225 Slant Six Build Ideas

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John Martin said:
I am wanting to build a 1970 slant six to drop into my 1972 Valiant. The car has power steering, and air conditioning. I will be keeping both. I was going to do a camshaft, and shave the head and the block a bit to increase compression maybe to 9:5, performance exhaust, and do a port and polish with gasket match on the head. Outwardly it will look stock, 1bbl, stock manifolds and needs to be a daily driver.
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If you're going to leave it a one barrel, there's no need for performance parts or special machine work.
 
John Martin said:
Nevermind then. Sorry I asked.
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So you're panties get in a wad because you don't hear what you want? Just trying to save you some money and aggravation. Without stepping up to at least a two barrel and bigger exhaust, you're talking about money wasted with a one barrel. A good, stock rebuild would be all you need with that.
 
RustyRatRod said:
So you're panties get in a wad because you don't hear what you want? Just trying to save you some money and aggravation. Without stepping up to at least a two barrel and bigger exhaust, you're talking about money wasted with a one barrel. A good, stock rebuild would be all you need with that.
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That is not exactly correct. Slants are notorious for have stock compression ratio's in the high 7s to low eights. So raising compression is always a good idea. Even with a 1bbl carb increasing compression will increase low end torque. Be sure to measure piston recession and cc the combustion chambers, use an online compression ratio calculator to get to your desired compression. Personally I think a target of 9.5 may get you into the need for mid grade gas, especially if you stay on course with a small cam. I would go with 8.5 as a target. Here is a link to one of the many online compression ratio calculators.
RSR Static Compression Ratio Calculator
IIRC shaving a slant six head .0069 will remove 1 cc from each of the combustion chambers.
A slightly more aggressive cam will also help, if you choose to retain the stock cam, have the fuel pump lob inspected for wear. It can be restored to new by welding. There are many shops that can do that as well as re grind your existing cam to a better profile. May slant six folks trust Oregon Cam Grinding for that. A cam grind for you to consider is what Doug Dutra, a slant six guru developed. Google 'Doug Dutra RV-10 slant six cam'. You will get some info that way. Oregon Cam has their own version of the RV 10. I just google Doug Dutra / RV -10 cam and found this statement, attributed to Doug: "The RV10/295 RDP is designed for a 1bbl engine with compression ratios (8.4 to 9.0) and to have smooth idle with strong off idle and mid-range power."
An upgrade to an HEI ignition to do away with the points should also be considered.
And lastly on this list, be sure to service and clean the oil pressure relief valve in the oil pump. Again, you can google a few words like 'slant six oil pump oil pressure relief valve service and get more info.
The work you described initially would not be lost work, It would provide some increase in engine performance, particularly at low RPM's. The best news is that if you do decide that you want more performance, the internal work is done and you will only be swapping the intake manifold and carb.
 
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my68barracuda said:
That is not exactly correct. Slants are notorious for have stock compression ratio's in the high 7s to low eights. So raising compression is always a good idea. Even with a 1bbl carb increasing compression will increase low end torque. Be sure to measure piston recession and cc the combustion chambers, use an online compression ratio calculator to get to your desired compression. Personally I think a target of 9.5 may get you into the need for mid grade gas, especially if you stay on course with a small cam. I would go with 8.5 as a target. Here is a link to one of the many online compression ratio calculators.
RSR Static Compression Ratio Calculator
IIRC shaving a slant six head .0699 will remove 1 cc from each of the combustion chambers.
A slightly more aggressive cam will also help, if you choose to retain the stock cam, have the fuel pump lob inspected for wear. It can be restored to new by welding. There are many shops that can do that as well as re grind your existing cam to a better profile. May slant six folks trust Oregon Cam Grinding for that. A cam grind for you to consider is what Doug Dutra, a slant six guru developed. Google 'Doug Dutra RV-10 slant six cam'. You will get some info that way. Oregon Cam has their own version of the RV 10. I just google Doug Dutra / RV -10 cam and found this statement, attributed to Doug: "The RV10/295 RDP is designed for a 1bbl engine with compression ratios (8.4 to 9.0) and to have smooth idle with strong off idle and mid-range power."
An upgrade to an HEI ignition to do away with the points should also be considered.
And lastly on this list, be sure to service and clean the oil pressure relief valve in the oil pump. Again, you can google a few words like 'slant six oil pump oil pressure relief valve service and get more info.
The work you described initially would not be lost work, It would provide some increase in engine performance, particularly at low RPM's. The best news is that if you do decide that you want more performance, the internal work is done and you will only be swapping the intake manifold and carb.
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With everything he mentioned, the one barrel will be a huge restriction.

Also, that article you quoted got the decimal point wrong. It's .00699, for 1cc, not almost .070" LOL

I stand completely by what I said. Look at everything he mentions doing and he wants go go through a one barrel. Now, had he mentioned upgrading to the Super Six setup, then we have a viable plan. What difference does it make though, since he pussed completely out and left?
 
RustyRatRod said:
With everything he mentioned, the one barrel will be a huge restriction.

Also, that article you quoted got the decimal point wrong. It's .00699, for 1cc, not almost .070" LOL

I stand completely by what I said. Look at everything he mentions doing and he wants go go through a one barrel. Now, had he mentioned upgrading to the Super Six setup, then we have a viable plan. What difference does it make though, since he pussed completely out and left?
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You are right concerning the misplaced decimal point, good find. I went back and changed my post, so someone does not get the wrong info.
 
I pretty much agree with what M68B said. My 64 Valiant street car was built like a race motor, but for economy. 170 engine, bored and honed .060 with a deck plate. deck cut for .005 clearance (170 not 225). Mildest MP cam, stock valves, but back cut, and blended the pocket, head milled for a tru 9.5 CR (that is too high for the cam used). Balanced, windage tray (because it couldn't hurt, and I had it) Stock intake (1bbl) and exhaust manifold, 2 1/4 exhaust and a holley economiser carb. HEI ignition (needed major recurve in dist) Did go over board with some items. Has 3 speed on the columm, and a 7 1/4 3.23 open rear. Car gets upper 20 mpg on the hiway.
 
Charrlie_S said:
I pretty much agree with what M68B said. My 64 Valiant street car was built like a race motor, but for economy. 170 engine, bored and honed .060 with a deck plate. deck cut for .005 clearance (170 not 225). Mildest MP cam, stock valves, but back cut, and blended the pocket, head milled for a tru 9.5 CR (that is too high for the cam used). Balanced, windage tray (because it couldn't hurt, and I had it) Stock intake (1bbl) and exhaust manifold, 2 1/4 exhaust and a holley economiser carb. HEI ignition (needed major recurve in dist) Did go over board with some items. Has 3 speed on the columm, and a 7 1/4 3.23 open rear. Car gets upper 20 mpg on the hiway.
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And I bet it's pretty snappy too.
 
RustyRatRod said:
And I bet it's pretty snappy too.
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I really am not sure of it's potential. I had a serious problem with "ping" (too much CR with too small a cam). Much better now, with a lot of dist rework. But even though I am a fan of the 7 1/4 rear, I need to be a little conservative. Car is a stick, and it is a open rear. The 7 1/4 peg legs don't like to beat on.
 
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