Im doing a little do it yourself port and polish and the head has hardened seats which are inserted slightly(1/8mm lip) under the surface of the chamber area. Can this lip be polished down to the height of the hardened insert?????

Originally posted by rogueturtle
Im doing a little do it yourself port and polish and the head has hardened seats which are inserted slightly(1/8mm lip) under the surface of the chamber area. Can this lip be polished down to the height of the hardened insert?????

RougeTurtle -- Can you give us an idea of WHAT you are porting?

Wish I had taken photo's of my $10 flow bench, but it gave me a better idea of what metal to remove to increase the air flow.

Flow Bench (el cheapo):
Shop Vac (supplies air flow)
4" diameter plex tube - 6" long. (the $10 cost. Inner diameter matches the piston bore to get an idea of piston wall shrouding effect)
Small DC fan (in the air stream)
Voltmeter

The more the air flowed through the port, the faster the fan would spin. This produced a DC voltage. Non Linear response, but I could measure the difference in flow rates.

To "adjust" vavle opening, I used a spring from a spiral binder in place the normal spring. A simple 20 tpi bolt was set up in a home made holder to press down on the valve. One turn of the bolt head, increased the lift by 0.050" (handy increment).

Back to your original question, smoothing the lip at the edge of the valve helps. You don't want to grind all the way down to the vavle seat, but smoothing any sharp edges is a help.

Odd thing, more flow doesn't always mean more power! The mixture of the swirl plays a very important part in the burning of the fuel, so sometimes it is better to offset the port, to help with a better swirl pattern, than have a huge port that flows a lot of air, but produces little swirl.

Credit for this setup goes to a buddy who was working on his Ph.D. He also showed me too other tricks: A string in the air stream to get an idea of air patterns on different areas of the port & valve. Also a simple spray bottle so we could see the swirl pattern of the water.

With my old job, I used to get to play in the some of the labs of engine development. Lots of quartz pistons, or quartz cylinder walls, and high speed photos & computer models of the burning patterns. Too much fun for words, but great learning. Ya, I'd love to go back for a Ph.D. in that area someday, but life gets in the way...

Lots of poor books on the market, but David Vizard or John Leightenfelter (spell?) both have written some great articles & books.

Tom :usa:

Hey Roundrock,
That flow bench sounds like one hell of an idea and it's been something the at has always been at the back of my mind. I have a couple of questions if you don't mind me asking. I would like to build a more permanent flow bench, would you go with a venturi tube instead of the DC motor/fan set up in the air stream? Did you measure air speed before the airflow went into the port as well? One last one, do you think and an centrally located integrated spray nozzle in the inlet pipe would be a good idea or would it cause to much disruption in the airflow? Thanks!

The venturi tube would work fine. It was more a matter of "what is around here that can be used". The DC fan was cheap, and "donated" from a dead computer. Still it needed SOME air just to get moving, but different fans acted differently. Just found one that worked.

You could measure the flow going into the port, or coming out of it (after that plexiglass tube). Usually I'll bolt on the intake manifold on the head, if possible, but very least will put some modeling clay around the intake port to smooth out the air flow, to get a more realistic idea.

Whole idea was to keep it cheap and simple. I could repeat results on the same motor/dc output. Still didn't have an exact cfm number, but this set up worked with "try this, and see what the results are".

What would you use the nozzle for? Water pattern? With the open intake port, and a mist bottle, you can see it pretty well.

For such a simple set up, it worked rather well.

Tom :usa:

Originally posted by roundrocktom


RougeTurtle -- Can you give us an idea of WHAT you are porting?

Wish I had taken photo's of my $10 flow bench, but it gave me a better idea of what metal to remove to increase the air flow.

Flow Bench (el cheapo):
Shop Vac (supplies air flow)
4" diameter plex tube - 6" long. (the $10 cost. Inner diameter matches the piston bore to get an idea of piston wall shrouding effect)
Small DC fan (in the air stream)
Voltmeter

The more the air flowed through the port, the faster the fan would spin. This produced a DC voltage. Non Linear response, but I could measure the difference in flow rates.

To "adjust" vavle opening, I used a spring from a spiral binder in place the normal spring. A simple 20 tpi bolt was set up in a home made holder to press down on the valve. One turn of the bolt head, increased the lift by 0.050" (handy increment).

Back to your original question, smoothing the lip at the edge of the valve helps. You don't want to grind all the way down to the vavle seat, but smoothing any sharp edges is a help.

Odd thing, more flow doesn't always mean more power! The mixture of the swirl plays a very important part in the burning of the fuel, so sometimes it is better to offset the port, to help with a better swirl pattern, than have a huge port that flows a lot of air, but produces little swirl.

Credit for this setup goes to a buddy who was working on his Ph.D. He also showed me too other tricks: A string in the air stream to get an idea of air patterns on different areas of the port & valve. Also a simple spray bottle so we could see the swirl pattern of the water.

With my old job, I used to get to play in the some of the labs of engine development. Lots of quartz pistons, or quartz cylinder walls, and high speed photos & computer models of the burning patterns. Too much fun for words, but great learning. Ya, I'd love to go back for a Ph.D. in that area someday, but life gets in the way...

Lots of poor books on the market, but David Vizard or John Leightenfelter (spell?) both have written some great articles & books.

Tom :usa:

Dayem! I think we've found our flowbench "official" source! Thanks for the advice, that ones a keeper!

Im doing the intake and exhaust ports and bowl area around the valve. Nothing major other than grinding down the valve bosses which stick waaaay out.

The other major grinding reshaping ive done is around the intake bosses which run right thru the center of the intake runner on a 292 Head. Higher Hp engine builders remove these altogether but this can actually hurt flow velocity at lower hp levels like a Landcruiser that plans on running sub 3000rpms. Ive shaped the bosses more like an airfoil versus the circles around the head bolts in original form.

Thanks for the answer to the lip above the seat area! I thought it looked a bit flow menacing and figured a mild polishing of the corners would do the trick.

Porting and polishing a 292 I6 is like putting a $50 saddle on a $10 horse: It may look nicer, but it isn't going to run any different.

It isn't going to develope the RPMs where port flow is an issue and the engine has more fundamental flow problems, like the intake manifold.

Im working on that end and throwing on a Clifford 4bbl intake manifold with a holley 390 carb. The intake runners on the cliffords look a bit larger and the clifford manifold has a 4bbl plate versus the monojet on stock one. Hopefully a little more gas and air to the mix will help things out getting to the heads.

My big dilema is what valve size to go with for a rig application. In stock form they are 1.72intake and 1.5exh. With an h55 tranny and 4.11s x 33 tires i will stay at around 3000rpms max. so i dont want to lose velocity with huge valves.......but want to get it to breath a bit better down low. 1.94intake runs into shrouding issues and 1.85 apparently steers clear but im not sure if the bigger size is going to lose velocity or if i should stay stock size and hope the intake manifold and carb changes do the trick. ????????