’ve got a spare sets of 50f8 /55f8 idle jets ,Can I modify These at all ?? I’ve got jet drills and solder
Regards
Nathan

Edited by natcamp10, 17 October 2019 - 10:54 PM.

[jd lj]

No the internal bore is too big to make them like an f6 designation idle jet. But you could solder the air bleed hole on the f8 jets and redrill them at 1mm (IIRC) and make them f9's.
The only difference between f8 and f9 idle jets is that f8s have a 1.2mm air bleed hole and f9's are 1mm from memory. I'll check that later.

James D

[jd lj]

I'm looking into getting some choke and auxiliary ventruis locking screws made that use a jam nut to lock them in like what's used on DHLA DELLORTO'S.

As many of you are aware the Weber locking tabs for these screws are ineffective and if the screws come loose the auxiliary ventruis can rotate and make the main circuit unable to operate. Lockwiring the screws is effective but very tedious being under the carbs, out of sight and with limited access.

So using my locking grub screws with the jam nuts is a simple solution that I've tested to hold up to harsh conditions.

For the guys that change chokes to suit different tracks I'm sure that you would appreciate the improvement.

So anyone who's interested let me know so I can get some idea of how many sets to get made. They'll be made from stainless steel.

James D

[jd lj]

For any of you using 45dcoe152 model carbs that experience problems with coming off idle or in the first few thousand rpms I can supply you with a solution.

As I have discussed previously I'm not a fan of the 45dcoe152 carbs due to the position of the first progression hole in relation to the throttle plates, the hole is too far upstream which means that the throttle plates have to open too far before any additional fuel is added by the first progression hole. This can cause a hesitation coming off idle and/or leaning out in the first part of the progression circuit.

Weber revised this progression hole pattern and modified it with the 45dcoe152G's and added an additional progression hole closer to the throttle plates.

I can supply you with the jig required to accurately add this additional hole to your 45dcoe152 carbs. Doing this will make your tuning easier and give better results.

The procedure can be carried out with the carbs fitted to the engine and all that you need is a dremel rotary tool or something similar.

Nathan who I've been helping in this thread did this recently and was pleased with the results.

So if anyone is interested just send me a PM and I'll help you out.

[jd lj]

This thread has been very quiet for a long time but I hope that it's been helpful to some people.

I've recently been making more batches of my DCOE Weber bakerlite spacers/heat insulators which replace soft mounts. They're 8mm thick so that your existing studs can be used. Softmounts aren't required for 6 cylinder engines as they have different harmonics from 4 cylinder engines. I have tested these extensively.
If anyone is interested in purchasing a set you can send me a PM through the forum but I also have them listed on Gumtree. I have sets of 45mm ones in stock but upon request I can make other sizes such as 40, 42, 48 and 50mm throats.


Dcoe Weber heat insulators,
https://www.gumtree....roid_VIP_sticky