Piston clearence dilemma
 

...bought a 67 428 4 bolt block.. ready for machining..and boring to 0.030...stock crank ...bought eagle rods and 0.030 piston from Dss racing,,,the whole assembly was professionally balanced... and now the shocking experience the 428 block had a crack was not seen until the machining process..long story block is not use able... got an other 428 block which was already bored to 0.030 but was a running engine..,so want to use this block but after honing...it was confirmed the piston clearence was to much now...piston from Dss call for 0.003 or o.oo4 clearence (4032 material) but now it works out 0.006....alot more .too much in my opinion......but now im very pissed cause have no other 428 block theyre rare enough....dont know what do ...running at that much clearence ..or not..?

Cracked 428 block on the Street might run forever?
2mil over (1mil/side) 428 block might seal on the Street forever?

Might just rattle some until wormed up.Tom

Ill think it nayve rattels when warm also...

.maybe...

You didn’t say where the crack is. In the cylinder? Put a sleeve in it.

FWIW, my 406 is up to about .007 after a few hones and rebuilds. Arias forged pistons, gapless rings. Does it rattle cold? Probably, but the exhaust drowns it out . . . .😎

Sadly its not repairable....

No assembbly.....0.007 is much for 4032 alloy or do have 2618

Fill it to the bottom of the pump holes.
.006 is the recommended clearance for my filled 400 block with Ross pistons. Remember to add .002 extra ring gap.

I'd run it! You're only talking about .002 difference, which is an extra .001 per side. It will rattle a little til warmed up, but will be fine otherwise.

Coat the piston skirts

You have to fill the water jackets before machining.

Sell the pistons and get a set of .040 over. Or send the .030 pistons you have off and get the skirts coated.

Beat me to it while I was typing

Got ahead of myself.



This company is being used by a local shop on a race BBC engine with used pistons that he wanted the clearances tightened up.
They are new to me but have been doing race pistons for awhile new. Also do roots blower screws and turbine parts.

Not anything like Calico coatings.
Line2Line Coatings

https://www.line2linecoatings.com/

FAQ https://www.line2linecoatings.com/faqs.html

This company looks to be the answer to the OPs problem and a lot of other people too.
When the local guy gets his car out to the track I will know how it worked out. Will report here.

Thanks for all your suggestion..the problem im from austria a 0040 piston would be a good option but the backside is that i had to do new balance job again ..they asking for that 1000$ ...once again plus the cost of new pistons.....maybe coating...but how long would the coating last....

You'd think a class racer would be a little quicker :D

First hand experience eighteen years and counting. Thousands of street miles, thousands of drag strip passes. Text book answer; indefinetly

Line2Line say no re balance needed.

Never thought of bracket racing as class racing. I did take a year off, getting slow.
Any experience with Line2Line ?