After reading through Doug's new book several times I have a few question. He has several ways of getting more compression/stroke/etc out of the /6. Without going to heroics to stroke it the next one is the non stroked stroker. This was using the 7" rods with 2.5 Turbo pistons to get the piston up in the bore. A few questions here:

1) What is the main advantage to this over decking the block? Is it just because you need to take so much off it to get near 0 deck? I do know the rod length/throw ratio gets better but the 225 is higher than the 1.5 limit. Is it smoother with the long rod with less side forces as the piston changes direction? Or is it just to get the lower cost, lighter turbo pistons with thin rings?
2) Quench. The book talks about quench but does not really explain how you get it in an open chamber head? Is the idea here to mill the head such that the areas around the circumference of the cylinder are quench areas. I does say to shape the camber so there is no quench area near the plug, but to only have this area opposite the plug.

Thanks
Jim

Raising the static compression ratio is a basic ingredient to improving engine performance.
Whether the compression bump comes from using stock style pistons and rods and milling the
block / head or using longer rods and pistons with a non stock compression height, in it self makes
little difference.
What the after market long rods and 2.5l pistons do buy are
1) they are lighter weight components, reducing weight in
rotating - reciprocating parts is anther ingredient in improving
performance
2) the pistons use thin metric piston rings. These modern rings
provide: better cylinder sealing, less friction and a weight reduction.
3) the piston pins are free floating in the rod and are held in place with
spiro-locks, another reduction in friction.

So the bottom line is you can get the compression increase with either
cutting the block - head, or by using modern rods and pistons.
The modern rods and pistons brings other positive changes to the party.

My thought is that if your performance slant will see little track time, maybe limit Rpm’s to
the 5k zone, I would build with stock style rods and pistons.
However if you are building a Slant with the strip in mind and want a
free reving engine for performance reasons, I would go with the light weight, low friction
rods and pistons.

For the quench and angle milling input, I’ll leave that to someone with that experience.

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

This is just a cruiser for the wife. It will never see track time I just want it to be fun for her to drive. The way it is today I can barely get out of its own way. I am really looking for torque below 4000 RPM, period.

For what you are doing there is no reason to spend $600 for a set of rods and however much more for a set of pistons. A good set of replacement pistons and cut the block or head to get the compression up to where you want it is all you need. Then get a nice camshaft, clean up the bowl area of the head and put on a nice 2 barrel or 500 Edelbrock and you will be amazed at how much difference it makes, even without oversized valves.

I pretty much run this combination in my 3550# truck and it runs nice.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Agree with Rick C, for what you are doing stay with stock rods, and new os stock pistons/rings.
I built the slant for my 83 D150 for low rpm torque and power.
It will easily rev to 5500 rpm but makes power at street / highway rpm range of
1800 to 3000 rpm
* small cam 212 and 206 @.050
* 340 valve springs
* I installed os valves and cleaned up the valve pocket
* static compression at 8.5
* aluminum 2 bbl intake
* Stock style Silvolite .030 pistons
* Molly rings
* Holley 2280 carb
* stock rods re conditioned ARP rod bolts
* dual Dutra’s exhaust
* HEI ignition

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

I can certainly second the advantages already mentioned regarding the longer rods. I built a very mild stock looking engine for a Resto a while back.

I ran stock 198 rods and the 2.2 turbo pistons. They are still a press fit in the rod. I opted for this piston so I could then open up the dish slightly to suit the comp. I was setting it up for at zero deck and wanted to control volume with dish, not deck or chamber volume. This way minimal decking of the block or head was necessary. Reason being is I wanted to keep the deck close to stock height so I could keep the cam base circle as large as possible without the need for different length push rods. The larger the base circle the better, not a huge deal in a slant but still good practice. Theses 2.2 turbo pistons have no valve reliefs. The better ring pack and lighter piston definately makes a nicer set up. Forget rod ratios, it’s not a big issue and isn’t worth considering, but you are correct, it does increase Rod ratio.

What I have noticed is a cleaner burning engine and a better tolerance to detonation. I run HEI and a oil filled Pertronix canister coil to keep it stock looking. I still run the stock exhaust manifold and a 2 bbl factory intake. The cam I ran is probably not what many would suggest but it works nicely and idles like a stocker. It is more aggressive on its ramps than say the RV10. People would look at the advertised .050” @ 208 as very small, but at higher lift it has more duration than many similar mild cams. It also runs extremely quiet at .015” lash and remains stable at this setting. Min lifter diameter for this profile is .830” (SBC) so the larger mopar lifter is very safe.

