Mild port and polish...

[Old-beat-up-77]

Stock heads that are being reused for a 350 SBC with a mild cam, TBI (Brand undecided) and most likely 2.5 inch exhaust.

Is it worth it? And by "Mild" I mean deburring the runners and giving them a shine with a Dremel and some time at the home workbench.

 

[Snoots]

Port match, shine the exhaust and above all else, wear goggles! Glasses are no good.

 

[GXPWeasel]

I'm thinking of doing something very similar in the near future. I was going to port / polish the heads to match the intake manifold gaskets. I figure the heads, at least for me, are the most permanent piece of my engine between the intake and heads. I thought of porting the heads on the exhaust side too. Not sure what I'll gain, but figure as long as I don't go too far, it's worth my time.

Sorry to hijack the thread.

 

[Snoots]

Port intake, port and polish exhaust.

 

[Old-beat-up-77]

Ok, so it sounds like its worth it but what are the gains? Anyone have any numbers they can throw at me?

 

[Catbox]

All I can say is don't go crazy.
Just take the sharp edges off and blend the valve seats to the port.
Leave the intake port slightly rough, don't make them totally smooth.

Also what heads?
I know the TBI heads flow worse than a toilet bowl.
If you are planning around a set of those, I would strongly recommend finding a different set of heads to work off of.
The TBI heads are done flowing at 4000 and they just suck.
I have a set on my 1995 Suburban and yeah, they are sad.

I second the idea of good fitting goggles.
I was working over a set of heads with a set of goggles that had a small gap.
The next day at the eye doctors office I had a piece of iron dug out of my eye.
Not rad.

 

[Catbox]

I am no pro, just a garage hack.
So this is my experience based off of what I have read.

While these are not Chevy heads, they will serve as an example.
These are a set of aircooled VW heads that I touched up.
You can see the mismatch that I colored red in the first photo...

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With a bit of time and a steady hand, I blended the mismatch smooth.
I made careful work of it as I didn't want to dig into the head to create more of a disturbance in flow down the wall of the port.
This is a bit harder to do in cast iron though...

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Just for example.
Here is my set of professionally ported heads that will make their way onto my 2332cc engine to go into my VW.
They are very expensive and wonderful to look at...

You must be registered for see images attach

 

[Old-beat-up-77]

I am no pro, just a garage hack.
So this is my experience based off of what I have read.

While these are not Chevy heads, they will serve as an example.
These are a set of aircooled VW heads that I touched up.
You can see the mismatch that I colored red in the first photo...

You must be registered for see images attach

With a bit of time and a steady hand, I blended the mismatch smooth.
I made careful work of it as I didn't want to dig into the head to create more of a disturbance in flow down the wall of the port.
This is a bit harder to do in cast iron though...

You must be registered for see images attach

Just for example.
Here is my set of professionally ported heads that will make their way onto my 2332cc engine to go into my VW.
They are very expensive and wonderful to look at...

You must be registered for see images attach

I have two sets of stock cast heads from two 350's. One came out of the 77 im building and the other came out of a 72 Nova.

 

[Catbox]

I have two sets of stock cast heads from two 350's. One came out of the 77 im building and the other came out of a 72 Nova.

If I was in your shoes, I would look up the casting numbers for each set of heads to see what you really have to work with.
From there I would then start looking on the interwebs for tips and tricks for doing the porting yourself.
I am sure there is a veritable plethora of videos online demonstrating exactly what you will want to do and to not do to your heads.

I used a smog era 350 head to experiment on when I did it.
I did one head and then lost my steam to finish it.

 

[Old-beat-up-77]

Ok. So what about finishes? Im hearing rough on the intake and smooth of the exhaust... What about if you're adding TBI? Doesn't that play into the intake finish as well?

 

[Catbox]

TBI is still a wet port design, so I believe that carb style porting still would be the way to go.

 

[shiftpro]

If you're spinning 10,000 rpm, go ahead and polish the intakes.

Polishing exhaust and combustion chamber just prevents excessive carbon buildup, does nothing for performance. But you won't lose preformance due to carbon buildup.

 

[Salty Crusty]

There is usually a ridge from the cutter on the short turn radius and smoothing this out will do more than just about anything else.
Rough finish in the intake helps keep fuel in suspension, so don't polish them. As far as the exhaust is concerned, as smooth as you want to make 'em.
Oh, and headers if you don't already have 'em.