304 advice

My 1973 has got the 304 in it, and I was wanting to improve its performance. It doesn't have too many miles on it (<75k), so it doesn't need to pulled and rebuilt, I was just hoping to improve its performance and driveability up until it actually does need a rebuild.

I am just looking for a good running 304, not a high horsepower dune runner, just something that starts and runs well in any situation it may encounter. I plan on using the Jeep to tow along to hunting and camping trips, and the last thing I want is for it to leave me stranded in the middle of nowhere. What are the usual tips and tricks for the stock 304? My thoughts are driveability/reliability first, performance second.

This is what I am thinking so far:

1) Electronic ignition. I am leaning toward the Performance Distributors DUI.

2) Fuel Injection. Leaning toward the Howell setup, although I would love the Edelbrock MPI if it weren't so much $$.

Any recommendations? Thanks for any help!!

 

What I've learned from reading the IFSJA board - The 360 responds well to an Edelbrock performer manifold and a 4V Quadrajet, plus a mild cam (Comp Cams 260H or Summit K8600). The FSJ guys really like QJs - great performance and they are excellent off-road. Less restrictive exhaust will help, although the stock manifolds flow pretty well. The Holley Truck Performer works well too. Some run the DUI, but most use the TFI upgrade to the original Duraspark ignition that's stock after 1978 (?). GM HEI is also available. For reliability, the HEI is probably the best, but it's debatable.

All that should be applicable to the 304 as well. However, the swap to a 360 or 401 from a 304 is so easy, that I'd imagine it's a much more economical way to get performance than a $1000 TBI. You do get some advantages with the TBI like mileage and all-weather performance, and if that's what you want... but it's not the cheapest way to boost performance. On a Wagon, the mileage goes from something like 12 to 15 with the Howell TBI (not stunning, but significant), and drivability is improved.

 

yeah you can still buy fresh 360 long block rebuilds for a liitle more than the TBI and the 360 is a bit more user friendly for performance.. it's just easier to get stuff for and the heads are a bit better.. I say 360 with edelbrock dual plane and the truck avenger and the 268H cam... then try to keep a tranny in it!

BUBBA

 

Stick with the 304. You aren't in the market for a drag vehicle or a mud bogger... if I'm wrong, disregard the rest...

The electronic ignition upgrade is a good start. But, if the existing motor hasn't been abused, just an overall tune up may do wonders - plugs, wires, points, condenser, coil, cap, etc...

To get a bit of a booste in power, maybe consider an electronic fan or headers. Gears, depending on the size of the tire you're running, may also dramatically enhance performance.

 

When I was at the Jeep dealer, the CJs seemed to be strong or not by chance. Otherwise identical 304 CJs would have different seat-of-the-pants feel in power. Mine was average, but still a hot rod compared to the cars I was used to.

I'd think you could make a noticible improvement by getting the jetting, float level, and spark advance right. I don't think you'll see much improvement with an electric fan, since the stock fan has a thermostatic clutch anyway.

The 4.27 gears (vs. 3.73) made a big difference.

Plunk suggests headers, but I'd go with simple dual exhausts exiting at the rear like the stock pipe. Headers are a maintenance headache typically. Plus they are noisy, hot, and breakable.

Re reliability, AMC V8s are notorious for low oil pressure. I'd be sure to get a mechanical oil pressure gauge and assess the hot idle pressure. If it's low, repair or replacement of the timing cover and oil pump gears will make your engine last much longer.

 

Excellent responses!! This is exactly the type of info I am looking for! Keep it coming! Thanks a bunch.

 

Re-gearing, in my experience, has the greatest effect on the ol' seat-o-the pants meter. Of course that depends on what gearing you have now. In terms of the reliability and easy starting - you nailed it with electronic ignition.

 

Definately go with an electronic ignition. You might want to consider getting a complete aftermarket distributor with adjustable mechanical and vacuum advances. An aluminum dual plane intake will probably do you good too. I'd suggest a 500cfm Edelbrock carb (yes, it's plenty big enough). I have one on my 283 and the thing works GREAT. They're very tunable too. An exhaust upgrade to dual pipes with a crossover (H or X pipe) would help low end torque. If you want to get into in a little more, a mild cam would make all of the above suggestions work lots better. If you have the intake off to change it, you're halfway to having the cam out

 

Here's a thread from Pirate with a bunch of links to AMC V8 HEI. I'd go with Zack - he's an IFSJA member.
http://www.pirate4x4.com/forum/archive/index.php/t-186539.html

I bleeve this is Zack's latest: http://www.zmjeeps.com/hei_8.php

One of these and an MSD AMC HEI wire set should do it.

 

you can always do this:
http://community.webshots.com/user/jpflat2a
"paxton on 304"

 

I have a 74 with a 304 and I am very happy with is performance. Here is what I have. I upgraded the ignition to duraspark ignition from a 1982 waggy. I added the tfi upgrade too. This was a great addition. I have a Holley 4160 4bbl carb and edelbrock performer manifold. The holley has a flat spot at about 1500 rpm and when I hit the gas hard but does ok on road. Its awful off road: it floods out lots on hills and does not like to be bounced. I also have an rv cam. I have 3.73s in da punkins. I also have fender well exit headers. The total package keeps me smilin lots. If I was doin it all over I would get shorty headers and run a single 2.25" exhaust inside the frame rails. I too am considering fuel injection, but its kindof pricey. Another option is the holley truck dominator. It might be too much carb though (670cfm).

Karl

 

i,am afraid that all my experences with this farm-boy boat anchor of an engine has left me with a sour taste in my mouth. my '5 has a 304 with a mild cam, in it right now and allthough it runs extreamly well ( for a 304 ) in all kinds of situations, and is for the most part reliable, this is only because of the insesent atention i give it to keep it running like that. i HATE it.

that is why, this spring there will be a 4.3 with tbi in its place, and i will guarenty that i will have more power, rpm, driveabilty, and reliabilty then the 304. the cost to do this is cheaper then anything that i would do to the 304 to get the same results.

al this is of course IMHO

 

I have stock 304 with Accel 4 barrel throttle body f.i., edel intake, dual exhaust, t-18, d20 with 2.46:1, 4.56 gears, 33" tires, and no complaints. My 360 buddies beat me on the street but when we get into low range on the trail, I see no difference.