@L18_B110
Thanks for the info. I think I must spend the money on something else. Maybe do some work to the cylinder head?

1. twin sidedraughts on a standard A12 is pretty much a waste of money.

2. twin SUs will perform fine on mildly modified engines. Webers on mildly modified engines won't do much if anything more than the SUs did, except use more fuel. The simple fact of having accellerator pumps means they have to use more fuel. it will sound faster but, which fools alot of people - just like loud exhausts often fool their owners into thinking their car is faster.

3. decent sized cams with SUs will give a very poor idle compared to webers. And once you get serious with camshafts, you will have to upgrade to webers - eg my old L20 would not even fire up with a 76 cam fitted with the twin SU's. I was told it wouldn't work, but I'm the kind of person who likes to see it first hand. I had the twin dellortoes ready to go on at the same time as the cam, but figured I'd fit the cam first with the SUs to see what happened.

4. My old old old 1200 coupe with twin SU A14 and lots of mods (ported head, about as big a cam as you can run with SUs, hi-comp mitsubishi pistons, ported oval head) ran 16.1 if memory serves. with reasonably sticky 205/60*13 yokohama A509 and 4.1diff - i think they were the A509. it was a long time ago...

5. so on an engine mild enough to run nicely on twin SUs, twin webers are unlikely to be worth the extra money. you'll get bugger all return for the money spent, except sound and looking tough when you pop the bonnet. but if you continue developing the engine you will get to a point with serious cams where you need the twin webers to support the other mods.

my L series 1200 evolved from
- standard L16 with twin 38mm Hitachis
- 72 cam, twin 38mm hitachis
- std L20 with the same 72cam and 38mm hitachis
- std L20 with 76cam and twin 40mm dellortos (108rwbhp)
- hybrid L16/18 with mildly ported SSS head, 76 cam, twin 40 dellortos (116rwbhp)
- hybrid L16/18 with mildly ported SSS head, 76 cam, twin 45 webbers
- wild SWR 1995cc L18 with everything you could think of (146rwbhp)

i think you will find there is a fiar bit of difference between 17.3 and 16.9 when you are driving that 1/4 mile.

and there are few na a12s that will break that 17 sec barrier.

I think if you look a bit further into it, some teams of professional racers spend thousndas to shave off thenths of a second, no different out of a 1.2 30year old engine thats been rebuilt.

well there is bugger al difference there....

Quote:
What work was done to the engine because boofhead ran 16.9 with extensive engine mods and webers.

I had a SU setup on my A12gx mockup engine.

My old coupe used to do 17.3 down the quarter mile. looking at the quarter mile log on the site there is a couple of A12 powered webber setups slower than mine.

The 1 3/4 don't bolt straight on. I turned up some plates but its very easy to do. Price wise I paid $100 for a rebuilt pair and $20 on some needles to tune it. Compare that to the near $1000 price tag some are paying for weber setups. And been completly honest it performs as well as the number of weber setups A-series ive been in but the power delivery is quite a bit smoother.

Dealing with A-series is bang for buck. Go for the cheapest yet almost as good upgrade.

Turbo and blow through Gas research LPG. Oh Yeah. Screw petrol....

for $$$ wise id go su's, but for performance id go webbers if tuned right.

either way i went su's and now twin su lpg.... easier than webbers but parts are getting hard to get in aus now from nissan for hitachis (needles jets etc)

for ultra budget and some performance, i was happy with 32/36 on a15.

all depends on budget and set up.

There is nothing quite like the sound of a pair of webers on full noise. They can be tuned to suit a variety of packages. The most important thing is matching the right choke sizes to the carby of choice. Too big a choke size will make the carby work best at higher rpm while a smaller choke size will make the carby's work best down low. There is a guy in Melbourne who is one of the best carby guys I have ever dealt with and runs a shop called 'The Carby Doctor' and he is located off Lewis Rd in Knox ( east melb) He is always up for giving advice and trying to get people on the right track first time.