I have some old Blackjack 1 3/4" primary headers I need to bolt up to my 290 heads. Read a lot of good comments about Mr. Gasket Ultra seal gaskets and was thinking of ordering some from Summit as my motor is to be coming home from the machine shop this weekend. Catalog lists 3 sizes for Big Chevy round:

1.93"
2.15"
2.43"

Does anyone know which I need or what I need to measure? The diameter of the openings in the headers are approx. 1 7/8"

I have old Black Jack AK-5000 headers and I use the MrGasket #5911 gaskets then I make a slight modification to them to match the ports better. I can send you a pic if you want.

Jim,
I'm not sure what part # my Blackjacks are but would like to see what mods you made to make yours fit better. Are yours 1 3/4" primaries?

Scott,I use these: http://store.summitracing.com/partdetail.asp?part=MRG%2D152A

I run 1 3/4" primary tubes on mine..at the header flange,the tubes appear to be about 2",then necks down to 1 3/4"

Chris,
Did you ever have any problems with the Summit brand leaking at all? Ever have to reuse them at all? Any trimming issues to match the ports? Did you use any permatex or any tricks?

thanks

Chris,
Sorry, I looked at them again and see that they are Mr. Gasket brand. The description sounds almost identical to the one in the catalog for the MRG-5911 but they are $15.88 for the pair. Wonder what the difference is? Maybe because the pricier ones are called Utra-Seals.

I e-mailed you a pic.
Yes, mine are 1.75" primaries

Scott,my $79 Summit headers don't leak at all,and neither did the gaskets that came with them.No permatex or tricks either.The part # is SUM-G9010