sr-71 headed 545 build

i was wondering what would be a good piston choice for my sr-71 headed 545 build planning for around 11:1 compression going to run on pump gas street strip car .
and cam choice as well. will order custom grind .
if i have to flycut pistons will do would rather find factory ones but..
4.5 stroke
6.8 rod
4.39 to 4.44 bore will pore to what i can get
i can deck block to fit as well d1ve block

I’d call Diamond Up and get the correct part and not have to hack on it.

jE, Ross, and several other offer good stuff too.

dfree383 wrote:I’d call Diamond Up and get the correct part and not have to hack on it.

jE, Ross, and several other offer good stuff too.

ya i ended up ordering a rotating assembly from kaase as well.
went with a 6.8 rod 4.39 mahle piston and a 4.3 stroke lunati crank . i decided to go to the 4.3 stroke as i have heard that the 4.5 can bring piston out on bottom and cause rocking .
now i just need to get a camshaft on spec and ordered and wait till after christmas to put it together when the parts come in .

Make sure you get the right size head gaskets for the big chamber.

https://www.429-460.com/t27219p225-jon-kaase-sr71-cylinder-heads

^Scroll down in the thread, it shows the deal.

What size intake valves did you get?

Unless you plan to re-notch a P-51 piston intake notch, a custom piston from a trusted supplier is necessary.

rmcomprandy wrote:Unless you plan to re-notch a P-51 piston intake notch, a custom piston from a trusted supplier is necessary.

yes i ended up ordering from kaase just ordered the whole rotating assembly from them .
but now i need get get a cam spec out and made for this engine .,.
any idea on the lift and dur? 521 ci

maverick172 wrote:

rmcomprandy wrote:Unless you plan to re-notch a P-51 piston intake notch, a custom piston from a trusted supplier is necessary.

yes i ended up ordering from kaase just ordered the whole rotating assembly from them .
but now i need get get a cam spec out and made for this engine .,.
any idea on the lift and dur? 521 ci

Kaase or Roger can do a cam for your engine

use as big a bore as possible with those heads.they have a 2.375 intake valve and need the space.they will put a smaller intake valve in it if you need,but thats where the power comes from.this has the dyno on 521

https://www.429-460.com/t27219p75-jon-kaase-sr71-cylinder-heads?highlight=kaase

^ I thought it was the intake also. It looks like it was the Exhaust valve that was the offender.

https://www.429-460.com/t27219p75-jon-kaase-sr71-cylinder-heads

If you scroll about 7/8 down the page Kaase shows a picture of the head with the smaller Exhaust valve from the 521 Dyno Mule.

Randy mentioned .030" offset Dow Pins but, that was never further expounded on as a solution.???

I don't know if the OP got some custom Mahle Pistons but the book ones with the 38cc dish come up to 9.77/1 compression with the 70cc heads .010" in the hole.

Nothing wrong with that, was just wondering if there are some 23cc ones out now for 11/1 compression or any smaller cc Dishes?

supervel45 wrote:^ I thought it was the intake also. It looks like it was the Exhaust valve that was the offender.

https://www.429-460.com/t27219p75-jon-kaase-sr71-cylinder-heads

If you scroll about 7/8 down the page Kaase shows a picture of the head with the smaller Exhaust valve from the 521 Dyno Mule.

Randy mentioned .030" offset Dow Pins but, that was never further expounded on as a solution.???

I don't know if the OP got some custom Mahle Pistons but the book ones with the 38cc dish come up to 9.77/1 compression with the 70cc heads .010" in the hole.

Nothing wrong with that, was just wondering if there are some 23cc ones out now for 11/1 compression or any smaller cc Dishes?

so i talked to kaase and they are going to set me up with a complete rotating assembly .
i am going to go with the mahle 38cc dished i know compression is a little lower than i like but i am going to get .003 shaved off the heads to bring it up a little . so after some research looks i can go with a 4.67 bore gasket so the combustion chamber is inside the gasket firing ring .

.003" off is nothing. You would have to take the heads down to 55cc at .010" in the hole with 38cc pistons to get 11/1 compression. So .030" to .040" off you will be getting closer.

Looks like a Fel-Pro 1099 at 4.660" was good?

I would ask Kaase about the Cam and the Gaskets and see what he recommends.

Kaase cut the 598 1211HP 16/1 compression Dyno Mule heads down .045".

https://www.429-460.com/t27219p100-jon-kaase-sr71-cylinder-heads

^ Second to last post on the page.

