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6 pack jetting

Bill Monk

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Yeah I know, another question. Thanks for putting up with me. What size jets are you 6 pack guys using on your 440?
 
I'm running 61's. I think stock is 62. outer carbs are set with all stock settings.
 
just curious, why did you go smaller?

Well, I went smaller because:
1. leaner is faster, not richer
2. these are the jets that the owner at "Six Pack Performance" in Albequerque said I should start with. He had a ton of trophies and pictures of him running six pack cars at the drag strip all over the shop, so he seems pretty knowledgeable.
3. I don't have an oxygen sensor or dyno tune yet.
4. "bigger" is not always "better" (or faster...usually it's slower)
5. All the modifications I'd done over the years to my six packs were bigger this & drilled out that & the engine ran like crap. It is VERY noticeable that the setup I've got now (99% stock) is MUCH faster than all the "bigger" stuff I was using.
 
Well, I went smaller because:
1. leaner is faster, not richer
2. these are the jets that the owner at "Six Pack Performance" in Albequerque said I should start with. He had a ton of trophies and pictures of him running six pack cars at the drag strip all over the shop, so he seems pretty knowledgeable.
3. I don't have an oxygen sensor or dyno tune yet.
4. "bigger" is not always "better" (or faster...usually it's slower)
5. All the modifications I'd done over the years to my six packs were bigger this & drilled out that & the engine ran like crap. It is VERY noticeable that the setup I've got now (99% stock) is MUCH faster than all the "bigger" stuff I was using.
Just curious, as you mentioned, most I have talked to recommend a 64. Thanks for the input!
 
Just curious, as you mentioned, most I have talked to recommend a 64. Thanks for the input!

Well, 64's might be right...only the oxygen sensor knows....or the 1/4 mile time slips
 
Well, I went smaller because:
1. leaner is faster, not richer
2. these are the jets that the owner at "Six Pack Performance" in Albequerque said I should start with. He had a ton of trophies and pictures of him running six pack cars at the drag strip all over the shop, so he seems pretty knowledgeable.
3. I don't have an oxygen sensor or dyno tune yet.
4. "bigger" is not always "better" (or faster...usually it's slower)
5. All the modifications I'd done over the years to my six packs were bigger this & drilled out that & the engine ran like crap. It is VERY noticeable that the setup I've got now (99% stock) is MUCH faster than all the "bigger" stuff I was using.
Sounds like your going to learn from trial n error
 
Sounds like your going to learn from trial n error

True. I can say that the tires break loose in 1st, 2nd & 3rd now where they didn't before and the car doesn't blow black smoke at idle, but yes, trial & error.
 
You have got the rite idea as the leaner condition compensates the bogging effect when the front n rear carbs are kicked in,sounds like you need a little more rear gear
 
What year carbs are you running? The stock center carb jets will be close. 1 or 2 sizes different is all. The real improvement as I have said in other posts, is taking the lead plugs out of the end carb idle mixture screws and adjusting them about 1/4 turn (usually open). makes a great difference in drivability. Trial with secondary vaccum springs is also worth trying.
 
What year carbs are you running? The stock center carb jets will be close. 1 or 2 sizes different is all. The real improvement as I have said in other posts, is taking the lead plugs out of the end carb idle mixture screws and adjusting them about 1/4 turn (usually open). makes a great difference in drivability. Trial with secondary vaccum springs is also worth trying.
I checked the list numbers and the outboards on the car are original 340 carbs. I don't know if that makes a difference as I think they were also 500 cfm but the lead plugs are still there so I guess I'm going to have to suck it up and take those plugs out. So are you recommending 1/4 turn out from bottom or an additional 1/4 beyond where the factory set them? I don't have a promax base plate on the rear so adjusting on the car isn't possible.
 
I know the SB carbs are different in the fuel curve, no idea how much. Take the lead plugs out, gently turn them in all the way, counting the number of turns, then back them out 1/4 turn more than stock. See how well that works. That's what worked on all three sets of my 440 carbs ('69, '70, & '71). You need to take the carbs off, at least the rear to get access to the plugs & mixture screws.
 
I know the SB carbs are different in the fuel curve, no idea how much. Take the lead plugs out, gently turn them in all the way, counting the number of turns, then back them out 1/4 turn more than stock. See how well that works. That's what worked on all three sets of my 440 carbs ('69, '70, & '71). You need to take the carbs off, at least the rear to get access to the plugs & mixture screws.
Yeah I know, I may bite the bullitt and buy the promax base. Too much trouble to do all that and then find out you need more adjustment.
 
Yeah I know, I may bite the bullitt and buy the promax base. Too much trouble to do all that and then find out you need more adjustment.
Probably makes sense, taking them apart was a PITA. Lots of good parts available today that weren't back then.
 
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