Who still cuts domes?

[Req]

I have a 760 girdled head (non removable domes) in the mail that has some dome damage. I got it for a good deal and I did not think finding someone to machine them local would be difficult, well, no one around here wants to tackle it.

I called Xscream and they just recently stopped messing with stock sized domes, they are only machining their own product line for the billet motors now.

Who should I talk to about re cutting the domes and milling the head these days? Anyone do it out of their garage that I can send it to this winter that wants to make a few bucks?

Thanks for the help.

 

[Big Kahuna]

I have a 760 girdled head (non removable domes) in the mail that has some dome damage. I got it for a good deal and I did not think finding someone to machine them local would be difficult, well, no one around here wants to tackle it.

I called Xscream and they just recently stopped messing with stock sized domes, they are only machining their own product line for the billet motors now.

Who should I talk to about re cutting the domes and milling the head these days? Anyone do it out of their garage that I can send it to this winter that wants to make a few bucks?

Thanks for the help.

View attachment 365254

Hit up Tricky1, He may have time to do it. Xscream has been going away from existing machine work for a long while, since Chucky left. You could try P&P Performance. Also hit up Erik at TPE

 

[zzylstra]

@Jr. @JetManiac @Nuklear6

 

[DAG]

domes are very easy to machine. Any back woods machine shop could do it if you give them your squish angle. On the other hand that head is next to impossible to chuck up and center without making custom fixtures. I mean its possible but probably not worth the price you're going to have to pay. Hopefully i'm wrong

 

[TheBuzzard]

I wouldn't even waste any money on it. its totally useable just the way it is and you aint going to notice anything. looking at the pic, the domes look small like its pretty high compression. as far as the dings go, just make sure there are no high spots, cause that's where heat will occur. if you use a thick fiber gasket that's even better. the problem with cutting non removable domes is you have to swing the whole head and it takes a fair sized lathe to do that and it has to be setup specifically for this job.

 

[Req]

I wouldn't even waste any money on it. its totally useable just the way it is and you aint going to notice anything. looking at the pic, the domes look small like its pretty high compression. as far as the dings go, just make sure there are no high spots, cause that's where heat will occur. if you use a thick fiber gasket that's even better. the problem with cutting non removable domes is you have to swing the whole head and it takes a fair sized lathe to do that and it has to be setup specifically for this job.

Knock the high spots off and run it seems like a decent option, I was just concerned about carbon building up in the grooves and causing it to diesel if it turns into an hot ember. When I get the head in the mail I am going to CC the domes. Do I just put the plug in, turn it upside down and use a graduated cylinder? Are we measuring the cc of the squish band as well or just the domed section?

Thanks

 

[restosud]

put a plate with a hole on top of head and put water in until the combustion chamber is full.use the sparkplug type you will be running.
you measure both the chamber and the squish.

 

[Storbeck]

 

[Storbeck]

What I did was put piston at tdc, seal edges with grease (using care to only get it in the "crack" between piston and cylinder, don't take up any volume of the actual combustion chamber with grease). Install head, fill with two stroke oil measuring with cheap ebay burette.

85.5mm bore with wiseco pistons and an ADA 40cc dome came out to 33cc installed volume. Evidentally the volume that ADA gives you is the full volume of the dome, so of course the piston occupies some of that space so the actual combustion chamber installed is a little smaller.

This was with a stock thickness base gasket (aftermarket gasket, but it was supposed to be stock thickness), measured .020" with calipers. . Squish clearance with this combination came out to .040-.045" (one cylinder seemed to be a little tighter than the other), that seems a little tight to me, probably going to go with a little thicker base gasket to open that up a little.

Sooo, the combination I have here is about a 12.8:1 compression ratio. If I add a .010" thicker base gasket, that will add about 1.5cc's to the dome volume and drop the compression ratio about half a point. Probably what I'll do. Based on a very rough thumb squint looking at what other people seem to be doing, I think I'll have a reasonably conservative setup with that.

This probably doesn't answer any questions, but maybe provides a point of reference.

 

[Harbor]

Like the buzzard already said, it will fine as is. From the image it Looks like it was already delt with and ran. Mine was like that too, worked just fine, only lost 2 or 3 psi on the compression gauge..

 

[Freakrider]

Chucky of Team Scream Racing in Clearwater FL, still cuts domes in his own shop if anyone in the future is interested.

 

[Ewert559]

Is .20 the stock gasket thickness or is that just what yours measured?

 

[Ewert559]

.020*

 

[Storbeck]

I have not personally measured an oem one because mine was aftermarket. @JetManiac told me OEM are .020"

I bought a .030 and a .040 from him and they both measured spot on when I got them. So I would be pretty confident believing him that OEM is .020"

My thickness measurements were as delivered before installing.

 

[Ewert559]

Perfect. Thank you for that.

 

[augustaf]

Yes, oem base gasket measures .020". Except in Europe, where it measures 0.5mm.

 

[Ewert559]

Haha thx. I wish it measured that way on this end of the pond too! Soo much simpler!!

 

[Req]

Reviving my dead thread. I am pulling this head out to use it here in the near future but I have reason to believe it may be a 701 head and not a 760 head. what should the diameter to the outer edge of the squish band be for the 701 and the 760 respectively? I forgot to measure it before I installed my known 701 head.

Thanks.

 

[Storbeck]

I believe ADA domes are about 83.5mm for their "701" domes, so they work up to 83mm bore, and they are about 86.5mm on their "760" domes so they work up to 86mm bore. I don't have one in front of me at the moment but that is my recollection, can check when I get home if that would be helpful.

 

[Req]

I believe ADA domes are about 83.5mm for their "701" domes, so they work up to 83mm bore, and they are about 86.5mm on their "760" domes so they work up to 86mm bore. I don't have one in front of me at the moment but that is my recollection, can check when I get home if that would be helpful.

As long as you dont have to pull the head that would be great. I need to take a set of calipers to them and double check but looking at them the other day they sure looked a lot like 701 domes to me. The 83mm pistons I have sit really close to the edge. I dont really care as I dont have a 760 cylinder yet and I can use it on other projects if its a 701.

Thanks.