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Post by lockie1994 on Apr 6, 2013 21:19:22 GMT 12
progress on the new su carby conversion made up a flange from 12mm alloy plate bored a 1.75" hole in it and then drilled and tapped the 4 8mm holes to put studs in for mounting the carb will get welded up sometime next week ready to try out next weekend have a variouse range of needles to play around with Attachments:
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Post by gordo on Apr 6, 2013 22:00:39 GMT 12
Have you checked the dashpot top will clear the bonnet? I still think you should be looking elsewhere for the problem, though, as a good stock 1256 h/b should be good for at least 150 - 155 and maybe more. Definitely no misfire or droning/booming sounds from the exhaust that could indicate a partial blockage?
When you get it welded, have them add material under the flange as well, so the wall material is thicker for the runners in that area and so you can get a good radius into the runners.
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Post by lockie1994 on Apr 7, 2013 10:07:16 GMT 12
Also thinking of fitting electronic ignition even though my points and condenser are new i am aware electronic is far superior. And for the bonnet clearance no i havent Will check that out today an su is only 1.5" taller than a stomrberg anyhow
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Post by lockie1994 on Apr 7, 2013 10:10:07 GMT 12
And exhaust is 1.75" free flowing only straight through resonstors no baffels
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Post by lockie1994 on Apr 15, 2013 19:58:32 GMT 12
su manifold all welded up and mounted on. have even had it running but have not driven it due to no throttle cable mount or air filter.Even has plenty of bonnet room i am planning to get the metering needle from a 1275 mini engine with a hs6 (1.75'') su mounted as i think it would be a good starting point as they are 56hp with the std 1.5' carb verry similar to the 1256 Attachments:
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Post by lockie1994 on Apr 28, 2013 1:31:28 GMT 12
finaly got it runnin sweet with the 1.75 su runs a heap smoother and goes alot better aswell . . . do not like strombergs anymore haha Attachments:
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Post by lockie1994 on Nov 13, 2013 19:56:00 GMT 12
Long time scince the last update, I have done a few things scince mainly to the engine being tidying up the intake and exhaust ports, had the head and valves ground with 3 angle seats , 0.5mm taken off the head for a we but more compression and the heads exhaust ports machined to to allow me to make up a custom manifold flange and make a set of headers with 4 primary pipes all with close to even lengths. The engine seems to run a bit stronger now should be even better when I tune the su properly
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Post by lockie1994 on May 11, 2014 21:34:16 GMT 12
Been a while since last update . The engine had been rebuild for the second time ( bad work done by engineers must have had dirt in oil galleries ) anyway it's got a fast road cam and heavy valve springs now and a dellorto dhla 40 side draft carby mounted up to it sounds super cool runs pretty good but need to get it properly tuned . Also tidied up a few other things
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Post by lockie1994 on May 11, 2014 21:42:13 GMT 12
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Post by cul8r on May 11, 2014 22:19:56 GMT 12
Looks good man, quite sharp indeed!
Going to lower it at all?
Nice side draught setup!
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Post by lockie1994 on May 14, 2014 20:10:44 GMT 12
Cheers ! It's coming along nicely . It has Gemini LOW coils in it the rear is ok but the front sits up a bit the 15x8s rub even with just 2 ppl in the car so no chance of going lower at rear . The side draft is in early stages I'm having timing issues with the new cam in . After I drive for even as little as 3km at 110kph the exhaust manifold will glow RED hot spark plug colour is rich so no idea whats going on ?!?
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Post by cul8r on May 14, 2014 21:48:49 GMT 12
Generally your timing out of whack and too rich - unburnt fuel in the system... - Have you rolled the guards on the rear or pumped them at all?
Does it rub both sides or just one - may need a adjustable panhard rod to centre the diff back up - due to the panhard being fixed length under the arc of movement it pushes the diff to one side, thus when you lower the car its sitting closer already to one side.
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Post by lockie1994 on May 15, 2014 7:50:23 GMT 12
Yeah guards are pumped out heaps unfortunately it buckled my rear quarters . Haven't made panhard rod adjustable yet but I may need to eventualy . The ignition timing is good but I need to check the degree of the new cam I put in just incase for some reason it is out of cam timing. As for fuel mix it is running slightly rich atm but when I had STD carb on it still made the exhaust manifold glow red and the STD carb was running lean as plug colour was verry light grey
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Post by lockie1994 on Mar 1, 2015 22:18:14 GMT 12
Been a while scince I've been on here now , the chevettes undergone a bit of " tuning " and it's 1 hell of a 1256 !! 84 hp on the dyno with the dellorto, room for more as I'm only running about 8.3-1 comp ratio and finer tuning of carb could push it to about 95 mayb 100 if I'm lucky ? . Pretty Much my daily driver for the summer ,love getting some dirty looks when a 1.3 litre vauxhall keeps up with 2.0litre jappas off the lights ? , what's the go with the rear diffs in these ? I'm about to fit my 2nd replacement as it chews out the spider gear shaft in the housing , I'm thinking a Gemini diff will work ? Cheers !
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Post by cul8r on Mar 11, 2015 22:01:36 GMT 12
Odd you're having diff troubles, Brad's/Tim's estate is running a 2.0 DOHC without issue. There's plenty of keyboard warriors that say they wont last however Tim's is proving them wrong.
However, Gemini Wagon diff will fit your Chevette Sedan. You will need to change the brake lines or joiner t-junction, and Either redrill or change the Torque tube mount. The rest will bolt up correctly.
Piazza diffs will fit but they will need the mounts chopped off, and pulled in 20mm per side to fit properly without binding the bushes up. (The diffs are 20mm wider per side) - You will also need to chop the panhard mount off and swap that over.
Chris.
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