DragStuff

I had a machinist I briefly talked to today tell me that I would be extremely lucky if I tore my engine down and it did not need bored w/ 15-20% leakage.

I am starting a poll to holpfully ease my mind...but maybe it won't. I'll report my findings. I hope to tear it down this weekend. I have bartered a case of beer for an in home visit from an ex-machinist to check for out of round and taper.

Got the engine torn down. The rings had .035 gap on the top. I also noticed the intake valve that I found that is hanging open is double springed where the other intakes are not apparently there was a known problem there...hopefully it can be fixed.

My friend is coming Sunday...we'll see what the verdict is.

What was your piston-to-wall clearance? More importantly how far out of round are the cylinders?

We will be checking that Sunday, my friend is bringing the tools to do so. The ring ridge feels the same all the way around to me, but my finger is no bore indicator

Its D-day, how is it going??

Ridge = time to bore it.

sc racing wrote:Ridge = time to bore it.

Im with you on this one, if you have any ring ridge, probably should bore it.

Well, he said the cylinders are .001 out of round. Piston to wall was .004 to .006 depending on where he measured the piston. He felt I would probably be ok to hone it and put some rings in it. I explained I was in no way trying to make a choice piece. I am just trying to keep it from smoking and make it another year. My oil control rings had very little tension he said.

As for the crank...it's toast. The rods were .010 under the mains were .020 and they need cleaned up. Luckily a friend said he has another steel one that I can have On the down side now it will need rebalanced.

The heads seem to need valve guides, you can wiggle them side to side a bit. Hopefully I just need guides? Don't have the money for valves.

As far as the ring ridge...it seemed to be composed of oily gook, not really a ridge in the wall itself. When I took the pistons out went around the ridge quick with some red scotch brite, they tapped right out.

Regarding my leak down test...I may not have had the engine warmed up all the way. It is most likely I pulled it out of the trailer and backed it into my garage and started testing. That and I could never seem to hold the crank in the right place, whomever had that engine before me damaged the balancer bolt threads. So I'm a bit happy that crank is going bye bye. But bummed I'll have to have things rebalanced.


Hopefully I don't sound like to much of a dumba$$ but I no very little about the machining side of things. Right now money is on the tight side, I'd love to build a 496 but it's not in the cards - and I can't warrant buying pistons for a 396 or doing any extensive machining to my current block. Later this year I'll be doing better as I am doing some software consulting on the side...so hopefully I can buy a rail car at the end of the year

With the current info you just gave it does sound like its in good shape and if it was mine I would just do the hone and new rings. A freind of mine had a 427 crank turned .030-.040 he ran 9.80's spraying 200hp it was fine but a free crank and rebalnce isnt much more than getting yours fixed. You should be up and running without too much $$$ keep us posted.

Thanks for the input. My heads will set me back $337. That's dis-assembly, cleaning, new guides, valve job, setting spring height and re-assembly. The crank I'm confused about. One shop was $200 to turn and $120 to spin balance. Another is $120 to turn and $150 to balance. I trust both shops...but I'm not sure what the swing is about in the different crank turning prices.

Most shops dont do cranks they send them somewhere, maybe they use different places also one might be index grinding it (which is what you want) the other might just be regrinding like in a stock rebuild.

If you don't mind me not beating around the bush and giving you straight answers.

There is only one place to measure pistons for sizing.
Any ridge is bad for a number or reasons and if you are changing any parts the ridge must be removed.
Piston to wall clearance is based upon ap not, OEM, unless it is an OEM. I assume this is a toy or racecar.
Cranks can be turn 0.020 or more. I am not a big fan or it but, if on a budget it could be done.
The 396/402/427/454 often have damage in the number 4 saddle.
Check the block very carefully and the crank also.
Last use the correct tools. It scares me to see plasticgage or any other bs.
Mic's were make for a reason. Again clearances are a design of purpose not OEM spec.
Good luck with the build.

Most of the measuring was done 90 degrees to the pin at the bottom of the skirt. One of the pistons had a scuff. Measuring at the scuff increased the p2w clearance...but again, I'm just trying to get by for this season. Figuring that it was running fine w/ no noises I am opting to put it back together w/ the scuffed piston. I'm almost wondering if 80% of my smoking rests in the worn out valve guides.