[steve25]

I meant to post this info a good while ago and I just got my iPad going again to get at these photos off it.

The early Edelbrock chambers have a major machining issue in that when the corners of the chambers get machined by two different cutters they, number 1 leave a bad recessed area ( fuel collection pocket)
and 2) leave very sharp edges that make for local hot spots.

These two recessed areas collect fuel that does not light off when the spark lights off the main pocket of air and fuel mixture in the chamber.

These two pockets of unburned fuel either get sent out the exh as wasted fuel, or worse yet (when the temperature gets hot enough to do such ) finally light off late in the burn of the main pocket and then these two colliding flame fronts create a power loss and destruction as in detonation.

In my seperate photos of the stock chamber in these two locations you will see that these two
Pockets I have colored up in black marker .

You can also see the sharp machining edges left also.

There is a particularly bad lip left on the corner of the intake valve that stands up close to .050” and very close to the edge of the valve

There are other restriction and sharp edges around both valves on the shallow side of the chamber that I will make a separate post about.

Mean while grinding and then polishing out these areas on the plug side of the chamber takes the use of some special cutters and a good portion of the material removal and polishing can only be done with the nose of a lot of tapered sanding rolls, and of course with sacrificial valves in place .

Although even then a few areas that needed rework of both valves I found I could only get these areas done without having the protective valves in place, and all of this highly tedious work took me near 3 hours to get the 8 chambers done.

One of my photos shows the ruff cutting with no blending polish done yet.

I hope these photos work well with my info above here, but for certain these two dimensional photos do not show the severity of these two fuel collection pockets left as Edelbrock shipped these stock.

[Gary H]

Originally Posted by steve25

I meant to post this info a good while ago and I just got my iPad going again to get at these photos off it.

The early Edelbrock chambers have a major machining issue in that when the corners of the chambers get machined by two different cutters they, number 1 leave a bad recessed area ( fuel collection pocket)
and 2) leave very sharp edges that make for local hot spots.

These two recessed areas collect fuel that does not light off when the spark lights off the main pocket of air and fuel mixture in the chamber.

These two pockets of unburned fuel either get sent out the exh as wasted fuel, or worse yet (when the temperature gets hot enough to do such ) finally light off late in the burn of the main pocket and then these two colliding flame fronts create a power loss and destruction as in detonation.

In my seperate photos of the stock chamber in these two locations you will see that these two
Pockets I have colored up in black marker .

You can also see the sharp machining edges left also.

There is a particularly bad lip left on the corner of the intake valve that stands up close to .050” and very close to the edge of the valve

There are other restriction and sharp edges around both valves on the shallow side of the chamber that I will make a separate post about.

Mean while grinding and then polishing out these areas on the plug side of the chamber takes the use of some special cutters and a good portion of the material removal and polishing can only be done with the nose of a lot of tapered sanding rolls, and of course with sacrificial valves in place .

Although even then a few areas that needed rework of both valves I found I could only get these areas done without having the protective valves in place, and all of this highly tedious work took me near 3 hours to get the 8 chambers done.

One of my photos shows the ruff cutting with no blending polish done yet.

I hope these photos work well with my info above here, but for certain these two dimensional photos do not show the severity of these two fuel collection pockets left as Edelbrock shipped these stock.

Great information! Thanks for sharing. One question. When you say early chambers, are you saying all heads before the "heart" shaped chamber?

[steve25]

Yes, although I don’t recall the 72 Chambers being quite as bad as this larger CC one .

[694.1]

Wow. Kinda surprised they even shipped those, much less someone accepted them.

[PAUL K]

The early 87cc chambers were a mess. Once fixed they worked

[tempest1964]

Great information. I had no idea. Thanks!