Two Questions

[Scotty]

(If this belongs in Modified, please move it with my apologies.)


1725, Weber 32/36, Log Manifold, near-fully Pertronix setup (Flamethrower 3ohms, Flamethrower wires, Pertronix cap and Ignitor with only the actual Lucas 25D distributor itself the lone originality survivor. Fires first time, everytime.

I recently swapped around the jetting to resolve an idle surge issue that I originally thought was due to a lean condition or a vacuum leak, from a previous post. The solution for this was in part to replace the gaskets and phenolic spacer with new ones and lightly Gasgacinch them together and snug the nuts down.

The Weber originally had a 55/50 for Idle Jets and. 145/140 Mains. I changed this to 150/145 Main and 60/55 for the Idle Jets. The rest of my jetting is the stock Redline Weber 32/36 DGV ones that you would buy from Rick since this Carb came four years ago from SS.

1. With using the log manifold is this ok or am I running it too rich? The Idle Surge problem so far has gone away.

The other question I have has to do with the Brake Booster port on the log manifold. Since I have owned the car it has had just a hose clamped to it at an odd angle just below the Weber's built-in fuel filter. I would like to try and fix this and clamp it onto a fitting that connects over the port instead of 'folding' a hose over it. It is a barb-ish fitting that looks like it belongs on the manifold.

2. What size and where would I find this fitting for the Brake Booster port on the Log Manifold that I can clamp a hose onto?

Driving-wise, the car is responsive and runs slightly heavy but not enough that it doesn't run well or power up when I need it.

Thoughts?

Thanks as always in advance!

 

[belmateo]

Do you know any shop near you that still has on older smog machine that has the sniffer to determine your A/F ratio to check it at idle and speed?

 

[husky drvr]

2. What size and where would I find this fitting for the Brake Booster port on the Log Manifold that I can clamp a hose onto?

Scotty,

I've got two suggestions for this situation. You're welcome to choose either way to change the situation - or not.

Today I stopped into a local Advance Auto store for some fuel line. While browsing through their "HELP" section of parts, I found a package of various sized vacuum caps that just plug onto a fitting - no clamp required. Here, the package was less than $9.00+sales tax. You'll need a 3/8" size cap.

The other option is leave the fitting and permanently connect your vacuum gauge there so you can utilize the gauge as intended for your tuning efforts.

The catch is there is not a readily available fitting or plug for replacement. Its got those "funny" BSW threads.

Have a good day,

 

[ausbeam]

A basic check for mixture is to remove the plugs every once in a while and check their color.

Coffee brown is ideal, black/sooty is rich and and pale white is lean.
Do this after a bit of round town running, then again after some high speed running and you should be able to factor in the idle jets as well as the main jets.

Plenty of info on the net re plug coloring.

 

[Asm109]

What exactly is the thread in the manifold? I know you can get BSPP and BSPT fittings from McMaster Carr.

 

[husky drvr]

What exactly is the thread in the manifold?

OK, would you believe 5/8-18 inch - parallel. I did find a note that those threads still use the Whitworth 55* thread form, but didn't re-find that information.

They aren't BSW, BFW (British Fine Whitworth), BSPP, or BSPT because the first is 5/8-11 inch while the following three are 5/8-14 inch.

Those threads seem to be related to AN fittings and those used for flared tubing fittings used with high pressure gases, fuel, and oil. Mainly used for the caps used to hold and seal the flared tubing against the cone shaped fitting.

Hope this helps,

 

[Scotty]

Scotty,

I've got two suggestions for this situation. You're welcome to choose either way to change the situation - or not.

Today I stopped into a local Advance Auto store for some fuel line. While browsing through their "HELP" section of parts, I found a package of various sized vacuum caps that just plug onto a fitting - no clamp required. Here, the package was less than $9.00+sales tax. You'll need a 3/8" size cap.

The other option is leave the fitting and permanently connect your vacuum gauge there so you can utilize the gauge as intended for your tuning efforts.

The catch is there is not a readily available fitting or plug for replacement. Its got those "funny" BSW threads.

Have a good day,

I will seek out the Help! (or related) assorted vacuum caps, see how those go and report back. Thank you for the idea!

 

[Scotty]

Do you know any shop near you that still has on older smog machine that has the sniffer to determine your A/F ratio to check it at idle and speed?

After some run-ins with shops on my end, I really don't trust anyone to give me an honest assessment. All the work I have done, with the exception of the brake rebuild just a few years ago which I had to go back and fix myself recently. Most of the really knowledgeable folks out my way that I know about who were directly responsible for rebulding bits for Pita have long since moved away. I think the closest I got is out of Stockton, Ca and that's a few hours drive for me.

I have been considering for awhile to pull the clock from the dashboard and replace it with a Air Fuel Ratio gauge and setup so I can read the numbers as I drive. I have the numbers for what the Alpine is supposed to register at somewhere, have to find it. Any suggestions on a really good one that won't kill my bank account I would totally appreciate.

