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Techical Discussions => Tech- - Engine => Topic started by: Jason Goldsack on January 22, 2011, 04:39:42 AM

Title: 361
Post by: Jason Goldsack 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.


Title: 361
Post by: Stitcherbob on January 22, 2011, 07:06:49 AM
First of all....  http://www.moparaction.com/Tech/quest/SOUND_IT_OUT.html (http://www.moparaction.com/Tech/quest/SOUND_IT_OUT.html)

but 361's can be woken up just like any big block Mopar
http://www.moparaction.com/Tech/quest1/NEW_PORT_or_SWAP_HEADS.html (http://www.moparaction.com/Tech/quest1/NEW_PORT_or_SWAP_HEADS.html)




Title: 361
Post by: Guests 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. 
Title: 361
Post by: Jason Goldsack 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...

Title: 361
Post by: Rich 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.....
Title: 361
Post by: Guests 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.
Title: 361
Post by: Jason Goldsack 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








Title: 361
Post by: Leaburn Patey 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....
(http://i51.photobucket.com/albums/f385/68Cbarge/other%20stuff/anewtoytoplaywith033.jpg)
 
Title: 361
Post by: Stitcherbob on January 22, 2011, 01:36:49 PM
How about leaving the cylinder walls alone and stroking the thing with a 440 crank?

Title: 361
Post by: Leaburn Patey 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
Title: 361
Post by: Jason Goldsack 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..

Title: 361
Post by: Leaburn Patey 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
Title: 361
Post by: Rich 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.moparmusclemagazine.com/techarticles/5115_cylinder_heads/index.html)

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


krautmaster2011-01-22 19:45:31
Title: 361
Post by: Jason Goldsack 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


Title: 361
Post by: Guests 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 (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 (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.
Title: 361
Post by: Jason Goldsack on January 23, 2011, 04:13:07 AM
Anyone have any luck with the MP porting templates that are sold... I could use them on the 516's...

Title: 361
Post by: Steve on January 23, 2011, 07:31:10 AM
Jason. . .Read over the thread in engine tech about modifying a small block.
http://www.moparfins.com/forum/forum_posts.asp?TID=3069 (http://www.moparfins.com/forum/forum_posts.asp?TID=3069)
 
POLARACO2011-01-23 12:31:46
Title: 361
Post by: Jason Goldsack on January 23, 2011, 09:21:55 AM
ok

Title: 361
Post by: Guests on January 23, 2011, 11:56:57 AM
http://www.moparmusclemagazine.com/techarticles/engine_challenge/mopp_1005_2009_amsoil_mopar_muscle_engine_challenge_laroy_engines_promax_performance/photo_12.html (http://www.moparmusclemagazine.com/techarticles/engine_challenge/mopp_1005_2009_amsoil_mopar_muscle_engine_challenge_laroy_engines_promax_performance/photo_12.html)
 
Here is a perfect picture to show what a combustion chamber of a closed chamber should look like. This is the LaRoy engine that made 723hp out of a 451 stroker 400, more than 1.6hp per cubic inch, and only 1hp less than the winner with a 500cubic inch stroker, but look at how clean this chamber is and then tell me that lip is a good thing.
 
http://www.moparmusclemagazine.com/techarticles/engine_challenge/mopp_1103_amsoil_mopar_2010_engine_challenge_dyno_contest/photo_16.html (http://www.moparmusclemagazine.com/techarticles/engine_challenge/mopp_1103_amsoil_mopar_2010_engine_challenge_dyno_contest/photo_16.html)
 
Look at the pistons and combustion chambers of these small block heads, you will see grunge and clean spots, including some "washing" on the surfaces, tons of work to fix this problem, but well worth the effort. It is an example of what the flow problem is, and what it takes to fix, and the results are more than worth the time. We are talking these engines could show greater than 50hp/lb-ft increases just by fixing these little problems. And the smog numbers go down, not up, and mileage will go up, not down. How can one argue with that?
Title: 361
Post by: Steve on January 23, 2011, 02:55:10 PM
Ed   You totally lost me with that  The head doesn't look like anything was done to it
Title: 361
Post by: Jason Goldsack on January 23, 2011, 03:29:33 PM
I think I better worry about fixing the leaf springs, put some gear in it and put the HP Manifolds on it first..

