Working at cylinder heads.

[Nekes]

Today I own a CJ7 with amc 304 V8. Nothing special, except here in Belgium it’s quite rare. Almost all cj’s here are 6 inline. Next month I finally receive my 401 . This engine I will try to rebuild completely and at the same time add some horsepower. In Belgium there are no AMC specialists so I need your help for working on it. Octane ratings in my country for gasoline are 95 and 98, but I will run most off the time on LPG (mix of propane and butane).
I will use the engine for towing, a sprint at traffic lights (I can’t resist ), sometimes pulling some loads, and occasionally some off road.
I already found a interesting article ‘building an amc brute’ of Carcraft, and that performance is infectious. This will be the first amc I rebuild. I will first start with the cylinder heads: porting inlet and exhaust and open the chamber, perhaps some bigger valves than stock.
So I need all info about porting the heads and unshrouding the valves,chevy valves..., pictures and drawings are very welcome!!!

Thanks

[jeepsr4ever]

If you are building a 304 for offroading you shouldnt need to port your heads. What I would do is get a good rebuild kit, a aluminum performer intake and a good carb with a performer camshaft. Going crazy is fun but you really need to understand that everything works together and if you have wildly ported heads and a smaller camshaft you can end up with less low end and your performance up top can suffer. I would pick a RPM range you wanted this engine to work in and build around that. Do you have any ideas where you would like your power to be?

[Nekes]

I will not rebuild the 304 but the 401. The 401 will replace the 304 in my Cj7. The usable torque must be from idle (or as low as possible) till max. rev of 6000rpm. But this will not be a problem I think with the 401.

[ironman_gq]

I would keep it somewhat conservative. maybe a mild port job on the heads and a good cam designed to work in your most often used RPM range and compression ratio. with the LPG you can probably bring the compression ratio up. I believe there are some buildup articles on this site using propane which should be similar to LPG as far as what compression ratio you should be looking for.

[PaintedRat]

I'm in the latter half of a novice 360 build for propane. It was recommended to install hardened valve seats, and I elected to use hardened valves as well. This was the greatest expense on the top end. I'm using AMC sized valves, but Chevy valves might be more available in Europe. You said first AMC build, I'm guessing that you've built other makes?

As mentioned, figure out what RPM range you want, what compression ratio you want for LPG, and what your budget is. If V8 AMCs are rare in Belgium, maybe you can make some money back selling the 304 block and heads to someone with a Jeep.

[jeep_man_401]

I will not rebuild the 304 but the 401. The 401 will replace the 304 in my Cj7. The usable torque must be from idle (or as low as possible) till max. rev of 6000rpm. But this will not be a problem I think with the 401.

You are going to decide a little narrower of a torque band I think.

Go with MC...

I built a motor that has a ton of torque down low all the way to 55000RPM....but believe me it costs a ton of money and is strictly a one purpose motor. I do drive it during the summer around town and on the highway. But at 10MPG not that much. I also would build a much less HP motor to go off roading in...less to worry about.

6000RPM is alot of noise in the woods....

[1980_Cj7]

[quote="jeep_man_401"]

I built a motor that has a ton of torque down low all the way to 55000RPM....but believe me it costs a ton of money and is strictly a one purpose motor. I do drive it during the summer around town and on the highway. But at 10MPG not that much. I also would build a much less HP motor to go off roading in...less to worry about.

6000RPM is alot of noise in the woods....

But not nearly as much noise as 55,000RPM!

[Goose]

55000 hmmm a simple GE Turbine swap should do the trick..(Sorry couldnt resist )
I would recommend staying on the mild side of the port work on those heads.. say port match to intake and maybe exhaust manifolds and clean them up..(the logic being, I bet if you find you have gone to far.. replacing them could be a problem).and the Stock AMC heads flow so well that the gains would be minimal on a streetable engine.

[jeep_man_401]

Oops....I stand corrected...lol I admit it now, I limit the RPM to 5800RPM not the 55000RPM as before.

I must have been thinking of my other truck...

[Nekes]

I will also drive it only in summer time and 99% on the road so this 1% in the woods isn’t a problem . I get assistance of an engine builder (most of the time he does performance tuning of motorcycles but he did already Corvet, Porsche and some other cars…) so difficult things isn't a problem.
Jeep_man_401 what is your recipe to obtain such nice torque band? Please tell me.