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Author Topic: 361  (Read 2491 times)

Jason Goldsack

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« on: January 22, 2011, 04:39:42 AM »

Can a 361 be bored out to a standard 383 bore? I wasn't sure how thick the cylinder wall is on a 361.

I was looking at some KB Pistons for down the road when I do a complete rebuild.

I know you will say that I should just get a 383, but I need a block with a boss at the front of the block tapped for the '65 motor mount and I'm not pissing around with tapping another block.


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Jason

(Eileen)1965 Chrysler Windsor, 361/727/2.76 16.49 @ 86 mph

Stitcherbob

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« Reply #1 on: January 22, 2011, 07:06:49 AM »

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« Reply #2 on: January 22, 2011, 08:07:37 AM »

There is one other solution that may or may not work with the 361, other than sonic measuring the cylinder walls to check for thickness, and that is to look at a Chevy 400 bore piston (4.125 bore), but the rod length would have to be checked to make sure they are long enough. or a custom grinding to match rod length and journal size needed. I wouldn't go with the recommendation of the newer heads and dropping of the compression, closed chamber heads are better, just remove the sharp edge at the middle of the chamber, allow flow to cover more piston area for a cheap 50hp right off the bat when done correctly. 
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Jason Goldsack

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« Reply #3 on: January 22, 2011, 08:39:31 AM »

I have the 452 heads on it right now.. the original 516's are on the bench and might get the bigger exhaust valve put it in it...

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Jason

(Eileen)1965 Chrysler Windsor, 361/727/2.76 16.49 @ 86 mph

Rich

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« Reply #4 on: January 22, 2011, 10:09:48 AM »

Don't attempt boring that out to 383 size: even if you could, the rings would never seal properly and it would run HOT all the time. Also, you are far better off with the 452 heads - just adding bigger valves to the 516's won't help fix their horribly restrictive ports-you'd have to spend a bazzillion hours grinding on those things to match the flow you get from the stock 452's. If you must have closed chamber heads, then go with Eddy aluminum ones, otherwise stick with the 452's.
 Best thing you can do is follow E-bugger's suggestions and pop in a magnum grind cam and decent intake and exhaust manifolds. Won't cost too much and it will run sweet.....
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« Reply #5 on: January 22, 2011, 11:50:24 AM »

It's a 361, you don't need the larger exhaust valves, it is a small engine and they are larger than a SBC that runs a 1.60 exhaust all the way up to 400cubic inches without a problem. With the exception of the Max Wedge heads, they all breathe stock within 10 percent of each other, Mopar Performance did a comparison on the 12 different castings and found that out, then ported them all within less than 10 percent of each other, combustion chamber, being closed and open chamber, and the hardened seats in the early 70s are the only real difference between any of the big block heads (oh, and the larger exhaust valve after 1967), so the only real gain you had in swapping to the open chamber heads is a drop in compression. I have yet to find a set of non-hardened seat heads burn valve/valve seats if the carb is adjusted correctly, in other words, running lean will hurt any heads, Mopar made better quality valves than the competition.
 
You could bore and re-sleeve the block, but that makes getting a 383 block and making mounts that much cheaper.
 
There are plenty of 4.125 bore pistons out there, deck height calculates to ones needed at 1.230-1.240(max), and the rods can be bushed to make up the pin size difference (they all seem to be smaller), which is still cheaper than boring and sleeving the block for safety.  Boring a block .125 overbore is a lot to bore to get to the 4.250 bore of a 383.
 
Look around and see what you find, I did a search on 4.125 pistons and found there are a lot more than I thought was out there, many even report the deck height.
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Jason Goldsack

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« Reply #6 on: January 22, 2011, 12:41:54 PM »

According to my Keith Black book...

353 Chevy piston ( 400 with 327 crank)
Bore 4.125
Stroke 3.250
Rod Length 6.00
Comp Height 1.38
Pin Diam .9272
Crank CL to deck height 9.025

383 Mopar Piston
Bore 4.250
Stroke 3.38
Rod Length 6.358
Comp Height 1.094
Crank CL to Deck 9.98








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Jason

(Eileen)1965 Chrysler Windsor, 361/727/2.76 16.49 @ 86 mph

Leaburn Patey

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« Reply #7 on: January 22, 2011, 01:33:19 PM »

Trying to hog out a 361 to 383 cubes is like trying to make a pepperoni pizza slice into a chicken wrap....

