snydes

In the plenum area, I have seen examples of 1966 3885069 manifolds with both the two holes on the drivers side, and with the webbing between those holes milled out. Was there a revision to the design, or is this just a common modification?

Thanks,
Steve

66427-450

For what it's worth, I was told the very early ones had the 2 holes on the left side, the later ones had the divider wall.

JohnZ

The 1st design (used through June, 1967) had the 3-hole closed plenum; the later 2-hole design with the top of the divider wall machined away was only used on the L-88 application.

66427-450

But wasn't there 2 versions of the "non L-88" 069? i'll post some pictures tonight of the 2 types I thought were used. Maybe the divided plenum variation (without the 2 separate round holes on the left side) was a factory over the counter (service/replacement) 069. I'll check the casting dates on several of mine.

JohnZ

No, not in production; the only production usage of the 069 for a non-L88 application was on the 1966 L-72, with the 3-hole closed plenum. The other subsequent variations (2-hole with the divider wall intact and 2-hole with the divider wall machined away) were only used on later L88's and many were sold over the counter.

snydes

The variation I am referring to is 2 hole with divider wall intact vs. 3 hole. I have a Dec. 65 cast 069 with the divider wall intact, but the webbing between the two small holes is milled away. It does look like old mill work done in a production enviroment, but I guess from what I am hearing here it would have been an owner modified unit. I see quite a lot of them cut out like this one (with divider wall intact). I wonder if there is any adverse affect to having that webbing milled out, or if it is actually a beneficial modification? I do understand that if the divider wall was removed, that can adversly affect things, but that is unaltered.

I also had a guy tell me that the "3 hole was the early 450hp intake" which I pretty much figured on that theory.

Steve

JohnZ

Photo below is the 2nd design 069 intake with two holes and the divider intact; don't have an exact date, but it entered production on the Corvette L-72 late in the '66 model year, and was also used on '67-'68 396/375hp Chevelles and Camaros.

knight37128

Here is the "three" hole intake dated late (in the model year) 1966.

Shurshot

That is the one (in the thumbnail) that was on mine (March 66) and I believe it was also on the 69 copo cars and maybe the LS6 Chevelle (that last one is a guess.)

I had never seen the three hole before the one above but I know a lot of 2 hole ones had the divider removed for more high end over low end. Back in 80 I had a builder suggest the divider being partially removed but only if I went further than the 560 lift and 4:11 gears that I already had

In the aftermarket scene Edlebrock's BB dualplane also has this divider but the Brodix dualplane does not. The Brodix has an advertised 300 rpm higher operating range than the Edelbrock.

Doug

knight37128

To get a big carb on the intake (back in the day), you had to go with the "three barrel" Holley. The intake would have to be modified to get it to work.

snydes

Mine looks identical to the 2nd design, but is dated Dec. 65, must have been modified. At least then it shouldn't have any adverse affect when put back on a stock built L72.

Thanks,
Steve

427425

The 069 intake disappeared in April/May of 1968 and was replaced by 3933163, which went through the 1969 model year. LS6 used a flat intake, made similar to 68-69 tri power intakes (height wise) and the # was 3963569.