The Ford Barn

JSeery · 02-24-2020, 05:33 PM

I have some 59a numbers, I don't mess with 8ba. From the Repair Manual Ford, Mercury & Truck V8 Engines 1937 to 1947 these are maximum ware limits.

Bore out of round .003
Bore taper .006
Piston to cylinder 6-10 lb pull .005 w/.5 feeler gauge
Rod bearings .005
Piston ring end gap .035

JSeery · 02-24-2020, 05:40 PM

Quote:

Originally Posted by AnthonyG

There’s about 4 or 5 listed on Amazon, I’ll just pick one. All come with both Red & Green.
Clearance chart for rod bearings on line?

See what you mean, I have always used the one(s) with Plastigauge trademark on them.

flatjack9 · 02-24-2020, 08:06 PM

You'll want the green and you'll want around 1 to 2 thou clearance.

Bored&Stroked · 02-24-2020, 08:35 PM

On the rods, I like to have about .015 to .002 or so - more on a race engine. On the mains, about .002 to .0025.

What type of rod bearings are you running - full-floaters or late style (49-53) tanged bearings? It is really hard to use Plastigauge with floaters - these types of bearings need to be "fitted" to the rods and crank - I can't see PlastiGauge being of much value to the full-floater process. Also, since you need clearances on BOTH sides of the full-floater bearings, plastigauge really can't tell you enough.

AnthonyG · 02-24-2020, 10:34 PM

Tanged type. Read an article on crank mains & rod bearing clearance. It was interesting. Indicated best rule of thumb is, .00075”-.001 per inch of diameter of journal is a good gauge! Then adjust for more oil pressure lean to .00075” for more HP lean more to .001”. Made sense. As my 8BA has the Merc 4” stroke crank, a 3/4” isky cam, Domed forged pistons & oversized valves I think I’ll do the .001 per in of diameter. So 2.1185 journal X .001=.0021185 or rounded .002” which is within range of what Flatjack9 & Bored&Stroked indicate.
Thx for the help guys!!

AnthonyG · 03-01-2020, 07:49 PM

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New Forged Ross Pistons installed! New gaskets & rest of assembly tomorrow. S/B running again this week. Thx for all the help & tips!

Phil Gillespie · 03-01-2020, 09:37 PM

Quote:

Originally Posted by AnthonyG

New Forged Ross Pistons installed! New gaskets & rest of assembly tomorrow. S/B running again this week. Thx for all the help & tips!

All the best. It will be a good feeling to fire it up again.
question: did you hone bores or just refit new pistons?
Phil NZ

AnthonyG · 03-01-2020, 10:43 PM

Just refitted new pistons, went w new rod bearings. Rods bearing races were line honed. With only 2000 miles on since rebuild original honing cross hatch still visible & could feel in cylinders with finger nail, was obvious engine hadn’t broken in yet. No ridge line either. Advise from several on FB & original builder was the risk of honing greater than the reward on this new an engine.

02-24-2020, 05:33 PM	#41
JSeery Member Emeritus Join Date: Nov 2012 Location: Wichita KS Posts: 16,132	Re: Installing replacement pistons I have some 59a numbers, I don't mess with 8ba. From the Repair Manual Ford, Mercury & Truck V8 Engines 1937 to 1947 these are maximum ware limits. Bore out of round .003 Bore taper .006 Piston to cylinder 6-10 lb pull .005 w/.5 feeler gauge Rod bearings .005 Piston ring end gap .035 Last edited by JSeery; 02-24-2020 at 05:43 PM.

02-24-2020, 08:06 PM	#43
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,526	Re: Installing replacement pistons You'll want the green and you'll want around 1 to 2 thou clearance.

02-24-2020, 08:35 PM	#44
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,064	Re: Installing replacement pistons On the rods, I like to have about .015 to .002 or so - more on a race engine. On the mains, about .002 to .0025. What type of rod bearings are you running - full-floaters or late style (49-53) tanged bearings? It is really hard to use Plastigauge with floaters - these types of bearings need to be "fitted" to the rods and crank - I can't see PlastiGauge being of much value to the full-floater process. Also, since you need clearances on BOTH sides of the full-floater bearings, plastigauge really can't tell you enough.

02-24-2020, 10:34 PM	#45
AnthonyG Senior Member Join Date: May 2013 Location: Pa. Posts: 2,171	Re: Installing replacement pistons Tanged type. Read an article on crank mains & rod bearing clearance. It was interesting. Indicated best rule of thumb is, .00075”-.001 per inch of diameter of journal is a good gauge! Then adjust for more oil pressure lean to .00075” for more HP lean more to .001”. Made sense. As my 8BA has the Merc 4” stroke crank, a 3/4” isky cam, Domed forged pistons & oversized valves I think I’ll do the .001 per in of diameter. So 2.1185 journal X .001=.0021185 or rounded .002” which is within range of what Flatjack9 & Bored&Stroked indicate. Thx for the help guys!! __________________ Nomad

03-01-2020, 10:43 PM	#48
AnthonyG Senior Member Join Date: May 2013 Location: Pa. Posts: 2,171	Re: Installing replacement pistons Just refitted new pistons, went w new rod bearings. Rods bearing races were line honed. With only 2000 miles on since rebuild original honing cross hatch still visible & could feel in cylinders with finger nail, was obvious engine hadn’t broken in yet. No ridge line either. Advise from several on FB & original builder was the risk of honing greater than the reward on this new an engine. __________________ Nomad