Hi, this is my first post on this website (created an acount yesterday) Ive been peeking around here for quite a while so im very excited to have joined it. The only reason I havent joined earlier was because i had origionaly planned. on swapping in a V8 (please forgive me) but the more I thought on what I wanted my car to be and how much I could spend I decided to keep the /6.

My car is a 1973 Duster I bought last summer and have been working on paint interior ect. and now its about time for the engine. It runs great just a few hot start issues that i believe i have sorted out. It has a 198 in it but i decided it isnt enough power for what I want and read on here how the 225 crank can be put into the 198 essentially making it a 225. What years are the cranks interchangeable? Where is the best place to get a 225 crank? also because I am putting in a new crankshaft I will need new connecting rods right? because of needing new ones are there any on the market that will give me higher compression? I read somewhere ( I think on fabo) that you can use the 125 rods and pistons from a 2.2 liter 4 banger to give you higher compression. has anyone tried this?

Sorry if i got a little wordy. I appreciate any help and if you have any concerns or worry about it please let me know, Thanks

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If you don't look back at your car after you park it you own the wrong car.

go to the FAQ listing in this section,,

once there ,click on the text that reads 'Tech Articles"

from there, find the article named, Stroking the Slant Six

once you get there, read the paragraph titled

A NON-STROKER "STROKER", THE "LONG ROD" 225

that will get you started.

If you want high compression, use a 225 forged crank from '68-75, (76 was the changeover year, and it was mid year) get your 198 rods resized, and use a set of 18cc dish KB "turbo 2.2" pistons. This will give roughly 9.5-1 with a stock deck height and a stock CC chamber.

225 rods can not be used with 2.2 pistons. You would end up with no compression.

This in and of itself will not give a lot more power, the key to making a Slant run is in the head and camshaft.

You will also need more stall speed in the converter if it's an auto, and more gear in the rear end.

What you really need to do first is set a goal for what you want out of it. Drag race, street cruiser, burnout king, etc..

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Official Cookie and Mater Tormentor.

Thanks for responding. When you say have the rods resized first of all why do they need resized? And what needs changed? My goal for the car is to just be a everyday driver that has a bit more kick to it ( at least a proper burn out) and maybe go to some drag or auto cross events but that is not priority. Are there any pistons that would work with the 198 rods without modification?

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If you don't look back at your car after you park it you own the wrong car.

It is to ensure that the new rod to crank bearing has proper contact against the rod's bearing surfaces... if contact isn't uniform at some point you'll spin the bearing and window the block....

Your other choice is to get another rotating assembly (crank kit, 225 rods, and pistons) and just make it a 225... either way you will be into some machine work... but maybe a little less for the 225 conversion than the 198 rod/225 crank/KB pistons with custom dishes...)

I was under the impression that the 198 and 225 pistons were the same... I guess I was wrong lol. what would make the most power 225 crank with 198 rods and 2.2 pistons or would it be very comparable to a 225 crank 225 rods and piston? how much of a difference are we talking? the main differences I can see (and I am by all means a pure novice at this) would be a better rod ration with the 198 rods and better compression. is there any other benefits?

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If you don't look back at your car after you park it you own the wrong car.

I would go with a stock 225 and send me the 198 rods so I can dispose of them for you.

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If it was easy, everybody would be doing it.

a bit more detail on rod re sizing,,
the inspection of the con rods crank bore diameter is a basic part of any engine lower end rebuild,, just like measuring the main and pin bore diameters on the crank shaft, to determine if the used condition is still within the part specifications.

The mains and pins on the crank shaft are wear points, so with a motor with some miles on it, the cranks and pins usually need some attention to get them back to specifications.

The con rod crank bore is not a wear area, but the shape of the con rod bore can be made to go out of round due to the stresses acting upon the rod as the engine runs. To bring a crank bore end of a con rod back into specification, the machine shop will: verify that the rod bolts are torqued correctly, then measure the diameter and roundness of the bore, using a gauge that reads to .0001 or better. If the bore is out of round they will remove stock from the con rod cap faces, which in effect makes the bore undersized, then reassemble the cap, torque the rod bolts and re machine the bore diameter to size.
This is a very common engine rebuild practice.

so whether you get replacement 225 rods or use your existing 198 rods the inspection and perhaps correction of the con rod crank bore needs to happen.

FWIIW, slant six con rods both 198 and 22 are pretty robust, the crank end of the rods in your motor may be fine. When I took the OE 103K motor from the D150 down, the con rod diameters were measure and found to be well in specification.

they are, it is the rods and cranks that are different.

and concerning an engine built with 198 rods and 2.2 pistons on a 225 crank
vs
an engine built with 225 rods and 225 pistons on a 225 crank

first of all the all 225 component engine will need to have some block-head milling to raise the compression to what the 198 rod and 2.2 piston engine will develop in a bolted together condition.

assuming the compression ratios are made the same and all other components are selected for a mild street build,
I bet that you will see no difference

However if the engine build components were selected to put together a
high HP, high effort engine
the 198 rod 2.2 pistons should show some advantage due to:
1) aforementioned rod ratio
2) the 2.2 piston is lighter, shorter skirt for less friction
3) the 2.2 piston has modern, narrow ring architecture, less friction, less weight, better sealing
4) the 2.2 piston although still a cast piston is made from an alloy with higher strength properties

The 198 / 2.2 piston combo has a higher build level potential,
but a lot can be done with the stock 225 parts.

What would be cheaper? I imagine the 198 rod 225 crank and 2.2 pistons would be slightly cheaper because there wouldn't be any machining necessary. ( or am I wrong?)

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If you don't look back at your car after you park it you own the wrong car.

You can do your own price comparison shopping, just google slant six pistons, you will get links to stock pistons, kb 2.2 pistons, wiseco and more, also watch the ads here and maybe on eBay, sometimes there are deals.
You should also be shopping for a machine shop, visit a few local shops, ask to go in and see the machining-cleaning-inspection equipment. Get basic quotes on what you want done,,,,

You will need to have the engine bored oversize.

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Joshua

[quote="DadTruck"]You can do your own price comparison shopping, just google slant six pistons, you will get links to stock pistons, kb 2.2 pistons, wiseco and more, also watch the ads here and maybe on eBay, sometimes there are deals.
You should also be shopping for a machine shop, visit a few local shops, ask to go in and see the machining-cleaning-inspection equipment. Get basic quotes on what you want done,,,,[/quote]



I've been doing some searching however I haven't been able to find any crankshafts anywhere.

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If you don't look back at your car after you park it you own the wrong car.

Napa carried crankshafts at one point in time,,you can also put an ad up in the
Parts wanted section of this forum,,,

Autozone, O'Reilley's, Pep Boys, Rock Auto all can get crank kits. Last time I looked all werr around $200 plus core charge.

I have a Car Quest kit in mine. It has been flawless every time we checked the bearings.

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Official Cookie and Mater Tormentor.