Jump to content
Forums Gone... but not forgotten!
Pontiac of the Month

hdkeno's 1969 Firebird

2023 March
of the Month

  • Welcome!

    Welcome to Forever Pontiac, where we keep the memory of Pontiac alive with great discussion, maintenance tips, restoration/modification progression "blogs" and help from professional & DIY mechanics. Also, wonderful competitions that occur regularly. Please register for an absolutely free account to join in!

1979 TA 400- matching block, heads, intake

Recommended Posts

Hi! I bought a 79 TA running but the guy said it might need head gaskets. The engine gets hot really quick, and antifreeze bubbles from between the intake and head, in the middle where the exhaust crossover is. The previous owner used copious amounts of red rtv- on but not limited to- the head gaskets. I pulled off the intake and it seemed sealed (red stuff oozing everywhere) I think I am pulling the heads, too. 

My block reads 03845012 xz, the intake 525355, the heads 6x (no 4 or 8). Are these components compatible? How would antifreeze get to the middle of the intake? The motor oil looks fine. The antifreeze is free of oil.

Just curious, any help is appreciated!

Link to comment
Share on other sites

  • 2 weeks later...

Tired of these Ads? Register Today!

My initial theory would be that the wrong gasket was used or it was not torqued correctly (either to the proper ft-lb or in the right order). It is also possible that the gasket was blown or damaged.

The casting number of the intake manifold is for a 1977 Pontiac 400 V8, not a 1979. A 1979 400 V8 intake would be 10003395. It should work well with your 6X heads. 6X (no 4 or 8) would be correct for '79 on a 400 engine. The correct casting part number for a '79 6X head is 400220.

I think you've read the block cast number incorrectly. I think you read it from the front passenger side front of the motor. That will be where the matchiing VIN # of the car the motor was originally built for is found plus the two letter designation for body style and transmission. In this case, I think it to be XZ. The casting number should be on the side of the block or at the distributor well. Assuming for a moment that XZ is the body style / transmission designation, then we may have some issues. XZ was used on 400 engines for B-body (both 400TH and 4-speed manuals) cars from 67-70, a long way from a '79 F-Body. The correct 400 block casting number for a '79 motor is 568557.

So I do think you have a bastard motor made up of either not well thought out parts or badly assembled parts. 

Link to comment
Share on other sites

  • 1 month later...

Sorry I am late in responding. Yikes you have aone helluva gasket mismatch. The center cross over is generally for heat - not water, to allow the intake manifold to warm up quickly in cold weather climates.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Tired of these Ads? Purchase Enhanced Membership today to remove them!
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.