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Looking for 360 Build Ideas

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2022 at 10:39am
343 pistons in a 360 will be about 10.7 SCR. Too much for 91 octane fuel.
Have to keep the SCR 9.5:1 or lower and DCR 7:1 to 8:1 for pump gas in our engines assuming they are adding ethanol to your fuel.
The DCR can go on the high side if the quench is kept tight. The more you go off the 0.045" QH the more likely you will run into detonation issues.
Not by any means a golden rule. I know someone running a Gremlin with a stock 343, Edelbrock 650 AVS
on 87 fuel, timing set at 4 degrees advance and he has no detonation issues. Stock 343 has 0.060" QH and 10.2:1 SCR. Go figure?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic Silver Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2022 at 10:55am
Originally posted by Trader Trader wrote:

343 pistons in a 360 will be about 10.7 SCR. Too much for 91 octane fuel.
Have to keep the SCR 9.5:1 or lower and DCR 7:1 to 8:1 for pump gas in our engines assuming they are adding ethanol to your fuel.
The DCR can go on the high side if the quench is kept tight. The more you go off the 0.045" QH the more likely you will run into detonation issues.
Not by any means a golden rule. I know someone running a Gremlin with a stock 343, Edelbrock 650 AVS
on 87 fuel, timing set at 4 degrees advance and he has no detonation issues. Stock 343 has 0.060" QH and 10.2:1 SCR. Go figure?
SC/397 has a 360 build with 343 pistons over on the International Full Size Jeep Forum in  which he calculated the compression ratio at 9.99:1 with 63 cc heads.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic Silver Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2022 at 10:58am
Originally posted by ericdowneast ericdowneast wrote:

I like the 702 cam idea but isn't a little too much lift for the bridged rockers without modification?  (Assuming the lower comp heads are bridged rockers)
That is what I have read. Supposedly limited to .510 lift, according to Sig Erson Cams.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jcisworthy Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2022 at 11:02am
Here is a 9.1 CR .030 over 360, 650 Edelbrock carb, air gap out of the box, street ported iron heads, small cam







Specializing in dyno services, engine building, and cylinder head porting

rbjracing.com
Phone Number 518-915-3203
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jcisworthy Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2022 at 11:04am
Bridge rockers on that one 
Specializing in dyno services, engine building, and cylinder head porting

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Post Options Post Options   Thanks (0) Thanks(0)   Quote CamJam Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2022 at 11:14am
Impressive numbers for what would seem to be a mild build.  I'm guessing that the porting makes all the difference?

I'm wondering with a 10.5:1 CR if I'd get by with 91 octane here at 3,400 feet and switch to 93 when I go to lower elevations.  Maybe I'm overthinking the need for higher compression if you got those numbers with 9.1 CR.

Maybe just a similar setup to jcisworthy's but with Edelbrock heads would get me there?


Edited by CamJam - Aug/07/2022 at 11:56am
'73 Javelin 360 (current project)
'72 Baja Bronze Javelin SST
'69 Big Bad Orange AMX (2018 Teague Heritage Award) SOLD

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic Silver Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2022 at 11:22am
Originally posted by jcisworthy jcisworthy wrote:

Bridge rockers on that one 
AMC Factory rockers?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CamJam Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2022 at 11:44am
Originally posted by Sonic Silver Sonic Silver wrote:


SC/397 has a 360 build with 343 pistons over on the International Full Size Jeep Forum in  which he calculated the compression ratio at 9.99:1 with 63 cc heads.

Thanks for that, Alex.  I always enjoy Rick's threads.


Edited by CamJam - Aug/07/2022 at 11:57am
'73 Javelin 360 (current project)
'72 Baja Bronze Javelin SST
'69 Big Bad Orange AMX (2018 Teague Heritage Award) SOLD

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Post Options Post Options   Thanks (0) Thanks(0)   Quote PROSTOCKTOM Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2022 at 12:08pm
If you went with a power adder the increase in torque would allow you to run a tall gear and not have to use an overdrive transmission. Then your power would just be a bolt on. Should you decide later to return it back to stock you have a mellow engine left.

Tom
Molnar Technologies Full Service Dealer - Crankshafts & Connecting Rods

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Aug/07/2022 at 12:20pm
Your likely looking in the wrong place for HP.
1 point of SCR is approximately 3% to 4% HP gain at 100% VE.
HP = 0.257 x CFM x number of cylinders, again approximately, at 100% VE.
You will get more HP with VE then you can gain with SCR.
Our older engines are typically 80% stock, 85%+ modified and up to 110% VE on a fully ported built race engine.
HP is in head flow. Thermal efficiency is in SCR. The best combine these into a working package. 
As Rick did with the Jeep build. I could take the time to calculate that engines head flow if I knew the camshaft used, but can tell you now it's heads were ported to no less then 250 CFM. 
I did say general guidelines for SCR & DCR.
 
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