Originally Posted by Ohio HD

The way I install the TB whenever the air breather allows it. I loosely attach the TB to the heads, loose enough for the TB to move a little under moderate pressure. Install the air breather backing plate to the TB and to the heads. Hand tighten those fasteners, and then tighten up the TB and then the backing plate. Never have issues doing it that way, even when the heads are milled or using cylinders that are longer or shorter.

I ran an HD SE 58mm TB on a 117" that had 0.059" shorter cylinders, and the 110 heads were to 93cc, or about 0.015" to 0.020" milled away, and an 0.030" head gasket. That's a total of about 0.089" shorter from the intake ports to the cylinder base. No issues with intake sealing.

I also use some Vaseline or seal lubricant to allow the seals on the TB to move without binding.

Originally Posted by Falkia

I thought when installing the TB without the backing plate attached and tightening the bolts little by little should center the TB to the ports in the best position possible.
I will try your way to do it. I use Vaseline as well.

Originally Posted by Max Headflow

Originally Posted by Falkia

Not sure how to interpret that emoji but using two gaskets solved the problem as you suggested earlier. Each gasket is 1mm. The TB was centered very well to the heads with the flanges. The bolt holes and cut outs have very little play to the screws so they have like a fixed position and the TB is centered in the flanges. Now the backplate isn’t pulling or pushing the TB.

Originally Posted by Max Headflow

Personally 2 gaskets are fine to correct the issue.

It's your response to OHIO below.


Your response was.



You didn't do it his way.. You did your own which is the way I sometimes do it.. Other times I simply eyeball it so throttle body / intake manifold (carbed) is flat / straight up and down. If it's off the manifold will still move due to the freshly lubes seals. I'll mount the AC so that there isn't any load on the manifold seals.

Unless I'm reading it wrong, I suspect that OHIO simply has a tighten sequence. I prefer to make sure that the manifold does not have any stress on it.. I done a few custom AC mounts and breather mods in the past and don't have any issues.. All the spacing is custom.

https://www.hdforums.com/forum/engin...l#post20511393

Originally Posted by Falkia

Now I know what was wrong all the time. The gasket I used from the Cometic kit was 1mm thick. I used it together with a home made 1mm gasket to fill up the gap of 2mm. Today I got hold of a geniune Harley-Davidson gasket 29241-08 and guess, it was 2mm thick! Now I feel stupid...