dlnoss

I would run the 21's.

That auction listing says 'new' but that design has been out about a year now. It replaced the first design which required changing the studs. It some drag race tests, the SURFACE temperature of the head and areas of the cylinder was 55 degrees cooler than a stock head and 10 degrees cooler than a PD head. The testing wasn't done by me; It was done by an Tulsa engine builder. -David

Yes, it will increase your bottom end power. I was asking about mods because, generally, advancing the timing by much makes you more likely to detonate and porting can lower your compression. So unless you are above 800' elevation 21cc domes would be a good choice for premium pump gas.

I just did a lot of testing with mine. I am running 340 mains, stock needles second clip from the bottom. My mods are: Fatty Pipes, Noss Head with 19cc, Open Airbox with Noss Flange/K&N/Outerwear, VForce Reeds. The only thing non-standard is the domes. They are a new configuration dome that seems to make the engine want more fuel. I would probably be at 320 mains with standard 19cc domes. Hope this helps. -David

Yes, 21cc domes allow you to run premium pump gas. You will notice a lot better power off the bottom. If you have other mods, like advanced timing or porting, or are above 1000' elevation it could change the dome size.

I don't know much about the Vitos SS pistons but if they don't raise compression and your aren't ported or advancing your timing, 21cc domes are what I would recommend for pump gas below about 700' and 20cc for above 700'.

IMO, orings do seal better than traditional head gaskets. They are much more forgiving of incorrect torque and sequence. An oring seal also allows better cooling because there is metal-to-metal contact of the cylinders, head shell and domes. A head gasket acts as an insulator causing differential temperatures and heat expansion.

BGHSCANDYMAN, I usually recommend 21cc for premium pump gas there. Some people run 20cc domes but you could have detonation problems. I try to stay on the safe side. Kind of like the old country barn building concept?

Is the clutch disengaging all the way?

I say the same as everyone else; 21cc for sea level on premium pump gas. -David

I'm sorry, I guess I didn't read your post very thoroughly. Your post said Noss but the sig didn't. I wish you would have called when you first had the problem. We probably could have saved you some frustration. If the leak is in the dome area, check to see if the edge is dented. They are fragile along the edge. If it's a 'Stock Stud' head leaking up through the studs, make sure the bottom of the nut is smooth and put a little silicone on the thread before putting the nuts on. I have found the dimension of the stock studs can vary somewhat in diameter. Call me if you still have a problem. If there are any problems or defects with the head, I will fix or replace it. It's pretty rare but not impossible.

It depends on your elevation, timing, and porting. If you are above 800' elevation with stock timing, you should be okay with 20cc domes and premium pump gas. Do the ProLite pistons raise the compression?

One of the main benefits of the head with changable domes is the versatility (sp?)of being able to change the domes to suit your conditions. From a manufacturing standpoint, I can machine any contour I desire with a CNC turning center on removable dome. Doing the same on a one-piece head would be much more difficult. Without giving it a lot of thought, I can't think of how a true one-piece, liquid-cooled head could be machined that would have any cooling capacity. I have seen very few instances of orings leaking and in every case there was a manufacturing flaw in the head and/or dome or in the installation or the way the engine was assembled. It looks like you are using a Pro Design head. I would be happy to check it out and see if I can help figure out the problem if you want to send it to me. If the domes sit too far up in the head so they aren't pressed against the cylinder, or the oring grooves are too deep, shallow, narrow, or wide they can fail to seal properly. I machine my oring grooves .050 deep +.002 (-).004, and .085 wide +(-).005 Some of the heads on the market use less orings than others. I designed and tested several heads before marketing my current design. By eliminating the 'base' piece, I could have saved some orings but would have sacrificed some strength and dome support by doing so. -David

Stock chamber size is usually 23cc to 24cc. You would notice a difference with 22cc and a better difference with 21cc. 21cc is as small as I would go with pump gas.

thats what im lookin for just a nice ol kick in the shorts when i gas her. Last weekend, two guys running +4 strokers built by Jim finished 1st and 2nd in the Open Pro Class at a short track race in Texas. It says something....

If you want to run pump gas, I'd say 21cc or 22cc because of the timing advance. If you don't mind running 110 octane, you could go with 19cc or 20cc. 18cc would probably be too much for the stock internals. To get the discount, you can call and order or order online and the 10% discount will be credited back to your credit card. Call if I can be any help. -David

I sell flanges and heads. Check out Noss Machine. BansheeHQ members get a 10% discount. -David

It depends on your elevation and the fuel you want to use. It sounds like you have stock porting and timing.

It depends on your elevation. If you are close to sea level, 21cc would probably be as small as you could go running premium pump gas with the timing advanced.

How much for the plastic? What condition?

If you shave the stock head, be sure to maintain adequate squish clearance. If much is taken off the stock head, it also needs to be rechambered. BansheeHQ members do get a 10% discount on anything from Noss Machine. -David

I think it would be pushing it with pump gas.

It depends on your porting. Since porting normally lowers compression, you can usually use smaller domes. It's best to check with the builder that did the porting.

The head uses orings instead of a head gasket. Most of the aftermarket heads are that way. Better seal and heat transfer.

It's a 'Personal Message'. Up towards the top of the page it should say '1 New Messages' -David