- Joined
- Jul 1, 2014
- Posts
- 6,160
- Reaction score
- 5,170
- Location
- ------
- First Name
- -------------
- Truck Year
- -------
- Truck Model
- -------
- Engine Size
- -------
The 1405 is "calibrated for performance", which means it is even richer than most Edelbrocks. So your carb tune is all wrong for that engine. And it's showing. I get 10 mpg in town with a K10 with a TH350 and 31" tires on 3.73:1 axles.
Edelbrock 1405 is .100 primary, .095 secondary, 70/47 rods, and 5" step-up springs. What you need for that engine is more like .092 primary, .095 secondary, 65/57 rods, and 8" step-up springs. These are easy changes. Here's the part numbers you need: primaries: jets .092 (#1425), rods .065 x .057 (#1461); secondaries: stock; step-up springs: 8# (comes with #1464). You will also need to replace the airhorn gasket (qty 5 is #1499) when you change the primary jets. Adjust the float bowls while you are in there, as they will be wrong, probably to the high side.
Then, you need to adjust your timing. Odds are you have the vacuum advance in the wrong vacuum port, are running the wrong vacuum advance can, and have the timing way retarded from its optimum setting. This will all cost you in fuel consumption.
Read this on timing: http://www.gmsquarebody.com/forum/showthread.php?t=14508
And put the AR23/VC1853 vacuum advance canister on the distributor.
http://www.napaonline.com/Catalog/C...cuum-Advance-Control/_/R-ECHVC1853_0168354142
Rich
Edelbrock 1405 is .100 primary, .095 secondary, 70/47 rods, and 5" step-up springs. What you need for that engine is more like .092 primary, .095 secondary, 65/57 rods, and 8" step-up springs. These are easy changes. Here's the part numbers you need: primaries: jets .092 (#1425), rods .065 x .057 (#1461); secondaries: stock; step-up springs: 8# (comes with #1464). You will also need to replace the airhorn gasket (qty 5 is #1499) when you change the primary jets. Adjust the float bowls while you are in there, as they will be wrong, probably to the high side.
Then, you need to adjust your timing. Odds are you have the vacuum advance in the wrong vacuum port, are running the wrong vacuum advance can, and have the timing way retarded from its optimum setting. This will all cost you in fuel consumption.
Read this on timing: http://www.gmsquarebody.com/forum/showthread.php?t=14508
And put the AR23/VC1853 vacuum advance canister on the distributor.
http://www.napaonline.com/Catalog/C...cuum-Advance-Control/_/R-ECHVC1853_0168354142
Rich