Quote: I have a 67 dart 225cyl. bored .060 plained .030 and .115 cut off the head. The cam is a Comp Cam .490 lift 230 duration at .050 and 340 valve springs.
the valves are 1.78 intake 1.50 exaust . A 650cfm 4BBL carb with a 6 into 1 header. the car has a 904 trans. 2500 stall tork 4.56 gears and is only 2650 lbs.
So why is my ET. 15.2 and MPH 89.9????
What am i doing wrong.
I will attempt to help,
If you are using a tire diameter of 26inches +/- then you are turning the engine around 6100 rpm considering a torque converter efficiency of 96% or better. Your cam specs are not fully given but if your lobe seperation is around 110degrees then your peak horsepower should happen at around 5700-5900 rpm. I suspect that you are hitting that engine speed before you reach the finish line. Remember that stock sl6 engine assemblies should not exceed that rpm. Rough calculations tell me that your combination should net ET's around 13.9-14.3 with trap speed at around 100 mph. You may want to consider a gear ratio of 4.10 or perhaps even a 3.91 if you plan on increasing engine output further.
Another item that I would address is your carbeurator size. It seems to be too fat for a SL6. Cfm of 500 or lower would perform better. Be sure to jet properly for your engine combo.
You can safely remove .100" of material from a SL6 head. this will raise the comp ratio of a 225 to about 9.8:1 depending on head gasket thickness. and block deck height. You will notice an improvement by doing so.
How is your 60 ft time? Can you get start line rpm up to 2500 using foot brake? If not then you may want to increase stall speed.
The rest will require the usual fine tuning: cam degreeing, advance curve, hot spark, cool plugs, tire pressure etc, etc, etc...
Hope this is some help.
Best eregards,
Ken Gibbs
|
