Piston/wall clearance & honing cylinders...

[Don Frelier]

CORRECTION, since it's a 440 original bore is 4.32 then maybe it was bored .020"?
Since (4.32 + .04 = 4.36) pretty close to what you measured.
I was thinking of a 383 (4.25 + .120 = 4.375).
My apologies.
Which is good you can always bore it later when you hit the lottery!

 

[Brandy]

So it sounds like the motor was already bored .060 over. Given that, it ran OK before you tore it apart and most importantly your budget.
Sounds like you are making the right move. Hopefully it runs real well when you get it all back together.

No. it was bored .030 over and the pistons have .030 stamped on the faces. I don't want to change that, just want to clean up the bores and put new rings on and go. Was only wondering about the .008 clearance between piston skirt and wall and whether that was a lot or normal in order to maybe get a sense of how much use this motor got after being bored 30 over. The other thing is the carb was very dirty and improperly adjusted, so having rebuilt that and applying correct adjustments I hope it runs better. I cant find anyone with a 4 5/8" ball flexhone I can use so I guess I will have to wait till I can buy one, damnit.

 

[Brandy]

The PO did some cylinder head work, badly, and that gave it a bit more HP. I have since cleaned up his work and finished them out. So I expect it to have some good HP and TQ once I have it back together. A flex hone and cam bearing tool are things you may only ever use once. I hate to buy the damn things if I could borrow them one time. My pal up the road doesn't have them, he sent his 400 off to the machine shop, he has money. I'm doing everything myself.

 

[Fran Blacker]

No. it was bored .030 over and the pistons have .030 stamped on the faces. I don't want to change that, just want to clean up the bores and put new rings on and go. Was only wondering about the .008 clearance between piston skirt and wall and whether that was a lot or normal in order to maybe get a sense of how much use this motor got after being bored 30 over. The other thing is the carb was very dirty and improperly adjusted, so having rebuilt that and applying correct adjustments I hope it runs better. I cant find anyone with a 4 5/8" ball flexhone I can use so I guess I will have to wait till I can buy one, damnit.

Those one time tools are tough. Trans tailshaft bushing puller $135.

 

[Brandy]

You can see everything on my build thread, The Yankee Express.

 

[69Bee]

If a bore & hone is $1200, I need to move my shop there... Check with Autozone for rental tools. Leave a deposit, and get it back when you return the tool. I charge $2.50 a hole to deglaze with the ball hone, 65 to clean and strip, $30 to install the cam bearings, and $15 for the freeze plugs if needed. Maybe the local shop could deglaze and install cam bearings if AZ doesn't have the tool.

 

[miller]

If your at .008 clearance, it's too much. Are you measuring the pistons at the skirt? That's usually measured about 1" up from the bottom of the piston. I usually fit mine for .0025, but like mine a little loose.

Much more than than, you deal with rings having a hard time seating, besides piston slap. Just saying...
Whatever you do, I'd consider new rings, hand fitted, cutting for the gap you want.

 

[MoparLeo]

Or load up your parts and pay a machine shop to measure everything for you. Then you can go home and do some soul searching on what to do next. At least you will have accurate numbers to make your decision with. If you need more money, think about selling something that you can live without. eBay, C.L. etc. are places to sell on.

 

[Brandy]

Or load up your parts and pay a machine shop to measure everything for you. Then you can go home and do some soul searching on what to do next. At least you will have accurate numbers to make your decision with. If you need more money, think about selling something that you can live without. eBay, C.L. etc. are places to sell on.

I have been doing that. Want to buy a transmission?

 

[MoparLeo]

What is it and are you advertising it somewhere ?

 

[Brandy]

Yes, here on FBBO. There are two of them, one's a 1966 BB 727 and the other a 1967 smb 727. The smb has 69,000 miles on it and the bb 727 I don't know. I intended to rebuild it but found out it's the wrong year. I have one now i'm going to use. $100 each plus shipping. In zipcode 05769.

 

[wyrmrider]

If you are really at.008 dbl check with some long feeler gauges since you do not have the correct mic and dial bore guage setup
Bottle brush
knurl the non thrust side of the pistons
cast rings
It'll run long enough to save some money and do it right
what's your deck clearance?

 

[Brandy]

If you are really at.008 dbl check with some long feeler gauges since you do not have the correct mic and dial bore guage setup
Bottle brush
knurl the non thrust side of the pistons
cast rings
It'll run long enough to save some money and do it right
what's your deck clearance?

Tons. On the pin depth ruler it looked like 6.75 cm. But I don't think i'm reading the right scale, maybe mm.

 

[miller]

check with some long feeler gauges since you do not have the correct mic and dial bore guage setup

It would be better, to be accurate, to run the block down to a machine shop. They have what it takes, to check the bores, and tell you what's what.
But, down and dirty, ball park, as wyrmrider says, feeler gauges. Only need the piston skirt in the hole, leaving the pin hole top side, then gauge it. That's the measurement you need. 90 degrees from the pin hole.

 

[Brandy]

That's the measurement I got.... .008.

 

[wyrmrider]

see number 32
find a shop with a piston knurlier (is that a word spell check)

 

[Hemirunner]

You could ball hone it which won’t take out any appreciable material and run it which will be slightly noisy on cold start up and be fine once warm or you can send the pistons in and have an abradable skirt coating applied which would probably cost as much as a new set of TRWs.

 

[Brandy]

VT Engine says they will hot tank and clean it up like new and replace the cam bearings for $206. While it's up there i'll have them look it over and give me their recommendations.

 

[69Bee]

I know some of you will call bullshit and disagree, but here goes anyway. Knurling pistons (and guides) is from a time long past, and quite frankly, isn't done anymore for the most part. You might find a shop that has to blow the dust off on one to do it, and hope that someone is old enough to know how to use it, but I wouldn't. It falls into the same category as the brake shoe re-arching grinding machine. If a piston or guide needs to be knurled to make it fit better, it is time to REPLACE it. If a piston is too loose, I bore & hone the cylinders, and if a valve guide is worn, I install replacement guides. I won't even knurl guides if asked. It is not worth doing a Band-Aid repair when you have to do it all over again soon. This ain't 1955 anymore so pay to do it once, and do the job properly.

 

[Garys1969RR]

If you don't mind some piston slap noise, I say Go For It! If it was running good before, should be better with new rings and a glaze breaker hone job, plus the other upgrades will help. I have been told, and I think a loose piston (.008) may run better in a racing application. I personally don't like the noise from a loose piston, especially on a street motor. Plus a loose piston rocking in the bore, doesn't seal the combustion pressure as well as a tighter fit does. Slap it together, and let us know how well it runs!