Two Issues - Help (possibly related)

[Rod]

Filled tank up today (only travelled 60 miles) and got 22.2mpg for around town running. More like what I was previously getting. Need to test on a run now. Don't know if I am pushing my luck in trying 44's. Will make my mind up after a couple of highway runs. What was also pleasing today I towed the same trailer again. It was chalk and cheese compared to last week. Did it much more easy. Then loaded up a metre of wood and you would hardly believe I was towing a trailer. This also tested the brakes out nicely also by putting more stress on them. Not once did they lock on hence causing the "clunk" sound. Much happier today.

Rod

[Rod]

Sorry for bringing an old tread to the top but I would like to give an update and after some advice. The clunk isnt present. I did change all brake hoses as well and I am sure this has helped.

However i still havent been 100% happy with the fuel use. I was running 45 mains and was living with the economy. While not up to the results prior to refurbishment I was willing to live with it (21 around town and 25 on the highway). About 5 or 6 weeks ago it starting using a lot of fuel and lacked acceleration. Decided the check floats, accelerator pump specs etc.. again. On doing so I found the accelerator pump link at the bottom of one of the carbys was missing. Put back together and while the acceleration improved the fuel economy didnt a lot. Anyway I bit the bullet and put the 44 mains in. I took it on the highway from Ballarat to Melbourne and was in peak hour traffic for about 2-3 hours where I literally could have walked quicker. It received 26 miles to the gallon. I thought it was pretty good for the circumstances.

The trouble I am having is the fine tuning of these twin carbys. I followed Harvs guide to a tee. What was and is frustrating is I am not sure that the carbys are synched properly. When I use the unisync the back carby is fine and I can get a reading ok without any difference in the running of the motor. The problem lies when I put it on the front carby. If I leave the sync on for too long the motor labors and begins to stall. I also tried using the garden hose method. Interesting to me was that there was a difference in sound eventhough I thought they were synched.Also interestingly I thought the front one was sucking more by the sound. I have synched them the best I can in that time.

I have a gunson colortune. This is where the spark plug is replaced by a clear plug. It allows the observer to read the color of the spark. Based on this at idle and under part load the rear carby is running slightly rich while I would say the front one is spot on. So I am at the point of rebuilding another carby but I am after suggestions on which one I should replace. Should it be the rear one which is rich but can use the unisync well or the front one which is running spot on but causes the motor to stall if the unisync is used too long. I have posted in Harvs Carby Guide thread asking if there is a difference internally to the USA and Australian made strombergs as I have one each (back one is USA). All jets etc... are identical when I rebuilt them.

Interesting to note also is a few months ago I put extractors on and I noticed no difference in performance while everyone is telling me I should have. I would be interested in anyones thoughts on what carby to be placed.

Sorry for being so long winded. Cheers Always

Rod

[Rod]

Another update and one which probably will close this thread.

As I mentioned in another thread I found different castings on the bodies of the carbies 1-1 and 2-1. Since writing that I found the same markings on the air horns (underneath). I set up two carbies making sure all was matched not knowing for 100% certainty that there may be differences between Australian and USA build carbies. I also got another set of venturi restictors, these ones from Frank Whitby and weren't they a pleasure to fit in comparison to the Holley ones I was using. They were an absolute snug fit where I wasn't convinced that was the case with the Holley's. In addition I found that the thickness of the materials in the Holleys was ever so slightly thicker than Frank's. I then trialed with the 44 mains that I was running prior to the modifications and noticed straight away that the motor was running lean and had to use the choke. I think the venturi wasn't as restricted as much with Frank's as the Holly's hence less vacuum to such fuel.

I used this set up for a couple fills with no real improvement in economy. Changed back to 45 mains with a minor improvement. I then played around with the syncing again. I continued to have trouble syncing at idle so I played around at part throttle. Not only did I see an improvement in economy but also power. I am now getting 23-24 mpg around town substantially better than prior to refurbishment. Also I am back to using the choke on cold mornings as would normally be expected. Yet to test it fully on a trip but I would expect 28-30 mpg. While I could just get it to sync at idle the sync wasn't present at part throttle. Once I reversed this thinking the improvements came.

I hope my experience may help others even though different motors breath differently.

Rod

[Harv]

Good news  .

Agree that Frank is a gentleman to deal with, and makes a nice product. He can also make the restrictors for the larger Strommies - good for tuning reds.

Cheers,
Harv