To Bore or Not to Bore?

[Wayne G.]

Searches did not yeild much on this. After inspecting the bores on my block
they look very good (a slight amt of cross hatch left) and no ridges marks etc. They all measure within 82.99 mm to 83.01 mm. Would you suggest just going back with stock size and light hone or go ahead with rebore (+.020) and oversize pistons. I will be using either JE or Weisco pistons. Machine work seems to be expensive in my area (Atlanta) compared to what I see others have paid. Block rebore $250 from what I have found localy. What do you guys think?

 

[MmmBoost]

the only reason to rebore is if there is damage to the finish on the cylinder walls. if you have a cylinder gauge, have you checked the bore at several different angles? and also at 1" increments going from top to bottom? if they are in good condition, you only need to hone(de-glaze) to get a good crosshatch for the new rings to seat and thats all.

also, boring out a block takes away metal between cylinders and in some cases can lead to overheating. not something i would do unless absolutely necessary on the 7m

 

[jdub]

You need to measure the cylinder bore per pages EM-74 & 75 in the TRSM:
http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?Section=EM&Page=74

If the cylinders are in spec, a hone is all you need and std size pistons will be fine. I do highly recommend you get the crank journal micro polished and the rods re-sized...balancing the crank and rod/pistons is also an excellent idea as well IMO. Another place I would put my $$$ is in a line hone for the mains and ARP hardware for the main and rod caps....both would have to be installed and torqued to ARP spec prior to a line hone or re-size.

Get a new oil pump
ARZ is selling a nice hard line upgrade to the crank case oil lines...check the "curing oil issues thread"
http://www.supramania.com/forums/showthread.php?t=31378&page=6

 

[starscream5000]

There should no problem whatsoever with overheating a supra do to boring the block out. The only reason it would do this would be due to improper HG installation or a tired cooling system in need of a refresher (new parts, hoses, rad., etc.).

If you do not have the means to measure the bore diameter from several angles/depths, then take it to a machinist and they will be able to tell you if a bore is in order .

Damn, I'm slow today , must be me trying to work and post at the same time eh?

 

[Wayne G.]

Very good info, it is appreciated. I have found a shop that does machine
work that is within reason. They do lots of work on 2jz and have done a
number of 7ms as well. I have a pile of new parts :suspension, brake, engine
body, etc. to go on this car. Will start a build thread soon. Cheers,

 

[starscream5000]

You can mail all of those parts to my address if you like, I'm in need of all the above .

 

[Supracentral]

Very good info, it is appreciated. I have found a shop that does machine
work that is within reason. They do lots of work on 2jz and have done a
number of 7ms as well. I have a pile of new parts :suspension, brake, engine
body, etc. to go on this car. Will start a build thread soon. Cheers,

I didn't realize you were in Lawrenceville. I'm in Buford, we're probably 10 minutes away from each other.

Which shop?

 

[bigaaron]

Make sure check the bore in at least 3 places on each cylinder. We've seen some cylinders with as much as .003" taper, and they looked just fine visually. I would go .020" over, unless the engine was rebuilt recently and already bored. The people who say not to bore the cylinders are the ones who would have a new engine they just rebuilt that smokes and/or uses oil, and blame it on the turbo or the valve seals.

 

[bwest]

One thing to make sure (pending which brand of piston and piston type) is making sure you can maintain the correct piston/wall clearance after a quick scuff. You 'should' be fine with any forged replacement, but I would buy them from a source you could return them to in case they would not yield a correct clearance after the hone.

Maybe overly cautious, but it would suck to get stuck with a set of $600 beer coasters. Good luck.

 

[bigaaron]

You could have them coated. :icon_wink

 

[bwest]

always a comedian in the crowd...:icon_bigg

 

[bigaaron]

I wasn't joking. :biglaugh:
You can add .001" or maybe .002" with a piston coating rather then buying a different set.

 

[Wayne G.]

I didn't realize you were in Lawrenceville. I'm in Buford, we're probably 10 minutes away from each other.

Which shop?

Its called Eagle Machine and their on Hwy 8 in Winder. I was refered to them
by Battle Ground Engineering in Smyrna. They use them for all the machine work. By the way my brother works for Bill Heard Chevrolet in Buford so I
know the area.

 

[Wayne G.]

One thing to make sure (pending which brand of piston and piston type) is making sure you can maintain the correct piston/wall clearance after a quick scuff. You 'should' be fine with any forged replacement, but I would buy them from a source you could return them to in case they would not yield a correct clearance after the hone.

