std 1256 way down on power scince rebuild

[lockie1994]

ver scince the engine rebuild on my 1256 it hasent seemd as peppy as it used to be things that i have done are New engine bearings,Rings,Hone,Re lapped valves into head all new gaskets and oil pump.
Have replaced coil,Points,Condenser,Leads,Dizzy cap and spark plugs
tried 2 different carbs have tried blocking the intake heating ports (think that made it worse as it will not go over 120kph on a cold night)
thinking of running standerd intake mainiold and mounting up a 1.75'' su and tuning it to suit the engine however i have been told they can benifit alot from an electronic ignition setup??
any help on this would be appreciated ...cheers

[burntrubber]

Have you done a compression test I know people who have had the rings not bed properly causing the engine to be sluggish or not as grunty as before.

[flyingbrick]

Did you drive a faster car while ya engine was being done?

[gordo]

Are you sure the cam' timing was right and have you checked the ignition timing?
Depending on the model of engine, some earlier Chevettes had a plastic piece of the throttle sleeve (at the adjuster IIRC) and it may need trimming back as the saddle that clipped onto the carbie lever would bottom out on it. Check you're actually getting the carbie fully open.
With the filter removed, reach into the carbie and lift the piston, it should lift all the way up smoothly, with some resistance, and drop freely. It may also be worth checking the diaphram for pinhole leaks, as they can also cause problems - I assume you had everything lined up when reassembling it, the diaphram has a couple of alignment marks on the moulding that line up with the body and piston assembly.
Oh, also check the air filter is clean and the mechanical advance works with a timing light - did you set the timing be a light or statically, as sometimes people get the latter method wrong?

[lockie1994]

not shure how the rings could not bed in properly i just took it quietly for the first few drives then just drove normaly (slow) until i had done around 2000 kms.
My other car is a 1.6 lwb suzuki vitara with mud tyres ect ect so definatly not more grunt than the chevette haha.
and the carb has been rebuilt with new diaphram ect ect looses its oil within a week tho i have set timing with a light with the vac advance disconected and blocked at idol.
cam timing was set to spec in manual it runs to well to be off as i have heard cars running with tming belts out 1 tooth and they ran like sh#t so would not expect it to be that.
I have a compression tester so no harm in testing it,It has alot of blowby for a fresh engine however i put that down to no stem seals on exhaust valves (maybe)
Just picked up a few 1.75' su carbs so im already in the process of making up a modified manifold to mount it they are alot easyer to work with than the strombergs(personal preference)
so should have it running with that on in the next few weeks see how it goes

[lockie1994]

oh and 1 more point engine was run in with 15w40 pentrite running in oil for 500kms then i changed the oil and filter and filled with 15w40 pentrite good quality mineral oil (was told not to use synthetic oils as it causes engine to glaze up )

[yammies]

Stem seals wont affect how an engine runs - you might get the odd puff of blue smoke but nothi g serious. go back to basics and work systematically, as presumably it ran with the ioriginal setup right?