piston question?

[Bens69PlymouthSatellite]

all the pistons i find aftermarket are at least .30 over bore if im building a performance street engine do i have to bore and stroke the engine,or can i get away with the stock bore and are there any companies that make oem bore pistons that will withstand say 550 to 600 hp?

 

[rumblefish360]

SURE! They all should. They, the sellers, just simply list an overbore due to the age of the engines and/or mileage when this is normally done. Just ask'em, they'll give you a standard bore.

Stroking is a crank issue and cutting a crank so it's good is not stroking.

 

[joesnow]

Cyilnder wall wear must be measured first. If the cylinder has abit of milage or a ridge at the top ,it will need to be over bored. Generally speaking it is the way to go.

 

[Bens69PlymouthSatellite]

well from what i heard about the engine its ready to run,the oil pan gasket is shot,but thats no biggie,the guy who rebuilt it put the 440 in an old hotrod like model t ford and ran it a few times,then got scared and pulled it out and it sat in his garage,the engine is pretty damn clean,i havent torn it apart yet,but im hoping i dont have to bore it over,so if the cylinder walls look rusty i should bore it or could i just get away with hot tanking it?I dont have a ton of $ right now,and boring an engine is not cheap.

 

[69HEMICORONETR/TCONV]

I would only bore if I had to because of cylinder wall wear or scaring, ...If you punch out a 440 .030 over and buy new oversized pistons you will only gain about 6 Cubic inches, ....That's expensive horsepower and not a good way to go if you want to get the most bang for your buck.

 

[Bens69PlymouthSatellite]

so unless the cylinder walls are scarred or chipped i would probably be better off hot tanking the block and calling it a day,could i get away with just sanding off any surface rust in the cylinder walls?

 

[69HEMICORONETR/TCONV]

I don't sand cylinder walls, that's a "No No", ....sanding removes surface rust but it also removes material, you don't want to do that, You want to keep them nice and round ......I spray them with penetrating oil and scrub them with brass wool, this only removes the rust and doesn't risk damage to anything. If it was Professionally built or at least built the RIGHT way, It shouldn't need to be bored after a couple passes, but I have no idea if it was built correctly the first time or just slapped together under a shade tree.

If you are going to have it hot tanked don't worry about the rusting the tank will take care of it, .....I would Mic it and inspect it after the tanking and then determine if a overbore was needed.

 

[Meep-Meep]

I have taken a lot of liberties with engines over the years and that includes honing and re-ringing. You can hone to about .002" over on the diameter and still be OK with the original pistons, so long as the piston ring lands are good. For a good job (unless you have the rigid hone and can do it yourself) I'd take it to the machine shop to ensure you get a round bore. It's OK to leave some witness marks after honing if you have a ridge. I'd rather see that then having the bore get too big. You can sand the what the hone missed in the ridge area with some 400 paper but don't sand the bore.

Boring an engine .030" - .060" is not done as a performance modification but rather it's an acceptable procedure to bring the bores back into tolerance.

 

[Bens69PlymouthSatellite]

Thanks again!

I figured sand paper would be to rough for the cylinder bores and suggested steel wool or brass brushes to my so called mechanics,they said that wouldnt be enough,even though I dont know what im dealing with yet because I havent even ripped the engine apart yet,the guy who sold me the engine is a well respected engineer,and very honest he told me to get my carb and test the engine and he would be pretty positive it will run fine,I just eventually want to build it up and wanna get all my ducks in a row before I rip it apart,thanks again to all of u!

 

[Meep-Meep]

The stones used in honing are around 400 grit, so hitting the missed spots with a little paper is no big deal. If you want to accurately asses the condition of the bores without tearing the engine down get a leak down test done on it. If leakage is at a minimum and oil pressure is at the maximum, keep driving!

 

[Pistol Pete]

Keep in mind if you hot tank it, should change the cam bearings as well. More trouble, more $$ IMHO.

 

[scotts74birds]

X2 on the leak-down test. I have a link for a homemade one if you need it.

 

[daredevil]

if you pull it apart hone it and rering it. if theres any rust in the bores it at least needs a hone plus you will know its fresh.

 

[rumblefish360]

About $60 in cam bearings. IF you have the tool or know someone that does, there easy to install.

I'd just drop the block off to the machinest and have him look it over and measure it all up. Wait for his opinion on what would be best to do next. Save yourself some greif and spend some money on peace of mind.