Does anyone have some good pics of a set of 781 heads after they have been ported and bowl work done?
How smooth do they need to be? Mirror finish or not?
I have been working on a set a little at a time, just need some visual aid....LOL

Sure, buy a copy of HPBooks old book, "How to HR BB Chevys" b/c there's good pic's of both large oval and rect. in it.

pdq67

Hope these help.
They were cut for 2.19/1.88 valves first.:D
http://i188.photobucket.com/albums/z106/Paul-ish_photo/DSC02304.jpg
http://i188.photobucket.com/albums/z106/Paul-ish_photo/DSC02306.jpg


http://i188.photobucket.com/albums/z106/Paul-ish_photo/DSC02305.jpg

Thanks, Paul-ish, that was what I was looking for....good pics. I will post some when I get a little farther along on the heads.
If anyone else has any, please post them also.....

Have you seen this thread?

http://www.chevelles.com/forums/showthread.php?t=238682&highlight=781+ported&page=4

And check the link in the last post by trmnatr.

I just had my 781s professionally ported. They will be re-installed on my 496. The previous owner had port matched both intake and exhaust but removed a bit too much from the area just under the valve seat. No radiusing of the short side was done or the ports. The porter did what he could do. Here are the results.

Before
.100", .200", .300", .400", .500", .600", .700"
80, 148, 215, 261, 277, 289, 295 (intake)
49, 98, 133, 159, 178, 182, 185 (exhaust)

After
.100", .200", .300", .400", .500", .600", .700"
82, 177, 239, 282, 295, 315, 325 (intake)
54, 106, 141, 169, 196, 215, 230 (exhaust)

Coupled with a new custom solid roller
273/289 advertised
243/256 @ .050
.655"/.639" lift
112 LSA (for vacuum for the brakes)

Replacing hydraulic flat tappet
276/284 advertised
234/241 @ .050
.554"/.572" lift
110 LSA

Should be a lot more fun.... :hurray:

echristie,

That looks like a pretty good improvement! Any pics of the work?

You really stepped up going from a hydraulic flat tappet to a solid roller. What are the goals for the new set up? Any E.T.'s for the old combo?

Rod,

I'll post some pics when I can get some good light on them. The valves are installed, so I'm trying to image a long dark port. No ET with the old cam. It wasn't in there very long - only a few thousand miles. Mainly street driven. This time around I wanted a bit more hp and lot more torque. That's why I stayed with the ovals. On the dyno, the flat tappet floated around 5400. The shop that helped me with the engine did not recommend going hyd roller because the problem could get worse with the added weight of the lifter. So, mech roller. I ended up with a custom cam so I could get some vacuum for the brakes. Also, with all the flattened lobes reported here, I never felt confident with the old build.

I hope to get some runs in as soon as I can.

Cheers,
E

Eric,

Thanks. It'll be interesting to see how you make out. I'm a solid flat tappet guy myself but I'm contemplating going roller at some point. The roller failures actually scare me more than the flat tappet failures, though. What roller lifters are you going to run? What's your plan on maintenance?

I selected Lunati for the cam and the lifters. It is the roller bearing style. For high RPM and trips down the track, Isky's EZ Rolls are the ticket. They are 2x the cost though. Most of what is on the market is roller bearing. Isky's EZs are bushing style. Most roller bearing style have forced oil feed now to prevent failure. From talking with Lunati, Comp, and my builder they recommended avoiding extended idling. That limits oil to the rollers. The solution would be drop into neutral, tap the throttle a few times to get the pressure and flow up.

I went with a high flow oil pump as opposed to a high pressure. I replaced the stock pan with a higher capacity Milodon so I have more oil to start with. Maintenance will follow the normal oil change cycle (3000 miles) with some ZDDP just for grins. Valve adjustments have been recommended about once a year depending on driving I'll check it at the end of the summer to see how it does.

Cheers!
E

echristie,

That looks like a pretty good improvement! Any pics of the work?

You really stepped up going from a hydraulic flat tappet to a solid roller. What are the goals for the new set up? Any E.T.'s for the old combo?

