Bottom end work

[Wendigo]

Since the valve in cyl #5 popped and the piston got a beating worse than Tyson in his last fight, I've got to replace it.

-What is the most cost effective way to swap out a piston?
-Must all hardware and bearings be replaced?
-can the oil pump be tested?
-what pistons should I consider/not?
-why is my navel fuzz always purple?
Thanks for all the help so far!

 

[Boostedstr8six]

How sure are you that it was one of the four valves in #5?

 

[supra90turbo]

you dont just "swap out" a piston..
there is much machine work to be done. and what does "valve popped" mean?
you may be in for a somewhat pricey rebuild. fixing smashed valves and damaged pistons isn't light work...

 

[kwnate]

I can only answer the navel fuzz one. Stop wearing purple shirts. Mine is white and I wear white shirts. I'd rebuild the engine. If you are going to take it apart, use new stuff to put it back together. Remember, no more purple shirts.

 

[Wendigo]

I'm sure. On Sunday I pulled the head for the ever loving BHG, and with much dismay discovered the rear exhaust valve had snapped/sheared/"popped" and was laying upon a much gouged piston. The other other three valves had been mashed into very uncomfortable positions. The cylinder wall appears untouched. SO......I will pull the block and begin surgery. But what pistons/bearings/machining I need remain in question. ARP hardware I know. I see pistons on Ebay from a seller named "guit-guit" that look like a decent price, but don't know about quality. Any ideas or comments? Thanks

 

[figgie]

I'm sure. On Sunday I pulled the head for the ever loving BHG, and with much dismay discovered the rear exhaust valve had snapped/sheared/"popped" and was laying upon a much gouged piston. The other other three valves had been mashed into very uncomfortable positions. The cylinder wall appears untouched. SO......I will pull the block and begin surgery. But what pistons/bearings/machining I need remain in question. ARP hardware I know. I see pistons on Ebay from a seller named "guit-guit" that look like a decent price, but don't know about quality. Any ideas or comments? Thanks

i got bad news.. if the valve was mashed that means the combustion chamber was also mashed MEANING that you are going to have to probably get a new head.

 

[GrimJack]

First off, what Figgie said is very true.

The most cost effective way to replace a piston depends... take the block into a machine shop and get them to check the crank and cylinder walls to see how close to factory specs they are. If they are still within factory spec, then buy a used piston, put it on your old rod, buy new bearings and rings, and put it all back together again.

If the block isn't still in spec, you'll need to rebore the cylinders and install new pistons as well.

If the crank isn't still in spec, you'll need to get it fixed up and buy bigger bearings.

You should absolutely buy new bearings and rings while you have it apart. Pistons are a maybe, so are rods, depends on how much power you intend to push through it.

There is a procedure to test the oilpump in the TSRM, I seem to recall. There is a way to fix it my machining down the inside of it if it's out of spec - but I don't recall exactly where that thread is on here. I'm sure it can be found with some elbow grease.

Stock pistons if you want 400 rwhp or less, JE forged units if you want 500 rwhp or more, and anything in between is anybody's guess.

The purple has been covered already.

 

[Stretch]

Maybe the valve popped out because the keepers at the top came out somehow. Maybe it revved to hig hand they shot out of the retainer or broke into pieces and sent the rod down into the piston.
eric

 

[Wendigo]

How the valve went the way of the DoDo bird I can't say. I can say it laid a mirror image of love on the cylinder head, it's shot. I found a replacement which I will disclose later. Is there a preference for bearings? I"ve found items on ebay and at horseyfreaks.pinchmynipples, but this being my first attempt on modifying my 6cyl love machine, I don't know the difference between clevite and toga bearings. JE pistons are recommended but what about Nippon racing? Does anyone know anything about OBX pulleys/cam gears? Will I ever find an engine cleaner that will really understand me?
At what point does make sense to just replace the motor?

 

[souprat]

i guess it makes sence to replace the motor with a used one when the price of a rebuild becomes an issue. if i were doing this to my motor i would look for a shop that has successfully rebuild a few 7m's i hear they are ticky to do. other than that this is beyond me, i just wanted to offer my condolances, sorry to hear bout this.

 

[crf_rider]

before you buy a used head make sure the seller has it checked for warpage. TSRM says .003 max for warpage.

 

[IJ.]

before you buy a used head make sure the seller has it checked for warpage. TSRM says .003 max for warpage.

Even more important for a used 7M is to have it tested for hardness!

The test takes 30 seconds and most shops will do it free.
(Most 7M's have been overheated at some time and are usually soft on the exhaust side)

 

[Wendigo]

If the head fails for "hardness" is there anything I can do? Talk dirty to it? I'm a little tweaked 'cause I just bought one from a guy the ebay way, and am worried that all my ordering has been in vain.

http://cgi.ebay.com/ebaymotors/ws/e...=7995333359&rd=1&sspagename=STRK:MEWA:IT&rd=1
Anyone know about OBX pulleys?
http://cgi.ebay.com/ebaymotors/ws/e...=7994779801&rd=1&sspagename=STRK:MEWA:IT&rd=1 Or Nippon racing pistons?
http://cgi.ebay.com/ebaymotors/ws/e...=7995068277&rd=1&sspagename=STRK:MEWA:IT&rd=1

 

[figgie]

umm for the pulleys. They LOOK like the unorthodox stuff which is UNDAPMED. I would stay away from the crank pulley and just use the alt, water pump and power steering pulleys.