hemi carb jet and metering rod sizes/numbers

[dan juhasz]

Still trying to solve an issue. Car is a 66 Hemi coronet. Took the carbs apart and thought this was weird but maybe not. I always would expect primary and secondary jets to be different sizes but the secondary jets are different sizes in the same carb. Is this correct?
I searched the internet for jet and metering rod sizes for the 4139s and 4140s but I can't find any literature so I could compare to what I found.
If all this proves fruitless can anyone suggest a good base line primary and secondary jet size for each carb? Would need cooresponding metering rods too.
dan

 

[Fran Blacker]

If you can't read this I'll enlarge it and repost.

 

[62MAX]

Step-rods :

4139 .071 x .061
4140 .665 x .058

 

[dan juhasz]

If you can't read this I'll enlarge it and repost.View attachment 756749

that's golden thank you so much, any idea why they stagger the secondary jet size so much on the front carb?

 

[moobster]

The jetting was developed in the R&D department for best mixture per cylinder with stock carbs, intake, heads, compression, exhaust and the fuel available in that era. The staggered jetting would result in each cylinders exhaust gas temperature, to be the same. EGT tuning is what we used to tune our racecars before A/F meters.
Any changes you've made from a stock engine will effect your jetting, even our fuels now-a-days require a smaller jet and/or larger metering rods from original as the fuel is so much lighter then it was back in the day.

 

[dan juhasz]

The jetting was developed in the R&D department for best mixture per cylinder with stock carbs, intake, heads, compression, exhaust and the fuel available in that era. The staggered jetting would result in each cylinders exhaust gas temperature, to be the same. EGT tuning is what we used to tune our racecars before A/F meters.
Any changes you've made from a stock engine will effect your jetting, even our fuels now-a-days require a smaller jet and/or larger metering rods from original as the fuel is so much lighter then it was back in the day.

That is interesting, but what about all the folks that don’t have original carbs and just bolt on 2 new edelbrocks

 

[moobster]

That is interesting, but what about all the folks that don’t have original carbs and just bolt on 2 new edelbrocks

Anything will work if they are jetted correctly.
Your engine will run on a single 2 barrel carb, but like eating celery for breakfast you might make it off the starting line and then fall flat on your face.
Your engine will also run on 4 split Dominators, maybe a little soft out of the hole, but the top end charge will be incredible.
Any carb works on any engine, all depends what your looking for.