Decided to rebuild my 304.

bkjolly

I've looked for a 401 or 360 around here for the better part of the winter. The best I can come up with is a running 304 in louisville to throw in there while I rebuild the Jeep's original engine. I'd like some input on which way to go with this. I can get the master rebuild kit with the RV cam and order the intake and carb seperate. But my question is does the Edelbrock cam make that big of a difference? Also What other modifications should I make? I'm not looking for anything spectacular just 200-250 horsepower and around 300 ft-lbs of torque.

dwg86

Just some info about piston selection for a 304. I built a 304 years ago and wanted to raise the compression without paying big $ for custom pistons. I talked with my machinist and we started looking at different pistons. I ended up using 199 amc 6 cylinder pistons ($13.00 each). The bore and comp height was the same. The top of pistons were plenty thick enough to notch for the valves (I think he charged me 100 bucks to notch). The machinist cut one big valve relief for both valves. I used a comp cams 280H cam 490 lift 230 dur @ .050 (a bit big for 4 wheeling). That little 304 would scream! Beat a few mustang 302's in my cj5. Don't know what the final static comp ratio was (i never cc the piston and heads). Heads were late model 58cc. I'm sure the comp ratio was pretty high because the pistons were flat tops but I never had detonation problems. It could be becuase the valve overlap of the cam was pretty big.

dwg86

Also you might want to check www.car-parts.com for engines. Its a junkyard search page.For instance search jeep wagoneer 401 engine. It will give price, location and condition of all 401's in junkyards that are listed in the system.

Goose

Hmmm I tried it and al it would search for was the 360 or 258

dwg86

TRY YEAR 1976. IT SHOULD GIVE YOU A SELECTION OF 401 CODE Z

bkjolly

Thanks for all the info guys. The piston info is great. Any idea what the compression was increased to? As for the performer intake and Clevite cam combo does anyone have any input.

dwg86

info from advance auto parts web site. 304 PISTON P/N 1079p30 - sealed power cast piston, 8.4:1 comp ratio; 3.750 bore .030 over; (2) 5/64 (1) 3/16 ring groves; 1.581 compression distance; recessed head .130 deep x 3.320 diameter 258 PISTON p/n 409p30 - sealed power cast piston 8.0:1 comp ratio; 3.750 bore .030 over; 2) 5/64 (1) 3/16 ring groves; 1.581 compression distance; recessed head .108 deep 3.125 diameter So it looks like you could use a 258 piston in a 304 and bump up the compresson. Same bore size and comperssion distance (distance from center of piston pin to the top of the piston) . The 304 piston is dished more by .022 and the dish diameter is bigger by .195 .I am assumming the 304 piston has 4 valve reliefs and the 258 has none (don't need valve reliefs on an inline 6 cylinder piston). You could use the 304 piston as a template and only cut 2 valve reliefs the same diameter and depth as the 304 piston...not hard for a machine shop to do. What do you think guys?

bkjolly

I think your a genius. I would love to have a great 304 and forget building a bigger engine I'd like to keep the heart of the Jeep original just beef it up and make it pretty. Any idea where to get AMC blue high temp paint?

jeepsr4ever

seymour paints part # en-66

dbesade

bkjolly wrote
I think your a genius. I would love to have a great 304 and forget building a bigger engine I'd like to keep the heart of the Jeep original just beef it up and make it pretty. Any idea where to get AMC blue high temp paint?

:lo1l: totally agree.. unfortunately.. my Cj is a DD.. and my 304 is starting to show some signs of rebuild time.. so I have a 360 on the stand getting ready for a rebuild..

-Dave

bkjolly

Nice part about that 360 is that edelbrock intake of your 304 will bolt right on.

bkjolly

I just got a used performer intake of ebay for 130.00 bucks now all I have to do is drop the engine off at the machine shop and order my rebuild kit. I think I order the carb from here thats the best price I've seen so far. Any idea of what my horsepower expectations should be?

AMX69PHATTY

I have heard mixed comments about quality but
www.egge.com shows AMC 290 Pistons available.
From the part numbers it looks like maybe obsolete TRW's.
They are listed on thier web page under RAMBLER not AMC.
The 290 had the same bore and Comp Ht as the 304
but where Flat Top Pistons in the 4V and a Small Dish in the 2V
and would definitely give pretty good CR in a 304 motor.
Just another possible option for higher CR pistons for a 304.

