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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: Mar 2013 Posts: 217 'Bolter | | 'Bolter Joined: Mar 2013 Posts: 217 | I need to replace the head gasket in my super charged 270 GMC. any suggestions of what type, brand name to get I have a water pressure problem I can't figure out. after driving it 10mi. or so it starts to push water out of the cap, replaced the cap and that didn't fix the problem.
Jay D. | | | | | Joined: Mar 2019 Posts: 1,003 'Bolter | | 'Bolter Joined: Mar 2019 Posts: 1,003 | Any pics of that supercharged setup? | | | | | Joined: Feb 2004 Posts: 29,760 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,760 | On the blower-equipped tractor pullers we built, we used solid copper head gaskets 1/8" thick and stainless steel O rings around the cylinders to seal the compression.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Apr 2005 Posts: 2,832 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,832 | How much boost do you have? Head gaskets can handle 10-12 #'s and above that one needs to "O" ring the cylinders as Jerry suggested. Before you start ripping things apart do a search for an "engine combustion gas detector". They run from $25-$50 and will show if a head gasket (or head) is leaking. Just plug into radiator cap hole and if detector fluid changes color something is leaking. You can even get fancy and test with each spark plug wire off till you find the one where the color doesn't change---that's the trouble spot.
Evan
| | | | | Joined: Feb 2004 Posts: 29,760 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,760 | Evan, NAPA sells that setup under the name "Block Test Kit". BTW, the similar kit sold by O'reilly Auto Parts has similar-looking blue fluid, but it's not nearly as predictable as the NAPA fluid for some reason. It turns yellow in the presence of a small leak, or green if there's a bad one.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Mar 2013 Posts: 217 'Bolter | | 'Bolter Joined: Mar 2013 Posts: 217 | | | | | | Joined: Jun 2011 Posts: 5,096 Crusing in the Passing Lane | | Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | What intake manifold is that?
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
| | | | | Joined: Mar 2010 Posts: 10,272 Renaissance Man | | Renaissance Man Joined: Mar 2010 Posts: 10,272 | Funny looking truck. No problem by me. That is definitely a truck engine.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
| | | | | Joined: Mar 2013 Posts: 217 'Bolter | | 'Bolter Joined: Mar 2013 Posts: 217 | What intake manifold is that?
Ed ED, I got the manifold from Ronny Cox probably 20 yeas ago. he was a inliners member and had a big truck dragger. I got the manifold, head, side cover, rocker cover and some other trinkets from the drag truck. also got a lot of help from [censored] Larrow that had Stovebolt Engine back then. its a real strong running engine. Jay D. | | | | | Joined: Feb 2004 Posts: 29,760 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,760 | Are you running studs instead of head bolts on that rig? I'd definitely recommend getting a gasket made from .090" thick solid copper for it. Machine a 1/16" wide groove .030" deep in the block around all the cylinders, and form a ring of .060" stainless steel safety wire to fit the groove, with a very snug butt joint where the ends meet. As the studs are torqued, the wire will imbed itself into the soft copper and seal the cylinder pressure much better than any regular head gasket can. Use Permatex Super 300 brush-on sealer on both sides of the copper to seal the coolant.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Mar 2013 Posts: 217 'Bolter | | 'Bolter Joined: Mar 2013 Posts: 217 | yep that would be the way to go, and I may very well do that to the 302 block I have. everything else will change over from the 270 except pistons.
Jay D. | | |
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