Stromberg Jetting

[Burnsy]

Just a tip for people.  My car had been running shite and fouling plugs.  Had it serviced and it seems the jet in my Stromberg was to big which was strange seeing as though I run a 138 and the carby was a recently rebuilt one off Surferboys old 132.

Anyway, they guy really new his stuff and he fitted an externally adjustable jet and tuned it on a electronic gizmo (technical name)  The jet was about $23 and allowed for infinite adjustment while the engine was running.  It has made an amazing difference, nearly doubled my power up the hill and cut my fuel usage considerably.

Anyway, point is, these jets are available and seemed to make things very easy compared to fiddling around trying different jet sizes, highly recomended.

[craiga]

Mike,

Adjustable main jets have been around for ages. Hate to spoil your party but I find that the 'o' ring leaks over time.  Other people may have had differing experiences, but personally every one I have seen leaks.

Its cheaper to buy a main jet removing tool and a few different jets and do it that way. This method, along with an exhaust gas analyser, is the best to get the air/fuel ratio spot on.

Good to hear its running better though.

Cheers,

Craig.

[Rod]

I don't want to hijack this thread, but what size main jets would be a good recommendation when running twin strommies. I'm currently running 51 thou, but never seam to get it to run lean enough as is evident by the blackened tail pipe. Any suggestions?? (Its on a grey motor which has only had mild (stage 1??) port work.

Cheers Rod

[craiga]

Rod,

Try 46's and work up.

Cheers,

Craig.

[griffo]

Craig


Perhaps you could tell us what size jet for a single strommie on a red 202 ?  Looking for a little better economy for mine as my last trip was 20mpg & it has a 278 diff !  Although it has started to surge at low seed
( 35 mph )
thanx
Griffo.

[Rod]

Craig,

Thanks for reply with regards to the jetting size of 46 and working up. I spoke with an arrogant unhelpful carby repairer with the view of buying the jets from him who thought I was trying to get better fuel economy and his response was to either don't drive it or back off with the pedal. (I don't know how these guys remain in business). I believe the car has more to offer than just fuel economy. He suggested that I would burn the valves out at 46 thou. Correct me if I am wrong, but if a single carby with 51 thou is standard, shouldnt 46-48 thou provide more fuel per cylinder hence not be in danger of burnt valves etc...(with twin carby's). More thoughts please.

Cheers

Rod

[EJ_Dave]

Rod,

I've got a 186 carby and modified manifold on my grey and have done a bit of fiddling to get jetting right (thanks ChrisB for loaning me carby, jets etc). Based on my experience, the bigger the jet, the richer the mixture. 51 is standard for the single BXOV-1 strommy fitted to all greys so I think you could go to the sizes Craig suggested without probs in your twins.

If it's running too lean, you'll probably have a miss cruising at constant throttle opening and a flat spot when you put your foot down part way (may happen after split second when the initial squirt from the accelerator pump is used up). If pulling the choke out slightly fixes it you need bigger jets. If too rich, there'll be surging at low revs/constant throttle and no flat spot when the throttle's floored. If way too rich it will cough and splutter unless throttle's held wide open (under load).

It probably sounds a bit rough, but I'm happy with the end result- runs smoothly, noticeably more power and quite respectable fuel economy (smack on 10l/100km on a recent 400k round trip, and 13.3l/100k around town- in an EJ wagon). Spark plugs look good too.

Griffo,

I think a 58 is standard in a 202 strommy.

Cheers,

Dave

[griffo]

 Dave,    thanx for the input ,

You have discribed my problems exactly.
Surging at low revs/ constant throttle and no flat spot when floored.
So what do I do to fix this ?
Keeping in mind that its all new to me !

Griffo.

[EJ_Dave]

Griffo,

a smaller jet will probably help. 55 was a common one in 186 and 179 so it would be worth trying one of these. You need to make sure everything else is spot on too- timing and spark plugs, vaccuum and centrifugal advance.  Its important that the carby is in good nick too- ie not sucking air in anywhere and that the throttle shaft isn't flapping around too much in the throttle body, although you'd probably have the symptoms of running too lean if this was the case.

Cheers,

Dave