Blown Head Gasket?

[MV8]

I think those are the correct plugs. You may want to index them, use a different type of tip, or grind a relief in the pistons because the head, deck height, and head machining along with the head gasket thickness have it sitting too close. You could also break a plug during removal or installation if a cylinder was on tdc, but you need to check the clearance first.

 

Gets some clay from the hobby store and put lumps on the pistons, install the plugs fully and seat the head bolts without a head gasket. You can loosen the head a bit to rotate each cylinder to tdc then reseat.

 

If there is a clearance issue, consider running a felpro standard thickness gasket versus a specialty laminated steel for raising compression. Compared the old one's thickness to the felpro advertised compressed thickness. Looking at the rusty gasket, it appears someone was running little to no antifreeze and those chunks could have blocked some of those small holes, causing an overheat like I described with the bigblock olds.

 

Modern fasteners like head gasket bolts are one-time use because they are "torque-to-yield". Any fastener with a spec to tighten based on degrees of rotation is likely one-time use. They can snap just trying to remove them. STOP at the first "pop" on removal, then release the tension so they can unload, before continuing to remove them. Older engine head bolts are not stretched to yield and will likely strip the block threads before it will stretch to yield.

Edited July 22 by MV8

[TEM]

Wouldn't a simpler solution be to just add a washer to the plugs?

 

The old head gasket measures 0.02".  The new one I bought measures was referenced at 0.04".  Not sure how much the new gasket will crush down.

[MV8]

That is what I mean by "indexed". Didn't realize you already had a gasket. It's better if the plugs clear and that future service can be performed by others without damage, and it is apart so it could be addressed, but as Red Green says, "Fixed is fixed". No judgment.

[TEM]

I'll take some measurements tomorrow to see if a standard washer will work.  Grinding a relief in the pistons would provide a permanent fix with no future risk but it also sounds like a dangerous proposition.

 

I have a new head gasket on order but it will be two days until it arrives so, I have some time to measure the head and ponder the next disaster.

[Dave W]

Check out Champion plugs, [I think their HQ's are in Toledo] they would hand out free copper plug spacers at the tracks. Several sizes and thickness. 

[joe7]

I have used the Fel-Pro 8360-PT1 head gaskets for a long time with out fail, as long as you keep it under 6,500.  However you will need to get the water holes in the "triangle" opened up. Check your new one to your old one. I always used hardened washer under the head bolts. Also, have the head checked, these often have a crack between #2 & #3.

[BirkinBernie]

When I was in my teens, my dad and I rebuilt the 472 V8 out of his '68 Caddillac Fleetwood.  Full machine shop treatment - rebuilt heads, block crack checked and honed, balanced, etc etc.  As I was torquing the last bolt in the sequence on the second head, the bolt started to feel "funny".  I about panicked envisioning threads pulling out of the block we were almost finished assembling.  When I pulled the bolt I found what you see below.  That big bolt had stretched way further than I would ever have thought possible.  I kept it to remind me to always install new head bolts!

 

[IamScotticus]

While on the subject, 

Does anyone endorse the use of torquing Lubrication?  Assuming the threads are chased and clean first. 

These products claim to allow for more consistent actual torque readings,  with the additional leverage of the lube adjusted for, say minus five lbs-ft.  They usually have thier recommended numbers to use.

This is one:

https://www.pegasusautoracing.com/productdetails.asp?RecID=5123

[DavidL]

I'll just add that checking the block and head for flattness is straightforward and important.  Buy a $25 precision straight edge designed for this (for example this one on Amazon), then use feeler gauges with the bar laying across the head or block in different orientations.  On my Acura Integra, the spec was anything more that 0.002 inches out of flat required machining.  I've never seen a flatness spec for a X-flow or other older engine, but figure it should be similar.  My Integra head was 0.007" out of flat due to an overheat, so I had it machined flat for a modest amount (I think the machine shop quote was under $100).

[fastg]

ARP head bolt sets come with a packet of lube and detailed instructions on how and were to use it. So I think the answer is yes it makes a difference. 

 

Graham 

[anduril3019]

A drop of oil or assembly lube on the threads and under the bolt head will also do the job. What you don't want is any collected oil in a blind hole, it creates a nice little hydraulic press as you screw the bolt in.

