fbekholden.com

Hi - would someone be able to clarify the benefit of me converting my stock grey motor to have a twin or triple manifold - does it result in better fuel consumption and performance ?? Is it easy to access parts, maintain, and service ?? I did a search on the forum here, and no one seems to have provided contemporary advice. I saw the grey motor twin manifolds on ebay and thought maybe people are dissatisfied with the performance.

Kind regards.

They will make you cool.

Hi Richard.

By all means, increasing the amount of air-fuel mixture you put into the motor will improve performance. However this will only happen if you also improve the "volumetric efficiency" of the motor with improvements in valve timing, compression ratio, and widening/polishing the intake and exhaust ports or even forced induction. Many people expect improved performance by just putting a bigger or more carbies on a motor, but only to find marginal at best power increase and significant fuel consumption. This is normally the product of the engine running a bit richer than before. The side effect if this can be fouled plugs and carbon build-up in the combustion chambers. Not to mention a stinky exhaust.
There's a heap of experience here when it comes to how to make a grey motor boogie, so you're in the right place.

Ps I know you others on here will roll your eyes at my use of "volumetric efficiency" and call me a nerd.

Oh yes, sorry WOT, I forgot, they will cool.

Richard,

WOT is right... twins and triples are significantly cooler than the factory single Strommie .

Bolting up a set of "eBay special" twins will give you a little more grunt, though as BlueHaze mentions, will likely come at the cost of more fuel consumption... unless you take the time to set them up right.

To get the most out of twins and triples, you can take many paths. Three of these are:
a) Take your "eBay specials" and overhaul them properly. Build a set of linkages that don't slip and need constant attention (divorced type with hex rod). Tune the carbs by running (significantly) smaller jets, venturi restrictors and potentially smaller power bypass valves. This will give you a bit more grunt, with just as good (if not better) fuel economy than the single Strommie. It takes a bit of faffing around though, which is why most people just bolt up the "eBay specials" and live with the crappy fuel economy. Rod (from the FE/FC forum) recently persevered with jet changes, and got measured fuel economy just as good as when he was running a single Strommie. This step will set you back $300-$600. If you want to tune your carbs, my offer of help still stands:
http://www.fbekholden.com/forum/viewtop ... 25&t=17922
b) Increase volumetric efficiency by adding a set of extractors or headers and larger exhaust. This gets the twins/triples starting to boogie a bit more (and gets bonus cool points for the noise). Add another $300 (second hand extractors and 2" exhaust) - $1000 (set of new headers and exhaust).
c) Increase volumetric efficiency by adding bigger valves/porting/polishing the head. Add another $1000-$1500.

By this stage, you have spent $1600-$3100. This is approaching the point where a red motor conversion (with a gutload more grunt!) makes economic sense... though comes with the dramas of engineering certification. You will still get blown off the lights by most 4-banger late model crap boxes... grey motors are all about going fast slowly .

More info on Strommies here:
http://www.fbekholden.com/forum/viewtop ... 25&t=14756

Cheers,
Harv.

Thank you WOT and Bluehaze - much appreciated! Thank you Harv: THAT'S FANTASTIC!

What awesome replies, and the thorough advice I really needed in a way even I could understand - I'm stoked!!

Kind regards - Richard

Buy a triple manifold. Blank off the two outside carbs and just run the centre one.
Looks cool and no hassles with tuning.

Thanx for your thoughts Bootlegger - interesting concept, lol.

Kind regards - R

bootlegger wrote:Buy a triple manifold. Blank off the two outside carbs and just run the centre one.
Looks cool and no hassles with tuning.

For what it cost me for the triple manifold,filters, linkages, smaller main jets and reconditioning kits for the carbies plus venturi restrictors I made sure mine was going to be functional

As far as the tuning goes, once they are set up they aren't hard to live with (mine are all linked) and with advice from here on the forum and Harv's Stromberg guide it was pretty straight forward.

Mick