Head Gasket Blowing out

smallccpower

New member
I have an old style predator engine that continues to blow out head gaskets no matter what I do, copper spray, paint, silicone nothing seems to stop them from going. What needs to be done to keep this from happening? Head studs? Copper thicker head gasket? The head gasket im using now is a .006" from Dover. Listed below are some engine specs.

(old style) Predator, 14cc head, stainless stock size valves, 1.3 ratio rockers ,26lb springs ,mod 2 cam, Billet rod, Billet flywheel, Flat top piston (still .050" in hole) Timing advanced and a 348 Tillotson on Methanol.
 
With the piston .050 in the hole that eliminates excessive compression, I would suggest warped head, have you checked it for flatness.
 
get some 220grit sand paper and a tile start wet sanding it down... look to see what doesn't get sanded... make sure it looks the same all the way across the head... finish with 400grit... if you don't see it on the head... then you need to look at the block... p.s. make sure the head pins aren't too long if using them...??? it will keep your head from sealing...
 
Maybe warped, but prolly his head gasket is too thin for those mods...I have had very little luck with .016" or less on mod motors with copper or steel. Deck the block .046" and use any "fire ring" head gasket (they are usually in the .040" range)
 
Maybe warped, but prolly his head gasket is too thin for those mods...I have had very little luck with .016" or less on mod motors with copper or steel. Deck the block .046" and use any "fire ring" head gasket (they are usually in the .040" range)

Great idea right here
 
I have to say I haven't had any head gasket problems (knock on wood).... The predator I just did has the same thin gasket that came on it, and I have ran it with a old style Predator head, a Hemi predator head, and now with a 5 bolt valve cover clone head (I even removed the 5 bolt head once to figure out my fuel pump pulse problem, which was a result of epoxying up the vent hole). I copper coat them, and use studs in the higher HP engines (Threaded rod in some of them). This engine has a stock old style piston (thick ring) with the dish cut down, (but still has some dish), with a 15cc head..it made 25.9hp with the 5 bolt valve cover head and a Tillotson. I will look to see how many pulls it has, but I think its safe to say over 200. I do lap the heads when ever I remove one.
 
Yes sounds like warp head or block.I run the thin .010 gasket on my mods and then coat it
with copper sealer.not the spary on the paste type even coat the head bolts with it.
and as what was said make sure the head is all the way down.I shorten the dowels some
just to be sure its a good tight fit.
 
Thanks everyone for the replies im going to have the head milled this week so I know its truly flat. and order some studs as well. Thanks again
 
got to be warped head or block...I have never had a head gasket problem and have been doing this for 12 years...good luck.
 
I know its not the block I checked it prior to this build im going to have the head milled some to be 100% sure its flat and im going to shorten the dowels up and order a stud kit.
 
I have a trick.

Get a piece of glass and coat it with some valve grinding compound.
Thin it with a little WD 40 if needed.

Rub the head on there and look at it.
Where you have a frosted appearance you head is touching the glass.
Where you don't see any frosting, your warped....

Gaskets need a bit of traction to hold ( my theory ).
if the block or head is too smoothly finished you get blow outs.

I keep some sharpening stones in oil and rub my decks and heads down to knock off any marks that may cause bad sealing.
Thsi can be real tricky and you could make things worse if not careful...
 
Get some of that dye that machinist use, it is blue and shows up real good, coat the head gasket surface with the dye and lay the head flat on a piece of glass but put a piece of thin paper between the glass and the head. Apply pressure to the head then lift it back up and look at the paper. Anywhere you see a void in the dye copy of the gasket surface, is where your head is not flat and needs to be trued up. I have done this several times to check gasket surfaces. Can also do it with just the glass and no paper, but the paper makes it much easier to see voids. You can also coat the deck of the block with the dye, put a piece of paper on the glass and apply pressure, then check the paper same as you would with the head, this lets you check the deck surface for voids also.
 
You can just take a sharpie, mark the head all over, use sandpaper (like 220 grit) on a known flat surface. The marker will show where its hitting.. Be careful guys suggesting sandpaper..the engine builder "police" may not find it acceptable.. :)
 
Surface plate prices have come down in price a lot in the last few years. You gan get a granite plate 12"*18" 3" thick a flatness accuracy of .0001" for 39.95. If you are using glass be sure it is well supported and at least 1/4" as it flexes a lot. I also have gone to counter top suppliers and gotten sink cut outs in granite or quartz. Not a guaranteed or certified flatness but I have not found one out by .0015" feeler guage and certified SS straight edge. I used to put one at each student work station. The abrasive paper is a perfectly acceptable method.
 
Get some of that dye that machinist use, it is blue and shows up real good/
prussian Blue
I use it when I pour Babbit .
Then I can see where to scrap bearings

Also mentioned was a sharpie.

Prussian blue has a shelf life and sometimes I soot from kerosene wick lamp to smoke a shaft and check the contact in a bearing.
Like the dye, and marker the soot would probably work.....

I like the valve grinding compound though it does not rub or wash off.

And there was a comment about sand paper....
I do that too, but I really like the finish left on head and block that is true by a rub on the glass with the abrasive.
My feeling about the texture and surface improving the grip on the gasket may all be in my head.
But i think there is something too it.

I use a piece of thick basilic furnace glass, its thicker than window glass and does not flex or warp.
I think its harder than normal glass too.

Some people baulk at the mention of sand paper.
But I admit to milling a head with a belt sander and it sealed up just fine lol.
 
Get some of that dye that machinist use, it is blue and shows up real good/
prussian Blue
I use it when I pour Babbit .
Then I can see where to scrap bearings

Also mentioned was a sharpie.

Prussian blue has a shelf life and sometimes I soot from kerosene wick lamp to smoke a shaft and check the contact in a bearing.
Like the dye, and marker the soot would probably work.....

I like the valve grinding compound though it does not rub or wash off.

And there was a comment about sand paper....
I do that too, but I really like the finish left on head and block that is true by a rub on the glass with the abrasive.
My feeling about the texture and surface improving the grip on the gasket may all be in my head.
But i think there is something too it.

I use a piece of thick basilic furnace glass, its thicker than window glass and does not flex or warp.
I think its harder than normal glass too.

Some people baulk at the mention of sand paper.
But I admit to milling a head with a belt sander and it sealed up just fine lol.

I was being sarcastic about the sandpaper, I got jumped on about it a while back. I have also glass beaded the surface after sanding it.
 
dummy question time... like the idea of checking the heads myself for flatness and for putting a finishing touch after the head is milled....but how do you get the sandpaper (and what grit do you use?) to stick to the surface of the glass/granite/whatever? water? Elmer's glue? i'm asking because you're checking for flatness and anything UNDER the sandpaper would create a bump or bubble that could throw you off....at least my poor brain is thinkin that's what would happen!! i'm asking because I would like to hold the head with both hands to keep even pressure on it while doing this....
 
I take a big sheet of emery cloth tape it to the glass then in circular motion I start to sand.I keep checking were it is shinny or not
I then do it in the other direction again in a circular motion.then if it looks shinny all the way around I then mark it with marker
then start over.then I check with a straight edge and feeler gauge.
 
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