I was asking about the Main/Jets just to see if someone out there might be running jets on their primary at my sizes. I know it all depends on what the engine wants, but I was looking for a sort of operating baseline because I've heard folks say that the Redline Weber jetting setup can run somewhat lean on the 1725 but I have no idea on this.

Sorry for the long response. It's been a long week.

 

[Scotty]

OK, would you believe 5/8-18 inch - parallel. I did find a note that those threads still use the Whitworth 55* thread form, but didn't re-find that information.

They aren't BSW, BFW (British Fine Whitworth), BSPP, or BSPT because the first is 5/8-11 inch while the following three are 5/8-14 inch.

Those threads seem to be related to AN fittings and those used for flared tubing fittings used with high pressure gases, fuel, and oil. Mainly used for the caps used to hold and seal the flared tubing against the cone shaped fitting.

Hope this helps,

Did the upright barb-styled nipple fitting that is on the log manifold for the brake booster come with the intake manifold? Curious where you'd get fittings for it if the fittings are that exotic.

 

[Scotty]

A basic check for mixture is to remove the plugs every once in a while and check their color.

Coffee brown is ideal, black/sooty is rich and and pale white is lean.
Do this after a bit of round town running, then again after some high speed running and you should be able to factor in the idle jets as well as the main jets.

Plenty of info on the net re plug coloring.

Thank you for this. I'll drive for abit and report back.

 

[pruyter]

I have a Weber 32/36 DGV 5 A and I run the following on this carburettor:
Primary main jet: 140 and Secondary main jet: 135
Primary air correction: 165 and Secondary air correction: 160
Primary idle jet: 52 and Secondary idle jet: 50
Primary emulsion tube: F6 and Secondary emulsion tube: F6

The car has no problems at all regarding carburation.

Regards,
Peter

 

[Tim R]

Scotty, with the 'log' manifold you will always have two cylinders rich or two cylinders lean. If you are able to change to the curved manifold you will see the difference of suddenly having all four cylinders working at maximum performance. Alpine Innovations are well worth a call as their set up is the biggest improvement you will ever make to an Alpine.
Tim R

 

[belmateo]

From an internet search quoting Kevin;

"I'm running the dreaded log manifold...."
And THERE is your problem. I know you want to make what you have work, but the fact is, it won't... the physics are dead against it. That log manifold allows the mixture to stagnate out at the ends, and the cold manifold then allows the fuel out there to condense, consequently making the cylinders either very lean under low-flow conditions, and become very rich when initially increasing the flow (RPMs), because the fuel condenses at the ends of the 'log' at low flow, and gets flushed out at higher speeds. This explains your plugs... they foul because they get flooded by the raw fuel being splashed onto them because of the condensation, and therefore they don't fire properly... and then once you increase the RPMs it runs fine because it blows out the fuel and draws a normal mixture.

If there was a way to successfully heat that manifold hot enough, this wouldn't be as much of a problem, but even the water tube inside it doesn't get it warm enough at the ends to prevent this issue. That's why the Alpine Innovations manifold works better - because the runners are curved and run directly from the plenum to the cylinder ports, there is far less likelihood for the fuel to condense out.
Puff4 – SAOCA (Kevin McLemore)

 

[husky drvr]

Did the upright barb-styled nipple fitting that is on the log manifold for the brake booster come with the intake manifold? Curious where you'd get fittings for it if the fittings are that exotic.

Scotty,

Yes, installed at the factory.

At this point in time, probably no way for determining why the use of something so unusual. A first level guess would be as a "safety" measure. By using something so unusual, the possibility of removing or comprising the fitting with some replacement is greatly reduced - brakes/braking force being a significant safety function.

Just a guess,

 

[husky drvr]

Curious where you'd get fittings for it if the fittings are that exotic.

Take 2 on this question.

Scotty,

I was a bit curious about trying to find one of these fittings in the wild, also. I spent more time than I want to admit searching for more information. I didn't find much info, but I did find a curious anomaly in the Parts Manual listings.

The parts illustration for the 1725 Z-S manifold has the PCV valve shown but only an open port for the vacuum fitting. The interesting one is the series 3/IV Solex Twin Choke manifold appears to have a hex headed plug in the vacuum port location, but isn't called out as a part. No fitting is shown, either.

What I finally found was a listing for a "check valve - fitted to induction manifold" ( Section Q - Brake Parts and Controls) which would explain the use of the "exotic" thread form. A definite safety item. The issue here is the fitting is straight through with no sign of a valve (the example I checked was from a sV).

I know the part number starting with "P." is an old style number. I think it's probably for the C-D booster used in the HLM cars which was superseded by the later "adapter" for the Girling servo. IIRC, the Girling servos have an internal check valve so none was needed on the manifold.

Comments are welcome as I don't claim to be correct on this subject.

Just some more information - and speculation,