Sucks that's a hurdle for sure,...I've never tore into but a few 350s ,..always just threw them in the scrap pile
Well then you should try one out and throw a big shot on it. I am going to throw in a solid lifter cam just to go different just want to do it.
I didn’t change the direction of the tail from what was already there (and didn’t really change it’s size or shape much at all either), but just created a bit more definition where the right side (in my pictures) of the tail meets the port ceiling/wall transition. I’d definitely like to know what advice you have for the upper common wall and exhaust port. I think what I want to do is “finish” the intake & exhaust of this chamber/cylinder and have it flowed just to see where it is and then (as long as the numbers aren’t awful) work on the rest of the heads. In the end this engine won’t be a race engine, or ever even get pushed past 5000 or so RPM. There’s no duct tape to try and give a clearer idea in the pictures of what changes I made so far. As far it being the final valve job, the answer is yes & no. 19 or 20 years ago the heads got a lot of work done at Bischoff’s (surface grind head surface, install new hardened exhaust seats, install bronze guides, cut for larger intake valves, & full competition valve job), but they’ve just sat until now, so I’ll lap the valves to be sure the seats are fresh.
I thought that the exh side had seats installed by the looks of it, but it’s hard to tell in photos sometimes. the exh bowl throat may now be smaller then what it was stock. Do you have inside snap gauges and a dial caliper? Can you report back with what that throat diameter is now?
The rest of the intake port rework needed is done on the common wall. If you look at the first photo here you can see where the upper area of the common wall where it transitions from the runner to the bowl has been moved over towards the head bolt hole. I removed .050”of meat over a length of the wall of close to 1 3/8”. This was only done on the upper section of the wall . This will change the rectangular shape of the runner into a taper that ends in a .050”wider trapezoid. The gentle wall taper starts at the mid height of the common wall, one again as seen in the second photo when you expand it and look close. This you can see in the second photo shot through the intake flange. This mod moves more air into the long side of the valve bowl while keeping the velocity high on the floor.
Stage 2 V6 heads?,.. because all factory 400 to 455 up to 74 had a closed chamber,..even the standard V6 "8445" heads were closed chamber,..
Weren't you changing that cam back in the spring of 2021...... Get r done already! Lol!! Back to the head porting.
All 68-80 buick 350 heads are open chamber. Yes the TA Alum 350 heads are closed chamber and yes I have some irons converted to closed chamber.
I tried to measure the openings at the deepest/smallest diameter point of the valve cut, and I only measured the 4 openings on the head I have set up to work on, but they were all just about the same. Going front-to-rear (red arrow) they were around 1.262", and diagonally (green arrow) they were around 1.290".
That’s good because the stock throat is 1.1750” length wise in the head ( head end to end) and a little more width wise, as in intake to exh flange.
Correct. I just used a photo I already had to mark up with the arrows because it was aimed pretty straight at the chamber.
Lapping the valves is fine for confirming complete contact area, but you should not use the standard grit Clover stuff, or for example the Permatex stuff in the tube. Use clover’s 400 grit polishing compound. The common stuff says imbedded in the head and valve no matter what you do and just chews up the seats over time. most times when everything is as it should be you can simple color up real wet the seat on the valve with a big black marker and just drop it down into the guide and have it hit the seat in the head. Then without spinning it quickly remove it and look for imperfections in the contact area.
Without being overly aggressive, I think I got in the ballpark of what you were describing for the runner-to-bowl section. Any pointers on the exhaust guide/bowl area?
Exh wise here are some pointers. since the exh valve is on one side of the chamber and most of the bore area is away from the exh valve ( my first drawing) a full 65% of the exh gasses that we need to get out pass into the exh bowl as in my 3rd drawing , especially at high lift. The hard part about reworking any exh port and especially if your not going up in valve size is for your porting work to not loose any of the stock amount of low lift flow. in my second poor drawing you can see that kicking out the wall of the exh port on the cylinder wall side will help with the natural way the mass of the exh flow wants to go as seen in my 3rd drawing. Besides kicking out this wall on the cylinder wall side of the bowl the roof can also be raised up by about .045”. This should start from the half way point of the valve guide hole on out to 1/4” after the roof meets up with the crown of the short turn below it. the valve guide should be boat tailed, but only from the center of its nose around to the cylinder wall side of the guide, If you boat tail the intake valve bowl side of the guide you will drop off low lift flow. A 3 angle valve job will greatly help exh flow coming in around the valve to use a lot more of the available bowl area. Changing over to 11/32” stem exh valves helps a nicely to move more high lift flow out of the motor. the exh valves as with the intakes should get a 30 degree back cut. this back cut should leave the exh valve with a .065” wide seat, and the intake with a .050” wide seat on it.
