Is this possible? I seem to remember that the cast crank and forged crank have different journal sizes.

Also, if I do the long rod build with the dished turbo pistons and with stock head (unmilled), what compression ratio could I expect?

_________________
Restoring Wife's Great Grandparent's 1963 Dart.
Built August 30, 1962 in St Louis
First month of production
Serial Number 599
Still is a basket case.

Factory 198 connecting rods (7.006 c to c) are made to the forged crank bearing widths so that is not a problem.
K1 makes aftermarket con rods in both bearing widths so you can do a long rod engine with either type of crankshaft.

What makes a long rod engine nice is the lighter pistons, thinner rings and the fact that you can get higher compression with-out a bunch of head or block milling.

Here are the numbers on a very common long rod build, using factory 198 rods and silvolite 1291H pistons and uncut (clean-up cut) block & head:

Head cc @ 56
Piston Dish @ 16 cc
.045 head gasket
3.504 (1mm o/s) bore

This combo gets you a 8.9 static compression ratio.
Use a mild cam with a 45 degree ICP and you will have a 8.0 dynamic CR.
Use a thinner head gasket or a smaller dish piston (1290H) to increase compression and use more cam.
DD

Great news. Thanks. My intention is to rebuild the old tired (and stuck) 225 and try to get more HP and the best MPG I can. I know with the correct selection of parts and proper machining, I can get some of both. I am not looking for a race motor, so the K1/Wiseco set is out of bounds.

I am figuring that with the Long Rod conversion, better exhaust pipe size, bigger valves, 2843169 cylinder head, and a mild port cleanup, I can get this motor to give more HP and be easier on the gas, without breaking the bank on a rebuild.

My intention is to keep it stock looking, so I want to keep the factory-looking 1bbl carb and factory intake.

Would the aluminum 1bbl intake manifold be better than my cast iron one, or is it the exact same design with just a different metal? The weight savings alone may be attractive.


Or, am I all wet on this idea????

_________________
Restoring Wife's Great Grandparent's 1963 Dart.
Built August 30, 1962 in St Louis
First month of production
Serial Number 599
Still is a basket case.

The only aluminum intake with bigger runner cross-section is the old Mopar M1 2bbl unit and the difference is small.
The main advantages with the aluminum intakes are weight savings and they heat-up / cool down faster.
DD

I was wondering about the crankshaft, because here in my country we only got three different cranks:

1- Slant 170" forged crank
2- Slant 225" cast crank with small flywheel pilot
3- Slant 225" cast crank with large flywheel pilot

We never got a 225" forged crank. Those are 4340 forged steel? At wich point we REALLY need a forged crank?

My new engine will use very long rods (7.559), with the big end at 2" (like Chevy inline six) so we will offset the rod journal to reduce the stroke from 104.77mm to 100mm, this should give me a safe 5000/7000 RPM plus.
And for this set up i only have the cast crank, will it be enough?

This engine will run on carb only, no nitrous, no turbo. and the CR will be around 9,5 / 9,7.

What do you think? Do I need a forged crank?

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

I double check you articles about cranks, and the normal Argentinean 225" crank is like the pre-'76 USA cranks, with the big rod journals.
So I'm confused with our argentinean cranks ...
I know for sure that AR 170" cranks are forged steel and 225 AR cranks are NOT forged steel ... very few 4340 forged steel crank were imported from USA at one time during '68 and that's it (have fun finding one in my country) ...

I think I should find out more about Argentinean cranks, I do still have time since I didn't started machinig mines yet.

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

If your 225 cranks are like the '76 and earlier US cranks then they are forged as are the 170 cranks. These cranks aren't forged of anything nice like 4340, but they are a forging rather than a casting. It's not that difficult to tell a forging from a casting if you know what to look for.

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Joshua

Well ... thats the problem .. I don't know what to look for!!! I'm just repeating myself from what I heard ...

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

OK, here is how to tell the difference between a forged crank and a cast one. Anything that is sand cast, like your engine block or cylinder head, will have a definite texture to the surface. Any surface of a cast crankshaft that isn't machined will look like most any other iron casting. Forging creates more identifiable markings. Because of the metal squeeze out between the dies the parting lines of a forging are wider. Also, because the forging dies are simplified the throws and such aren't in their final position right out of the die. The forging is twisted so that the counter weights and throws are in their proper position so the parting line moves. Castings also have parting lines from the mold, but those parting lines are narrow and line up with one another. On the US forgings I've seen it appears the forging process creates thin little lines in the metal which stand up from the surface. These lines are usually visible on the center counter weight and on the crank throws outboard of the rod journal.

Have a look at the 2nd and 3rd pictures here: http://www.guy-croft.com/viewtopic.php?f=6&t=1443

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Joshua

Thanks Joshua for you explanation! i undertood everithing, also the picture helped a lot!

So now I can say that 100% of the crank in Argentina are FORGED. But the question for me remains since all engine builder say that the 170cu crank is much stronger than 225cu engines crank, since both are forged I can only think that different steel has been used on them.
Another thing that I can assure is that all 170 cranks in Argentina were imported from USA and NOT manufactured here...

Again thanks!

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

The 170 cranks are stronger because of the shorter stroke.

The 170 has more metal overlap between the main bearings and the rod bearings.

_,-,_ vs _/"\_

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

The 170 cranks were probably imported as forging dies are expensive and for a limited number of engines it was probably cheaper just to import them.

As Ed says, the 170 crank is stronger because of the journal overlap. I'd be willing to bet the 170 and 225 cranks made in the same place are made of the same material.

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Joshua

I don't think they reffer to the 170 Stroke crank as stronger over the 225 because of the shorter stroke, they are talking about forgin material for sure! But maybe in ARgentina since 170 cranks were USA made and 225 cranks Argaentinean made they use different steel.

Thanks!

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Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)

Martin
I thought most of the racers in your country used a 198 based slant instead of the 225. These are the slants we see in the You-Tube Vids.
I know they spin these up to 8500rpm.
Frank

_________________
Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

The basic short block for a Slant Six ACTC Race Engine was:
- 225cu "906" Casting Blocks
- 91,5cm bore (aroung 3,60 inchs)
- 170 Crankshaft modified with 12 counterweigths or a custom billet but based on the 170 stroke
- "H" Connecting Rods with 2" big end, 190/192cm (7,48-7,56inchs) center to center distance and 22mm bronze bushed pin bore.
- Total Seal Rings
- Final cm3 was from 3000/3300 depending on they rules
- and yes, they were turning 8500RPM in high gear

The Rods were produced by Saenz (ARG), Ercoli (ARG) and Carrillo (ARG-USA) and the pistons by IASA (ARG), the crankshaft was modified by Galante (in Venado Tuerto-ARG) they also produced the billet ones.

We never had the 198 Slant Six in my country, too bad!!! I Think that one of those cranks with the 192 Long rods can spin very good above 7000RPM even 7500 ... ohhh lord!!!!!! Think of the Rod ratio there!!!

_________________
Martin Zappettini
1974 Dodge Polara RT 318cu.
1965 Valiant III Coronado Slant Six 6-Pack (soon!!)