Started right up this morning.. no choke....it was -22 C ...


Title: 361
Post by: Guests on January 23, 2011, 04:26:10 PM
Quote from: POLARACO
Ed   You totally lost me with that  The head doesn't look like anything was done to it

The small block heads that are clean are not touched at all. The LaRoy article and the couple chamber pictures you can see the "edging" at the middle of the cylinder, which is a sharp raised lip,  when not removed does some major restriction that has consequences with flow and burn. With the lip removed you can see the metal that was removed because it will remain looking like that for a million miles, and you can see the flame/burn pattern goes over about 95percent of the combustion chamber itself, and it will remain as clean as it is in the picture forever because the burn is better, as in more efficient. (http://www.moparfins.com/forum/attachments/300/piston.jpg)
 
 
Here is the back side, meaning the piston with a raised dome. Notice the clean edge at the top, notice the garbage on the back side and notice the outside edge is clean. This is basically a reverse of the combustion chamber and it is not right. This is one reason I don't like domed pistons, but there is the ability to fix this as well to reduce the garbage carbon build-up, which is fuel that is burning but at a much lower compression ratio and after the piston is down in the bore, which is a total waste of using a dome to increase compression. If the raised dome is rounded so the flame can travel around the top of the dome and keep burning at a higher compression, the piston would be cleaner, much more power would be made, and the efficiency would go up, and it can run on lower octane without a problem (higher octane produces more power, just like engines used to when running higher octane, you used to notice the difference, now you don't) not down, which is why the higher compression engines run better at higher rpm vice lower rpm.  This is an extreme example inside a 3.3 CanAm Mopar engine, one of 50 produced at the inception of the 3.3 (early 80s I believe), so this 300hp engine could actually produce more than 375hp and an increase of torque if it were done correctly.
 
Send pictures of combustion chambers, any chamber, and I will describe what needs to be done to fix the chamber or piston to make it more efficient. Remember, most engines are described at about a 65percent efficiency, which is sad when it takes so little to get them into the 85-95percent efficiency range.
 
dana442011-01-23 21:39:19
Title: 361
Post by: Steve on January 23, 2011, 05:03:10 PM
I think I know where you are talking about. . .   But that was not the case on those 65 heads
Title: 361
Post by: Guests on January 23, 2011, 05:28:27 PM
Are you saying the '65  heads were open chamber heads? There is still a lip on all the closed chamber heads. Ford, Chevy small block, all of them with the exception of the early Hemi heads (the 426 can gain out of piston edging/massaging), the rest of the Hemi heads are all sealing head gasket problems as I recall, and the new Hemi 5.7 etc., has this same chamber problem on them ( the sparkplug pockets in the head throw the flame to the opposite plug and that is wrong, there is still quench edges that need to be rounded or "edged" for some extra gains that are noticeable), all the quad valve heads have problems, and the list goes on. I egdged the head on my 2.4 PT Cruiser and the torque increase is definitely noticeable, equivalent to the amount of power she used to have empty and is now the same with 500lbs in her (very identifiable on hills and at lower rpm power levels) and having to shift on those big hills. I also lost the "jump" at 3000rpm, you know, where the engine has to rev up to to have power, gone, she pulls all the way to redline without huffing hard above 5000rpm and she is all stock down to smog requirements of California. She is cleaner than the bottom average for smog limits, so can't go wrong there, either. 
 
Have you ever had anyone tell you a small block 283 sounded like a big block Mopar? I have. Including being able to pull the front end off the ground of my 39 Nash after it was done with this 283. I can set off car alarms outside when idling by alarmed cars. One of the reasons I stopped driving the Nash to work actually.
Title: 361
Post by: Rich on January 23, 2011, 05:55:46 PM

My whole point about using the 452's over the 915's is who is going to go to all the trouble of porting the 915's and then put in a cam with more than .480" lift in a tiny little 361? That would be a complete waste of time and money. If you're going to go to all that trouble you better have some cubes to go with it!!
I think he's better off with a mild cam, HP manifolds and a good 2.5" exhaust system using the stock 452 heads.
krautmaster2011-01-23 22:57:03
Title: 361
Post by: Guests on January 23, 2011, 06:32:25 PM
I don't like running greater than .480ish on the street with a hydraulic cam either, a little hard on the lifters and drivability on the street, roller cams are different because you can have a shorter duration.  Me, I would run the 915 heads on the 361 all day long over any open chamber heads, what with the short stroke and lower compression with the 452 heads.
 
