Hand Porting Boss 302 Manifold (Help)

[tdstuart]

Just picked up a used Boss 302 manifold. Previous owner attempted to port it, but I think there could be significant improvements made.

My goal is to cut the manifold in half (cut the top off) and fill in any crevices and completely port the inside of the manifold. Like what AFS does for the cobra jet race porting.

I might also try to port the intake port bigger by 3D printing an adapter to convert it to 90mm.

Does anyone know what glue and filler I should use? Anyone have any general porting advice (never ported before)? Thanks!

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[K4fxd]

Just like porting cylinder heads you really need a flow bench or templates.

 

[tdstuart]

Just like porting cylinder heads you really need a flow bench or templates.

Eh the goal is just to smooth everything out. Don’t see why I would need a flow bench.

 

[K4fxd]

If all you do is clean up where the glue squirts out you should be fine. It is real easy to mess up the airflow. What looks good to the eye not always works.

 

[tdstuart]

If all you do is clean up where the glue squirts out you should be fine. It is real easy to mess up the airflow. What looks good to the eye not always works.

My plan was to smooth the glue and fill in cracks and for the ports smooth out the bumps. I don’t know if it’s from the previous owners port job or factory but there are some weird bumps.

 

[K4fxd]

Sometimes the weird bumps are there for a reason. I hope you don't have much money in the manifold.

Several days ago someone posted dyno results from a ported CJ manifold that were way down in power from unported.

I'll repeat again, just because it looks good to the eye, does not mean it flows better.

 

[tdstuart]

Sometimes the weird bumps are there for a reason. I hope you don't have much money in the manifold.

Several days ago someone posted dyno results from a ported CJ manifold that were way down in power from unported.

I'll repeat again, just because it looks good to the eye, does not mean it flows better.

I’ll post pictures later if you want to look at it. It doesn’t look intentional and looks like it was caused by previous owner.

Manifold was a present and only costed $250 so far

 

[tdstuart]

My biggest concerns are cutting the manifold open and resealing it. Don’t know what glue or poxy to use

 

[K4fxd]

JB weld will work.

 

[tdstuart]

Finished cutting open the manifold. Here is what it looks like.

Also here are some tips for anyone else who is attempting this:
Use a Dremel and a reciprocating saw that has enough clearance to go around the manifold. Use the Dremel to start cutting into the manifold along the seam of the two pieces. Use the saw to cut the rest of the way. Make sure the saw is actually cutting and not just melting the plastic. If you go the slow and the saw gets too hot the plastic will melt and seal the cut. Once you cut all the way around use some pry bars to make sure the edge of the lid is free. After the edge is free get a small hand saw with a long blade and cut the supports in the middle. Cut towards the top of the supports to await the metal screw in the middle.

 

[tdstuart]

Here is what I plan on making the manifold look like. I’m gonna cut out the supports and add a spacer along with smoothening the manifold and filling in any gaps.

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