Holley TBI adapter

[Nasty-Z]

I actually did the same thing when I made mine , I use 1/4" bolts to attach so I countersank the bottom of the adapter plate , threaded the hole 1/4-28 and threaded in flat head machine screws till they were tight and sealed them with red loctite . Now 3 1/4-28 nuts and the TBI is off .

TOM

[lightning-jr]

Seems I did a good bit of "configuration" on that Holley adapter before I was happy with it.

A decent part for the job in the end.

[PJG1173]

Ok, I got my tbi adapter in the mail yesterday. I guess I missed the fine print or something because it is a 2" bore. will my 1 11/16 work with this? when I put the gasket over it there is a big difference and when I bolt one of my junk TB's to it there are some of the passages exposed on the bottom of the tb when I use the 2" gasket that would normally be covered.

[Nasty-Z]

It will be fine

TOM

[EagleMark]

Seems I did a good bit of "configuration" on that Holley adapter before I was happy with it.

A decent part for the job in the end.

What exactly did you need to do? It's a fine piece when compared to 1/4 plate steel adapters...

[PJG1173]

do I use the 2" gasket or the 1 11/16?

[EagleMark]

do I use the 2" gasket or the 1 11/16?

Hmmm? Sure you can't return it for correct one?

The Big Block TBI gasket is very thin in arease and does tend to cause vacuum leaks, on the other hand if you use the SB gasket you'll have exposed gasket in the bores. I don't like extra gasket in the bores as it came start to break down and fly through motor. Not that I think little pieces of gasket material would hurt it... just don't like the idea.

Mount up your TBI with both gaskets and look from underneath, sounds like the BB gasket would have none exposed in bores, but may be better with SB trimmed in bores?

[Nasty-Z]

Yup , Mark hit it , use the SBC gasket trimmed up to match the larger bores .

I used the "Holley" (Made by me) adapter on my dad's S10 on top of a single plane intake for years without an issue , 2" bores with a SBC TBI on top using a modified SBC gasket .

TOM

[PJG1173]

I may look into seeing if I can order another one with the correct bores or have the local machine shop use this one as a template. I'll use this one on my next project since I already have a BB TB for it.

[EagleMark]

Or use this?

[PJG1173]

Or use this?

that will work!

another question I've had...
is the placement of the tb on the opening have an affect on anything? i.e. on a square bore intake would it make a difference if it was more oriented towards the front, middle, rear, of the opening? keeping in mind this is a v6 so the intake ports are not symetrical from side to side like a v8

[EagleMark]

I'd shoot for center. Although the SpreadBore adapter, or at least one is set to rear?

[lightning-jr]

What exactly did you need to do? It's a fine piece when compared to 1/4 plate steel adapters...

The bores had to be enlarged to match my TB. I blended it to the intake, after having to open the manifold some. There were width and offset problems. I cut the rear 1/2 of the bore outlets back about 45*, maybe 1.5".