So in 2002, I had a 225 block built for my 1964 Valiant since the 170 died. I didn't know what I was doing then, but I did ask the guy to bore the engine 0.030" over and he charged me accordingly. I just started my engine breakdown all these years later and, surprise surprise, it's bone stock in there.

So now I'm looking for something new to do. I read Doug Dutra's stroker article and that sounds pretty interesting. Anyone tried that?
http://www.slantsix.org/articles/stroking/stroking.htm
How does that affect the streetability of the engine? For reference, here's what I have so far for the car:

1964 Valiant 2 Door Sedan
- 225 out of a 1970s Dodge van. I was told 1974, but I never saw it. Could be newer. Not really sure if it's a forged or cast crank. Looking into that.
- 904 Pushbutton
- A/C
- Power steering (Saginaw)
- large valves (1.70/1.44) from engnbldr, porting job, with 340 valve springs, planed 0.100" off cylinder head
- Erson 280 int/270 exh duration cam, 0.465" lift with lifters
- Recurved distributor
- Double roller timing chaing
- Stock oil and fuel pump
- 90 Amp Alternator
- HEI
- Offenhauser 4bbl intake and Edelbrock 500cfm 4bbl with electric choke
- Dual Dutra Duals into a Y-pipe and single 2.5"
- 8.75 3.23 Sure Grip

TBD: - 2600-3000 RPM stall converter
(Thanks again to Lou [Dart270] for helping me with the list above.)

I'm also doing some serious suspension upgrades, but the only one I think is even slightly relevant is I'm moving the battery to the back. The car is being built to be quick and handle well on the street.

So with that configuration, what would you do with the block itself? Is it worth looking into boring it out still? Doug's article seems to imply not, but I know many people have said they bored theirs 0.060" over and seemed happy with the results.

Thanks for the help!

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Chuck and the Flying Valiant

I would first determine if the block needs boring. If the bores are straight and withing specs then it's optional.

Hi Chuck,

Sounds like fun! Bummer to hear about the ripoff. If your engine is/was not burning oil or had low/uneven cyl pressure, then you might just leave it as is. You will not gain a ton by boring, if the bottom end is in good condition. Head porting with those bigger valves will get you the biggest gains.

Stroking is a lot of work for also not huge gains. If you need/want to overbore the engine, go for 0.060" over since that will unshroud the valves a bit and you can still bore most blocks to 0.100" or more later. You might look for a 83(or so)-up Slant with the light cast crank and block. This will drop 40 lbs off your front end and has no negatives unless you want to make 450+HP. My 64 Dart now has that short block with k1 rod and Wiseco 3.445" piston combo.

Why power steering? My experience is that it is much worse feel and response than manual, but you need to make sure the susp and steering components are in good shape to see the real difference.

We can discuss more...

Lou

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Home of Slant6-powered fun machines since 1988

Normally boring is just to make sure you have nice, straight, round cylinders. Opening up the bore will aid flow on a small bore like a Slant, but .030" wouldn't help a whole lot.

If you don't already have one you will need the adapter that Charlie sells to mate your late model crank to the PB converter.

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Official Cookie and Mater Tormentor.

Note: Any piston, con rod or stroke change requires a fresh, clean bore so see if your current, worn bore is in spec, then decide what to do.

As for your parts list, find the Intake Valve Closing point with that 270 / 280 cam and work the DCR numbers. You will find that you will need more static compression so block / head milling needs to be in the plan. ( and likely shorter push rods)
DD

Good points, Lou. The 83 up option sounds great! Will it work with a drool tube head? I don't see why not, but that's what I had built so it would look kind of period correct.

What are the risks for going .100" on the bore the first go around? Is it just cost?

Fair question on the power steering. A friend of mine that's had A bodies before recommended that said it would be what I'd want for a car that's built to handle. Honestly, I have no experience with old Mopar power steering. I have all the pieces for both. We were just talking about how we'd run A/C, P/S, and the alternator off the crank. Maybe it's something we need to revisit.

