[RUDOLFSSON]

How about some photos of various Pontiac heads ?? Sure would help in many ways...

Here's a junk #96 head I cut up on my big horizontal band saw..... Valve spring pad measures 5/16" thick.

I didn't want to cut through exhaust because it had hardened seats in it.


Thanks,
Kris

[Half-Inch Stud]

nice to see no rust penetrations

[taff2]

Very thin on the long side to the right of the guide, just where you need to grind it out! It's where I usually break through and need epoxy. Short turn into the bowl has plenty of meat to reshape it though.

[steve25]

There's lots of internal rust in the Head as the rear of the valve bowl is normally much thicker.

Those heads must be off of what we call a southern motor here in the US where you can get away with little to no antifreeze!

If your breaking thru the port wall at the junction of the rear of valve guide boss and the roof of the port then your not porting the Head right and wasting time to boot!

The area of the port roof that needs to be raised and have a arc to it is above the crown of the short turn, and even this only need to be done once you get up to certain valve bowl Throat percentage.

Also note that as you lay back the short turn to keep control of the air mass that you are pushing the crown of the short turn even further back towards the Intake flange!

[RUDOLFSSON]

This head had valve job work and the last cut reaching pretty deep and wide. Blending the valve job and the runner resulted in a through hole in the early stages of the port work....


PS.. Kudos on your cylinder head posts Steve !!

[steve25]

Thanks and your welcome!

[RUDOLFSSON]

Thanks to Screamingchief...

6X-4 exhaust section photo

[charlie66]

looks like alot of meat there on those 6x-4 heads

[RUDOLFSSON]

Yup Charlie. Clearly shows what can be done to these EGR bosses and valve spring seat remachining capabilities just to name a few.

... was hoping that people would share their findings. Sections on various heads that is.


KRIS.


Sent from my iPhone using Tapatalk

[steve25]

Pull the seat out of that head and then cut thru it and post that picture up if you would?

[taff2]

I like that thin section to the right of the guide in the bowl (in the first pic) to be as straight as possible. Smokey Yunick described that area as a 'storage pocket'.

[steve25]

Maybe so in a 23 degree SB Chevy head, but not in a 14 degree valve inclination angle Pontiac Intake port!

[taff2]

Ah, perhaps that's why my 400 Pontiac with heads home ported as I mentioned used to rev to ,and make power to 7000 rpm, with a very mild cam and an old Toker 1 inlet. It also only ran 9.60's at 2700 lb, I guess I was just lucky...

[lust4speed]

Here's a chunk of a 670 as-cast head. We cut this one up in 1985 to see where the thin parts were.

[taff2]

I like the shape of that 670 intake port, it looks like there is a lot of room for improvement too. How do these compare to later d port heads when both are properly ported?

[steve25]

Thanks for that 670 cut away shot!

[Steve Barcak]

I did the same thing around the same time with the 670s once I learned how good in the intake port was. After the cut away, I learned it was no problem opening up the chambers to convert to open style.