They also show, the same way under Rambler, 343 pistons
in both 2V small dish and 4V Flat Top style which
fit in a 360 block and also give goood CR.

There's a thread here by PaintedRat whith pics where he used
the 343 flat tops from egge in a 360 build.

All these pistons are Cast.

fifesjeep

bkjolly wrote
I just got a used performer intake of ebay for 130.00 bucks now all I have to do is drop the engine off at the machine shop and order my rebuild kit. I think I order the carb from here thats the best price I've seen so far. Any idea of what my horsepower expectations should be?

When I built my 304 I used an Edelbrock 600 cfm Carb matched to a Performer Intake... Dynomax 1 5/8" Hedders.. 3 angle valve job... Comp Cams 280H Magnum Kit... And that little 304 screamed... She ran hard up to 7800rpms..... Then after a few runs the rear bearing ran dry...
A stock 304.. has minimal hp... if you bore it .030", raise the CR to 9:1.... run the 280H magnum K-Kit (which is a little over kill for a DD or off-roader) with the performer set-up (600 cfm/performer intake) you'll run about Low/mid possibly high 200 hp... if you let the 304 breath... Mechanical efficiency is a must. Also, for extra protection You have to do the extra oiling precautions etc... Build it to last (Over-build it).

fifesjeep

Hey man... My ole' lady sent those Pistons... The shipping /box/tape ran $25.... You should have them Tuesday maybe Wednesday?.... Give or take a day.... Hopefully you'll be able to use them... :razz: :lo1l:

AMX69PHATTY

As oiling issues have been disscussed here extensively the first oil system modification that should be made is an increased capacity oil pan and longer pickup tube as soild here by Bulltear, adds 1-2 quarts to oil capacity. Starvation of the rear most crank and rod bearings is as much a result of pumping the pan dry at high rpm's due to the fact that the stock oil pump is a high capacity unit, pump gears are nearly twice the height of a chebbie, and the fact that so much oil goes up onto the heads which have very limited and restricted oil drain back, as is it speculatively that the internal oil passages are inadequate and the valley bypass line is "needed". Along with the increase capacity pan it is also very helpful to make modifications to the block and heads to improve oil drainback to the pan from the heads and lifter valley by smoothing and chamfering holes, such as those at the front of the valley in the vertical wall that drains into the timing cover. I have seen somewhere where they even drilled some small holes in low spots in the block valley near the lifter bores to aid draining oil out of the valley and back into the pan. It all comes from high rpm's, too much oil up top, insufficient oil drainback passages, and pumping the pan dry. These areas are more effective at improving AMC oiling than the valley bypass line. This is why BullTear also sales "restrictive" cam bearings, Pushrods with reduced size oil holes, and self made increased capacity oil pans. Modifcations to the block for improved oil drain back can easily be done by and idividual and more or less cost nothing, but must be done before the block is cleaned and machined. After low cost cast pistons have been chosen and the compression height is known for sure, when machining the block the deck can be milled to achieve 0.000 deck clearance, improved compression ratio, and a good .045 quench distance. Cylinder heads can also be milled considerably, as much as .060 as the intake valve seat is the limiting factor, to increase CR and when both block deck and heads are milled the intake manifold must also be milled on the both sides by the same amount of the two combined and the horizontal ends by 1.4 times as much, to allow proper alignment of the Intake passages in the manifold and heads. Another option to increase CR and improve quench distance that may be more cost effective, will reduce the amount of deck mill to the block, and will increase displacement and CR, is to offset grind the crank by .010 or .020 which will is likely to need to be ground anyway and offset grinding should have nominal impact on cost. If connecting rods are re-conditioned they we be slightly shorter and this can also be compensated for by offset grinding and/or deck milling. The rotating assembly should be balanced since the pistons, rods, and crank are all now different, and the dampener/balancer and flexplate/flywheel will be needed to do the balancing. It is also highly recommended to have a torque plate used on the block for final honing, but diffucult to find a shop that has Torque Plates for an AMC.

fifesjeep

AMX69PHATTY Damn good info (Short and sweet). :lo1l:
Jolly... Let me know when they (The pistons) arrive... I can't get a hold of my ole' lady (She's on vacation) :razz: to get the tracking number... But, I would definitely have the Machine shop clean them up... :idea:

fifesjeep

BKJOLLY... Are you still alive?.... Or was it a HIt-&-RUN?... :razz: They should arrive today... maybe last night??? Let me know.... 8)