Jon Kaase SR71 Cylinder Heads

G-Code wrote:

68formalGT wrote:G-Code, is that any better?

Much better.  

Thanks

It says nothing about raising the port, or altering the floor on either of them to make for a better short turn.   Rats
That would be helpful. Changing that push rod pinch is certainly a winner and that would eliminate the turn before the short turn, so the floor would be more balanced.

New A460 head progress.
Last night on the flow bench we saw 450 cfm with a 2.320" valve through a 3.47" CSA  =  311 fps.  0n a 4.50" bore.

Got the flow to mellow out through it's rough section  @ .750" - 800" lift where it wants to get unstable.

We hope to maintain the smoothness and flow percentages  with a 2.380 valve. ... Work in progress

Raising the port would give the brand X guys a way to complain that it's no longer "conventional port" legal

^ $4,350 for steel rocker stands, Kha Ching. Looks like you could have 8-10K in those A460's pretty quick.

I surprized nobody snagged the Thor's for $2,500 yet. They look like Gen II's and you never see them up for sale.

You will make your goal with what you have G-Code and have plenty of money left over for gas.

supervel45 wrote:^ $4,350 for steel rocker stands, Kha Ching. Looks like you could have 8-10K in those A460's pretty quick.

I surprized nobody snagged the Thor's for $2,500 yet. They look like Gen II's and you never see them up for sale.

You will make your goal with what you have G-Code and have plenty of money left over for gas.

The Thor's -  solid heads no water. And yes the Eliminators are going to be costly with those stands.

[quote="68formalGT"][quote="G-Code"]

68formalGT wrote:G-Code, is that any better?[url=https://servimg.com/view/18825961

Raising the port would give the brand X guys a way to complain that it's no longer "conventional port" legal

True .

rmcomprandy wrote:

Lem Evans wrote:

nascar429 wrote:

Lem Evans wrote:It appears that the exh. side of the chamber is wider that the 4.562" bore. Is that the case?

Yes that is correct there is a slight over hang of the bore into the exh side of the chamber maybe about .020" or 0.30" or so.. i'd say a 4.600" bore would have little or no overhang into the chamber.. I did put the dowels in the deck to make sure the head was square.  

when i get a chance out of curiosity i'll do a dummy up with cam, lifters, rocker etc..and see how much exhaust valve clearance there is from the bore when the valve is open..

That being the case, a guy needs to get a head gasket that fits the chamber rather than the bore. The TFS A460 heads are the same way in that regard.

Do you think .030" offset dowel holes would be enough for a 4.390" bore using the normal 4.500" bore gaskets...?

Did you ever get a chance to look into that?

It sure looks like it would unshroud the exhaust valve from the pictures here, even on the large bore block it's on, on page 10, and center the chamber better?

I could see where it would be a lot of hassle for little gain, and would affect intake valve radial clearance.

Any other issues do doing it?

Looks like they make offset dowel pins for BBC and none for BBF.

What is the typical ignition timing people are using with the SR-71 heads? I saw that Kaase was listed 27 and 28 on his dyno sheets. I've seen other dyno sheets with 26 degrees timing. I'm building a 521 with flat top Mahle pistons. Compression ratio should be around 13.2 with the pistons 0.005 in the hole. Probably use a 112 or 114 race gas.

One thing I should've paid more attention to in this thread was the head gasket discussion. I bought a set of 4.50 Cometic gaskets on the assumption that they would be fine with the 4.390 bore. Found out during assembly that the chamber requires a 4.600 head gasket, even with the smaller exhaust valve.

I run SR's on my 585 with E85. Timing is at 25 degrees. I'm using the Lem Evans Cometic gasket for a 4.500 bore.

Interesting. I think we'll start at 26 or 27 on the dyno and see how it goes.