I have a 361 myself, guess I will just have to build her up myself and see what I can do with a 4.125 inch piston, might go with 440 rods and crank, come up with a 401 stroker right from the start. There are SB Ford and Chevy (and Olds) pistons that can work with a little bit of finesse.
Title: 361
Post by: Jason Goldsack on January 24, 2011, 03:13:06 AM
Right now it has a 383 Magnum cam in it and seems to work not to bad.. but with the weight I'm thinking an RV grind might have been a better choice

Title: 361
Post by: Guests on January 24, 2011, 06:08:55 AM
There isn't that much difference between the two, both are a slight increase in stock duration and slight bump in lift, so changing the cam isn't worth the cost and time.
Title: 361
Post by: Jason Goldsack on January 24, 2011, 08:00:07 AM
Maybe switch to a different rocker ratio?

Title: 361
Post by: Guests on January 24, 2011, 08:06:09 AM
Not worth the cost to increase the lift by another .030 (figuring the lift is around .450ish). That's sever hundred dollars to do it, what you need in stockish form is compression lost from the 452 heads. You went from a 68cc chamber to a 87cc chamber, which dropped your compression by a whole point. Not the direction one wants to go to make power (and torque).
Title: 361
Post by: Jason Goldsack on January 24, 2011, 08:42:31 AM

Time to get the old 516's off the bench.. LOL

Anyone know what the stock compression ratio was for the '65 361? I think it was around 9:1

1965Windsor3612011-01-24 13:42:47
Title: 361
Post by: Guests on January 24, 2011, 09:31:33 AM
That's about right. Remember, high compression is essentially more power. Why do you think superchargers and turbochargers are so great? Why are NASCAR 355 cubic inch engines making over 800hp? It isn't because of all the cool steel braded lines and such, it is because they are starting out with 14-15.5:1 compression to work with.
Title: 361
Post by: Jason Goldsack on January 24, 2011, 10:09:30 AM
So you don't think I need the bigger exhaust valve in the 516 heads since it is only 361 cubes.

Title: 361
Post by: Guests on January 24, 2011, 10:19:46 AM
No, GM used a 1.60 exhaust valve in a 400 without a problem, and I never had a problem with them until you get up to the 440 engine, which did have slight overheating problems with the small exhaust valve, not a 361. You have the advantage of having the larger 2.08 intake already, so there is the advantage you need over a 350/400 small block engine with an extra 11 cubes. Go with the edging and you will be good, you can use several tool to do it, I prefer the carbide burr cutter in a die grinder or drill to do the chamber. I sent Polaraco (Steve) some hand drawing pictures he will post (they were too large for me to insert directly), they will give an idea of what needs to be done in freehand. Even with stock ports these modifications will have a noticeable improvement over stock chambers.
Title: 361
Post by: Jason Goldsack on January 24, 2011, 10:24:09 AM
How much can I mill the heads before I get into problems with intake alignment?

For sure I will port match the intake runner to the intake port on the heads.. that should be easy to do.

I'm also going to use my 1 inch spacer this year as this engine seems to long the long runner length down low. I had it on before but removed it so i could run the stock breather. Now that I have seen Steves set-up I might go that way and be able to run the spacer again.



Title: 361
Post by: Steve on January 24, 2011, 11:07:54 AM
If I recall, .025.  But I would never go over .015
Title: 361
Post by: Guests on January 24, 2011, 12:08:11 PM
915s are fine without shaving, mine had 225K miles on them, thought I would clean them up and they were only .002 off so they cleaned up easily, and they had overheated many times without damage (wrong radiator cap didn't seal the radiator. ooooops).
Title: 361
Post by: Snotty on January 25, 2011, 09:44:10 AM
[/QUOTE]


 
I have a 400 in my back yard.  It was what I traded for the Gremlin, but the guy never picked it up.   In another year the statute of limitations on bhis ownership will run out.  (http://www.moparfins.com/forum/smileys/smiley4.gif)