I have a BBK/Edelbrock 52mm tb...I don't know what is the the better option, My car idles a little rough for the first 2 minutes then smooths out & seems to be fine once warmed up. I currently adjusted the throttle blades and the TPS. I don't have any tuning tools to know what my BLM's are but it seems to run ok, Just a rough idle for a couple of minutes. I've been wondering though with that method could everything still be as accurate with the BLM's as Drilling the hole in the passage of throttle body, Or should I do the 11/64 hole thing?

 

Here is some reading, also searching on split BLMs will give some other hits on aftermarket TB problems. There are two types of drilling so don't get confused. One is drilling TB plates to allow more air in and this really can be bypassed by adjusting TB stop screw and slotting the TPS to get voltage correct. Then verifying IAC counts are around the 30-40 range. The OTHER drilling is to allign IAC air port on aftermarket TB to the hole for the LT1 intake idle air runners. Some aftermarke TBs require plugging incorrect IAC passages or channels. It's important to get idle air to all 8 cyls evenly to eliminate split BLM's. The air passing the TB plates does not reach all clys correctly in modified high air volume at idle setups. And the intake runners solve that problem. Apparently some aftermarket TBs were for TBI and IAC holes do not align to the LT1 TPI intake air runners or they channel or leak IAC air to TB plate bypasses. Drilling a TB for 306 Cam? - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums

 

Yeah, i wouldn't drill the throttle blades, I don't like that idea.. I currently have the throttle blades cracked open a bit....It idles around 900 rpm and smells a little rich.. My tps voltage is .67. I guess I'm wondering if this method can indeed yeild the correct numbers for my blm readings.

 

You really need a scanner or software capable of telling you the IAC counts that the PCM is using. The PCM IAC counts run from 0 no idle air being added to 160 max idle air being added. You want to have an IAC count near 30-40 to give he PCM full control of the idle. Without this reading you are shooting in the dark as correct idle depends on a combination or balance between the TB stop air, the TBS voltage and the IAC air (counts). It also assumes your aftermarket TB IAC port aligns with the intake idle air runners (previous posts). If you have a laptop you can get setup for under $200.00 with TunerCat, $$EE definition file, Freescan. and an ALDL cable. Or look around for a hand held that supplies IAC data.

 

I guess I'll have to buy something that tell me whats going on so I know what I need to do. I probally need it anyway now that I'm this far in to my mods .