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Twin carbs - are they worth it?

Posted: Mon Jan 18, 2016 12:18 pm
by FJWALLY
Managed to pick up a Speco Twin carb manifold and a Speco rocker cover at good price and getting the 138 rebuilt in the next few weeks(developed a bit of a knock)
I was keen on putting the twin carb on with a couple strombergs but just about every carby shop I talk to says "DON'T DO IT" as you'll have never-ending issues with tuning and getting them to work together as the linkages are pretty crap.

Whats the consensus? - Am I better just sticking with the single Stromberg and adding a nicer filter plus the Speco cover to tiz it up a little and a set of Extractors to help it breath?

It's going to be as much a daily drive as possible so I don't want to have to be mucking about tuning it every weekend.

Re: Twin carbs - are they worth it?

Posted: Mon Jan 18, 2016 12:44 pm
by Harv
The carb shops are not right. A well tuned Stromberg rarely needs touching again. Plenty of guys on the forum running them. Good info for tuning twins here:
http://www.fbekholden.com/forum/viewtop ... 25&t=14756

The main issue is that some linkage kits use either "W" clips or round rod for the main shaft. The clips (or shaft arms) are only held together by friction. Over time, they slip... leading to one carb being out of kilter with the other, and poor performance. Many people see this as "the carbs are out of tune", and start fiddling. The way to prevent this is to either:
a) tighten them well, use spring washers and keep checking them,
b) tack weld them on,
c) use hex-bar for the main shaft.

Twin carbs will give you a noticeably better drive. Still not like a modern rice-rocket, but better. A good set of headers adds a bit more. Think about getting the head done (ported, bigger valves, relieved, shaved... depending on your budget) whilst you have it all apart - budget $600-$1600 though depending on how much headwork you want done.

Cheers,
Harv

Re: Twin carbs - are they worth it?

Posted: Mon Jan 18, 2016 1:38 pm
by FJWALLY
Thanks Harv - makes sense re the linkages - the one on my Speco is round bar with brass linkages screwed on.
I'm getting Top Torque in Nunawading to do the build so will have a chat to them once they have the motor in bits and we can see what she can handle.
I don't have carbs as yet so if anyone has a pair of matched carbs and looking to sell pls let me know.

Ive seen a few on eBay for about 240 refurbed but not sure their quality.
They don't need to be show quality - just look neat and most importantly WORK.

Re: Twin carbs - are they worth it?

Posted: Mon Jan 18, 2016 3:31 pm
by FJWALLY
Done and Done - found a pair of matched carbs from Extreme fuel systems - ordered extractors - just need grab a couple Intake filters when Custom bits are back next week - Jeepers it's easy to spend money. :yeahhh: