Fix one thing and there's another that pops up...

[Richard M.]

Re: Fix one thing and there's another that pops up...

Rich,

Are you sure about the blind hole? See my prior post with photo showing all center bolt holes going through to the lifter galley. Maybe square and oval port heads are different?

Mark, Oval port must be different then. Never had one in front of me.

That one at right center in my photo Is definitely blind. The reason I marked them is because I had to drill and tap all intake holes for Threadserts on both heads using a Bridgeport. I wanted to be very careful of depth.

Rich
PS I'm still baffled where Owen's leakage problem is sourced from. Doesn't make sense why at the crossover areas.

[Owen L.]

Re: Fix one thing and there's another that pops up...

These are 3904381(square port) BB heads but I believe a similar configuration of the exhaust crossover circuit on oval port 390hp heads. ONE of those intake manifold bolt locations is a blind hole. I don't recall if they bottom out into a coolant passage or not. IF they do, I suppose it's possible they could be damaged if extra long bolts were used overstressed the blind hole bottom areas.

Thank you, Rich. My oval-port heads (4/6/67) have the same blind holes (driver's side front to rear, #3,4,6,8) - all 16 of the bolts are the same length though I didn't measure them. No head work in the 40 years I've had the car and it's got steel head gaskets. I'm leaning toward a leak traveling along the gasket to the center as I've found nothing that looks suspect at this point. RTV is definitely going to be used. I plan on buttoning it all back up and monitoring it very closely.

I've got the judging manual on my wishlist... Are the bolts supposed to be all identical for '67 regarding integrated washer head w/o any sort of loose or captured washer? Three of mine don't match this head style of the other 13 (FP w/3 radial lines) and I'm thinking they are replacements.

[Richard M.]

Re: Fix one thing and there's another that pops up...

Thank you, Rich. My oval-port heads (4/6/67) have the same blind holes (driver's side front to rear, #3,4,6,8) - all 16 of the bolts are the same length though I didn't measure them. No head work in the 40 years I've had the car and it's got steel head gaskets. I'm leaning toward a leak traveling along the gasket to the center as I've found nothing that looks suspect at this point. RTV is definitely going to be used. I plan on buttoning it all back up and monitoring it very closely.

I've got the judging manual on my wishlist... Are the bolts supposed to be all identical for '67 regarding integrated washer head w/o any sort of loose or captured washer? Three of mine don't match this head style of the other 13 (FP w/3 radial lines) and I'm thinking they are replacements.

Owen, Ok hopefully you'll be all set. Please let us know the outcome.

All Intake bolts are same length and the heads have a integrated flat washer area under the base. No loose washers.

Rich

[Richard M.]

Re: Fix one thing and there's another that pops up...

The two center intake bolt holes on each head pass through to the lifter valley. They are not near any coolant passages or jackets. So they can wick oil but I don't see them as a source of coolant even with a leaky head gasket or cracked head.

Is it possible the front intake bolts or thermostat housing is leaking and the fan is blowing the coolant back?

I'm not clear what you mean by "casting chambers above the exhaust crossover". Can you clarify or post a photo?

[ATTACH=CONFIG]110833[/ATTACH]

Mark, As a follow up, since Owen's L36 heads blind hole locations are the same as the 3904391 L71 heads, I just checked a few things.

It appears there were 4 different part# heads used for the 390/400HP in 1967.

3872702 Early
3909802
3904390 to Dec 1966
3917215 Late

This might explain the exhaust crossover port configuration and blind hole location differences. I notice on your photo, there seems to be no crossover port. Is that so? What is the part# of the heads in your photo?

Edit... I just found all 4 part#'s photos on Ebay and all have a exhaust crossovers appearing just like the L71 heads. Links below.

3872702
s-l1600.jpg

3909802
s-l1600.jpg

3904390
s-l1600.jpg

3917215
s-l1600.jpg


Rich

[Owen L.]

Re: Fix one thing and there's another that pops up...

Follow up:
After cleaning and examining every surface, I'm thinking the coolant in the upper cavity of the exhaust crossover ports merely collected there after traveling along the compromised gasket from the rear ports. The loose manifold bolts didn't help anything - stumped as to how they loosened and how long they've been that way. I believe the oil filling the lower cavity collected there after seeping up the adjacent bolt threads over a very long period of time. It was thick and stinky.

Today I finished buttoning it all back up with new Mahle intake gaskets, rtv around the coolant ports on all surfaces, thread seal on all the bolts, and repaint before and after reassembly. Other than a drip at the thermostat housing hose, everything appears to be sealed and operating as it should. I'll keep an eye on the oil's appearance and spark plugs at each end for coolant but I'm pretty confident my old friend is back in business. Tomorrow's supposed to be a nice sunny day so I'll take her out for a shake-down run.

Thank you everyone for your comments, questions, and advice.