Re: 360 to 408, or 340 to 410?
[Re: wkroncke17]
#1794619
04/02/15 12:58 AM
04/02/15 12:58 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Master
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Posts: 52,972
Romeo MI
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The bigger bore helps unshroud the valves but if your using a 2.02 valve it doesnt matter... I use 340 blocks because all my stuff has the small mains... I went with a 416ci for my street/strip
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Re: 360 to 408, or 340 to 410?
[Re: wkroncke17]
#1794620
04/02/15 12:59 AM
04/02/15 12:59 AM
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Joined: Oct 2003
Posts: 7,506 Az
Crizila
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master
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The 340 block is the rarer of the two, so I would keep the 340 and do the 360. - looking at it from a financial standpoint.
Fastest 300
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Re: 360 to 408, or 340 to 410?
[Re: MR_P_BODY]
#1794622
04/02/15 01:19 AM
04/02/15 01:19 AM
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Joined: Oct 2007
Posts: 2,808 Wisconsin
wkroncke17
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Quote:
Quote:
The 340 block is the rarer of the two, so I would keep the 340 and do the 360. - looking at it from a financial standpoint.
Save it for what... if ya got it.. use it EDIT If he wants to sell the 340 block I'll buy it
Haha! Sorry Mike......I will use the 340 if it's the better choice? So don't go telling me the 360 is better just to get me to sell you the 340. I'll be using the stock heads,,,,,,stock '72 heads have 1.88 intake, correct? Might get Eddys at best.
Wally.
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Re: 360 to 408, or 340 to 410?
[Re: wkroncke17]
#1794623
04/02/15 01:26 AM
04/02/15 01:26 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Master
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Quote:
Quote:
Quote:
The 340 block is the rarer of the two, so I would keep the 340 and do the 360. - looking at it from a financial standpoint.
Save it for what... if ya got it.. use it EDIT If he wants to sell the 340 block I'll buy it
Haha! Sorry Mike......I will use the 340 if it's the better choice? So don't go telling me the 360 is better just to get me to sell you the 340. I'll be using the stock heads,,,,,,stock '72 heads have 1.88 intake, correct? Might get Eddys at best.
Wally.
Really.. if your using stock type heads it wont matter.. its gonna be the same stroke so the torque will be very close either way... if you were racing it then yes the 340 is better.. bigger bore and smaller mains
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Re: 360 to 408, or 340 to 410?
[Re: MR_P_BODY]
#1794625
04/02/15 11:07 AM
04/02/15 11:07 AM
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Joined: Oct 2007
Posts: 2,808 Wisconsin
wkroncke17
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Quote:
The bigger bore helps unshroud the valves but if your using a 2.02 valve it doesnt matter... I use 340 blocks because all my stuff has the small mains... I went with a 416ci for my street/strip
Can you explain "Unshroud the Valves?" Also - the 340 has smaller mains - less resistance I assume - is a cast crank not good for this? I plan on 10:1 comp at the most?? Thank you very much guys!!
Wally.
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Re: 360 to 408, or 340 to 410?
[Re: wkroncke17]
#1794626
04/02/15 11:26 AM
04/02/15 11:26 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Quote:
Quote:
The bigger bore helps unshroud the valves but if your using a 2.02 valve it doesnt matter... I use 340 blocks because all my stuff has the small mains... I went with a 416ci for my street/strip
Can you explain "Unshroud the Valves?" Also - the 340 has smaller mains - less resistance I assume - is a cast crank not good for this? I plan on 10:1 comp at the most?? Thank you very much guys!!
Wally.
As the air is coming in it hits the bore on half the valve so the bigger bore helps ... you got the idea of the smaller mains
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Re: 360 to 408, or 340 to 410?
[Re: Crizila]
#1794629
04/02/15 12:59 PM
04/02/15 12:59 PM
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Joined: Jan 2003
Posts: 9,876 Weddington, N.C.
Streetwize
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If you have an uncut 340 and the bores clean-up at .020 you wind up with a standard 4.06" bore which has lots and lots more piston and ring pack choices readily available. Plus you get to save the block for additional incremental bores later...If I can I go 4.06 I will and I'll save for a possible need for 4.07 down the road. Valve shrouding is IMO more of a concern on Big block Mopar Wedges than on small blocks due the SB superior valve angle, on-center valve/bore placement, the limiting factor on SBM's is generally port cross section and pushrod pinch shrouding. all else being equal a 340 stroker will have a bit less frictional losses at the mains due to its' smaller bearing diameter....a 360 will also be a bit heavier due to those thicker crank mains (steel is heavier than cast iron) 360s are a lot more plentiful though As for why mopar went to a 360 instead of just a 4" bore 318 block, I suspect cost cutting with the longer 3.58 stroke allowed for cheaper but still strong cast crank production and external balancing saving millions ofver the mass production multi-year run of the engine. As evidence of that, (to my knowledge) there was never a steel or internally balanced 360 made. The 360 was also intended as a gap bridger for trucks and the big C bodys between the 318 and the (was 383, now 400).