People will tell you it’s a Chev grind blah blah but it’s not an issue, most mild cams can take any lifter diameter. Lift is also very mild. I ported the head , bigger intake valves and matched the manifolds, but after discussion with a friend who does a lot of porting he felt a high valve lift was not really necessary. I ended up with only .410 lift, very very mild, but this profile suited me and it was a Resto and I wanted standard springs. It’s also a symmetrical grind (same profile intake and ex). I felt the improved head should be ok with this setup and not need a dual pattern cam. Without actually flowing the head it’s hard to say what was lost or gained with more lift, but I seriously doubt you would notice it at these power levels. It’s also on a wider lobe sep, which reduces overlap which many don’t like, but it’s silky smooth , great torque and not discernible from a stock running engine, but it has a massive boost in torque and revs freely.

Could it be improved? Possibly, but I can tell you it has zero issue breaking traction at the stop lights and beating the general traffic flow. It’s not a race car and it never will be, but as a Resto build I’m very happy with it. Also check actual valve lift on every valve, the rocker arm ratio is not all that accurate, I went through a few sets to finally come up with equal lifts. Always degree the cam, I’ve yet to see one dead nuts correct and this was certainly no exception.

This car has been in my family since new, I have had a couple of mild builds in it with a variety of different cams and lobe seps and lifts and I feel this is by far the happiest and best performer. Other cams were very dependent on lash for idle quality but this is far more tolerant . Personally I wouldn’t run it as mild, but it isn’t my car an it’s a good thing really, as it really is a nice setup for a cruiser. Economy is also very good when I have taken it on longer drives.Good luck with your build and hope this helps

What cam are you running?

It’s a custom cam from Tighe cams here in Australia. I can email you the cam doctor sheet, every cam he does comes with it. Advertised specs alone don’t mean much really, you need complete data to compare. I’d dare say it’s similar if not identical to many other lobes offered by others in the US. Ive used Bullet near Memphis for a solid roller custom cam and found them really good. They do nice work and are very helpful. Everyone has their favourites, but if they don’t send me complete lobe specs I keep looking.

I did it mainly because of the lighter pistons and ring package, and the small end of the rod matches the hole in the piston so I didn't have to ream anything. I did shave the deck to a near zero deck height, but only lightly skimmed the head to make sure it's flat. The cam is reground (2106r) so the rocker arm adjustment negates any effect of the shaving. Since it's going into a truck that occasionally sees duty as a truck but is mostly just a cruiser during nice weather, I didn't need a high winding engine. Piston availability and lightness were my main motivators, followed closely by "it's something different".

My 2 cents, if you are just looking for a reliable, proven package, just use stock pistons and 225 rods.

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If it was easy, everybody would be doing it.

Stock replacement pistons and stock rods are my vote, for what you want to do. I have made plenty of power and had great durability with stock cast pistons and resized rods with new bolts. Maybe shoot for a true 9:1 compression ratio and a bit bigger cam. Do you want to run regular gas or is premium an option? You will gain most power/torque by putting bigger valves in the head and doing some bowl porting.

Lou

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Home of Slant6-powered fun machines

If you have a bone stock, pre-emissions 225 and you are not happy with it's power....and you have it in a car like an A body....your expectations need to be amended.

The point being....raising the CR a little or using a bigger cam or carb is not gonna make the difference.

Hard to guess at the OP's expectations. I guess it depends on what is meant by "can't get out of its own way."

If this is the original engine and it's worn out, just a fresh rebuild (and making sure the carb, ignition, valve lash, etc. is set up correctly) will make a big difference. I was honestly surprised at how not-slow my '64 "Art Dart" felt when dropping a re-ringed stock engine into it. I think it could almost keep up with an 80's Toyota Corolla.

Following Lou's advice and opening up head flow along with raising compression and beefing up the camshaft, installing a good 2-barrel carb and dual exhaust with a Y-pipe, now you're talking about real improvement. I know it made a difference in my Lemons car. That thing will keep up with a 2000's Corolla, easily.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing

Thanks. I have no idea how well it was running but we bought it and I drove it down the road and when you floored it you could'n't tell if it was accelerating or not. It barely went any faster but it would sputter and die after you drove it for a bit too. It needed something.

We just stripped the car for restoration and the motor appears to be an original 1968 225 Truck engine. It has not been bored and the crank has not been turned.

As for my expectations my car is a 1968 Coronet with a stock 318 with EFI and a RV cam. I am perfectly happy with it. It seems to me that I should be able to get the /6 to move an A Body in a similar manner.

What you're describing is way below a stock Slant Six....as you can imagine, they wouldn't have sold many had they sputtered and hardly accelerated.

A stock 225, with EFI and an RV cam, will move an A body in a very spritely manner. I'm not suggesting you rebuild it 100% stock, but don't think you need to do a bunch of mods to get it to run well.

Tell us more? Are you referring to emissions tests results?

- 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.