I think this is the appropriate forum. It's this kind of discussion that gets people thinking about little things that matter very slightly. Like .01 seconds of time.

My combo is a bit radical, but makes in the 300 HP range.If I were you, I would start w/ porting to head.polish it.....balance the whole rotating assembly,pick a compression ratio you can live with.You can run 10:1 on the street just fine....and get a cam that comes in and pulls till you want to shift.If 1000 to 5000 RPM is your range......just match everything you are going to run to that.
Hope I helped.....
Andrew/Kidd

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Wife's: 64 Valiant
My: 70 Road Runner, 67 Barracuda, AND the 62 Valiant drag car!!

I've often wondered about balancing the in-line 6....see below:

"An inline six engine is in perfect primary and secondary mechanical balance, which can be achieved without using a balance shaft. The engine is in primary balance because the front and rear trio of cylinders are mirror images, and the pistons move in pairs. That is, piston #1 balances #6, #2 balances #5, and #3 balances #4, largely eliminating the polar rocking motion that would otherwise result. Secondary imbalance is avoided because an inline six cylinder crankshaft has six crank throws arranged in three planes offset at 120 degrees. The result is that differences in piston speed at any given point in rotation are effectively canceled."


Additionally, my friend, Chuck at Best Machine said he has balanced 60-75 in line 6 engines and never had to do a thing to any of them as they were all in balance.

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11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc

Yes, with stock dimensions, you're correct: the piston never gets closer than .140 inch. But then if you shave .100 off, you're in the ballpark of where it matters (according to the article I linked). Since you asked for explanations, I'll repeat that link here:
Also, you are correct about noting this is more important with closed chamber heads. Doug provides a great summary of available head shapes, which I mentioned, but didn't provide an explicit link... try this.
http://slantsix.org/articles/combustion ... hamber.htm

- Erik

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Lots of early Valiants and Barracudas have crossed my path.
Also a handful of other toys for variety now and then.

Andrew, I would be interested to know what you are running. Maybe that would give me more insight on how to approach my goals. And Shaker223, I understand what you mean about self balancing. However, I think you can still benefit from having all the pistons and rods weighing the same. Not because of vibration at high RPM's but some benefit in hp gains. I guess I just don't like the idea of my #3 cylinder slapping down a heavier piston and rod than my #5

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Kenny P
28 Rat Rod Slant 6

If you take .100" off the top of a stock 225 block the pistons are then usually about .080-.090" down the hole. Even if they were only .040" below the block deck the combustion chamber is still fully round and open with the shallowest part being over .200" deep.

I took .100" off the block and .100" off the head of my road race 225. The piston still never got within .200" of the cylinder head. There is no quench happening here!

I've read the article you cite a number of times. You seem to be missing the fact that no part of the combustion chamber is flush with the cylinder head deck. Unless you get the piston quite close to the combustion chamber you will not have quench.

I am in the process of building a zero deck height 170. With a stock cylinder head, even one cut .100" the pistons are still about .150" from the nearest part of the combustion chamber. Still no quench! My engine will have quench because the combustion chambers have been welded to fill them. The quench distance will be the thickness of the copper head gasket (.043" in this case).

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Joshua

I have a question for you slant geniuses. Along the topic of getting the piston closer to the cylinder head. Is it possible to just swap the 7.005" 198 rods on the 225 crank? The reason I ask, if it is possible, this would allow you to get the piston out of the cylinder wall (-.140 ) into the combustion chamber (+.015) due to the difference in rod lenghth of .305. I'm sure you smart guys are about to tell me what a bad Idea this is. But it sounds cool on paper.

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Kenny P
28 Rat Rod Slant 6

If the pistons were originally .185" down the cylinder then .305" longer connecting rods would stick the pistons out of the bore .120".

With a 3.430" bore, 4.125" stroke, 60cc combustion chamber, .039" head gasket and the piston .120" above deck the compression ratio is almost exactly 14:1.

How far down the piston is the top ring? It cannot be allowed to go above the deck so the top of the top ring would have to be at least .150" from the piston crown.

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Joshua

The reason I asked the question, was to see if the 198 rods would fit. If so, you could use a newer style lightweight turbo piston and adjust compression by choice of piston.

Like I said, I am just in the design stage and my mind gets a little carried away over here in the desert. Maybe the heat.

Sorry about the calculations. For some reason I was thinking about crankshaft math and divided my numbers by 2. Like I said, maybe the heat.

Can't wait to get back to the states and put all your knowledge to work. My thanks to everyone that has commented so far

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Kenny P
28 Rat Rod Slant 6

Yes the 198 rods will fit and you coud use custon pistons to adjust how far down the cylinder the piston is by moving the wrist pin location.

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Part of Tyrde-Browne Racing

Thanks guys, I was very curious because it would allow you to use a lightweight piston and give a nice rod ratio of around 1.7

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Kenny P
28 Rat Rod Slant 6

K-1 has a nice connecting, in the 198 length for the slant. Wiesco also has a nice piston/ring package. Their piston could have the compression distance modified for Whatever CR you would like.
http://www.slantsix.org/forum/viewtopic ... ht=k1+rods

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I don't see anything wrong with starting this topic in this forum. You are discussing engine related issues and this is the engine forum. I don't see that it matters what the ultimate puroose of the engine might be.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

a v-8 eating slant

My slant has the K1 rods, and the Weisco pistons......I am at 12:1 compression ratio.I like my stuff to weigh the same.....and the last crank I knife edged when balanced,had to have some material removed....besides the pistons and rods need to weigh the same.LOL., I run a crank scraper,Hughes double roller timing chain,Mopar Performance 528 cam.Roller rockers from Cox brothers,Pushrods from Smith Brothers.Clifford intake 4bbl,clifford shorty headers......electronic ignition.You know, normal stuff. I just bought a long ram intake, and it came w/ zoomie headers.....zoomies would m=be cool on a bucket.LOL

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Wife's: 64 Valiant
My: 70 Road Runner, 67 Barracuda, AND the 62 Valiant drag car!!