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66rebel View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 66rebel Quote  Post ReplyReply Direct Link To This Post Topic: 304
    Posted: Jul/20/2014 at 2:31am
Ok, i have got a 304 and bw trans out of a 70 rebel, motor is going to have a complete overhaul.
Before we all jump in and say get a 360 consider the fact i am in the uk and parts are not readily available for amc cars at all.
So i am stuck with the 304! Its going in my 66 so it will be a major improvement on the stock 232.
SO A FEW QUESTIONS.
1. CAN I RUN 290 PISTONS? If so what will it bump compression up to?
2. WHAT WOULD BE A GOOD CAM CHOICE? I would like to take it to the strip and have a little fun rear end is a ford 8,8 with 4 10s.
3. if pistons are a no go how much can i take off the heads and block before piston hits valve?
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limachine View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote limachine Quote  Post ReplyReply Direct Link To This Post Posted: Jul/20/2014 at 9:47am
Well, you could use the 290 pistons, both have the same bore. But compression ratio will depend on the style of piston. I remember the flat tops were higher (10 to 1). I don't remember seeing domed pistons. I'm not a machinist, so someone's gotta back me up here, but I remember some guys that used to run 304 engines punched out 0.125" with high compression 6 cyl (4.0L) pistons? I also remember someone running Chevy pistons...don't know how available they are across the pond, or how easy that setup is.
Good luck
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crazyamc View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote crazyamc Quote  Post ReplyReply Direct Link To This Post Posted: Jul/20/2014 at 11:42am
I believe the advertised compression ratio difference is in the deck height/chamber volume difference...  It's been a little while, but I remember doing the math and discovering that the longer stroke 304, in the taller block, with the bigger chamber head, makes it and the 290 piston virtually the same....  basically, a " 9 to 1 304 piston"  is a " 10 to 1" 290 piston......  I could be wrong though- it has happened on rare occasions..  :)
Ronnie Kaplan Engineering :)
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Boris Badanov View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Jul/20/2014 at 12:51pm
A 1970 304 is a pretty strong motor as it is.
If your boring it just get flat top single valve relief
piston and a mild cam in the 270 degree advertized duration
range. Depending on head casting number you could net 
about 10:1 to 11:1 compression.
 
Sounds like you are on a tight budget, but there is a lot you can do with a 304.
 
 
Gremlin Dreams
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limachine View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote limachine Quote  Post ReplyReply Direct Link To This Post Posted: Jul/20/2014 at 7:16pm
Hey 66Rebel, (in case you didn't know and if you did I apologize) Summit Racing ships internationally (located in Ohio, USA) they are always very helpful to me and can be contacted online through their site, good prices, they got me through my 390 rebuild.
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wantajav View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wantajav Quote  Post ReplyReply Direct Link To This Post Posted: Jul/20/2014 at 7:36pm
Sir:

My comments as useful or useless as they may be:

basis for my comments: I have a 304, a 290, a 343, and two 360's in various stages of disrepair.

If you are sticking with the 304 :

1.304= Good stout engine
2.See if you can ball-hone and re-ring it, that will be your best option
3.304 stock vs 304 lively = better exhaust (headers), better intake (aluminum from summit and carburetor), mild cam (summit) and improved ignition (summit)
4.If the Borg Warner still works -by the way M35 used in LOTS of Jaguar saloons -go with that
5.Rear gear -can you swap in a set around 3.54 if you have the 2.87 rear otherwise don't bother for a 250 hp street car on stock tires

one single compression point on a mostly stock engine won't get you much the 290 and a 304 had pretty much the same CR one point extra = 10-20 hp then it will knock above 10:1 on iron heads anyway

use the high zinc oil at all times -not today's oil

Mike
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gremlinsteve Quote  Post ReplyReply Direct Link To This Post Posted: Jul/20/2014 at 7:43pm
Or keep the low compression and try to build cyl pressure so it will run decently enough to justify a cam swap.
I used a 261/267 lobe on a 108 las and had four degrees advance ground it.
So she comes in at a 104.

That should work fine with a 8.4 304 on pump gas.
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66rebel View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 66rebel Quote  Post ReplyReply Direct Link To This Post Posted: Jul/21/2014 at 11:13am
I got another plan, i also have a 360, i have been told the 304 and 360 cranks are the same is this true?
The big issue for me on this build is that i had a 360 and a th400 from a jeep i know about the tailshaft problem with the jeep having a transfer box, so i bought a 70 rebel.
it is a 304 well was until i pulled the motor!
But now i am looking at my 360, it appears that the BW trans will mount to it but if i am correct the 360 crank cant be used without modification but if the 304 crank is the same i can swap it into the 360 right?
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Boris Badanov View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Jul/21/2014 at 11:23am
304 crank and rods are a perfect match.
Depending on the year of the 360 you may
want to swap the crank.
 
Use the 304 crank with the 360 harmonic balancer
and flywheel/flex plate.
 
The only thing i am not sure of is the bolt pattern on the flex plate
matching the BW converter.
 
 
Gremlin Dreams
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SC397 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SC397 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/21/2014 at 11:59am
I like to use the Edelbrock Performer type grind for a 304 along with the Holley Street Dominator intake.  This makes a nice low end torque engine.  BTW... I have shipped a 360 to England before so we know that it CAN be done.Thumbs Up
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