Ported Chevy 049 heads

[mag2555]

Don't forget that the Exh valve is canted also so this means that the roof from around the center height of the valve guide area on out to the flange on the non cylinder wall side can be raised up more then the other side for more flow area.
This also means that the floor if your reworking it should have some degree of compound arc to it where the cylinder wall side is a tighter arc.

A long Boat tail of the Exh guide is not a good thing at times ,as there is flow that wants to cross over on the roof dependant on the overall shape and valve job used, I would try it both ways

Investigating with a velocity probe on the Exh side will turn up good info on where the flow mass is looking to go instead of trying to force it to go somewhere else !

[Carnut1]

Don't forget that the Exh valve is canted also so this means that the roof from around the center height of the valve guide area on out to the flange on the non cylinder wall side can be raised up more then the other side for more flow area.
This also means that the floor if your reworking it should have some degree of compound arc to it where the cylinder wall side is a tighter arc.

A long Boat tail of the Exh guide is not a good thing at times ,as there is flow that wants to cross over on the roof dependant on the overall shape and valve job used, I would try it both ways

Investigating with a velocity probe on the Exh side will turn up good info on where the flow mass is looking to go instead of trying to force it to go somewhere else !

I would think the same for the boat tail. It will go at the end of the mods and see if it gains or loses flow. I would love to see some pics of your work! Thanks Charlie

[Carnut1]

0407161825a.jpg

Good port redux.

[Carnut1]

0407161827.jpg

Bad port redux

[Carnut1]

0407162103.jpg

Reflow redux. Ave up on Bad port, down on good and exhaust.

[Carnut1]

0407161858a.jpg

Good port slight deshroud and plug boss work.

[Carnut1]

0407161858.jpg

Bad port slight deshroud and plug boss work.

[Carnut1]

0407162133.jpg

Reflow after deshroud and plug boss. Almost same flow as original.

[Carnut1]

0407161942.jpg

Quench pad cut. Bob took a big slice out of one pad and left the other stock. The left one is more the way I like the shape.

[Carnut1]

0407162153.jpg

Reflow after quench cut. Slight gains on all ports.

[racear2865]

Played with the 049 and 781 quite a bit. At some place, you will need to go to the dyno to see what you have. When you made slight change in the quench, did you increase or decrease in the swirl. Also did the rework of the quench affect if the incoming charge will hit the cylinder wall especially with a 4.280 to 4.310 bore. Then shift the head .030 to get better clearance on the intake charge and see what happens. Then radius block down to close to top ring. Simulate that in your cylinder you are using on the flow bench.
reed

[Bob Hollinshead]

Good stuff! Thanks for the extra tuning and testing!

[Bob Hollinshead]

Played with the 049 and 781 quite a bit. At some place, you will need to go to the dyno to see what you have. When you made slight change in the quench, did you increase or decrease in the swirl. Also did the rework of the quench affect if the incoming charge will hit the cylinder wall especially with a 4.280 to 4.310 bore. Then shift the head .030 to get better clearance on the intake charge and see what happens. Then radius block down to close to top ring. Simulate that in your cylinder you are using on the flow bench.
reed

When you notch a 4.310 bore what is it worth for flow? A friend of mine put a set of profiler 320's on a 4.280 bore and didn't do the chamfer-always wondered what it might have been worth? it's a 10-1 compression 4.25" crank combo that is down in the low 9's. Made 670hp on pump gas with a street roller, now on methanol with nitrous and a cam and carb upgrade.

[Carnut1]

Good stuff! Thanks for the extra tuning and testing!

It is a learning curve. No real gains so far. I will try a few more mods and hopefully find more air.

[Carnut1]

0409160749.jpg

Added a slight 75 degree bowl cut and some srr work. Slight loser on both ports.