BKOLFO4 Posted March 22, 2006 Report Share Posted March 22, 2006 Is there a way to figure out which domes are installed with my cool head without taking it apart? Is there an easy way to figure out which domes they are if I take it apart? If it has small domes, can you mix octane boost with the fuel, or is it better to buy race gas? Thanks! Brian Quote Link to comment Share on other sites More sharing options...
Tim C Posted March 22, 2006 Report Share Posted March 22, 2006 The Pro Design ones are stamped on them. If the topend is fairly new you could get a good idea by doing a compression check and knowing your elevation. If your close to sea level 21cc is about the smallest cc you can go on pump gas. Quote Link to comment Share on other sites More sharing options...
RNBRAD Posted March 22, 2006 Report Share Posted March 22, 2006 You will have to pull the top plate of your head off. The domes will have the size engraved on the back. You really need to know this for future reference. Quote Link to comment Share on other sites More sharing options...
txblueshee Posted March 22, 2006 Report Share Posted March 22, 2006 Just be careful when taking it apart and putting it back in so you don't pinch the o-rings... My 'shee had smaller domes in it when I bought it... detonated on me before I even knew what a cool-head meant... Mike Quote Link to comment Share on other sites More sharing options...
BKOLFO4 Posted March 22, 2006 Author Report Share Posted March 22, 2006 17's in it!!!!! One of them is already pitted in a few places. I can clean that up, but now to decide if I want to run race gas or buy new domes. More than likely I will be getting new domes. But I am glad I took it apart - Still has the factory pistons in it, so I will more than likely rebuild the top end. Brian Quote Link to comment Share on other sites More sharing options...
hittintrees srh Posted March 23, 2006 Report Share Posted March 23, 2006 17's are pretty small-whats you compression at? anything higher that 155, you should raun at least 50/50 mix with race fuel Quote Link to comment Share on other sites More sharing options...
BKOLFO4 Posted March 23, 2006 Author Report Share Posted March 23, 2006 I will more than likely rebuild the top end and replace the domes with 21cc. Quote Link to comment Share on other sites More sharing options...
Tim C Posted March 23, 2006 Report Share Posted March 23, 2006 What elevation are you at Quote Link to comment Share on other sites More sharing options...
rsheppick Posted March 23, 2006 Report Share Posted March 23, 2006 im at 135PSI with 18MM domes at 5,500FT.. I spoke with Pro Design and Trinity and decided that 16MM domes are what Im going to run. Because of the elevation I am one of the unusual to use the smaller domes. Other option was to have machine shop take some of the cyl down to make a smaller squish but I decided it is faster to put the domes in Quote Link to comment Share on other sites More sharing options...
BKOLFO4 Posted March 23, 2006 Author Report Share Posted March 23, 2006 I am at 226 ft elevation. I really do not want to mess with race gas. I like going down to the local Quick trip and grabbing 93 oct. Brian Quote Link to comment Share on other sites More sharing options...
Tim C Posted March 23, 2006 Report Share Posted March 23, 2006 (edited) I am at 226 ft elevation. I really do not want to mess with race gas. Edited March 23, 2006 by Tim C Quote Link to comment Share on other sites More sharing options...
mondtster Posted March 23, 2006 Report Share Posted March 23, 2006 21cc the the most you should go...........I'm running about 150lbs of compression w/ 21cc. You'd be taking a chance running any higher then that on pump gas. 491486[/snapback] The domes may be a band aid for a worn out top end though so I would do a compression test to see what it comes out at. They may also be there if there is some other work that we are unaware of that would lower the compression as well. Bottom line is that a compression test needs to be done as well as further investigation to see what you really have. My buddy bought his 'shee which he thought had a stock motor but he ran into similar issues and found out that he had a long rod motor and with the way it was built required either 17 or 19cc domes (I can't remember right now) to reach the upper limit of compression for pump gas. Quote Link to comment Share on other sites More sharing options...
Tim C Posted March 23, 2006 Report Share Posted March 23, 2006 The domes may be a band aid for a worn out top end though so I would do a compression test to see what it comes out at. They may also be there if there is some other work that we are unaware of that would lower the compression as well. Bottom line is that a compression test needs to be done as well as further investigation to see what you really have. My buddy bought his 'shee which he thought had a stock motor but he ran into similar issues and found out that he had a long rod motor and with the way it was built required either 17 or 19cc domes (I can't remember right now) to reach the upper limit of compression for pump gas. 491504[/snapback] My #'s is shortly after a rebuild and NO porting. Your right if the exhaust port is raised it will be a different story. But for none ported cylinders near sea level 21cc is probably the max you can go and still run pump gas. Quote Link to comment Share on other sites More sharing options...
Tim C Posted March 23, 2006 Report Share Posted March 23, 2006 The domes may be a band aid for a worn out top end though so I would do a compression test to see what it comes out at. They may also be there if there is some other work that we are unaware of that would lower the compression as well. Bottom line is that a compression test needs to be done as well as further investigation to see what you really have. My buddy bought his 'shee which he thought had a stock motor but he ran into similar issues and found out that he had a long rod motor and with the way it was built required either 17 or 19cc domes (I can't remember right now) to reach the upper limit of compression for pump gas. 491504[/snapback] My #'s is shortly after a rebuild and NO porting. Your right if the exhaust port is raised it will be a different story. But for none ported cylinders near sea level 21cc is probably the max you can go and still run pump gas. Quote Link to comment Share on other sites More sharing options...
mondtster Posted March 23, 2006 Report Share Posted March 23, 2006 My #'s is shortly after a rebuild and NO porting. Your right if the exhaust port is raised it will be a different story. But for none ported cylinders near sea level 21cc is probably the max you can go and still run pump gas. 491521[/snapback] I agree, but I just thought I would mention it since he is working with an unknown motor. It is easier to investigate things first rather than pay for something later that could have been avoided. Honestly, I'm guessing that you are right but there is only one way to tell... Quote Link to comment Share on other sites More sharing options...
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