The Ford Barn

luvmyclassics · 06-04-2018, 12:06 PM

I am attempting my first flathead engine build.

When I put in the first piston I noticed this slot on the dome head.

From what I am reading I think it might be a fire slot? Not really sure.

If it is a fire slot I guess I have it facing the wrong direction.

Appreciate any help. Thanks.

flatjack9 · 06-04-2018, 12:08 PM

That should point to the front of the engine.

Ggmac · 06-04-2018, 12:35 PM

Who hung your Pistons ?

Mart · 06-04-2018, 12:43 PM

That is just a marker to indicate the front of he piston.

Bored&Stroked · 06-04-2018, 02:38 PM

Since this is your first flathead, a couple things to know (really this applies to any engine):

1) Rod Orientation: -- depending on the engine year, rod type, etc - usually there is a specific way the rods need to go into the engine. The issue is that many have a larger radius/fillet on one side of the rod (big-end) than the other -- this is designed so that the rod doesn't drag on a fillet on the crankshaft journal. So - if there is a fillet, it goes toward the outside of each journal - one rod is oriented one way, the other the other way (always pointing to the outside). Some rods also have oil spray holes - designed to lubricate the cam and/or bore in a specific manner . . . such that they need to be installed in the correct orientation.

2) Piston Orientation: Given that your pistons have a notch in them, as others noted - the notch almost always goes toward the front of the engine. Usually any writing on the piston will be "right side up" - such that you can easily read it when the piston is in the right orientation.

3) Ring Orientation: The rings should be rotated such that the various end-gaps are not aligned (top to bottom). Depending on whether or not your block is relieved (yours is not), then you also don't want the end-gaps to be orientated toward the relief area - as it makes it really easy to break a ring during piston insertion. (It is hard to get rings by the relief area in general - I use a wooden 'paint stick helper' on my race style engines.

Given the above, it is very important that the pistons/rods/rings are correctly assembled - or you can cause some BIG problems . . . ones that can ruin a brand new engine in a very short period of time.

Good Luck - Keep the Questions Coming . . .

B&S

GordonC · 06-08-2018, 09:37 AM

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Also if the rods and caps were stamped with the numbers of the cylinders the number faces out towards the oil pan rail.

Ritzy1 · 06-08-2018, 09:52 AM

Here's a pic of my newly completed short block showing those marks on the pistons facing forward.

revkev6 · 06-08-2018, 09:57 AM

btw, those are words to live by, but only REALLY matter if the piston pin is offset in the bore. the 8ba I pulled out of my roadster because it had a couple cracks in the exhaust ports was run for 25 years with one bank of pistons installed backwards! quiet as a mouse and smooth running motor.

this motor is going to be a test platform for a blower setup I'm making cracks and all... guess what?? I'm leaving the pistons as is...

Ol' Ron · 06-08-2018, 12:14 PM

The ford crank is also offset in the block. Back in the 60's we reversed the pistons to improve power. One of the approved mods allowed in the stock division. I did this on my 392 Hemi with Craine 292 H cam. The power above 4000 was hard to believe. Not sure why?? Off set pistons ware used to quite the engine.

06-04-2018, 12:08 PM	#2
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,527	Re: Flathead Engine Build That should point to the front of the engine.

06-04-2018, 12:35 PM	#3
Ggmac Senior Member Join Date: Jul 2016 Location: Lake worth Florida Posts: 1,104	Re: Flathead Engine Build Who hung your Pistons ?

06-04-2018, 12:43 PM	#4
Mart Senior Member Join Date: May 2010 Location: Solihull, England. Posts: 8,755	Re: Flathead Engine Build That is just a marker to indicate the front of he piston.

06-04-2018, 02:38 PM	#5
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,070	Re: Flathead Engine Build Since this is your first flathead, a couple things to know (really this applies to any engine): 1) Rod Orientation: -- depending on the engine year, rod type, etc - usually there is a specific way the rods need to go into the engine. The issue is that many have a larger radius/fillet on one side of the rod (big-end) than the other -- this is designed so that the rod doesn't drag on a fillet on the crankshaft journal. So - if there is a fillet, it goes toward the outside of each journal - one rod is oriented one way, the other the other way (always pointing to the outside). Some rods also have oil spray holes - designed to lubricate the cam and/or bore in a specific manner . . . such that they need to be installed in the correct orientation. 2) Piston Orientation: Given that your pistons have a notch in them, as others noted - the notch almost always goes toward the front of the engine. Usually any writing on the piston will be "right side up" - such that you can easily read it when the piston is in the right orientation. 3) Ring Orientation: The rings should be rotated such that the various end-gaps are not aligned (top to bottom). Depending on whether or not your block is relieved (yours is not), then you also don't want the end-gaps to be orientated toward the relief area - as it makes it really easy to break a ring during piston insertion. (It is hard to get rings by the relief area in general - I use a wooden 'paint stick helper' on my race style engines. Given the above, it is very important that the pistons/rods/rings are correctly assembled - or you can cause some BIG problems . . . ones that can ruin a brand new engine in a very short period of time. Good Luck - Keep the Questions Coming . . . B&S Last edited by Bored&Stroked; 06-04-2018 at 07:13 PM.

06-08-2018, 09:37 AM	#6
GordonC Senior Member Join Date: May 2010 Posts: 201	Re: Flathead Engine Build Sponsored Links (Register now to hide all advertisements) Also if the rods and caps were stamped with the numbers of the cylinders the number faces out towards the oil pan rail.

06-08-2018, 09:57 AM	#8
revkev6 Senior Member Join Date: Nov 2012 Location: western Mass Posts: 365	Re: Flathead Engine Build btw, those are words to live by, but only REALLY matter if the piston pin is offset in the bore. the 8ba I pulled out of my roadster because it had a couple cracks in the exhaust ports was run for 25 years with one bank of pistons installed backwards! quiet as a mouse and smooth running motor. this motor is going to be a test platform for a blower setup I'm making cracks and all... guess what?? I'm leaving the pistons as is...

06-08-2018, 12:14 PM	#9
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,860	Re: Flathead Engine Build The ford crank is also offset in the block. Back in the 60's we reversed the pistons to improve power. One of the approved mods allowed in the stock division. I did this on my 392 Hemi with Craine 292 H cam. The power above 4000 was hard to believe. Not sure why?? Off set pistons ware used to quite the engine.