Hello TheHemi.com,
I found your site during a google search for this topic. I belong to a few other forums and I'm usually amazed at the level of knowledge and experience out there on the internet. I have a question about Hemi AFB jetting. I have a 68 Road Runner with a Hemi rebuilt back to stock (factory solid lifter cam, exhaust manifolds, dual point ignition, etc.). The stock carbs were rebuilt but the existing rods and jets (at that time) were left in place. The car runs pretty good and I’m not blowing black smoke out the exhaust. But stand behind the car at idle after it being fully warmed up and it smells very strong from being too rich. The previous owner mentioned that he thought the carbs were set up per the old Direct Connection Book instructions for Super Stock, however I checked it against those numbers and they do not match. I mapped the area of the jets vs. area of the metering rods of what I have against the factory jetting and found that I’m running 40%-60% richer on the primaries and that the secondaries are either same as stock or in one case 30% leaner. I have noticed in the Mopar forums that many Hemi owners state that the factory jetting, with today’s gasoline blends, tends to make the motor run on the lean side. Most have said that they either fattened the jetting or reduced the metering rod diameters but did not call out actual numbers for both rods and jets. Anyway, these are the jets/rods currently in my carbs.
Front carb – Pri .101, Sec .080 / Rod #341 (.068/.059)
Rear carb – Pri .098, Sec 077 / Rod#544 (.0715/.058)
Factory jetting is this,
Front carb – Pri .089, Sec .080 / Rod#341 (.068/.059)
Rear carb – Pri.089, Sec L.092 R.077 / Rod L #543(.069/.054) Rod R#544 (.0715/.058)
I would like to hear from others who have gone this route before with a stock Hemi. What combo of jets/rods did you end up with? I noticed that the factory jetting for the rear carb went richer on the left side vice the right side. I’m assuming that they were compensating for fuel distribution issues with the stock intake manifold??? I’m guessing that jetting would need to be 10%-20% richer for today’s gasoline blends???
Jim
Hemi AFB jetting
Discussion of the 426 Street / Strip HEMIs.
Moderators: scottm, TrWaters, 392heminut
Return to “(LEGACY) 426 Street / Strip HEMIs”
Jump to
- Announcements
- ↳ TheHemi.com Updates
- ↳ Mopar Events
- ↳ Mopar News
- 1st Gen HEMI (241-392 "Early HEMI")
- ↳ How-Tos, Tips and Tricks
- ↳ Projects and Products
- ↳ (LEGACY) 331-354-392 HEMIs
- ↳ (LEGACY) Early Dodge / DeSoto HEMIs
- 2nd Gen HEMI (426 "Elephant HEMI")
- ↳ How-Tos, Tips and Tricks
- ↳ Projects and Products
- ↳ (LEGACY) 426 Street / Strip HEMIs
- ↳ Registry Entries
- 3rd Gen HEMI (5.7L-6.4L "New HEMI")
- ↳ How-Tos, Tips and Tricks
- ↳ Projects and Products
- ↳ (LEGACY) New 5.7L-6.1L-6.4L HEMIs
- General Discussion
- ↳ General Hemi Discussion
- ↳ HEMIs in our Garages
- ↳ Decode My Hemi
- ↳ Marine / Industrial Hemis
- ↳ Australian 6-cyl Hemis
- ↳ "Nearly Hemi" Polys
- ↳ Prototype Hemi Engines
- ↳ Crate Hemi Engines
- Racing Action
- ↳ Current Hemi Racing
- ↳ Nostalgia Hemi Racing
- ↳ Nostalgia Super Stock
- ↳ Nostalgia Road Racing
- ↳ Nostalgia Factory Experimental
- ↳ Hemi Timeslips
- Trading Floor
- ↳ HEMI Items Forsale
- ↳ HEMI Items Wanted
- ↳ General Mopar Items Forsale
- ↳ General Mopar Items Wanted
- ↳ Group Purchases
- Sponsors
- ↳ Announcements
- ↳ RockAuto.com
- ↳ Hot Heads
- ↳ TR Waters Early Hemi Parts
- ↳ The Auto Review
- Extra Curricular
- ↳ Automotive (Not HEMI)
- ↳ Off-Topic
- ↳ Politics