The Ford Barn

flatford39 · 02-02-2016, 09:59 PM

Rebuilding a Mercury 8BA motor. 1953 I think. It's time to buy the pistons and it's not as easy as doing a SBC. This is a stock bore that has been bored out .030. It also has a 4" crank.

So I am looking for 3.2175 pisons that are compatible with the 4" crank.Has anyone used to .030 over Sealed Power pistons that Summit Racing is selling. They are four groove but they don't differentiate between a 4" crank and the ford 3.75 crank.

Should I be concerned??? Are there camshaft clearances with the longer stroke???

Internals on this engine will be pretty much stock.

Thanks for any help.

Diavolo · 02-02-2016, 10:19 PM

Pistons should be matched to the stroke. The rod is the same and the crank stroke will push the wrist pin higher in the bore. If you are using a 4" (255) crank, you need the matching pistons for the 4" stroke. If you don't, you will have a bad day.

If you look at the selection from Summit Racing, you will see that the only stroke offered is 3.750. Here is the link. http://www.summitracing.com/search/p...rd-flathead-v8 You need pistons for 4.000 stroke with the 4" crank.

Seek another vendor, maybe reds? I personally would go with a machinist that knows flatheads and let them buy the pistons according to my preference and do the machine work.

flatford39 · 02-02-2016, 10:22 PM

Quote:

Originally Posted by Diavolo

Pistons should be matched to the stroke. The rod is the same and the crank stroke will push the wrist pin higher in the bore. If you are using a 4" (255) crank, you need the matching pistons for the 4" stroke. If you don't, you will have a bad day.

If you look at the selection from Summit Racing, you will see that the only stroke offered is 3.750. Here is the link. http://www.summitracing.com/search/p...rd-flathead-v8 You need pistons for 4.000 stroke with the 4" crank.

Seek another vendor, maybe reds? I personally would go with a machinist that knows flatheads and let them buy the pistons according to my preference and do the machine work.

Thank you...That's what I thought. Look's like I will give Van Pelts a call in the AM.

Ronnie · 02-02-2016, 11:00 PM

I believe the sealed power number is W1014p but I think they are only available in .040" no other sizes.

The badger number is P135 ask the members here someone may have them they came in lots of over size's.

R

flatheadmurre · 02-03-2016, 03:34 AM

An Egge set not sure how customs and shipping will turn out.
http://www.ebay.com/itm/Ford-Mercury...pVtrQ1&vxp=mtr

Mac VP · 02-03-2016, 06:00 AM

Sponsored Links (Register now to hide all advertisements)

The size you gave is 0.300" over standard......you sure that is correct? Or are you looking for 0.030" oversize? We should have the.030" in stock. I sure don't have .300"........

34PKUP · 02-03-2016, 07:44 AM

Quote:

Originally Posted by Mac VP

The size you gave is 0.300" over standard......you sure that is correct? Or are you looking for 0.030" oversize? We should have the.030" in stock. I sure don't have .300"........

Oooop's, too early in the morning?

Walt Dupont--Me. · 02-03-2016, 07:56 AM

If your using a 4 inch crank you have to use a piston that is 1/8 shorter from the center of the wrist pin to the top of the pistons than the 3-3/4 crank piston. Walt

GOSFAST · 02-03-2016, 09:25 AM

Don't know your budget but can help with some really nice Ross forged pieces for the 4.000" stroke and a finished bore of 3.228", these would be +.040 over and have the special "moly" metric ring pack.

They help with the balancing operation being only 316 grams with a 120 gram pin and a 30 gram ring set. The cast 4-ring pistons weigh over 400 grams and use some 65 gram rings.

These Ross pistons (see below) are more expensive than the conventional cast/4-ring pieces but are well worth the cost for what they add to the build. We do stock the cast pieces also but only in +.030's or +.060's with the 4 "cast" rings!

Thanks, Gary in N.Y.

P.S. These pistons with the metric rings free-up a whole bunch of HP in the Flatheads whether your looking for it or not. This is the ONLY size I keep available here (forged) for the 4.000" stroke.

Bored&Stroked · 02-03-2016, 07:49 AM

3.2175 is .030 over . . . but maybe he want back and changed the number?

34PKUP · 02-03-2016, 07:52 AM

Quote:

Originally Posted by Bored&Stroked

3.2175 is .030 over . . . but maybe he want back and changed the number?

Nope, post would have shown that it was edited.

Bored&Stroked · 02-04-2016, 07:19 AM

I checked the Summit site - all the Sealed Power pistons that they show have a compression height of 1.519 inches - which is wrong. They showed them as 8BA replacements, so they would be for 3 3/4 inch stroke. The "off the shelf" compression height for 3 3/4 stroke is 1.561", for 4" stroke it is 1.436". I have no clue where they came up with 1.519?

