16 replies to this topic

[TempesT]

So I haven't been around here much of late as I have been playing with the 4x4 and my guns.

 

Today I decided to pull the wrapping off my 400 sbc block to clean and re lube the bores.

 

Anyway it turns out I didn’t wrap it so good when I was in Mackay and she had some surface rust in one of the bores.    I gave the offending area a quick emery and wd40 rub and the area had pitted the bore. 

 

The block is 0.04 over already and I was just going to have it honed and decked before I decide to build it.

 

These photos are from the top of the bore looking down at the pitting. Im not even sure it would be within the piston rings travel stroke.

So how bad it is? Would it clean up with a hone? Have I frocked it and should pencil in a new block.

[S pack]

Looks like a light hone isn't going to fix that. Bore out to 60 thou OS (if you can get 60thou OS pistons) might be enough if you're lucky or sleeve the cylinder or look for another block.

 

That said, pics can be deceiving so best to get it checked out by an expert then decide what to do.

 

Cheers

Dave.

[Bernie]

Every 400 (5 built ) I  have had has had rust stain marks after boring .To date none have had issues as far as leakage of either compression gas out or coolant in .Me I would go with it .

Bernie

[S pack]

Every 400 (5 built ) I  have had has had rust stain marks after boring .To date none have had issues as far as leakage of either compression gas out or coolant in .Me I would go with it .

Bernie

To me that looks more like the rust has pitted the bore rather than just a rusty stain mark.

[Struggler]

As you said, it may be out of the rings range of travel anyway.

 

Can't say for sure without looking at it in person but it doesn't look too bad. Worst case it may use a tiny bit of oil.

 

I am tempted to say hone it and don't lose any sleep.

[Bernie]

Is it near the siamese side or whereabouts ?

Bernie

[TempesT]

I agree that 40+ seems to be the limit that most are comfortable taking a 400 to and i don't intend on punching this block out any further.

 

Here is another pic, again taken from the bottom of the bore looking up. The pitting is located about 95mm from the top of the bore so the rings would just come into play (I would need to dig my pistons out to check).

 

This is from the top of the bore looking down. As you can see my bores have crud in them , the location of the pitting is the stain center of the picture located over the steam hole in the Siamese bore join. 

 

 

I figure that in a bad situation I'll scrub a set of rings out and have oil consumption or a lot of blow by. In which case Ill drag everything across to a different block.

[Bernie]

Don't worry about it at all .That is the thickest part of the block .It would have to be through into the other cylinder to cause issues .Whack it together and get them tyres frying

Bernie

[TempesT]

BTW that first pic was zoomed in. I was surprised that I got that good a shot of the pitting with my phone.

[TempesT]

Its just a plane jane 2 bolt

Edited by TempesT, 26 May 2013 - 09:45 PM.

[Bernie]

2 bolt is the better one to have .Only has the 2 core plugs on the side like all other smaller small blocks .(harder for Mr Plod to ruin your day) .Can also easily put splayed caps on it and turn it into a 4 bolt with much more strength around the base of the Bearing housings than the 4 bolt factory unit .Just don't get it hot .

 

Bernie