62 replies to this topic

[ACDodd]

I meant have seals. Those are not the right seal. You need the seals as provided in the crk162 rebuild kit these form a full seal on the shaft. They must also be fitted the right way around to work correctly. This is likely a lage part of your problem when coupled with used bushes.

AC

[colinu]

Hmmm, those seals were the ones supplied in the SU service kit I used. I do agree that they don't seem to be an ideal fit. I'll try to get a hold of the seals you recommend seperaty as rebuild kits cost a small fortune here in the US.

[colinu]

Hmmm, those seals were the ones supplied in the SU service kit I used. I do agree that they don't seem to be an ideal fit. I'll try to get a hold of the seals you recommend seperaty as rebuild kits cost a small fortune here in the US.

[colinu]

AC - before i go shelling out USD$100 on a CRK162 repair kit (just to use a couple of seals/bushes etc from it) can you confirm if the service kit CRK75 includes the correct seals that you recommend... because that's the kit I used on this carb. I assume the correct/recommended seal are JZX 1994 yes? Also which way around should the seals go (flat end inserted into carb body first - the way I think they should be as per my photo below, or the flanged lip first)?
FYI... the seals I'm using (from CRK75) do not sit snugly around the throttle shaft until they are inserted into the carb body (only then do they squeeze onto the spindle).
Here's a photo of the seals I have on my spindle (in the correct orientation???). Looking on the sucarb web site they look like JZX 1994 to me (see http://sucarb.co.uk/...seal-15694.html )

Attached Files

•  image.jpg   47.46K   17 downloads

Edited by colinu, 24 June 2013 - 06:29 AM.

[ACDodd]

That is the correct seal. And the correct direction.

AC

[colinu]

Thanks for confirming that AC. Carb is stripped down on the bench awaiting delivery of new throttle spindle/bushes. Stay tuned...

[colinu]

Final stage of the carb refurb completed (new throttle spindle, bushes, seals and butterfly disc)... but not much improvement on my problems. I'm finally able to get idle down to a lopey idle of 950>1000rpm but the AFR is still bouncing around more than I'd expect (a good +/-0.5% of bounce... acceptable???). However no amount of messing with the mixture can solve my other headache... blip the throttle to 3000rpm then release it quickly and the engine stalls. In fact the only way I've found to 'eliminate' that is if I remove the damper form the dashpot (i.e. zero damping and the engine won't stall).

 

Note: I'm doing all this with the car sitting static in the garage as I'm reluctant to take it on the road until I can  get this problem resolved... I don't want to risk messing up a freshly build engine.

 

So, any further thoughts before I go in search of another carb???

 

   Cheers,

   Colin.

 

P.S.

AC - you've said I really need to get a CO meter on the car. I borrowed a Gunson but I'm thinking it may be goosed... do a 10 min calibration in fresh air to 2%, stick the probe up the exhaust and the reading doesn't change (no matter how much I alter the carb mixture). 

[colinu]

Another thing maybe worth mentioning... even though I live in sunny California (temperatures between mid 70's to high 90's) the engine won't start without a little bit of choke, and I need to keep it on for a minute or so or it'll stall.

[jaydee]

You'll soon find out that the gunson is useless when you have a proper AFR gauge

[krusher74]

Are you running a manifold tube to with the megajolt?

 

You should not need 18 degs at idle 

[colinu]

Jaydee -- Gunson's vs AFR... yes that's why I invested in a AFR gauge (AEM gauge, with Bosch UEGO sensor fitted in the manifold's collector).

 

Krusher74 -- not quite sure what you means by 'running a manifold tube to with the megajolt' but I guess you mean do I have a vacuum tube between the manifold and the megajolt's MAP sensor. If so then yes (fitted to the inlet manifold - not the take off point on the barb's body which I've plugged). 18deg at idle... that's AC's MAP (and I bow down to his superior knowledge). What would you suggest/expect for advance at idle?

[ACDodd]

I would go for more like 14 degrees. The idle will be lopey with that cam. What are your cylinder leakdown figures?

 

This carb is still not functioning as it should. Are there any airleaks in joints or inlet manifoiled to cylinder head joint. Use wd40 or similar while the engine is running, a rise in idle speed indicates a leak.

 

What idle vacuum reading have you got?

 

AC

Edited by ACDodd, 14 July 2013 - 10:34 PM.

[ACDodd]

Hmmm, starting with choke at those temsp is indicative of lean running at idle. You need to get a working gas analyser to see with the idle mix is. You also have to understand that with a lopey idle the emissions reading will also not be perfectly steady.

 

AC

[colinu]

AC - yes the behaviour points to an air leak somewhere on the inlet but no matter how much I search for one I can't find any (I've used WD40, freeze spray, propane, you name it to spray all around the carb and the inlet manifold... even using tubes to reach that awkward to reach area underneath the manifold where it mates to the head.

 

Lopey idle = non-steady emissions... yes I understand that's going to be the case. So to get around that am I best focusing on emissions with revs at say 1200rpm?

Idle vacuum (as shown on the Megajolt software app) is approx 50kPa.

 

I'll try to get my paws on a working gas analyzer but is that a better method that using an AFR/lambda gauge (other than ruling out that the UEGO sensor is faulty)

 

Leakdown test - I don't have that kit but might be able to knock something up and "improvise" (I assume the theory is to pressurize each cylinder with its valves closed and check that the pressure doesn't drop/leak... or rather that if it does it is very slowly and at an equal rate for all cylinders?). I'd be surprized if there's a leakdown problem as I had the head completely rebuilt (new valves and guides).

 

FYI - even though the symptoms say lean or air leak the AFR is currently idling in the mid-12's (remembering I'm using E10 fuel here) and the plugs are a little on the sooty side... which to my mind is too rich to safely run in this engine, or even take for a short run to the nearest garage for some emission testing/tweeking

 

Although I have an HIF44 back in the UK that I could ship here I'll see if anyone my local clubs has one lying around that I could borrow just to verify if mine is good/bad/indifferent.

 

The more i think about this the more I feel there's something really simple/stupid I'm overlooking 

 

   Cheers,

   Colin.

[Gulfclubby]

If you have access to the original airbox and paper filter assembly, try fitting that and see if the behavior improves. The restrictive nature of that box richens the mix quite a bit compared to a K&N and you don't need to change any other settings which may just make things more confusing.