Rod,

It took me a while to get the pics posted as I am trying to get the engine reassembled and running by this weekend. Here's some pics. Sorry, but a couple of images are a little blurry. You can still see how smooth the ports are and where the valves were unshrouded. Short side radius' are very smooth and helped flow a bunch. That was where the bulk of the work was done. The porting of the intake and exhaust was done by the previous owner. I am eager to see what this is going to do in the car! :hurray:

Intake 1 (http://www.austintx.net/echristie/TC/781Intake1.jpg)
Intake 2 (http://www.austintx.net/echristie/TC/781Intake2.jpg)
Intake 3 (http://www.austintx.net/echristie/TC/781Intake3.jpg)
Combustion Chamber (http://www.austintx.net/echristie/TC/781CC.jpg)
Exhaust 1 (http://www.austintx.net/echristie/TC/781Exhaust1.jpg)
Exhaust 2 (http://www.austintx.net/echristie/TC/781Exhaust2.jpg)

E.

Mine are 049's but they are basically identical.

http://www.macswebs.com/richl79/65tudorwagon/headunder.jpg

http://www.macswebs.com/richl79/65tudorwagon/headpockets.jpg

http://www.macswebs.com/richl79/65tudorwagon/headintake.jpg

http://www.macswebs.com/richl79/65tudorwagon/headexhaust.jpg

Rich,
Did you have the heads flowed? If so what are the numbers?

-Bobby-

Rod,

It took me a while to get the pics posted as I am trying to get the engine reassembled and running by this weekend. Here's some pics. Sorry, but a couple of images are a little blurry. You can still see how smooth the ports are and where the valves were unshrouded. Short side radius' are very smooth and helped flow a bunch. That was where the bulk of the work was done. The porting of the intake and exhaust was done by the previous owner. I am eager to see what this is going to do in the car! :hurray:

Intake 1 (http://www.austintx.net/echristie/TC/781Intake1.jpg)
Intake 2 (http://www.austintx.net/echristie/TC/781Intake2.jpg)
Intake 3 (http://www.austintx.net/echristie/TC/781Intake3.jpg)
Combustion Chamber (http://www.austintx.net/echristie/TC/781CC.jpg)
Exhaust 1 (http://www.austintx.net/echristie/TC/781Exhaust1.jpg)
Exhaust 2 (http://www.austintx.net/echristie/TC/781Exhaust2.jpg)

E.Eric, Thanks for following up with pics! Great shots. This thread should be a sticky!

Rod

Eric, Thanks for following up with pics! Great shots. This thread should be a sticky!

Rod
Bump. Moderator? :)

E.

Thanks for the pics, guys, I have one of the heads almost finished, I will take some pics and post them later....
I have read that the intakes ports need to be a little coarse, 80 grit?, and the exhaust need to be polished smooth, any feedback on this?

The intake side should be rough to promote turbulence and provide a more homogenous A/F mixture, the exhaust side and the combustion chamber should be polished smooth.
In the following pic notice the radiused tip of the valve guide, the tip of the valve guide should flow smoothly into bowl as shown..

http://i188.photobucket.com/albums/z106/Paul-ish_photo/DSC02304.jpg

now if you observe the valve seat and notice how it comes very close to edge of the chamber this is the area where A/F is impeded or (shrouded), installing bigger valves increases the A/F potential but also further shrouds the valves, hence the need for unshrouding the valves.
The sharp edges in the chamber where the valve seat is installed and the edges of the combustion chamber itself should be radiused also, not only are we concerned with smooth flowing characteristics inside the chamber but the sharp edges also get hotter than rounded edges and can promote detonation issues when combined with healthy cylinder pressures and pump gas.
Use a head gasket that is .010" larger than the finished bore size, the gasket bore will decrease slightly when compressed and we don't want the edge of the gasket protruding into the chamber. Nor do we want a gasket bore size that is more than .010" larger than the finished bore size as this decreases the sealing area of the gasket itself and may cause gasket failure..
Its ok if the intake runners in the head are slightly larger than the manifold, but not vice-versa.
The only place you want to polish on the intake side is all of the short-side radius's, this is the inside corner of a runner, whether it be on the side or the bottom of a runner. Polishing the short-side radius helps the A/F mixture (turn the corner) w/o running into the corner wall and knocking the fuel out of suspension.
Its easy to make an engine go fast, all ya have to do is think like an aircraft designer, the above head shows proper technique and is well on its way but still unfinished at this stage..

Good stuff guys and thanks, George....
I need to work on the heads a little more....LOL

Paul-ish, good pics.

Did you not backcut behind the ex valve? risky, as you can put your fingers in the waterjacket and feel the seat, but there's supposed to be around .100" min there.

Those ex ports, is the roof raised a bit?

As I pondered the ports on my 781, it looks like both the in and ex ports can use a bit of "roof raising".