Datto carby options

[sssgtr]

Is the hole with the stripped thread in an easy enough position to tig it up and redrill?

[nastysven]

good to see you have come to your senses :D

what cam?

[stockymcstock]

Carbs are Flat tops. 260z's came with the flats (with the pollution gear).

bummer, need the ones without pollution gear.

just spoke to that guy with the ones on ebay, he's going to call me back - hopefully he'll take 150 for the whole lot and i'll just do that to save fucking around

[stockymcstock]

Is the hole with the stripped thread in an easy enough position to tig it up and redrill?

maybe..... i'm about to go have a look at it, will take some photos. I *think* it goes down into the top of the float area so i might be able to tap it out larger and collect the swarf without even dismantling the whole thing if i'm lucky

[Mighty Mouse]

instead of tapping for next size a helicoil or similar might be a better option.

[stockymcstock]

had a look and play around with it just now - here's what I did:

Here's the float bowl cover removed and the dodgy fixup job of the bolt with some silicone around it. I pulled it out and cleaned it all up. As you can see the bolt merely holds the top section of the carb to the middle section. The hole goes all the way through into the top of the float bowl area and there are no vacuum paths around it luckily. It's quite tight - It's a little M6x1.25 bolt and I considered tapping it out to M8x1.25 but that was pushing my luck with meat around the edge of the bolt hole. Luckily on closer inspection the hole was only tapped 2/3 of the way through, not completely down into the float bowl top. So I tapped it out to M6x1 all the way through into the float bowl, and put a longer M6 bolt in there that I ground the edges off so it could screw in. That sealed up well and it clamped down nicely. I then had a look around for other problems and noticed that all four of the bolts holding the carb to the manifold were finger tight only..... the plot thickens. I put some spring washers under them and did them back up and fired it up. Idling nice and smooth, idle screws all needed adjusting due to better vacuum and whatnot I think. it seems to rev more freely but the flat spot at partial throttle is still there FUCK

So next idea is to play around with the float level slightly (raise it) so the main comes on a bit earlier, that might help although we tried that on sunday and it did nothing to help the problem. I've ordered a kit for the carb which I will put through it if I could be bothered.

Talked to oldmate on ebay this morning who has a pair of roundtop, no emissions SU's and manifold so I might just go and get them, put some kits through them and call it a day. Can't wait to tune the dual carbs, i bet it's nice and easy. Goddam old cars - should have just done the auto RB30 swap that I was considering when I bought the thing.

pics;

[nastysven]

IIRC SU"s typically are not that hard to live with.

If you worried go see the dude I mentioned at westside carburettors near tottenham station.

[Chase Rockwell]

Flat top SU pollution gear is easily removed and holes blanked off and plugged.

[stockymcstock]

Paul yeah i'm gunna just give them to somebody to set them up and make sure the jets and shit are correct and all that jazz. happy to pay a bit so that they run perfectly!

[townie :)]

While on the topic of datto carbs, I picked myself up a few motors for the 1200, one of them is running a weber 34 ADM, this is an a12 for your information, seemed to run ok, I was just going to whack it on the good a12 and see how it goes.

Should I be worried that a 34 adm is too big for the a12?.

[stockymcstock]

Yes you should be worried, and you should sell it to me!

I guess the worst that will happen if the carb is oversized is that you might need smaller jets (could already be in there) and it might bog down at partial throttle (like mine, ironically) if the accel pump is too big etc. shouldn't affect top end/WOT too much I believe.

[townie :)]

well stocky, I plan to have the datto running again by next week for testing with the motor etc, If I have major hassles with getting the thing to run with that carb i'll give you a yell.

[MRMOPARMAN]

if you end up going SUs, make sure the throttle shafts arent flogged out. they are notorious for it and to fix them you could just about inject the cunt.

[Mini]

if you end up going SUs, make sure the throttle shafts arent flogged out. they are notorious for it and to fix them you could just about inject the cunt.

Some of the later carbys were bushed but as a rule you have to bore & bush them with new shafts. Not that expensive at all given a good mill operator and we made our own shafts. Strombergs ala Torana XU1 were another constant depression carby that worked well but the diaphragms fucked up on them fairly regularly. The beauty of the SU's is the huge range of needles to tune with, this used to be a bit of an adventure but with a wide band and four gas it would be pretty easy these days.

[Andrew Bolt]

Except that many of the needles were unavailable even 10 years ago when I had triple SUs on my Corona Mk2.

I'd just look for another carb - go to Centre Rd Wreckers. They have tonnes of this old shit.