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Discussion Starter · #1 ·
i traded my blaster for another 440. now i have 2. the new one i just got runs pretty well but there is a good bit of smoke rolling off the head after running it for about 5 minutes and if i gun it i can see white smoke puff out of the head gasket. is it just loose or a bad gasket? why is it smoking so bad? i can understand if it was just burning oil off the head from the previous rebuild (engine was just redone before i got it). i dont see any oil seeping and it has good compression idk if the head isnt tighteded down the whole way or if the gasket is garbage or what. any help would be appreciated.
 

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You need a good mechanic to rebuild it right.

My guess would be whoever rebuilt it either used the old gaskets or failed to get the proper oversized 440 kit replacement gaskets.

Using standard 400 gaskets would cause the piston to press the gasket between the crown of the piston and the head causing the gasket to fail leading to your symptoms.
 

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Discussion Starter · #3 ·
i didnt think of that. it would be pretty easy to get the wrong gaskets. i just rebuild my 440. i had to splt the cases and replace 3rd gear. i think i can handle doing this one. i dont like spending money to get work done i can easily do myself. i'll take it apart soon and check it out i have an extra 440 head gasket so i wouldnt have to buy one.
 

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just my 2 cents...Over the years i've heard a lot of negative things about the 440 kits...apparently no matter what precautionary steps are taken and/or how "correctly" the job is done they prematurely blow-out head gaskets. Also been told 426cc is the largest bore to go with for longevity and peace of mind. It appears another inherent problem with the 400 engine is head studs pulling out of the cylinder...there's a great write-up by 4 stroke tech...google it.
 

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just saying i build these 440 motors and i had the same problem after one of my races. turned out the head stud had pulled the threads out so i went on ebay and ordered a set of gt thunder heavy duty head studs and put them in. you have to drill and tap your jug but its easy and if your going to build a 440 you need to do it.
 

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Yep...that's the way to go...

A few months ago I bought a "1 size over" engine that was rebuilt and fresh...started it up...blown head gasket...pulled head, checked stud torque...at least one stripped...bought the fat GT studs...had my machinist install studs and surface head...put it all back together...runs great!

[and if anyone knows the engine cc size of a 1 over off top of their head, feel free to post...lol]
 

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The engine has an 85mm bore and a 70mm stroke which calculates out to 397.3788434631148cc rounded to 397cc which cast into the base of the cylinder (397cm3)

The first oversize is .25mm (0.010in) - if the engine is actually bored .25mm oversized then it is now 399.71980360496923cc = 400cc

You gain 3cc for every ten thousandths of an inch overbore.
 

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i didnt think of that. it would be pretty easy to get the wrong gaskets. i just rebuild my 440. i had to splt the cases and replace 3rd gear. i think i can handle doing this one. i dont like spending money to get work done i can easily do myself. i'll take it apart soon and check it out i have an extra 440 head gasket so i wouldnt have to buy one.












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