 
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1968 Newport Custom project BOAB
1973 Satelitte wagon
1983 Dodge 400
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Stitcherbob

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« Reply #8 on: January 22, 2011, 01:36:49 PM »

How about leaving the cylinder walls alone and stroking the thing with a 440 crank?

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Leaburn Patey

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« Reply #9 on: January 22, 2011, 01:44:16 PM »

383/440 cores are still plentiful.
In all honesty,rebuilding a 440 is cheaper than a 383.
My suggestion is save the stock original 361, and have some fun with a 413 or 440.
Machine shop costs will be the same for any size B/RB depending on what needs to be done.
440 parts are cheaper ad more readily available
400's are a dime a dozen and a good motor to build up if you want to keep the low deck big block theme.
 
You can fine tune the 361 to its max,but in this case,there is no replacement for displacement.
Why not cut out the mount of a 66-up C parts car and weld it in to accept 66-up mounts??
CBarge2011-01-22 18:52:38
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1968 Newport Custom project BOAB
1973 Satelitte wagon
1983 Dodge 400
2006 300C HEMI!!

Jason Goldsack

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« Reply #10 on: January 22, 2011, 01:50:47 PM »

But it's a pain to tap the front of the block for the motor mount.. and that's if there is even a boss on the block I find..

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Jason

(Eileen)1965 Chrysler Windsor, 361/727/2.76 16.49 @ 86 mph

Leaburn Patey

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« Reply #11 on: January 22, 2011, 01:54:11 PM »

There are plenty of parts car C-bods with rotted out frame rails but still have the 66-up motor mounts in them.
Cut 'em out and weld them back into your car so you do not have to be limited to the blocks with the bosses.CBarge2011-01-22 19:30:24
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1968 Newport Custom project BOAB
1973 Satelitte wagon
1983 Dodge 400
2006 300C HEMI!!

Rich

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« Reply #12 on: January 22, 2011, 02:21:09 PM »




Quote from: dana44
 Mopar Performance did a comparison on the 12 different castings and found that out, when ported them all within less than 10 percent of each other, combustion chamber, being closed and open chamber, and the hardened seats in the early 70s are the only real difference between any of the big block heads (oh, and the larger exhaust valve after 1967), so the only real gain you had in swapping to the open chamber heads is a drop in compression.


http://www.moparmusclemagazine.com/techarticles/5115_cylinder_heads/index.html

http://www.moparts.org/Tech/Archive/bb/62.html


krautmaster2011-01-22 19:45:31
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Jason Goldsack

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« Reply #13 on: January 22, 2011, 03:11:08 PM »

Man I wish I could have kept the drivetrain out of my 12 second Big Block Aspen . I ran a 400 in it.

Anyone with a 400 or 383 kicking around? LOL


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Jason

(Eileen)1965 Chrysler Windsor, 361/727/2.76 16.49 @ 86 mph

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« Reply #14 on: January 22, 2011, 06:19:42 PM »

Krautmaster, that was the article I was referencing, took three months to print it all, all good information. On the exhaust side you notice the 915 head was a drop in exit until the lift reaches the .550/.600 lift range then it catches up just fine????? That is from the lip I am talking about in the middle of the cylinder. Like I have been saying since 1979, remove that lip completely at the angle of the valves themselves and those numbers rise across the board for both intake and exhaust, including the actual hp/torque numbers from the burn, not just the flow numbers.  I'll give you a really good example of what is going on, notice the numbers for flow are great for the different companies, but the amount of gain on the torque side is very poor, meaning nothing was accomplished with the flow numbers, because no improvement in the burn was done whatsoever.
 
http://www.hotrod.com/techarticles/engine/hrdp_1102_ls3_l92_rectangle_port_cylinder_heads_test/index.html
 
And here is the combustion chamber, which is unchanged, thus great flow and the real increase in numbers over all the others was due to an additional .040 lift through rockers (if you read the article in full).
http://www.mastmotorsports.com/2010/product-view.php?cat=Cylinder Heads - Assembled&id=360
 
Now, I know this is a Chevvy and all, but it goes to show that just because you have high flow numbers, doesn't mean you will have greater performance numbers through porting, especially if the combustion chamber remains the same.  It is a comparison, doesn't matter if it is Mopar, Chevvy or Ford, anyone, if the combustion chamber isn't done properly, job just isn't done to its full potential.
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