[fastg]

Checkout https://arp-bolts.com/p/arpultratorque.php

 

Graham

[anduril3019]

Have you decided to get the head surfaced? The area where the gasket failed definitely looks suspect. (based only on the photo, of course)

Back to the can of worms theme, you might as well measure your compression ratio while you've got it all apart and determine if surfacing the head will affect it. It may affect it negligibly, but you won't know if it matters, unless you know where it is currently.

 

General note: All the advice and collective knowledge your getting may be overwhelming (or it may be just what you were looking for?), but it's all the small details that help eliminate potential failure points when it's all back together and you turn the key. You could potentially yank the head off, clean it all up, put on a new gasket and be good to go. It might work, and get you on the road, or it might not, and you'll be right back to where you started, or worse off, and trying to troubleshoot again.

[MV8]

For reusable bolts, I usually torque to the mid-range with oiled threads, no washers to end up with one or two fewer threads to take the full load.

I mentioned other plug designs where the electrodes are two or four on the sides versus the end.

[IamScotticus]

Are original Ford head bolts available anywhere?

 

In Jake LaMont's excellent Formula Ford engine building book, he gives excellent advice on preparing the head:

Pack it up and send it off to a specialist.

Edited July 23 by IamScotticus

[TEM]

Measured the all the bits and there is indeed a potential 0.03" interference between the spark plugs and pistons.  It was interesting to learn that the threads start at different locations on both the spark plugs and the head.  So, you get a very random orientation of the electrode.  The 0.03" interference can be obtained by mixing and matching the plugs and holes to get an electrode into the most disadvantaged position.  I had two 9/16" spacers of different thicknesses and the thicker one eliminated the interference, giving 0.005" of clearance.

I was wondering how this could have happened if the spark plugs are correct.  I have noted in many documents a reference to flat top pistons on these early Sevens and the few picture I could find seem to show a flat type of piston.  But, if you look at my pictures, my pistons have a "D" shape protrusion on the top.  Is it possible these pistons were replaced with "taller" pistons?  There are very few picture out there to go by.

[MV8]

There are often many variables on performance replacement pistons including crown height from the top ring groove (most engines don't run zero deck height) and shape, domed and dished, valve relief notches for high lift and overlap cams, etc. Indexing the plug is not normally for critical clearance. If you use washers, I suggest making them all the same thickness based on worst case. Otherwise, anybody that changes the plugs should have a great memory.

I would use the clay to see where the problem is with each piston at tdc or slowly turn a sacrificial plug in to score the piston, cover the deck openings to oil and coolant jacket, then use a ball or tree shaped, bastard cut carbide mill bit in a drill to dress the scored area, apply a little clay and recheck. A dremel works too. The pressed clay can be cut in half with a razor and one half removed to reveal the clearance. Fit the longest plug with the deepest seat, worst tip index, on the highest piston (i.e. worst case), make that fit and have .050" clearance, then duplicate that cavity on the others before checking actual clearance. Minor differences in the cavity size and depth are not critical to compression ratio. Radius the edges to blend into the piston without sharp edges.

Ditto on ARP. Rolled thread studs are best or cap screws and washers to spread the load (heads are smaller) can substitute for oem head bolts (though some come original with socket head cap screws). Studs should be tight enough in the block that combined with red loctite, won't rotated when the nut and washer is torqued, but ideally, the studs would be finger tight in the block, not torqued to a head bolt spec.

[SENC]

10 hours ago, TEM said:

if you look at my pictures, my pistons have a "D" shape protrusion on the top.  Is it possible these pistons were replaced with "taller" pistons?  There are very few picture out there to go by.

I was wondering about that protrusion, and thought it was maybe just an optical illusion. 

[SENC]

Mine were flat and replaced with flat (picture below).  There isn't much clearance, so I'd think that protrusion on yours could be the issue.  Maybe wasn't originally but if the head got skimmed and/or a thinner head gasket used?  

 

[TEM]

I understand that there are a lot of replacement piston profiles out there, my question was what was original?  I have found very few non-original parts on this car so different pistons would be worth noting.  Were the pistons changed or did someone over skim the block and head?  No problems, just knowledge.

 

Yes, I plan to use the same size spacer on all plugs.