Also, I do have Charlie's adapter ring! Thanks for reminding me. I checked on that the other day to make sure I didn't lose it!

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Chuck and the Flying Valiant

In a car that light manual steering is the way to go.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Going .100" over opens up a greater choice of pistons. 3.500" gets you into Chevy territory. It also aids head flow by getting the valves farther from the cylinder walls.

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Official Cookie and Mater Tormentor.

Does boring that big compromise street driving at all?

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Chuck and the Flying Valiant

No you are just adding another 13ci, and probably 10 horse power or so. Drivability should not be affected at all. If you bore .060 then you can use stock replacement pistons on the 225 rods. If you want to go to .100 then you will need K1 rods (Or 198 rods) to go with your new pistons.

Rick

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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

Thanks, Rick. 10HP sounds good to me. My original goal was to try and build a 200HP engine that would still be fun to street drive, so every little bit helps! Looks like I may need to update my budget, but this seems like some cool options I previously didn't think were available.

Now I have to figure out where I'm going to find an '83 up block around here... Slant Six parts are pretty hard to come by in North Central Florida outside of Charrlie_S's shop!

Note that I do not think you can bore the 80s blocks as far, so keep it to 0.060 over or less with the 83-up motor. For your engine, 0.100" is no problem. I only bored my 84 motor 0.045" over. It makes about 270 HP with a big cam (~0.550") and a good Jeffrey head. 200 HP is fun to drive and not hard if you have a decent head.

Doc is right about compression too - milling needed if using stock bottom end or stock type pistons and rods.

Lou

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Home of Slant6-powered fun machines since 1988

Head over to www.vanning.com and post a want ad. There are lots of vanners in the south and, being form the south near nascar territory, they usually yank the slant six out of their van and swap in a V8, even chevy v8s (the horror!).

Some of the bigger pistons are metric........

So don't bore, then try to get pistons.

Get the pistons, then bore to match the pistons......

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I usually do my tear down first so I know the measurements to run the compression calcs so I can get the block and parts in for checking and machining...

I have overbored 20, 30, 40 and 60....on various builds and give a little unshrouding to the oversized valves (doing a little relief at the outer edge of the chamber for the intake especially).... there is better room to do it wiht 40 and 60...(my last hi compression builds have been in this range since pistons are easy to get)...there is no gain in the overbore in displacement...just extra math to make the target compression ratio... if you go to the upper end you risk the problem of not being to step up to the next size if the engine has to go back in after much wear or you have an 'oops'...so mostly I stuck to 40 and if something came apart I could easily go to 60.

Looking over your list, you already have most of the components to make a 190-200hp at the crank 'Lou' build....you can do the overbore to 040, mount the head before loading the block with the rotating assembly and see how the chambers line up, a little more porting and bowl blending will be desired, ...with the 280/270 Erson cam a target of 10:1 SCR and running the correct cam advanced indexing on a DCR calculator to get the proper 8:1 DCR will yield your goal, if the mock up of the head shows room to do some unshrouding without compromising the head gasket or the edge of the cylinder, you can safely do the calcs with the necessary overbore to make this relief....with a measurement of your current deck height and the displacement of your current chambers, you can tell a competent machinist what you want, and if done right you can aseemble the bottom end, check your measurements and adjust the clean up cut on the head to make your final target...

I have run this particular build with the hyperpak intake and in a derated format with an offy, single exhaust and a holley 390.... both had excellent driving manners, got acceptable gas mileage and had no problems keeping up with all the modern cars....

The long rod version has the benefits of better rod ratio, better pistons, and should be a little more resistant to detonation if pushing more compression... (I have a long rod build already penciled out for my EFI Hyperpak manifold....should run on regular at 11.2:1 SCR and be quite a step up from the 10:1 build...but not as "brutal" on components as the 12:1 builds I am working on now for racing).

If going with any cast crank engine, the benfits there will be the lighter crank will allow you to rev back up up faster after shifting to the next gear compared to a forged crank engine.


Food for slanted thought.