jbschneeweis
Well Known Member
Will try to explain this to the best of my ability. Over the winter I had my 1804 500 CFM carbs modified by a professional to change them to 650 CFM specs. My racing performance decreased. Old carbs were set up with 86 primary & 80 secondary & used 68 x 55 rods. New carbs were changed to 650 specs & using 98 primary & 95 secondary with 75 x 47 rods. I have 1 inch 4 hole spacers & engine specs from Jack are his 4 inch stroker 489 CI, with Edelbrock aluminum heads & matched ports. Last year at the end of the season with the old carbs at a 1/8 mile track at 5000' altitude. Times were 60' 1.61, ET 7.51 & MPH 90.74 corrected altitude 6050. this past weekend with the new carbs setup same track times were 60' 1.67, ET 7.71 & MPH 88.33 not sure of the altitude forgot my meter. A 2 tenth slow down on ET & a little on the 60'. I have a PG trans set up for racing & a trans brake & two step & I launch at 4000 RMPs. Spark plugs look good with a light tan color. I changed the rods to 68 x 37 for 2 runs & not any change to mention except the plugs were a little tanner. I would think with the increase in getting & smaller rods I would think my times would be better not worse. Any ideas or suggestions. Thanks.
Joel
Joel