12mm Posted January 30, 2009 Report Share Posted January 30, 2009 (edited) I built a 4mil stock cylinder motor that i used the spacer plate on the bottom of the cylinder,but i was told that i would make more power if a removed the plate and had the domes cuts.........is this true ? and also the domes are 18cc, so if i cut them how much needs to be cut out for a race gas setup ? cylinders are fully ported also. IS IT WORTH THE TROUBLE TO REMOVE THE PLATE AND HAVE THE DOMES CUT? thanks Edited January 30, 2009 by 12mm Quote Link to comment Share on other sites More sharing options...
98_shee Posted January 30, 2009 Report Share Posted January 30, 2009 Are the cylinders ported for a 4mill? If not i would just leave the spacer plate. Or have a builder look at the cylinders and see if they can be reported for the 4mill. If you want buy a set of dome's already cut i have a set of 18's for a pro design i may sell when i get the other set in. I need some uncut domes for my new build. Quote Link to comment Share on other sites More sharing options...
tundish2800 Posted January 30, 2009 Report Share Posted January 30, 2009 I have some 17cc uncut domes i will part with if you need them Sorry for jackin the thread Quote Link to comment Share on other sites More sharing options...
elwilliams13 Posted January 30, 2009 Report Share Posted January 30, 2009 The cylinders have to be ported to run the domes if you want max power. I knew a guy that did not port it and ran domes it worked but not to full potential. By adding the plate you are making up for the added stroke by raising your ports up to match. Quote Link to comment Share on other sites More sharing options...
12mm Posted January 31, 2009 Author Report Share Posted January 31, 2009 (edited) The cylinders are ported for the stock crank,so i guess its better to leave the plate in place then?. sounds like if i were to remove the plate and run it the way it is i'd lose some power if i don't report. Edited January 31, 2009 by 12mm Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted January 31, 2009 Report Share Posted January 31, 2009 i would never under any circumstance run a spacer plate setup. the one time i did, was from passion racing, and that shit was junk.. never again. do it right and have your cylinders ported correctly and run the cut domes. Quote Link to comment Share on other sites More sharing options...
spurdy Posted January 31, 2009 Report Share Posted January 31, 2009 If your runnign a spacer plate then you likely close to stock crank prot timings. If you remove the plate and run cut domes you will change your port timings and it may very well run like shit. Check with a builder and see what your options are. SP Quote Link to comment Share on other sites More sharing options...
12mm Posted January 31, 2009 Author Report Share Posted January 31, 2009 i would never under any circumstance run a spacer plate setup. the one time i did, was from passion racing, and that shit was junk.. never again. do it right and have your cylinders ported correctly and run the cut domes. what needs to be changed in the ports ? Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted January 31, 2009 Report Share Posted January 31, 2009 what needs to be changed in the ports ? i believe the port timings have to be lowered since youre moving the cylinders back down 2mm. they will have to be reported. who is your builder? sounds like they took the easy way around having to port your cylinders correctly for use with cut domes. Quote Link to comment Share on other sites More sharing options...
Wildcardracing Posted January 31, 2009 Report Share Posted January 31, 2009 It may or may not run better without the plate with your current portwork. If the transfers have been raised much it will likely run better without the plate, too much transfer duration won't let the motor rev out like it should. If your port heights are close to stock it will run harder with the plate. It will run the best if re-ported for the 4mil crank and I always recommend no plate, because it is just one more sealing surface prone to a leak. I would have to know your port measurements to tell you which way would be best with your current porting. Quote Link to comment Share on other sites More sharing options...
12mm Posted February 1, 2009 Author Report Share Posted February 1, 2009 It may or may not run better without the plate with your current portwork. If the transfers have been raised much it will likely run better without the plate, too much transfer duration won't let the motor rev out like it should. If your port heights are close to stock it will run harder with the plate. It will run the best if re-ported for the 4mil crank and I always recommend no plate, because it is just one more sealing surface prone to a leak. I would have to know your port measurements to tell you which way would be best with your current porting. well we did a speed test with a gps and it runs around 94mph,does that sound about right for a stockcylinder 4-mill with PRO-C pipes ? the intake ports are cut from top to bottom,its MUCH bigger than stock,and so is the exhaust side....to me it looks like its ported for a big motor. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted February 1, 2009 Report Share Posted February 1, 2009 well we did a speed test with a gps and it runs around 94mph,does that sound about right for a stockcylinder 4-mill with PRO-C pipes ? the intake ports are cut from top to bottom,its MUCH bigger than stock,and so is the exhaust side....to me it looks like its ported for a big motor. MPH alone isn't a tell tale of how well it runs or if it runs correctly... I'd run a spacer if I HAD to...but I'd much rather have the port timings corrected and run cut domes. Quote Link to comment Share on other sites More sharing options...
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