Hi Comp+ X Heads+ 93 Octane possible?

M_Body_Coupe said
OK, let me clarify...I am not saying my ET is high ONLY because of bottom end issues....heck, the car pulls fine, but on the street, the butt-meter says that there is definitely more "umph" with the dual plane...and since I'm not WOT on the street I will go with the combo that gives me best behaviour in the 90% situation I am in, that being street manners where part throttle does matter.

Yes, I think you are right about something else being a problem...quite frankly I do not know where to go next with my troubleshooting as I have checked the "usual suspects" already. The motor easily pulls to 6500, no problem there...but I do find is strange that I can run so much initial advance and a total of 38 and still have no detonation of any sorts...that is usually the case with low compression motors...

I wasn't questioning you butt meter.

My point was that you are saying you have a 4000 stall converter. Did you actually verify that? Because if it is actually 4K stall and your shift point are correct, then the engine will be right at, or just above stall speed at the gear change. In that case, 'bottom end" no longer is a consideration and the SD or M1 will eat a RPM AG all up.

As for the butt meter and street driving, most of the time it is an ignition and/or carb issue. It sounds like you have the timing correct, but posting a picture of a spark plug or 3 can help verify that.

That leaves the carb. If you are soggy by the butt meter it is possible with the single plane intake the carb is a bit big (you can ALWAYS run a bigger carb with a dual plane intake because it effectively cuts the carb in half and guys sometimes don't consider that when swapping on a single plane intake and they loose drive-ability because the best carb on the dual plane probably won't be optimal on the single plane).

Also, the tune up (considering not just jetting here but emulsion/air bleed/jet) is different between a single plane and a dual plane intake. You may have to help the single plane out in transition by working with the air bleeds and idle feeds and emulsion.

So there is more to it than just saying a dual plane is good for this and a single plane is only good for that. You can make both work and work well. They just won't be tuned anything alike.