2BBL Slant Issues

[MOPARJ]

My 74 Duster with a 225 Slant has a two barrel intake and two barrel Holley off of a 318. It runs smooth. It usually gets 15-17 mpg on the hwy and 11-13 in the city. It has some miles on it and the valve seals may be needing to be replaced, but it runs smooth on all 6. The gearing is 2.76 behind a 904. Does this milage sound reasonable for a setup like this, or should it be a tad better? The valve lash seems alright, as there is no valvetrain noise. The exhaust manifold leaks a bit, as the idiot who had it prior to me did not put much of a gasket on, mostly RTV( ). I am going to fix that this weekend.

The exhaust is 2" from the manifold through a Flowmaster (not good sound on a /6) and the tires are 215/70/14s. The motor does not knock, but sounds a bit loose upon shut down.

 

[mguner]

The milage is a little low (20-22 is common) but with a 318 calibrated carb you may want to make some jetting adjustments or find the correct carter BBD. Your timing specs will be of great importance in this rergard: initial, total mechanical and total with vacuum....

 

[furz4]

I had a 78 aspen with a /6 2bbl super 6 and a 904 with 2.76 gearing and it would get between 19-20 on the highway and about 15 around town. Yours may be a bit low but not terrible if the engine has a lot of miles on it. Make sure the choke is not sticking and if your running an open air cleaner it will do better with the heated one in colder weather.

 

[MOPARJ]

How hard is it to jet a Holley two barrel like what was found on 318s in the mid 70s?

Would the slant 6 version of the carb make that much of a difference between the 318 version?

 

[Tarr]

I think the later /6's with two barrels had progressive linkage. It ran on one barrel and when mashed on the second barrel kicked in produceing more power but the better mileage while on the road was from running on one barrel. The 318 carb would be better for performance around town but will cost you mpg's.