X2 Twins over 350 Holly

[Digger]

G'Day,

I need a bit of advice,
Im currently running a 350 holly cuppled to a blue inlet manifold on a red 179 HP motor and have been offered a x2 twin down draft manifold. Could anyone tell me if there would be any power gain in running the X2 set up over the Holly.
And if I where to run the X2 manifold what carbies would be best suited 149,186 ect.
The motor has the normal mods balanced,head work,big cam,electronic dizy and 186s exhaust  manifold.

any advice please!

Regards,
Steve

[nicko]

the twins look better as they are a little nostalgic ,
but as for performance the holley is up to the job but would be better with proper manifold such as speco or cain and a few others available cheap on the net,
you can go fairly radical with twins also,

[nicko]

i had a pair of 161 carbs on my old HR prem with great results, but ive seen some really terrible linkage set ups that dont allow good tuning, you must set twins up with a lot of care,when done they not only look great but will keep up the fuel to a hot motor

[Jockster]

Digger
I was running a Holly on a Redline manifold on my car and changed it to genuine twin X2 Carbs and Manifold. Apart from looking better (in my opinion) I find the car is much more responsive in low and midrange accelaration and perhaps has a little less in the top end range. Open road fuel consumption did not change and town consumption improved (for normal driving, not leadfooting).
I'm with Nicko, go for the twins
Jock

[Digger]

Thank's guy's,

Nicko,
I have used a speco manifold but the blue motor manifold with some modification to fit the red head gave me better down low response, left the speco for dead.

Jockster,
I think I will give the twins a go, are the X2 carbs the same size as the 161 carbs as Nicko used or should I use another size.
The cam I have is a Wade 373 much like an XU1 grind do you think the twins will keep up to it.

Steve

[Jockster]

Steve
As far as I know the original X2 carbs were 149 units, I am using 161 Carbs on mine with twin sports air cleaners and they work fine with my setup, I am running a TQ 30 camshaft which is a bit milder than XU-1 spec, roughly what would have been called a 3/4 race cam in the old days. My motor has a ported head with XU-1 intakes and heavy duty valve springs, balanced, bored to 192 with hypereutectic pistons, trw anti-pump up lifters, high volume oil pump, alloy timing gear and cast iron XU-1 headers. As a package it works pretty well, it has a top speed of 115 mph (genuine) and is no slouch through the gears (not that it is driven hard all that often.
I think the 161 Carbs would be ok for your engine, but it is critical to  ensure there is no excess wear in the throttle butterfly shafts and to make sure you get a good linkage setup (I use the original X2 but these are getting a bit harder to come by.
Cheers Jock

[Digger]

Jock,

Thanks heaps, my motor is not far off in what you have but the block is a HP 179 up 40th with good old TRW forged pistons and I'm only running 9.0 to 1 comp ratio.

I found the specs on stromberg carbs tonight and the 149 and 161 run the same carb as the X2 with the only difference beeing the X2 has a slightly bigger idle tube size; X2=70 drill and 149, 161=68 drill size, should be easy to change.

[nicko]

just remember the x2 was a mild spec motor and yours is hot so maybe you need the 186 carbs or even the 202, you can experiment though

[Digger]

Jockster, Nicko,

I had good think about the cabie set up and I have changed my mind. Im going for tripples with the 149, 161 carbies, did a bit of shopping around today not much in second hand manifolds but I can get a new redline from a company in SYD for $180.00 or If I get some time I will  make up my own manifold. One carbie feeding two cylinders has got to be better.

"Any one got a tripple stromberg manifold they wont to part with" !

Steve.

[Jockster]

Steve
A set of triple downdrafts is what I was originally looking at for my car, but I missed out on a manifold at a swap meet by about ten minutes and it sold for $50.00. The Redline manifolds are good, but if you buy one make sure it comes with a linkage kit. The best carbs to use in your case would be the standard 149/161 carbs, I think Redline still make an oval air cleaner to suit this set-up as well. I ran a set of these on a hot HD I had some years ago and they were brilliant once I got the set up right.
Good Luck with them
Jock

[Digger]

Jock,

Redline do sell a linkage kit to suit, but i didnt think of a air cleaner not sure on set up to use as yet, I like the look of single cleaners.
Steve.

[Digger]

Just an update on the carbie set up and a big thanks to 4hammers for the tripple manifold.
I went with the advice from Jockster and ran the 149 carbies,It took a lot of mucking around to set up the throtle cable and linkages but in the end it worked out fine.
And how dose it run, it absolutly flies    and money for value its the way to go.

Thanks again guy's

[FEHOLDEN]

GIDDAY DIGGER

JUST OUT OF INTEREST, I HAVE HEARD OF PEOPLE HAVING TO MODIFY THE FIREWALL WHEN FITTING TRIPLES. DID YOU HAVE TO DO THIS? IF NOT WHICH MANIFOLD DID YOU USE? I AM CONSIDERING A GENUINE X2 FOR MY FE BUT I AM SURE IF I COULD SNEAK IN AN EXTRA ONE IT WOULD BE SO MUCH NICER PROVIDED I DIDNT HAVE TO  DO TOO MUCH MODIFYING.


DENIS

[Digger]

Hi Denis,

I am running tripple up-right stromberg carbies and they fit in fine, the back carbie is a bit close to the wiper motor but I will fabricate three small filters soon.
If you run triple side draught carbies you would have to modify the fire wall to fit them in, I lent a hand in fitting webbers to a mates FC and all we did was heat up the firewall an hit it in, sounds a bit crude but it did look good.

Hope it helps,
Steve

[FEHOLDEN]

thanks steve

it does help. i have probably got three single barrel strommies for 186 amongst my collection of parts. i think they are the same as 149 with only the jets different but i may be wrong. what is it like on fuel compared with what you had? do you think the gain in performance was worth it?


denis

[Digger]

G'Day Denis,

Here is a pic of the engine bay with the carbies set up, you can see that the back carby with an air cleaner fitted would be close to hitting the wiper motor (FB,EK elec wiper motor).

I havent done any calc's on the fuel usage as yet but it dosent use any more around town than it was with the Holy 350, but when you start playing the racer boy it dose drink a bit.