My question would be on the China Wall spacers and Valley Pan fitment, as well as Intake Alignment, if you cut them that much.

maverick172 wrote:i was wondering what would be a good piston choice for my sr-71 headed 545 build planning for around 11:1 compression going to run on pump gas street strip car .
and cam choice as well. will order custom grind .
if i have to flycut pistons will do would rather find factory ones but..
4.5 stroke
6.8 rod
4.39 to 4.44 bore will pore to what i can get
i can deck block to fit as well d1ve block

" street strip car "

For lifters I would look into the DLC BAM's of this sort.

https://vincentperformance.com/shop/bam-b-2010-16-bb1/

supervel45 wrote:Kaase cut the 598 1211HP 16/1 compression Dyno Mule heads down .045".

https://www.429-460.com/t27219p100-jon-kaase-sr71-cylinder-heads

^ Second to last post on the page.

My question would be on the China Wall spacers and Valley Pan fitment, as well as Intake Alignment, if you cut them that much.

ya i asked him about this he said .003 would not be a issue but i am sure if you cut more you would need to take some off the china wall and possibly the intake too.
,but i am sure as you cut the heads more i might need to start cutting pistons as well.
i was planning to run the pistons 0 deck why you say go 10 in the hole . when i talk to roger at kaase he said it would be fine with a .041 gasket but.. let me know what you guys think about 0 deck
thanks

I built a 572 with SR 71 heads, 4.5 bore 4.5 stroke and used shelf pistons from ICON. They were made for the P51 heads but I checked piston to valve clearance and had very adequate clearance on the intake and exhaust valves. This thing is zero decked, with a .029 mls head gasket. Cam is a Kaase spec with .787 lift intake and exhaust. I was skeptical about the quality of a piston in that price range for this kind of build. So far I was wrong, The fit and finish of the ICON pistons was on par with some of the other brands I have used but at half the price. So far about one hundred 1/8 mile passes in the low 5 second range and touching 8200 rpm a couple of times. Someone at Kaase told me to run a 4.500 head gasket, it has been almost two years no problems yet.

hbstang wrote:use as big a bore as possible with those heads.they have a 2.375 intake valve and need the space.they will put a smaller intake valve in it if you need,but thats where the power comes from.this has the dyno on 521

https://www.429-460.com/t27219p75-jon-kaase-sr71-cylinder-heads?highlight=kaase

The intake valve size in those heads present no problem with a 4.390" bore because it is moved over slightly; the exhaust valve used needs to be smaller at 1.710" maximum diameter for that bore size.

maverick172 wrote:

supervel45 wrote:Kaase cut the 598 1211HP 16/1 compression Dyno Mule heads down .045".

https://www.429-460.com/t27219p100-jon-kaase-sr71-cylinder-heads

^ Second to last post on the page.

My question would be on the China Wall spacers and Valley Pan fitment, as well as Intake Alignment, if you cut them that much.

ya i asked him about this he said .003 would not be a issue but i am sure if you cut more you would need to take some off the china wall and possibly the intake too.
,but i am sure as you cut the heads more i might need to start cutting pistons as well.
i was planning to run the pistons 0 deck why you say go 10 in the hole . when i talk to roger at kaase he said it would be fine with a .041 gasket but.. let me know what you guys think about 0 deck
thanks

Are you positive he did not say .030"?

Yes you always want to keep an eye on PTV.

I alway's like a little margin for error for piston rock, ect. is one of the reasons for the .010" in the hole. Also it's a pump gas street strip deal with deep dish pistons, so the Quench deal is out the window, not that you would not have any even at .051".

Some may get by with the 4.5" head gaskets but, the bigger ones look like better fit to me. If you look at the Picture Closely of the 4.5" gasket you can see the Wire Ring Hanging Over the Inside of the Chamber by the Exhaust Valve.

snuff98 wrote:I built a 572 with SR 71 heads, 4.5 bore 4.5 stroke and used shelf pistons from ICON.  They were made for the P51 heads but I checked piston to valve clearance and had very adequate clearance on the intake and exhaust valves.  This thing is zero decked, with a .029 mls head gasket.  Cam is a Kaase spec with .787 lift intake and exhaust.  I was skeptical about the quality of a piston in that price range for this kind of build.  So far I was wrong,  The fit and finish of the ICON pistons was on par with some of the other brands I have used but at half the price.  So far about one hundred 1/8 mile passes in the low 5 second range and touching 8200 rpm a couple of times.  Someone at Kaase told me to run a 4.500 head gasket, it has been almost two years no problems yet.

