Piston/wall clearance & honing cylinders...

[33 IMP]

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!

I agree with Gary.Budjet is budget. I'd put it together and run it.
In the eighties, a friend and i ran a 440 duster with a cast piston engine with .008 piston/wall, about four times recommended. It was noisy enough from the .590 solid that you couldn't hear the piston slap, it had some blowby, and smoked a little at full throttle, but it went 11.70s at 117 at the old riverside raceway, and ran fine in limited street duty. We eventually bored it, put in forged pistons and picked up only a couple tenths.
If i remember those pistons, you're only about .002 over high end of spec.

 

[Brandy]

Thanks guys! I will have the professionals take a look at it and give me their opinions once I get good numbers on everything. Hell, I know just enough to screw it up. Better let a pro look it over.

 

[Fran Blacker]

Known zero about their products.
http://store.440source.com/Platinum-Series-Pistons-4360-4-FT/productinfo/4010/

 

[Brandy]

Known zero about their products.
http://store.440source.com/Platinum-Series-Pistons-4360-4-FT/productinfo/4010/

I saved the page, looks like I would be right in the zoom, zoom zone at 9.61CR. More or less considering gaskets and porting/polishing.

 

[wyrmrider]

I agree with Garys more than BG
running it down to the shop could cost a couple of hundred dollars which evidently he does not have
.008 is a lot but not "too much" pistons have relatively long skirts
do get the deck clearance measurement if you get a chance
Knurl works for someone without $$ for pistons and bore and hone with a deck plate
Why does he think he needs new cam bearings- if you do check for tight ones BF you put motor together
and clean out all the crap while they are out- usually best left alone unless something is evident
Now guides
I Knurl NEW GUIDES with this new unleaded gas- just to hold some oil Knurl almost all the way through but not quite- then ream and hone to size
Before unleaded we used to do this on propane motors and those breathing bad polluted air for ground pollution clean up and marine
now do it on everything
using the k-lines is easier and gives a similar result but does not live quite so long
you have to resize out of the box heads anyway why not do it right
let us know what the pro thinks (Um let me guess)

 

[wyrmrider]

Fran found some 6 pack pistons well almost
"full floating .990 pin size."
wonder what they weigh?
I prefer the step quench KB for open chamber heads
also stock TRW/ Sealed Power 6 pack pistons are way heavy
lighter pistons make a big difference- you could bush the rods for the BBC Pins if they are light

 

[Brandy]

I agree with Garys more than BG
running it down to the shop could cost a couple of hundred dollars which evidently he does not have
.008 is a lot but not "too much" pistons have relatively long skirts
do get the deck clearance measurement if you get a chance
Knurl works for someone without $$ for pistons and bore and hone with a deck plate
Why does he think he needs new cam bearings- if you do check for tight ones BF you put motor together
and clean out all the crap while they are out- usually best left alone unless something is evident
Now guides
I Knurl NEW GUIDES with this new unleaded gas- just to hold some oil Knurl almost all the way through but not quite- then ream and hone to size
Before unleaded we used to do this on propane motors and those breathing bad polluted air for ground pollution clean up and marine
now do it on everything
using the k-lines is easier and gives a similar result but does not live quite so long
you have to resize out of the box heads anyway why not do it right
let us know what the pro thinks (Um let me guess)

The cam bearings looked pretty scorched. I was advised that only a fool would reuse cam bearings. Plus the Crane that was in it got wiped by a stuck lifter and the fall out from that went everywhere in the block so better safe than sorry.

 

[Brandy]

I may end up going .040. Have to see. Money is tight, just put a new standing seam roof on the cabin, $22,000 bucks.

 

[wyrmrider]

In that case. lots of trash, new cam bearings, but check with a cam prior to leaving the shop- one is usually tight
strip block completely including lifter/oil passage plugs and brush out everything after hot tank
B4 hot tank open up oil feed to mains (I've found broken off drill bits in the passage with the only oil around the flutes)
If you have a stick shift drill a .041- .061 through the cast iron into the oil feed through the rear (pressure side) of the crank thrust es-ecially on a stick- I've had several thrusts go bad over the years (later drill your new main bearing and chamfer the parting lines to the rear on the thrust bearing) The crank thrust tends to make the oil go out the front instead of out the rear where it's needed
make sure the oil galley plugs in the front are drilled not only for cam chain oil but to vent foam and air from the oil galley
get a cheap bottom tap or grind an old tap and bottom tap the mains - sometimes they are incompletely drilled and/or tapped
the factory resharpens tools and you may get one that is about out of spec
use tap or cutting oil- do it dry something can break (well it can break anyway but improve your odds)
did you check the deck height on all four corners yet- dial caliper $10 at harbor freight will do it close enough
or put it back together and save your money for the next build
have pistons in hand b 4 any boring/ honing and make sure they have a torque plate

dam nice looking log job

 

[condor74]

One option is to buy some nos old school forged pistons .030 over. Old forged pistons required large piston to cylinder wall clearance. I just recently built my 383 with NOS Direct Cinnection 11.5 to 1 forged pistons. They required .010 clearance on the cylinder wall. It makes a but of noise cold but quiets up pretty quick as it warms up. If you do that you can have the bored finish honed professionally to fit your pistons and have arrow strait bores. Just an option.

 

[dvw]

Ideally you'll like to have perfect ring seal. But you already own the parts you have. Ran good enough for you before? No reason to believe it shouldn't runt the same. Ideal, no. Perfect, no. Will it run, sure. Dingle ball hone, clean well and go.
Doug