Last edited by Streetwize; 04/02/15 01:13 PM.
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Re: 360 to 408, or 340 to 410?
[Re: Streetwize]
#1794630
04/02/15 01:18 PM
04/02/15 01:18 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
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I Live Here
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Posts: 12,419
Kalispell Mt.
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Selling the 340 could pay for some of the machine work on the 360 block or a little professional help on porting the heads or some other upgrade that will be more beneficial than a .040 bore and smaller mains. I sold all my 340s I had been hoarding and am mostly building 360 magnum blocks.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 360 to 408, or 340 to 410?
[Re: Streetwize]
#1794631
04/02/15 02:24 PM
04/02/15 02:24 PM
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Joined: Oct 2003
Posts: 7,506 Az
Crizila
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Quote:
If you have an uncut 340 and the bores clean-up at .020 you wind up with a standard 4.06" bore which has lots and lots more piston and ring pack choices readily available. Plus you get to save the block for additional incremental bores later...If I can I go 4.06 I will and I'll save for a possible need for 4.07 down the road.
Valve shrouding is IMO more of a concern on Big block Mopar Wedges than on small blocks due the SB superior valve angle, on-center valve/bore placement, the limiting factor on SBM's is generally port cross section and pushrod pinch shrouding.
all else being equal a 340 stroker will have a bit less frictional losses at the mains due to its' smaller bearing diameter....a 360 will also be a bit heavier due to those thicker crank mains (steel is heavier than cast iron)
360s are a lot more plentiful though
As for why mopar went to a 360 instead of just a 4" bore 318 block, I suspect cost cutting with the longer 3.58 stroke allowed for cheaper but still strong cast crank production and external balancing saving millions ofver the mass production multi-year run of the engine. As evidence of that, (to my knowledge) there was never a steel or internally balanced 360 made. The 360 was also intended as a gap bridger for trucks and the big C bodys between the 318 and the (was 383, now 400).
also thought there was a SCCA / NASCAR cubic inch rule change involved there. The 340 was always touted as the "performance engine", mostly because of when it came on board (1970)and of course the performance options available. When the 360 showed up ( 1971 - with a 2-barrel only ) the performance party was on the way out. On the market, that 340 is probably worth 2-3 times what the 360 is worth.
Fastest 300
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Re: 360 to 408, or 340 to 410?
[Re: Crizila]
#1794632
04/02/15 02:34 PM
04/02/15 02:34 PM
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Joined: Mar 2007
Posts: 12,012 Finally a HUSKER again
Moparnut426
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I Live Here
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For your application Im thinking you wont see a difference. But Mikes right, smaller mains, less resistance, bigger bore, unshrouded air charge. I used a 360/408. I hade a block, I used it, I would have done same thing VS a 340 block but I didn't have one Id trust. So.... 408 for me only because its what I had. I have a K1 crank, and Indybrock heads. 602" solid roller, and I LOVE IT!!! Its really fun in a light A body.
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Re: 360 to 408, or 340 to 410?
[Re: Moparnut426]
#1794633
04/02/15 03:31 PM
04/02/15 03:31 PM
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Joined: Feb 2004
Posts: 6,257 acworth / N. georgia - south e...
cheapstreetdustr
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acworth / N. georgia - south e...
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I would look at it this way... start shopping for a crank.. look for the best deal.. and depending if its a large main or small main that would dictate which block you use.. yr back I had a 340 block I sold off to use the money to build a 385 cui class rule engine. and planned on using a early 360 block. as soon as I sold off the 340 block all I could find deals on for cranks was for 340 mains.. some killer deal on a k1 3.79 stroke crank came available but It was a 340 main.. I didn't have the 340 anymore so couldn't take advantage of the killer crank deal. shop for a crank first ....that will dictate which block to use. that's my
365" Iron J heads,,3480lbs best 1.39 60ft on SS springs.10.54,124 mph ...6.67 1/8th et.average 60fts 1.46 w/ small cam &.063 no2 pill tagged & insured [image][/image]
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