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Author
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Topic: Got a 302 block for free!! Low buck street motor buildup
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rockafellz
Gearhead Posts: 935
From: San Lorenzo, CA, USA
Registered: Aug 2001
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posted 03-31-2003 07:55 PM
   
Hey Fellas,Over the weekend I came across a 302 block and crank from an 87 mustang. I traded up for some computer parts.  The block has never been bored and the cylinders seem to have a lot of cross hatch (is that the term?) in it. I hope that's a good thing. The crank is still in the block and moves very smoothly without any freeplay. I have the opportunity to get the rods and forged TRW pistons for a few bucks but passed on it. Should I get them? The goal for this block is to build a stout low buck street motor  with the tips and help from you guys here!! It will be a slow build but I won't be skimping on the quality of the parts used. 2nd question. How would I determine of I could still use the stock forged TRW pistons? The guy I got it from said it came off a car that was reared and had 70K miles. Thanks in advance. Erik ------------------
1966 Ford Mustang 2+2
Mine - Restomod in Progress 1966 Ford Mustang Coupe
Dad's - Original Unrestored
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itlbrnmoff
Gearhead Posts: 560
From: Indianapolis,IN.USA
Registered: Nov 2002
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posted 04-01-2003 09:40 AM
A little backyard advice...
Inspect the piston ring lands with the rings removed for cracks or damage.
Look for scuffing on the the piston skirts.
Not sure if this would be the best way to measure, but, put a piston in a bore, without the rings, hold it tight to one side, and use feeler gauges on the other side to get a measurement, then subtract half of that measurement and compare that to the piston to wall specs in a service manual?
That was crude.
Or take the block and have the bores and pistons measured the right way. It shouldn't cost an arm and a leg for measuring by a machine shop. ------------------
Low Dollar 1983 Mustang GT W/T-tops...
306 4bbl. T-5 3.45 trac-loc...it'll burn 'em off
1988 Lincoln LSC
5.0 auto full power
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rockafellz
Gearhead Posts: 935
From: San Lorenzo, CA, USA
Registered: Aug 2001
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posted 04-04-2003 10:04 AM
Ok, should I get the rods and TRW pistons? They are notched so maybe I could use a bigger cam with it. What are the tools I need to properly measure the bores to see if they are still good for standard bore or if I need to overbore them.Also, what are the steps I need to ask the machine shop to do to properly prep the block for heavy duty use? Thanks in advance. Erik ------------------
1966 Ford Mustang 2+2
Mine - Restomod in Progress 1966 Ford Mustang Coupe
Dad's - Original Unrestored
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JCQuinn@work
Gearhead Posts: 331
From: Lakewood, CO, USA
Registered: Jun 2001
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posted 04-04-2003 11:34 AM
Cross hatch is the finish left by a hone. It consists of very fine scratches in the cylinder wall that cross each other. If that is what you are refering to, yes that is the term.If the cylinders still have a cross hatch pattern it is possible that the motor was disassembled befor it was broken in. To measure the fit of the pistons you need an outside mike to measure the piston in the thrust face just below the ring lands. To measure the block you need an inside mike or a dial bore guage. Then you need the recommended clearance from the piston manufacturer. What I would do is take one piston from the set and deliver it with the block to a good automotive machine shop. They can tell you if the pistons are re-useable. If you give them some work from your build up they might even not charge for the check. Forged pistons are expensive and it would be good to use them if it is possible. The main thing if you are looking for performance is to have a honeing plate (aka torque plate) put on the block to see if the bore is round when the heads are torqued on. If the motor was bored and honed for the used pistons without a plate, the bores will not be round when the head is torqued down and you will lose horsepower. You can also mike the crank and the bearings in the mains to see if you need new bearings. Again I recommend letting the machine shop people tell you what to re-use. Most of them are honest and will advise you well. get some recommendations about which machine shop to go to. Selection of a good machinist is critical to high performance projects. John
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