59a with Scat Set Up Your thoughts please.

[Brian]

Are you sure it's sleeved? That is a C69A block, these things have thick walls. I've just built two of them with 3 5/16 + .030 " walls myself. Ultrasonic test showed .125" wall thickness left. Thing is, with that size bore, if sleeved, you'd be into the water jackets; no support for the sleeves.

[Phil Gillespie]

Originally Posted by Brian

Are you sure it's sleeved? That is a C69A block, these things have thick walls. I've just built two of them with 3 5/16 + .030 " walls myself. Ultrasonic test showed .125" wall thickness left. Thing is, with that size bore, if sleeved, you'd be into the water jackets; no support for the sleeves.

Brian, as I was told it was sleeved. This I will check on again. Take you point on this one also. Concering entry into water jacket and no sleeve suppport.
Seems like these pistons are definitely not for this set up.
Is it"true" with a fitted blower to use flatop pistons? Or maybe another myth.
Phil NZ

[flatheadmurre]

Boring into the waterjacket when sleeving isn´t the problem.
Issue is that with such a large overbore and enough thickness of the sleeve you get no support between deck and bottom end of engine.
Blower or turbo charger doesn´t dictate the shape of the piston it´s the combustion chamber that do...lower compression for supercharging can be achieved in many ways.

[Phil Gillespie]

I understand the heads have a 74cc combustion chamber. Once I have the engine I will check some compressions first then remove heads and check clearances and go from there. Main driving will be street and highway driving. Our speed limit being 100km/hr
60mph. All things subject to change.
Thanks to all as always for sharing ideas, thoughts and knowledge always freely shared at this site.
Phil NZ

[my4dv8]

What times did it do in a previous life?

[Bored&Stroked]

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In a blown flathead, if you need a lower compression ratio, you don't do it with flattop pistons and a domed head - it is typically done with larger transfer areas, larger chambers around the valve area, etc.. The combustion chamber and pistons should both match and you still want a tight quench area - this is key.

Now, there are some piston/head combinations that are designed for flattop pistons. An example is one of the Tony Baron heads that use pop-up pistons with flat tops - with flattop chambers that are high up into the head.

[Phil Gillespie]

Originally Posted by Bored&Stroked

In a blown flathead, if you need a lower compression ratio, you don't do it with flattop pistons and a domed head - it is typically done with larger transfer areas, larger chambers around the valve area, etc.. The combustion chamber and pistons should both match and you still want a tight quench area - this is key.

Now, there are some piston/head combinations that are designed for flattop pistons. An example is one of the Tony Baron heads that use pop-up pistons with flat tops - with flattop chambers that are high up into the head.

Appreciate the information and it assists with making decisions.
Have looked up some info on Ross pistons and seems their dome height is 0.180. so it is possible it may have dome type pistons. A first hand inspection will confirm.Not sure if the flat top are special orders unlike the dome type which would be the standard configuration?
Phil NZ.

[Brian]

I run flattop Ross pistons in one of my engines [with the appropriate heads]. I got them custom made by Ross. All standard Ross flattie pistons have their own specific dome with the .180 dome height.

[Phil Gillespie]

Originally Posted by Brian

I run flattop Ross pistons in one of my engines [with the appropriate heads]. I got them custom made by Ross. All standard Ross flattie pistons have their own specific dome with the .180 dome height.

Yea when I get the engine, see it for myself, check it and see for sure piston type. If flat top will go for the standard dome type and fit these. As I would not be happy running a set up that is not compatable. Seems dome height of Edelbrock heads are compatable with these Ross dome pistons. Max
Phil NZ

[my4dv8]

Yes Phil , we went from Navarro heads to Edelbrock .with the bigger cubes the compression with Navarro would have been too high for what we wanted,can’t remember the numbers now but Edelbrock and ross pistons was a good combo.

[Bored&Stroked]

Edelbrock uses a consistent radius dome - so they should match the standard Ross pistons. What can't be known is if the compression height of their 'off the shelf' pistons is such that with the typical .052 thick head gasket, that you'll have .040 to .045 over the pistons (quench area). If you don't, then you can mill the heads a bit.

If you end up needing new pistons, you can measure the actual compression height that is needed and Ross will move the piston pins to give you the exact pin location that is required - for the .040 to .045 clearances. They will do this for a nominal fee (if you call them directly). Talk to 'Ed' he is a good guy and has helped me with custom piston orders.

[Bored&Stroked]

Originally Posted by Brian

I run flattop Ross pistons in one of my engines [with the appropriate heads]. I got them custom made by Ross. All standard Ross flattie pistons have their own specific dome with the .180 dome height.

Sounds like you're having some fun with a 21 stud early motor???

[Phil Gillespie]

Originally Posted by Bored&Stroked

Edelbrock uses a consistent radius dome - so they should match the standard Ross pistons. What can't be known is if the compression height of their 'off the shelf' pistons is such that with the typical .052 thick head gasket, that you'll have .040 to .045 over the pistons (quench area). If you don't, then you can mill the heads a bit.

If you end up needing new pistons, you can measure the actual compression height that is needed and Ross will move the piston pins to give you the exact pin location that is required - for the .040 to .045 clearances. They will do this for a nominal fee (if you call them directly). Talk to 'Ed' he is a good guy and has helped me with custom piston orders.

.

I had planned on checking to ensure I get this 40 to 45 clearance once I have checked piston type and some compressions prior to head removal. Milling heads as required is in the plan also.
Our Virus Level is now dropping to Level 2 so this will now enable engine & transmission to be shipped from North Island to my location in South Island.
Phil NZ

[Ol' Ron]

Once you have the heads finished and bolted onto the block. You can measure the clearance by using a piece of rosin core soder theugh the spark pluh hole to measure the clearance you ended up with.

[Brian]

Sounds like you're having some fun with a 21 stud early motor???


Dale, I only build two specific engines; 21 stud and for my big cube motors, C69A

[Phil Gillespie]

Just contacted Ross who tell me they engrave the pistons, probably at underside.
This is their ID for specs of piston so another area to be checked.
Phil NZ

[Bored&Stroked]

Originally Posted by Brian

Sounds like you're having some fun with a 21 stud early motor???


Dale, I only build two specific engines; 21 stud and for my big cube motors, C69A

Hey Brian, sounds like you've managed to "contain your madness" for these darn engines to a select few models --- smart man! Maybe I need to take your focus to heart in my own flathead world! LOL

PS: I have never built a 21 stud engine (though I have a few). I might pickup a 36 LB that I know of - just for the heck of it. Been kind of wanting to build one for awhile . . .

[Lawrie]

The 21 stud engines in my lot are the smoothest engines,
Maybe its the low comp
Lawrie