Toymods Car Club Inc: Tech & Conversions => 3K Rally Motor Performance Rebuild to 1400cc

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CLG
Forums Junkie

I supported Toymods

Location:
Perth, Western Australia
Registered:
December 2002

Re: How far can I bore a 3K out to?	Tue, 07 January 2003 23:01

Ok, quick update for those who have replied, are interested, or for the archive infomation! We stripped both a 4K and a 3K last night, and had a fiddle! We took the 4K crank annd rods with pistons still attached, and threw the rest of the motor back in the shed. Next we put the 3K bare block on the work bench upside down (ie, with the sump on the top!). We placed the 4K crank in the 3K block to find some light binding on the original locating holes at the front and back of the block (used to mount the block into a jig to drill all the holes in the head of the block). This doesn't really concern us - it will be easily relieved to clear the crank. Next we placed a 3K rod and piston on the 4K crank. In full standard form the piston skirt just fouled the counterweight on the crank. This could be avoided by machining the piston skirt, or reducing the mass of the counterweight (crank lightning, knife edging, ... anyone?!!!). Both the 3K and 4K were found to have a full floating style Gudgeon pin - we took the snap rings off and removed the pistons from both connecting rods. We then placed the 3K rod back onto the 4K crank, and placed it in the bore as it would sweep during revolution. It was found to foul the bottom of the piston skirt on both sides (there was a factory relief cast into the block at both contact points). Next we placed the 4K rod on the 4K crank in the 3K block and again spun it through the crank sweep. Again it fouled but not as much as the 3K rod/4K crank combination. We will also have to ease the block around the sump mounting face as the connecting rod bolts only just clear. At this stage we pulled the 4K block out again and started looking for differences. Most noticable was the fact that the 4K block had a higher deck height of approx 10mm (will measure this properly unless anyone can give us the exact difference?). Also of note was the fact that both the 3K and 4K pistons were identical in visual appearance (the 3K were however a set of aftermarket pistons, can anyone confirm they are the same piston?). So some block relieving to take place and some more in depth study into pistons, with revised gudgeon pin heights. More on this later! Clint! [Report message to a moderator]

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