Maybe overly cautious, but it would suck to get stuck with a set of $600 beer coasters. Good luck.

Yes you are correct - this is what I was afraid of thats why I asked. I may
just bite the bullet and do without food and get it rebored-----

 

[Supracentral]

Its called Eagle Machine and their on Hwy 8 in Winder. I was refered to them by Battle Ground Engineering in Smyrna.

I've never done business with Eagle, but they have a decent reputation.

For a personal recommendation, I only use:

Bryan Maloof Racing, Inc.
2860 Buford Highway Suite D, Duluth, GA 30096
Phone: (770) 622-4979

This man has incredible attention to detail and he doesn't need any "coaching" to get the job done right. In the 20+ years I've been building & racing cars, I have never found a better machinist/engine builder.

Bryan is familiar with the JZ & M series Toyota motors and has built a ton of them.

He has been the machinist on every 1000 + RWHP MKIV I've laid hands on in the last 5 years.

He is still the builder for my old race team (current NDRA World Champs for pro street tire). At 1,200 + rwhp, the motors last a full season or more. The guy is good, really good.

I can't say enough about the quality of his work or his professional integrity.

 

[Wayne G.]

I've never done business with Eagle, but they have a decent reputation.

For a personal recommendation, I only use:

Bryan Maloof Racing, Inc.
2860 Buford Highway Suite D, Duluth, GA 30096
Phone: (770) 622-4979

This man has incredible attention to detail and he doesn't need any "coaching" to get the job done right. In the 20+ years I've been building & racing cars, I have never found a better machinist/engine builder.

Bryan is familiar with the JZ & M series Toyota motors and has built a ton of them.

He has been the machinist on every 1000 + RWHP MKIV I've laid hands on in the last 5 years.

He is still the builder for my old race team (current NDRA World Champs for pro street tire). At 1,200 + rwhp, the motors last a full season or more. The guy is good, really good.

I can't say enough about the quality of his work or his professional integrity.

Brian is very good indeed. I have talked with him however he is moving in
about 2 mos. to Clarkson Ga. shop and all and I don't know if I will be ready
with$$$ before he moves.
Whats the chance of getting you to look at what I have (engine) and give your opinion. I am only 2 miles from Gwinnett Mall. PM me if you like.

 

[bigaaron]

I've never done business with Eagle, but they have a decent reputation.

For a personal recommendation, I only use:

Bryan Maloof Racing, Inc.
2860 Buford Highway Suite D, Duluth, GA 30096
Phone: (770) 622-4979

This man has incredible attention to detail and he doesn't need any "coaching" to get the job done right. In the 20+ years I've been building & racing cars, I have never found a better machinist/engine builder.

Bryan is familiar with the JZ & M series Toyota motors and has built a ton of them.

He has been the machinist on every 1000 + RWHP MKIV I've laid hands on in the last 5 years.

He is still the builder for my old race team (current NDRA World Champs for pro street tire). At 1,200 + rwhp, the motors last a full season or more. The guy is good, really good.

I can't say enough about the quality of his work or his professional integrity.

Those type of machine shops are hard to find these days, especially with people who care about getting the job done right! Sounds like a great shop.

 

[ViR2]

its just my luck, i'm also rebuilding my engine and I would like to go with forged internals. My engine has 256 000km's on it, and what bore should i go with? What are cons and pros of STD vs. 0.25 over???

 

[Wayne G.]

its just my luck, i'm also rebuilding my engine and I would like to go with forged internals. My engine has 256 000km's on it, and what bore should i go with? What are cons and pros of STD vs. 0.25 over???

Seems most pistons come in Std. or .020 over my block is a very low milage
JDM unit and I still will probably bore. With 256k miles (wow) plan on a rebore.

 

[Supracentral]

Brian is very good indeed. I have talked with him however he is moving in about 2 mos. to Clarkson Ga. shop and all and I don't know if I will be ready with$$$ before he moves.

Clarkston is so much cheaper than Duluth it will ensure he stays profitable for a long time. Personally, I'd deal with getting the motor to Clarkston rather than deal with anyone else. Bryan won my loyalty a long time ago.

I am only 2 miles from Gwinnett Mall. PM me if you like.

I live behind Mall of Ga. I'll shoot you a PM.

its just my luck, i'm also rebuilding my engine and I would like to go with forged internals. My engine has 256 000km's on it, and what bore should i go with? What are cons and pros of STD vs. 0.25 over???

Read this:

http://www.supramania.com/forums/showpost.php?p=180360&postcount=10