Yeah Kaase says the 4.50 gasket works which is why I bought them, but the engine builder showed me how much it overhangs the combustion chamber and said he wouldn't put it together that way. So maybe it does work and maybe it doesn't. I wasn't going to argue with the engine builder so I just bought another set of gaskets. The 4.500 bore gaskets can go on another build.

Same thing with the Manley valve springs. Kaase says they work, Manley says they won't, and the guy I usually buy cams from told me they won't work. The engine builder I'm working with looked it over and said "might work, lets try it". So we're going to try it.

We checked for valve clearance and the exhaust valves seem to clear the cylinders at 4.390. I told Kaase that we were using a 4.390 bore size and they said they would put the smaller valves in them. I guess we could run into a situation where it clears fine on the engine stand but at RPM the valves start wiggling around. That would be bad.

maverick172 wrote:ya well they told me that the 4.39 bore would work i only had i think .008 of lateral cylinder wall clearance . not near enough . i eyebrowed thm and now i got .040 lateral clearance . would hate to see you wreck your engine when it can be easily clearanced although i did it before i had crank in the block . yes the 4.5 gasket does overhand edge of combustion chamber but apperantly its fine .. again according to several guys on here and kasse

AndyF wrote:Yeah Kaase says the 4.50 gasket works which is why I bought them, but the engine builder showed me how much it overhangs the combustion chamber and said he wouldn't put it together that way. So maybe it does work and maybe it doesn't. I wasn't going to argue with the engine builder so I just bought another set of gaskets. The 4.500 bore gaskets can go on another build.

Same thing with the Manley valve springs. Kaase says they work, Manley says they won't, and the guy I usually buy cams from told me they won't work. The engine builder I'm working with looked it over and said "might work, lets try it". So we're going to try it.

We checked for valve clearance and the exhaust valves seem to clear the cylinders at 4.390. I told Kaase that we were using a 4.390 bore size and they said they would put the smaller valves in them. I guess we could run into a situation where it clears fine on the engine stand but at RPM the valves start wiggling around. That would be bad.

X10 on That!

https://www.429-460.com/t28967-521-cid-broken-camshaft-dowel-for-timing-gear-bent-valves

In case you missed it. You want about .030" clearance or more.

AndyF wrote:Yeah Kaase says the 4.50 gasket works which is why I bought them, but the engine builder showed me how much it overhangs the combustion chamber and said he wouldn't put it together that way. So maybe it does work and maybe it doesn't. I wasn't going to argue with the engine builder so I just bought another set of gaskets. The 4.500 bore gaskets can go on another build.

Same thing with the Manley valve springs. Kaase says they work, Manley says they won't, and the guy I usually buy cams from told me they won't work. The engine builder I'm working with looked it over and said "might work, lets try it". So we're going to try it.

We checked for valve clearance and the exhaust valves seem to clear the cylinders at 4.390. I told Kaase that we were using a 4.390 bore size and they said they would put the smaller valves in them. I guess we could run into a situation where it clears fine on the engine stand but at RPM the valves start wiggling around. That would be bad.

Hopefully "Seem" and "Might" or Right.

worthy competitor to the SR-20?

FordPriest wrote:worthy competitor to the SR-20?

I kinda doubt it, in X275 they were adding weight to the SR-20 guys and Ford guys were doing serious work to A460's. That being said I haven't looked at the rules for a while for that class but the SR-20's had a lot of advantages to them and are 30+ years newer then the A460's

rmcomprandy wrote:

68formalGT wrote:

FordPriest wrote:worthy competitor to the SR-20?

I kinda doubt it, in X275 they were adding weight to the SR-20 guys and Ford guys were doing serious work to A460's. That being said I haven't looked at the rules for a while for that class but the SR-20's had a lot of advantages to them and are 30+ years newer then the A460's

SR-71 heads are NOT A460 style heads.

Correct, they are a raised port head but so far hasn't proven to be on the same level as the A460's and likewise with the SR-20....unless you've seen something out of them to say otherwise.