MLS is the key to your statement. Wire Ring is the problem with regular gaskets.

Are you positive he did not say .030"?

Yes you always want to keep an eye on PTV.

I alway's like a little margin for error for piston rock, ect. is one of the reasons for the .010" in the hole. Also it's a pump gas street strip deal with deep dish pistons, so the Quench deal is out the window, not that you would not have any even at .051".

Some may get by with the 4.5" head gaskets but, the bigger ones look like better fit to me. If you look at the Picture Closely of the 4.5" gasket you can see the Wire Ring Hanging Over the Inside of the Chamber by the Exhaust Valve. [/quote]
yes sorry .030 cut i typed it in wrong
so a 38cc dish with a 30thou cut on the heads , he told me a could zero deck it no problems. but.. can anyone else chim in on this
also there is no quench with dish pistons?i thought might be some around the edge as there is a flat spot around the edge of piston.

rmcomprandy wrote:

hbstang wrote:use as big a bore as possible with those heads.they have a 2.375 intake valve and need the space.they will put a smaller intake valve in it if you need,but thats where the power comes from.this has the dyno on 521

https://www.429-460.com/t27219p75-jon-kaase-sr71-cylinder-heads?highlight=kaase

The intake valve size in those heads present no problem with a 4.390" bore because it is moved over slightly; the exhaust valve used needs to be smaller at 1.710" maximum diameter for that bore size.

yes they are putting the smaller exh valve in .
i think the cam is somewhere around a .726 lift
he never gave me all the details .
with the mahle pistons do you know how mcuh clearance there is in the dish . just thinking after the heads are cut mught have to cut a relief in anways ?

Before assembly I put dowels in the heads then test fit the gaskets on the heads, "fire ring" area was well outside of the combustion chamber although some of the gasket does hang over in the chamber near the exhaust valve.

snuff98 wrote:Before assembly I put dowels in the heads then test fit the gaskets on the heads,  "fire ring" area was well outside of the combustion chamber although some of the gasket does hang over in the chamber near the exhaust valve.

did use use a multi layer steel gasket? or was it like a felpro 1028

maverick172 wrote:


Are you positive he did not say .030"?

Yes you always want to keep an eye on PTV.

I alway's like a little margin for error for piston rock, ect. is one of the reasons for the .010" in the hole. Also it's a pump gas street strip deal with deep dish pistons, so the Quench deal is out the window, not that you would not have any even at .051".

Some may get by with the 4.5" head gaskets but, the bigger ones look like better fit to me. If you look at the Picture Closely of the 4.5" gasket you can see the Wire Ring Hanging Over the Inside of the Chamber by the Exhaust Valve.

yes sorry .030 cut i typed it in wrong
so a 38cc dish with a 30thou cut on the heads , he told me a could zero deck it no problems. but.. can anyone else chim in  on this
also there is no quench with dish pistons?i thought might be some around the edge as there is a flat spot around the edge of piston.[/quote]

You are corerect....the bigger bore gaskets are a better fit. I had a customer with 4.50" gaskets for his SR-71 heads and the gasket was in the bore. I sent him a set of our 4.640" cometic mls which resolved the issue.

Lem Evans wrote:

maverick172 wrote:


Are you positive he did not say .030"?

Yes you always want to keep an eye on PTV.

I alway's like a little margin for error for piston rock, ect. is one of the reasons for the .010" in the hole. Also it's a pump gas street strip deal with deep dish pistons, so the Quench deal is out the window, not that you would not have any even at .051".

Some may get by with the 4.5" head gaskets but, the bigger ones look like better fit to me. If you look at the Picture Closely of the 4.5" gasket you can see the Wire Ring Hanging Over the Inside of the Chamber by the Exhaust Valve.

yes sorry .030 cut i typed it in wrong
so a 38cc dish with a 30thou cut on the heads , he told me a could zero deck it no problems. but.. can anyone else chim in  on this
also there is no quench with dish pistons?i thought might be some around the edge as there is a flat spot around the edge of piston.

You are corerect....the bigger bore gaskets are a better fit. I had a customer with 4.50" gaskets for his SR-71 heads and the gasket was in the bore. I sent him a set of our 4.640" cometic mls which resolved the issue.

ya those cometic gaskets look like good quility stuff . felpro has a 1099 looks like it would work as well.anything else you would recommend doing for this build .
cam is a .730 lift @ 50 272 intake and 280 exhaust 109 lsa
he said with a 30thou cut would cc them around 64cc