Choices on twin carbs

[Santos]

the rebuild for my engine is going slow... the head stuck on and can't get it off... might invest in a rubber mallet as i don't want to hit it to had with a metal hammer (even one wrapped in cloth)

So in the mean time I'm hoarding and modifying parts. ( which till now roughly translates fixing non-engine related things like a driver side mirror )

Since both 121 and festiva's never came out in EFi (later model festiva's did aka Aspires to you) I'm looking at my options on carbi performance for my 'big block' build up.

The twin carb ford lasers and Mazda 323 all turn out to be E5 motors and the rumours that Australia produced a twin-carb B6T could prob be linked to the E5T motor.

So my options have to be a bit more err.. :idea: agricultural.
Idea's i have so far is:

-just using E5T twin carbs
- Twin or quad carbs from a large bike ( 900cc - 1500cc)
- Honda Twin Carbs

Looking closely at a carb intake manifold I'm thinking it should be to hard to modify into a twin Side draft manifold. Bike carbs would probably involve a scratch job.

I know nothing much about the Honda carbs (think they where in a prelude or accord circa 83) but what attracted to me to them was the fact the airbox sat vertical (parallel to engine) rather than on top of the engine like Mazda design. Also looked alot simpler to adapt providing there was enough clearance to the firewall.

So any knowledge about these options would be helpful, I'll have to research the carbs a bit more... be interesting to see what turns up cause a lot of japan only models had Twin Carbs in the early eighties before everyone virtually switched to EFi.

[gdawgs]

You might want to take a look at SU carbs. Most people have never heard of them, but they were used extensively on European cars such as Jaguar, MG, even Bentley and Rolls. Datsun also used them on the 280 Z's before they switched to F.I. They are similar(but different) to motorcycle carbs. Pretty simple to work on, and they work very well when adjusted properly. And that's the good news, they are easy to adjust.

Here's a link that gives some basic info.

http://www.classiccarclub.org/SU%20Carbskb.htm

Some Pictures

http://www.wvbscc.org/baugues/carb.html

Problem here is that they are side drafts, so like you mentioned, room might be an issue, and you'll have to do some fabricating.

I just saw a pair sell on ebay a couple weeks ago for $40. I almost bid on them so I'd have a spare set for our Midget, but decided against it at the last minute.

[FB71]

ah Solex...... toilet bowels in my opinion. I prefer Weber downdrafts, 38 for performance.

[gdawgs]

Yeah I was going to mention Webers and Zeniths as well, but I don't know anything about them so I opted out.

I don't know how common they are either. Can you find them as easily as SUs?

SUs get a bad rap. If you've ever owned them, they aren't nearly as bad as everyone makes them out to be. Once you are familiar with them, they're actually quite good.

The only major problem that I'm aware of is that the throttle shafts and the housing eventually wear out and leak air. Pretty easy to fix though, you just buy oversized shafts and bore out the housing.

I really don't have any gripes with them. Besides it's kind of fun when you pull up at a gas station and fill up your carbs(with oil). People always come over and ask what the heck you are doing.

[FB71]

yup, those are two reasons I don't care for the SUs. Weber are very proliferated. They came as OEM on many vehicles through the 1980s, including makes like Toyota, Honda, and BMW. Their performance carbs are rock solid reliable, require almost no maintainence, and relatively inexpensive. For street driving, I'd go with a 32/36 progressive carb, or a 38/38 parallel link for performance.

[Santos]

i think the Mazda/Ford twin carb are zeniths and SU are quite common here in Aus on a range of vehicles.

The problem with Weber's and Dellorto's is that the whole old school community chase after them (on account of not much is available new anymore) so price wise I'd be paying a lot more than a SLIGHTLY inferior carb :?

If i see one on eBay i will prob hands down opt for a 34mm quad carb of a motorbike\... perharps a keihin or if I'm lucky a Mikuni (Solex i believe in cars).

I also like the idea of the torque and throttle response, sure at full throttle one big carb will flow a lot of fuel into a single cylinder helping at top end, but i doubt the volume metric efficiency would be exceeded from these carbs anyway as they are designed for bikes in the 900-1100cc range.. that red line at 10,000+ rpm's :shock:


Still a week or two i will go back to the yard and sus out the dimensions of both carb designs and see if they fit between the cylinder head and firewall

[Rumnhammer]

carbs

The quad bike carbs get my vote, probably the easiest if you are fabricating, nice throttle response too.
most likely the cheapest to get too.
Chris Rummel