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I have a 1988 class c motorhome and I am going to build a 460 short block , I picked up a 1990 short block with unknown miles to have bored , I plan on putting in forged pistons , it has the original front balance weight but didn’t come with the flex plate , the engine in my motorhome is a 1991-93 I think , first question is can I use the flex plate off the 91-93 ? And by using forged pistons do I need to have the whole rotating assembly balanced ? I won’t be turning over 4000 rpms as it’s a RV , I’m using forged pistons to make my bottom end extra tough because I recently went on a trip and was going up a bunch of steep hills in 110 degree temps and melted a hole in a piston with no pinging before it happened so I had to have a shop in the area I broke down in put in the used newer engine to get me home as I didn’t have time to have a rebuilt engine done so that’s the reason I want the forged pistons so the engine can take the extra abuse of having to always be hauling around 10,000-12,000 lbs including pulling my Jeep and I am going to put in other performance parts such as comp cams 4x4 cam, so what does the Ford guys hive mind know to help me , thanks guys 😉
460 engines are all externally balanced from '79 up. Those engines all use a weighted flexplate and the "hatchet" weight spacer. A piston that's either cast or forged can be very similar in mass you'd just have to weigh them and see. Either way a forged piston would have had a hole in it too under the same conditions. The piston was the victim not the cause of the problem.
Having owned and abused several 460s I can attest that the stock rotating assembly in a 460 is good for 500+ HP. Ive owned an 87 Class C and I used to tow 5k lbs behind it. My class C weighed 13,500lbs. The only upgrade I did was a straight up timing gear and a high flow water pump. I towed my trailer through the mountains for 4 years until I sold the setup for a 5th wheel. I wasn't winning races but I always got there. If everything is working correctly you can't beat the reliability of the 460 for a big block for a medium hauling engine.
If you want more power and retained reliability just have someone professionally port the heads, buy a set of Banks headers and use all OEM parts for the rest of the rebuild.
Cast pistons are for lawnmowers
All Hi-Perf engines should have forged pistons
Just because you can get away with using cast pistons, does not mean you should
Cast pistons are for lawnmowers
All Hi-Perf engines should have forged pistons
Just because you can get away with using cast pistons, does not mean you should
Really? What type of pistons did Ford use in the HP 289 engines? Either way this isn't a high performance application and a forged piston would have provided zero advantages.
Boss 302 had a lot of problems with skirt cracking.
I can't think of a single medium or heavy duty gasoline truck engine application that used a forged piston. 391, 429 Lima, 366 or 427 Chevy all used cast pistons. Why?
In this type of application the engine has to be built to handle a very high duty cycle with long periods of high load and even wide open throttle. The compression ratios are low so peak cylinder pressures are controlled to keep the engine out of detonation and preignition. This puts a lot of heat into the piston and a cast piston does better than a forging in this situation because alloys that are used in castings have lower thermal expansion rates. They can even be hypereutectic and forged pistons can't.
Boss 302 had a lot of problems with skirt cracking.
I can't think of a single medium or heavy duty gasoline truck engine application that used a forged piston. 391, 429 Lima, 366 or 427 Chevy all used cast pistons. Why?
In this type of application the engine has to be built to handle a very high duty cycle with long periods of high load and even wide open throttle. The compression ratios are low so peak cylinder pressures are controlled to keep the engine out of detonation and preignition. This puts a lot of heat into the piston and a cast piston does better than a forging in this situation because alloys that are used in castings have lower thermal expansion rates. They can even be hypereutectic and forged pistons can't.
Piston selection can be a tricky thing.
I can tell you why manufacturers didn’t use forged pistons, it’s because cast pistons are faster to mass produce and are cheaper to make , all corporations are about money and not for the best quality
A casting is used because the material is more suitable to the application than a forging. Do you really think that making a piston with a reinforced top ring groove would cost less to manufacture?
I recently purchased an 86 F250 4wd and was looking at either having the valves done or doing them myself. When it comes to adjusting the valve lash.. as I have a ton of play at the Rocker arms is rotating the push rod whilst turning the dampner 2 full rotations at 90°per going to be accurate enough to set the lash to zero? Damn she's got a fat ***!
what is the best way to go about adjusting the valves?
I am asking as I do NOT have experience in this area, but it seemed simple enough
If it's a stock engine (or stock replacement) it won't be adjustable. This ain't no Chevy. Ford had good enough machining tolerances to actually be able to hit the mark when it came to pushrod length and lifter preload. Hell, Chevy couldn't even machine a starter pad consistently from one block to the next.
You might have a flat cam, bent pushrod or collapsed lifter if you're looser than zero all the way around. Most of the time when the rockers are bolted down tight they compress the lifter somewhere between about .040 and .090. It is very forgiving. Finding the problem should be easy once you've taken the intake off of the engine.
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