Twin Stromberg Advice

[Jolls]

Hi Team,

I am in the process of getting the grey up and running. I have not decided on the twin stromberg or triple SU setup and I will probably not do so until the motor is fitted and I can check for clearances etc. I am keen to get the triples up set up in due course; however, think it would be prodent to start with the twins until I bed everying down as I know that they will be a bolt on solution in regards to engine bay space etc.

I have a set of twin strombergs that I have stripped down and am in the process of putting carby kits through. The previous owner has jetted them down to 47s so I am happy to start with that setup. I have read though Harv's excellent guide on everything Stromberg so I'm pretty well prepared for setting them up; however, the setup I purchased has been "modified" so before unmodifying it I thought I would reach out for some advice.

The modifications: both vacuum advance takeoffs soldered over, centre runner to the head tapped for manifold vacuum, second choke butterfly removed and,as metioned previously, the jets replaced with 47s. I also have the distributor that came with it - the vacuum advance being blocked off - but no idea if the mechanical advance has been altered.

My assumption is that the previous owner had done some cam work and decised that there was not enough vacuum signal to advance the distributor so blocked it off. I could be wrong, but suspect that the manifold vacuum pressure was tapped to support a brake booster as part of the mods. I will be adding a booster so I will tap into that port.

So my questions are:

1. I am in the Southern Tablelandsso it is regularly below zero during winter. Is one choke butterfly enough or should I source another plate and have the chokes operating in unison?
2. I have a mild cam and running a head with 202 valves and heavier springs etc. Am I best running the setup as is (no vacuum advance) or tapping into a single carby and running with a standard advance curve (I have what appear sot be an unmolested dizzy). With either option I have the parts to replace the points with an Accuspark upgrade.

I have the tools and bundy tube etc to make a hard vacuum line so swapping between the options would be pretty easy so I'm not phased. I just thought it best to reach out to those with more experience to save a lot of trial and erro.

Thanks in advance for your advice.

Cheers
Craig

[Errol62]

Hi Jolls,
We had a night in our new Mercedes van at Bega recently, snd I know what you mean, gets cold. I would re-fit the missing choke, if only for evening out the air flow. I would also try snd tsp in to ported vacuum as you suggest. If nothing else it does help somewhat with economy when cruising on light throttle.


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[Jolls]

Hi Jolls,
We had a night in our new Mercedes van at Bega recently, snd I know what you mean, gets cold. I would re-fit the missing choke, if only for evening out the air flow. I would also try snd tsp in to ported vacuum as you suggest. If nothing else it does help somewhat with economy when cruising on light throttle.

Thanks for the advice. Even with the 5 thou oversised throttle shaft both of the bases were sloppy and had clearly been "restored" previously and the bushing had worn. Probably why they were so cheap. Unfortunatley they drilled through the base as opposed to reaming them out with a pilot so there was a shoulder. The upside is that I have a good friend who restores carbies for a living so I dropped over with a few cold and frothies to have a chat about the best way to solve the problem and the woes of out footy teams (his St George and my Tigers).

My original plan was to purchase a 5/16" and 6.5mm pilot reamer and install a 5/15" OD 1/4" ID sintered bronze bush and then ream it out to 6.5mm (1/4" plus 7 thou = 5 though oversize to 2 thou clearance). While a workable solution he advised against it as there would not have been much meat left to work with. His recommendation was to use Delrin, an engineerd plastic, or Teflon (PTFE). He has different options in stock and is going to turn them down and instal them for me so that is a job I don't have to focus on.

Although one of the carby bodies is stamped 23 3001.1 indicating that is was off an automatic EK/EJ the base it was combines with was from a manual so I can pick up throttle vacuum from either and I'll also check the diaphragm in the dizzy. I have built a distributor tested so I can check the mechanical advance of the blocked off one against the standard dizzy to see if the advance curves differ before I run it up.

I pulled a choke plate off the spare carby and installed it. I can always tie it back if I find I don't need it.

I ordered in some Speco pancake filters; the ones with the flange that is held onto the carby with ahose clamp. My plan is to chuck a couple of old hub caps on the lathe and cut them down to suit the filter and secure (JB Weld or Similar) tab with a rivnut instert in the centre under the hub cap dome so I can screw them down. I expect that the red paint, stanless socket head screws and twin lins should add at least 10 ponies to the output! 

[Errol62]

A mate if mine made his throttle bushes from nylon chopping board sections and drill press. These in a set of SUs. I was lucky enough to find a set with no play.


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[fcee]

 Oversize throttle body shafts for Strombergs are readily available ,try carb parts Echuca . cheers  Steve .

[Jolls]

Oversize throttle body shafts for Strombergs are readily available ,try carb parts Echuca . cheers  Steve .

Thanks, I have the O/S throttle shaft but they were still too loose in the body so will get the Delrin bushes installed so I am starting from a good base. Cheers