Carb/Cam combo for 304

oldscout401

About to rebuild a 77 304 for a CJ7. thinking about running a comp 262 with 670 holly truck avenger. Just wanted to know if anyone out there was running something like this or similar, and how it worked out. Oh yeah, I"ve got an old edellbrock sp2p I was thinking of useing. What do you guys think?

82Waggy

Are you going to be running stock compression pistons?

oldscout401

Most likley I will run stock compression. This will be a daliy driver. A 670 cfm carb may to much for what I'm after. For foot to the floor, push ya back in the seat fun I've already got a CJ5 with a 401. With the 304 I'm just looking for good response and hopeing to get better gas milage. A lot of guys keep telling me to put in a fuel injected chevy cause they can get up 20 mpg. But I want to keep it AMC so if I can get 15mpg I'll be happy.

tufcj

The 670 will probably be too much carb for a fairly stock 304. The 2BBL flows somewhere around 375-390. I'd go with a 450-500 CFM carb to keep the throttle response crisp. The SP2P manifold was a gas crunch era manifold, not much flow, but small runners to keep velocity up. They work OK on 304s, usually restrict flow on the bigger cube engines. Keep your cam in the 260-270 degree range, lift in the .460-.480, and lobe separation at 110 or above. My basically stock 304 used to get around 15 MPG, better than some of the 6's. Bob tufcj

82Waggy

Well, I'd keep overlap and intake valve closing point short to help build cylinder pressure and torque, and run as much lift as you can to take advantage of the large diameter tappets of the AMC engines to increase power and widen the curve. Check out the Engle 5015-H or 5052-H. These are special grinds for the AMC lifters. 260-270 duration would be a bit long for a stock compression 304 - your bottom end torque below 3500RPM would evaporate. Also consider the 570CFM or smaller Holley Truck Avenger Carburetor with Vacuum secondaries.

tarior

oldscout401 wrote
A lot of guys keep telling me to put in a fuel injected chevy cause they can get up 20 mpg. But I want to keep it AMC so if I can get 15mpg I'll be happy.

I've had two AMC's that got well over 20 mpg;
1) 1969 Rebel, '71 304, very mild RV cam, stock overhaul, 2bbl holley. 26 mpg on the fwy. @65 mph.
2) 1966 Rogue, '73 360, stock overhaul, Comp 268H, R4B, Carter 625 AFB, 5spd.
25 mpg on the freeway @ 75-80 mph.
It's all in the tuning.
Btw, the Rebel had points ignition and a stock coil. The Rogue had a Pertronix and a stock coil.

ironman_gq

i've got a holley 600 and am very happy with the throttle response. gas mileage isnt so great but i've also got 35's and stock gears so its kind of like driving up a big hill all day

zero cool

If I was doing a 304, I would put serious thought into the Edelbrock cam, SP2P intake and a 470 CFM Truck Avenger. Neither the SP2P nor the carb will flow well at higher RPMs but with that combo you should see some good throttle response and low to midrange power, just where you need it.

82Waggy

Zero, I'd go along with the carb an manifold recommendation but that Edelbrock cam is a bit long on duration and overlap with a late intake valve closing point to be of much use in a stock 8.5:1 compression motor - I'd bet torque would fall out of the entire power range. I'd still lean heavily toward the Engle 5015-H since a 304 has rather small valves. This cam takes good advantage of the .904 lifter diameter for better off the seat valve acceleration, will help build cylinder pressure, and has good lift for better flow. All these things conspire to increase and widen the torque range.