head port work

B

BCOWANWHEELS

Well-known member
fixing to start port work on my head. the exhaust ports are really small IMO has anybody got any pictures of there ported head they can post. this is for a D/D so race porting isn't my end result.
thanks
bob
 
BCOWANWHEELS":3qf5m3p3 said:
fixing to start port work on my head. the exhaust ports are really small IMO has anybody got any pictures of there ported head they can post. this is for a D/D so race porting isn't my end result.
thanks
bob
Click to expand...

Porting without a flow bench is a recipe for disaster, you can just as easily make a head flow worse as you can make it flow better... Find a good head guy, who has a flow bench, and turn him loose with it...
 
I'll check my pics tonight. I'm not done yet. I've cleaned up the combustion chambers and done the port matching on the exhaust. Waiting to get machine work done before I work the bowls. I'm not doing anything in the bowls besides cleaning them up. No shaping beyond teardropping the guide bosses. Primarily cleaning up the casting flash.
 
Since my engine is a mild build. I opened up the ports slightly. Spent more time cleaning, smoothing the ports.

My port divider required more work. The 2 separate ports it created, were smaller than the OEM ports
 
RichCreations":x5dteu1p said:
BCOWANWHEELS":x5dteu1p said:
fixing to start port work on my head. the exhaust ports are really small IMO has anybody got any pictures of there ported head they can post. this is for a D/D so race porting isn't my end result.
thanks
bob
Click to expand...

Porting without a flow bench is a recipe for disaster, you can just as easily make a head flow worse as you can make it flow better... Find a good head guy, who has a flow bench, and turn him loose with it...
Click to expand...

I agree with this.
Watch porting ,what looks good may not be good especially the short turn radius .
the gaskets are way to large on these engines a little smaller on the head side is good. These are thin wall castings be careful. If going headers you can knock down the redirect bumps some because flow may be a different direction. I thin the guides.
 
I,ve been doing port work for 30+ yrs, you don't need a flow bench for a street engine. its not rocket science. just picture a water hose. what makes the most water come out ? thanks for the thoughts and ideas. I just never did a 250 head before, mostly sbf,s,chevys and early hemis an occasional chevy 6.
 
BCOWANWHEELS":144xygy5 said:
I,ve been doing port work for 30+ yrs, you don't need a flow bench for a street engine. its not rocket science. just picture a water hose. what makes the most water come out ? thanks for the thoughts and ideas. I just never did a 250 head before, mostly sbf,s,chevys and early hemis an occasional chevy 6.
Click to expand...

Once you account for variable densities, wet flow, etc, it is far from a water hose, and honestly, for a street engine, the gains will be small at best, and possibly could reduce power if done wrong...
 
Here's mine, but this is probably overkill for the return on the investment.
AFAIK, the most gains are to be had pocket porting the valve bosses.
porting.jpg
 
BCOWANWHEELS":242yuyuj said:
fixing to start port work on my head. the exhaust ports are really small IMO has anybody got any pictures of there ported head they can post. this is for a D/D so race porting isn't my end result. guess I,ll do like always just make exh, port match gaskets.
thanks
bob
Click to expand...

Bob
The exhaust ports may look small but they actually flow as much as the intake ports.
The intake port needs for more attention than the exhaust.
Do not gasket match the exhaust ports. It is better to have the exhaust port exit smaller than the exhaust manifold/header entry.

As mentioned, for both the intake and exhaust, the most gains are made by modifying the boss for the valve stem guide and cleaning up the rest of the bowl area around it.
Don't touch the short turn radius except to clean up the casting.

The valve job is also a good area to pick up flow.
You can use valves that have undercut stems
The intake valve head can be back cut just below the 45 degree contact area.

It is also important for low to mid-lift flow not to open up the intake throat too far so there is sufficient material for a reasonable 60 degree cut below the 45 degree valve seat.
This helps direct the flow to the edge of the valve head as it starts to lift off the seat.
 
Now were getting into the "meat" of port work. I,ve got SI 1.84 / 1.50 VALVES going to install hard exh. valve seats and let my machineist use his stones to relieve around the int valves a little then get into the ports with my carbide burrs followed by buffs of varying grits. Since I,am going to run headers I,ll keep ports a tad smaller than header opening. going to weld in a port divider also. thanks for all the tips. the more minds in anything brings out better results IMO. think I,am also going to dress up the outside of the log for a better appearance. sure is a lot of casting line flash. also going to do some oil return hole work to get oil back down quicker I think. going back to shot clean the casting Monday so carb flanges will have a good clean area for furnace brazing my water jetted flanges on # 2 and 5 port areas. I,am excited to see how these 2 duces ( ford 94 carbs ) is going to run. Schneider ground a cam for me last Wednesday. also with custom forged pistons opening up the combustion chambers a little should be easily made up with piston top design. I ,am doing resherch on light weight wrist pins now.
 
WoW,
roughly how many hrs 4 sompin like dat!?!

Thanks for an example of what's been talked about, makes it much clearer for this guy.
But,
aint that further along - ie near race quality? (or is that the same but mirror like)
I don't think my hands would hold up for one like that in ur photos but don't know ~
 
Yeah, I'd say I had around 4 hrs in mine. It goes pretty quick once the grinding bit is done with the bur and you switch to the sanding cartridge rolls. I used a ~3/8" cylinder shaped bur with a rounded tip
 
lill bit of a pineapple shape?
got one.

I C U didn't go 'wild' but it looked like alot more than 4 hrs.
U give me hope, think I'll get to wrk on the '69 "M" -or- hold on,
better practice (my 1st attempt) on 1 of the others.

Thanks ~

BTW: what is the slightly different looking surface immediatly around the exh. port openings, does not extend down in or far from the immediate surounding edge? Was that what was left from the machinist's pass or something from your own wrk?
 
Didn't Perry simplify things AND make it so larger pic can be shown (as we update since Mike's death)?
/OR/
is that just on the test site.? I saw guys exclaming their happiness w/the improvements.
I thought I also saw the "how to" thread…

Sorry, I concentrate on other stuff & some of these things kinda just pass by w/o my attention...
 
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