You should checkout VanPelt's site - he has a part number of EAC-6108S-040 that is what you're looking for.

http://www.vanpeltsales.com/FH_web/e...prices-pg1.htm

Side Note: On my recent 42 Merc stroker engine, I had Ross make a set of pistons with my exact compression height, 1.5mm, 1.5mm, 3.0mm ring grooves, lightweight pins and they also supplied a set of TotalSeal moly piston rings. I've used TS rings on other OHV builds - decided to just try them for shits and giggles on a flathead . . . will be interesting to do a leakdown once the motor is broken in.

02-02-2016, 09:59 PM	#1
flatford39 Senior Member Join Date: May 2010 Location: NE Illinois Posts: 499	Some advice on 8BA pistons Rebuilding a Mercury 8BA motor. 1953 I think. It's time to buy the pistons and it's not as easy as doing a SBC. This is a stock bore that has been bored out .030. It also has a 4" crank. So I am looking for 3.2175 pisons that are compatible with the 4" crank.Has anyone used to .030 over Sealed Power pistons that Summit Racing is selling. They are four groove but they don't differentiate between a 4" crank and the ford 3.75 crank. Should I be concerned??? Are there camshaft clearances with the longer stroke??? Internals on this engine will be pretty much stock. Thanks for any help.

02-02-2016, 10:19 PM	#2
Diavolo Member Join Date: Jan 2011 Posts: 67	Re: Some advice on 8BA pistons Pistons should be matched to the stroke. The rod is the same and the crank stroke will push the wrist pin higher in the bore. If you are using a 4" (255) crank, you need the matching pistons for the 4" stroke. If you don't, you will have a bad day. If you look at the selection from Summit Racing, you will see that the only stroke offered is 3.750. Here is the link. http://www.summitracing.com/search/p...rd-flathead-v8 You need pistons for 4.000 stroke with the 4" crank. Seek another vendor, maybe reds? I personally would go with a machinist that knows flatheads and let them buy the pistons according to my preference and do the machine work.

02-02-2016, 11:00 PM	#4
Ronnie Senior Member Join Date: May 2010 Location: Canada Where it snows Posts: 2,059	Re: Some advice on 8BA pistons I believe the sealed power number is W1014p but I think they are only available in .040" no other sizes. The badger number is P135 ask the members here someone may have them they came in lots of over size's. R Last edited by Ronnie; 02-03-2016 at 10:12 AM.

02-03-2016, 03:34 AM	#5
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: Some advice on 8BA pistons An Egge set not sure how customs and shipping will turn out. http://www.ebay.com/itm/Ford-Mercury...pVtrQ1&vxp=mtr

02-03-2016, 06:00 AM	#6
Mac VP Senior Member Join Date: May 2010 Location: Cincinnati, OH Posts: 1,430	Re: Some advice on 8BA pistons Sponsored Links (Register now to hide all advertisements) The size you gave is 0.300" over standard......you sure that is correct? Or are you looking for 0.030" oversize? We should have the.030" in stock. I sure don't have .300"........ __________________ VANPELT SALES LLC Cincinnati, Ohio Office: 513-724-9486 www.vanpeltsales.com www.classictransmission.com

02-03-2016, 07:56 AM	#8
Walt Dupont--Me. Senior Member Join Date: May 2010 Location: Gardiner Me. Posts: 4,200	Re: Some advice on 8BA pistons If your using a 4 inch crank you have to use a piston that is 1/8 shorter from the center of the wrist pin to the top of the pistons than the 3-3/4 crank piston. Walt

02-03-2016, 07:49 AM	#10
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,723	Re: Some advice on 8BA pistons 3.2175 is .030 over . . . but maybe he want back and changed the number?

02-04-2016, 07:19 AM	#12
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,723	Re: Some advice on 8BA pistons I checked the Summit site - all the Sealed Power pistons that they show have a compression height of 1.519 inches - which is wrong. They showed them as 8BA replacements, so they would be for 3 3/4 inch stroke. The "off the shelf" compression height for 3 3/4 stroke is 1.561", for 4" stroke it is 1.436". I have no clue where they came up with 1.519? You should checkout VanPelt's site - he has a part number of EAC-6108S-040 that is what you're looking for. http://www.vanpeltsales.com/FH_web/e...prices-pg1.htm Side Note: On my recent 42 Merc stroker engine, I had Ross make a set of pistons with my exact compression height, 1.5mm, 1.5mm, 3.0mm ring grooves, lightweight pins and they also supplied a set of TotalSeal moly piston rings. I've used TS rings on other OHV builds - decided to just try them for shits and giggles on a flathead . . . will be interesting to do a leakdown once the motor is broken in.