Pulled Intake Manifold on My 70 Challenger 318

[wagenbob]

Looking for some input here. 70 Challenger 318 (original motor), manual trans (not original... someone swapped out the 3 speed MT for a 4 speed MT at some point).

[History] When I first bought the car, I added water to the radiator and noticed it went into the oil. So I drained the oil, flushed it with another oil change, and just kept the car without water in the radiator. Car ran okay, but I wouldn't run it very long without water. [End History]

After amassing parts for an intake/carb upgrade, I decided to compression test the motor to make sure there wasn't a head gasket issue. I recorded 150 across all cylinders, except 140 on #2, and 155 on #6. Thinking I dodged a bullet, I pulled the valve cover. Immediately felt sick. Pulled the intake, felt sick and sad.

I have to pull the motor anyway to replace the firewall, so I'm planning on having the block rebuilt. My question is, should I rebuild these heads, or use a clean set of 67 318 heads?

[734406pk]

Hello Bobby and welcome to the site!

Your compression readings are pretty good. No head gasket issues there. Small block Mopars use a cast aluminum alloy "combination" timing chain cover/water pump housing that has been the cause of many "coolant in the oil" issues. Cavitation erosion and electrylosis will take it's toll on this cover and eventually and leaks happen. Remove the water pump from the housing and check the gasket surfaces where it mounts to the block. It's highly probable that is your issue.
 Why do you want to use '67 cylinder heads? Are they the same casting number as the original? Have you considered a larger displacement small block i.e. 340-360 cid, or stroked version? Good luck with your resto!

[Cudacat]

Yes, building a larger displacement costs about the same as the original.  Something to consider.

[wagenbob]

Hello Bobby and welcome to the site!

Your compression readings are pretty good. No head gasket issues there. Small block Mopars use a cast aluminum alloy "combination" timing chain cover/water pump housing that has been the cause of many "coolant in the oil" issues. Cavitation erosion and electrylosis will take it's toll on this cover and eventually and leaks happen. Remove the water pump from the housing and check the gasket surfaces where it mounts to the block. It's highly probable that is your issue.
 Why do you want to use '67 cylinder heads? Are they the same casting number as the original? Have you considered a larger displacement small block i.e. 340-360 cid, or stroked version? Good luck with your resto!

Thank you for the insight. I will definitely be changing the water pump after the rebuild. I just checked mymopar.com and the 67 heads are a different casting.

Mopars are hard to come by here; our junkyards in Hawaii are full of Hondas and Toyotas, and shipping costs are killer. So I'm hoping to freshen up the 318 and make a dependable cruiser out of it.

[Cudakiller70]

Welcome from California  Ahhh Mopars in paradise. Worked with a great guy from there, he retired and makes ukuleles. Great site here. Best of luck! 

[734406pk]

Thank you for the insight. I will definitely be changing the water pump after the rebuild. I just checked mymopar.com and the 67 heads are a different casting.

Mopars are hard to come by here; our junkyards in Hawaii are full of Hondas and Toyotas, and shipping costs are killer. So I'm hoping to freshen up the 318 and make a dependable cruiser out of it.

 AH, the price of living in paradise! Well the 318 will make for a dependable cruiser power plant! You can install a modest cam and a 4 bbl manifold to gain some HP without killing the mpg. Good Luck with your rebuild!

[wagenbob]

AH, the price of living in paradise! Well the 318 will make for a dependable cruiser power plant! You can install a modest cam and a 4 bbl manifold to gain some HP without killing the mpg. Good Luck with your rebuild!

Nice place to live, but limited in the available mopar stock.

I was loosely following steps from this article: http://www.streetmusclemag.com/tech-stories/fuel-cooling-ignition-tech/common-upgrades-for-an-la318-in-a-1971-dodge-dart-swinger/

Thank you for the well wishes. I'm several months out from any real progress, as I'll be slowly working my way through the firewall replacement.
I really  miss coming home from work and firing it up.

[734406pk]

Nice place to live, but limited in the available mopar stock.

I was loosely following steps from this article: http://www.streetmusclemag.com/tech-stories/fuel-cooling-ignition-tech/common-upgrades-for-an-la318-in-a-1971-dodge-dart-swinger/

Thank you for the well wishes. I'm several months out from any real progress, as I'll be slowly working my way through the firewall replacement.
I really  miss coming home from work and firing it up.

Firewall replacement- WOW- that is a major undertaking! Post in the "body" forum if you need any guidance with this project. There are many knowledgeable professionals here on this site with years of experience in E-Body restoration. Good Luck!!

[wagenbob]

Firewall replacement- WOW- that is a major undertaking! Post in the "body" forum if you need any guidance with this project. There are many knowledgeable professionals here on this site with years of experience in E-Body restoration. Good Luck!!

I will definitely check the body section for some wisdom when the time comes. Thanks for the tip!

[wagenbob]

Motor is out.

As luck would have it, there was a guy selling a freshly built 340 on craigslist, so I decided to upgrade rather than rebuild.

[Chryco Psycho]

Good Score . do you know the builder ?
 might be worth a teardown to check everything

[anlauto]

Car looks pretty solid 

[wagenbob]

Good Score . do you know the builder ?
 might be worth a teardown to check everything

The work was done by one of the reputable shops here in Hawaii. He kept the pan and pickup (it was for an A-body), and it looks very clean inside.

[wagenbob]

Car looks pretty solid 

It's not in too bad of shape. The firewall/cowl is my next... it has some huge holes in it. Everything else will just be a matter of money and time.

[1 Wild R/T]

It's not in too bad of shape. The firewall/cowl is my next... it has some huge holes in it. Everything else will just be a matter of money and time.

Island cars rust differently than snow/salt belt cars.... My 71 Hemi Challenger had firewall rot & roof rot way back in 79.... Just like every other car that had been on the island more than a couple years....  I know modern cars are better rust proofed for Chicago/Detroit conditions, don't know if that improved rust protection is effective in an island environment....