nonhog

I understand the idea behind why it should be done. What I'm wondering
(because all I can afford to do is wonder)
Why not add a port divider to the header flange? Need a better seal to make it worth while?

don71

Thats an idea that could be done. Not a perfect one..but none the less its been done before.

Somewhere on the few olds forums I've seen it. I think the poster was a circle track guy.

geckonz08

Seen it too somewhere suggested before --only as a suggestion I believe-

Seems there are all sorts of methods used to block off the ports and not crack the cast whilst so doing .

I too was worried and so made a clip (copied the idea off here somewhere ) and then had the clip welded in place at each end ( little spot welds )using a high nickel content rod .The chap then milled 1/2 mm off the xhaust face. $20 / head .
I was very pleased with the result

67 Cutlass Freak

Here's a link with some helpful information for you-
http://www.realoldspower.com/phpBB2/...xhaust+divider

russroyce

My heads have been rebuilt and it is too late to braze or weld. Is there anywhere I can purchase some of these clips and fit/tack before installing the heads? The link from 67 cutlass freak is no longer valid?

I have a set of hooker supercomp headers that I have never been succesful in making seal for very long without the divider extended to the roof...

Any other options?

I'm not ready to drop the $ for aluminum heads - maybe in a few years.

Advice is greatly appreciated!

grampy

Here a question I have yet to see if anyone has done back to back testing on divider ,no divider how much power is it really worth.at least I think Smitty has said removing the egr bump has little improvement on air flow on stock exhaust port.

russroyce

I'm not as worried about the flow as I am about being able to get headers to seal and not blow out gaskets...


Any other ideas/suggestions?

johnnyjaws

mr gaskit now makes new header gaskits ganented not to leakthere thick layers of aluminiumand are reuseable

joe_padavano

It's been done since at least the early 1970s. I've seen this in old car magazines in Olds buildup articles (back when car magazines actually RAN Olds engine buildup articles... ).

67 Cutlass Freak

Yeah sorry that link is dead. ROP crashed last year and we lost a ton of good information. I started a thread about "Home Porting Techniques", that covers the different options for the divider on page 4. This thread is really long, but it's packed with useful information. Give a look-
https://classicoldsmobile.com/forums/
Another option might be to mill the head on the exhaust surface. I have not done this, but a lot of guys have. I would be worried about header fitment. There's a thread on ROP right now where Josh is having problems with a set of heads that were welded up. They are now cracked and leaking water-
http://realoldspower.prophpbb.com/topic6147.html
Joe Mondello said this mod was good for 10 HP gain on a mild BB.
russroyce, it's not too late to braze or weld your heads. It should not effect your valve job.

Lars

I guess there's 4 options, I don't think you could weld it to the flange, but the header will hold the clip in place.


1 make a header clip out of angle iron
2 make a header clip out of bar stock
3 weld or braze
4 pour molten aluminum in there


The resbond method didn't work.


The angle iron tends to break when bending unless you use heat while you bend. As long as you have some torches a guy MAW pour the crossover at the same time as you fill the devider. If you have time and some various grinders you can make a clip out of bar stock. I may have some bar stock blanks left I could send you.. 67 freak should have a set.


this topic should be a stickey

hilbily

From what I've seen after putting a 455 in my 68 Cutlass if you had a flange sticking out of the header flange I'm not sure if you could get the headers on, then trying to slip the gasket in, I don't know if it could be done.

Bernhard

What about mill flush and make a spacer to add the same amount that was removed?

What is this mod worth?

russroyce

Thanks for the advice all. The motor has been bored .60 and I have followed pretty much all of the performance guidelines prescribed in Joe Mondello's engine build guide. I am not going to be slot racing so the HP gain is not the objective, but I do think that the SuperComp headers would breathe substantially better than the W/Z manifolds. I have had headers on and off about a half dozen times and everytime I couldn't get them to seal up. Since the last time on I have rebuilt and resurfaced the heads and they are now sitting true.


I guess I could sell the Supercomps, but I figured that if I could make the wedge it would be worth the attempt. The heat crossovers have already been filled with Zinc a while back. I could have sworn I saw some manufactured divider inserts a few years back, but can't seem to find them or a reference to them anywhere. I'll Let you know what I come up with.


This is the car a few years ago.


At the time I didn't rebuild the motor because it reportedly only had 10k miles since the previous rebuild... Long story but it was running hot and ended up having to be rebuilt. A hack job got a hold of it and I have been fixing everything he messed up.

Lars

Dick Miller use too have "flow plates". They had a bar in the middle for the center devider and bent in flanges that also raised the port floor. I'm pretty sure you had to mill the head and grind fit the flanges to the head. Don't know if this mod was worth any extra power or not????


The header clip goes not require heat or milling, just a lot of grinding and time to fit correctly. This clip is only for sealing/sound of the exhaust system. IT doesn't give you extra power...


I glued these in with jb weld, milled them flat with the garage floor and a big belt sander belt. they have been running on the car now for 5 months without any issues

russroyce

LARS or 67 Freak I would be happy to purchase some of the blanks from you if you have some. I contacted Dick Miller about the flow plates and he didn't think any gasket would seal up when using headers nor that the flow plates would correct that issue.

Thanks again for the advice/assistance.

Bernhard

Lars you did a nice job in fitting the clip nicely, if welding,brazing,milling,filling makes a gain in power your nicely fitted clips should also.

Lars

Thanks Bernhard, I want to believe they would help flow and performance but don't have any flow proof..


russroyce, contact Dave (67 Cutlass freak) he will have your best solution


good luck...