Quick question- the intake manifolds by Edelbrock, Holly, or Wiedand: do they require machining of the bolt holes to fit onto stock '89 305 tbi heads?

 

What part numbers are you looking at? Generally the ones for 87-92 would not require machining.

 

If your using a true tbi intake no. If your used a carb intake with adapter, yes. Professional Products is the only company I know of that offer a carb intake for use with tbi heads.

 

So I'm asking because someone is selling an Edelbrock intake 2101 that they said they had drilled to accept the 1081 heads of their '87 IROC. I thought that intake should be a direct bolt on?

 

the 2101 is a carb intake. An adapter will be needed to place your tbi on top.

If you go with-
http://www.summitracing.com/parts/PFS-52001/?rtype=10

It has "bungs" supplied that will allow you to bolt right in. It will save you time in grinding.

you will still need-
http://www.summitracing.com/parts/TRD-2211/

to bolt your tbi onto.

 

besides the extra gasket, is there any downside to running a carb intake with a tbi adapter? Or is the Edelbrock TBI intake really good?

 

I've never used the edelbrock tbi unit. I just wasn't willing to pay over 250$ for an intake. Carb intake + adapter = 180.00.