Twin carbies????

[Eeek]

Hey there guys and gals, just a question for the ones in the know. I have lined up some twin strombergs for my ek and am wondering if its worth putting them on a stocky engine? Does it give the old grey much more go.. Are they hard to tune and keep tuned. hope my pictures arent too much further away. Cheers

[newman]

If you are going to put them on go the extra and put extractors on as well, they will make a difference. Like anything once you start to modify one thing leads to another, twin carbs,extractors, cam & steel timing gears,headwork,modified ignition (electronic) etc. if you can stop at just twin carbs then you've got more willpower than me

P.S. As far as tuning goes,set them up with a synchroniser and they'll be fine.

[fb cruisin]

I agree with newman fit extractors and a good sports exhaust.
Even just this will make a vast improvement on power to your grey motor.
they are not hard to tune, just make sure you have them adjusted in sync to each other and adjust mixture screw.
I tuned mine a very primitive way with a length of garden hose, a funnel and a keen ear for that sweet sound.
Cheers Rob

[newman]

Hey Rob,

Before I bit the bullet and brought a Synchroniser I tuned mine by the funnel/hose method but the problem I have is I have industrial deafness from working in hydro power stations, so after "tuning" the twins with the funnel/hose and thinking they sound good I changed ears and they sounded out I borrowed a synchroniser off a mate and after using one I had to buy one

[Stygian]

Eeek,

With twins on a stock grey you might want to jet them down a bit. The stock main jets are #51. For twins on a stock engine you might want to go down to #48 jets.

Andrew

[newman]

Jetting is always an interesting question,so many opinions . When I set mine up I ended up using 44's and they run great in conjuction with the cam,headwork and extractors, at least the strombergs are a lot more user friendly than setting up triple su's. Recently went to the Little bit Country Rodrun in Griffith its about a three hour drive each way for us and the car ran really well and returned better than expected fuel economy

[michael1964]

I was going to put twin strommies on my Ek ute until I spoke to an old holden restorator & he put me onto zenith 30iz carbies off of the four cylinder torana LC LH LJ modle with the 1200cc engine or 1156cc they fit strait onto a twin grey menifolds with no jetting required at all & they have got more talk down low were you want it then the strommies and I get 28mile to the gallon & with the strommies you will get 18 to 20 if ya lucky.There is also an added bonus with these carbies,they fit under the bonnet of an EJ & the strommies wont unless you cut holes in bonnet.Handy to know if ya got an EJ.One thing with these little zeniths is they come in two sizes that look identical on the out side but if you look down the throat of the carbie you will see a 22mm or 24mm stamped on the venturie wall,hard to see but clean it up with steel wool & you will see it.Just make sure you put two 22s or two 24s.My addvise is to atleast add extractors.Good luck Mick1964 email michaelkulmer1@ gmail.com if you need more info

[Mick]

this all sounded good till you come up with this little gem, twin strommies won't fit under the bonnet on an EJ got no idea what you must have been trying to do

[OldMan's Lacky]

Eeek,

With twins on a stock grey you might want to jet them down a bit. The stock main jets are #51. For twins on a stock engine you might want to go down to #48 jets.

Andrew

Hey Andrew - I know this was from some time ago but can I ask why you suggested this? I don't know too much about carburetors and I have quite a few of them (included a couple of manifolds to suit twin strombergs). I am toying with the idea of putting twins on Pa's Ute or at least keeping the hardware in case I want to do it later.

Have also had a look around on the web for a synchroniser, that is also mentioned in the thread, but can't find any. Anyone know where I can purchase one from?

Cheers.

Danny

[ash]

I have just fitted twin Strombergs to my 132. (in an EJ)
I will say;

- Fitting them should be easy in theory but there are a number of traps which can make it a royal pain in the arse.

1) If you don't have reconditioned carbs then they could have any number of problems, magnified x 2.
2) If you do get them reconditioned the person doing it could be a f*$kwit and do a lame job, magnified x 2. (Cough..xtreme...systems...cough)
3) Your aircleaners may NOT fit under your bonnet. Mine did not, had to buy these - http://www.uniflow.com.au/contents/en-us/d141.html (round ones)
4) It may be difficult to make the stock linkage work, especially if your manifold does not have linkage mounts. Mine did not, had to go with a cable throttle. (new throttle pedal, cable, cable mounts and brackets etc etc)
5) "W" clips suck. I don't know if there is an alternate way of linking the carbs, but I will be taking it as soon as I can..!

- They do give a good power boost. I am happy with mine but they are still not tuned properly. (stumble when accelerating)

- They sound great.

- Fuel economy does not seem to have changed.

- My motor is stock aside from fitting extractors as well, I found the ideal jets to be #46.

- Recommend reading Harv's Stromberg guide and following the bit about venturi restrictors and power bypass jets.

- Here is a balancer - http://www.ebay.com.au/itm/Uni-Syn-Carb ... 856wt_1139
I bought one yesterday, so cant vouch for it yet.

[Devilrod]

Ash I use one of those Uni syns for my twin carb setup on my roadster Not hard to use and work well.

Danny as for why the re-jet. It avoids having the car run too rich. think what in esence you are doing, doubling the fuel intake and on a stock motor it can be too rich at idle and down low and do nothing but foul plugs and run like a pig.

[OldMan's Lacky]

Excellent!!! Thanks Ash.

I did read through Dr Harv's guide but could only find this:

"Main metering jets will be a lot smaller than when running a single carburetor. 46, 47 or 48 jets on a standard to mild grey motor is a good starting point for twin or triple Stromberg carburetors (though will need to be tuned as all engines run differently)."

So I am assuming because fuel is now delivered by the two carburetors it maybe too much (run rich) and so to balance that you run a reduced size metering jet?

[OldMan's Lacky]

Ash I use one of those Uni syns for my twin carb setup on my roadster Not hard to use and work well.

Danny as for why the re-jet. It avoids having the car run too rich. think what in esence you are doing, doubling the fuel intake and on a stock motor it can be too rich at idle and down low and do nothing but foul plugs and run like a pig.

Aaah ... got in before me Brett!!! Thanks.

[Harv]

I did read through Dr Harv's guide but could only find this:

That's funny right 'thar ... I'm probably the only doctor you'll meet with a coffee in one hand, beer in the other and bruised fingernails from operating BFH's .

"Dr Harv" would probably have written something like this (you'll have to imagine the David Attenborough voice):

"Installing multiple carburettors on the Holden grey engine increases the propensity for fuel to be added to said engine. Whilst the fuel inlet orifice dimensions are increased (in fact doubled) by the addition of the second carburettor, the flow of fuel is not linearly increased. As the idle system is fed from orifices located downstream of the (largely closed) throttle plate, vacuum signal to the idle system is not significantly affected by the addition of the second carburettor, and accordingly the fuel flow at idle is near doubled. Note however that under idle conditions the air flow through the paired venturis may not be linearly halved. Many installations report significant skew in air loading (and hence idle port vacuum) under idle conditions despite balancing of throttle plate position by either audio or manometer techniques. This may be resultant from inlet manifold harmonics. The main metering and power systems however are fed from orifices located upstream of the throttle plate. Pressure drop across the venturis at the reduced air flows generates significantly lower vacuum (higher pressure) at these orifices, inferring that main metering and power system fuel increase induced by the addition of the second carburettor is significantly less than that of the idle system".

I like Devilrods explanation better .

Cheers,
Harv.

[OldMan's Lacky]

My old man always says 'give credit where credit is due' ... so you will forever be known, to me , as Dr Harv