Blown Head Gasket Tips Needed Please

Wcnwzrd

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Hey all. After some hard desert driving my wife managed to pop a radiator hose in my burban and the resulting overheating lead to a blown head gasket. I have changed em before but never by myself and it has been a few years (about 8 or so) since then. so looking for some tips/tricks on changing the head gasket out on a chevy 350 engine. no fuel injection no computer no O2 sensors just a good old school engine that i have yet to tear apart. Thanks in advance.
 

HDi fun

TC ModFather
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If you're confident that there's no distortion of the block and heads then geasket replacement is pretty simple. You might as well replace the manfold gaskets at the same time as they all have to come off anyway.

What's actually happening at the moment? Is there compression loss? oil/water getting mixed together?

In such a traditional engine of simple but elegant design I'd be tempted to replace all the top end seals and then apply some oil and coolant conditioning additives to take up any small amount of slack that might be there as a result of overheating. Without the complexities of EFi and lambda sensors, turbochargers etc you will probably get away very lightly indeed.

Do replace the bolts as well - they are stretched when originally torqued up and could well fail if you try to re-use them. Certainly do not over-torque the bolts. This will causes subsequent problems.
 

obi_waynne

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With the head off I would be tempted to do some porting and polishing. You may as well maximise the engines efficiency.

I would also get the head skimmed before it goes back on regardless of whether you think it is smooth or not.

Pay close attention to the order of the bolts and tighten them up in sequence and in stages also get the torque settings spot on.

The biggest pig is often getting off the exhaust headers as the bolts can rust on.
 

Wcnwzrd

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From what i can tell there isn't any warping to the heads (eyeballing). I would port and polish her but she is only a 2WD and I really don't wanna reduce the MPG any more than it is atm. Only getting 8 in town and 11 on the freeway.

From what it looks like I will need to do an oil/coolant change due to having a greenish white substance (oil/anti-freeze mix) in the oil cap. Was planning on replacing anything that I have to take off as far as the gaskets go. Gonna throw on a new distibutor cap/rotor/plug wires and plugs while I'm at it. Getting it skimmed might be a bit of an issue, as the shops around here are pretty spendy for anything along those lines. Gonna pick up a straight edge tonight and see if it will sit flush with the heads/covers to double check for warping.
 

lutonmatt

The Torque Meister
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think the 350 engines are easy have one in my 87 trans am
headers off intake off rocker covers off rockers off pull the push rods out heads off

then all back on say way
 

nismo25jerome

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nissan b13 sr20de
have a nissan b13 with sr 18 engine just upgrade from carbs but now i blow head gasket can it cause but thermostats cause when i took it out it was seize what else damage can cause by blowing gasket and would i have problems after repairing?
 

obi_waynne

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If the car overheated badly you might have piston ring damage. What caused your car to blow the head gasket in the first place? Sometimes a blocked coolant pipe makes the engine temp spike so you might have an underlying problem that caused it to go in the first place.
 

yankfan101

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Hi wcn, ok, firstly, have u got ally heads, if so, skim it, if not then dont bother, the heads never warp enough to worry about it, just use a fair amount of gasket sealant, AND flush the block twice. Had same prob, both heads on Seville '75-6, 425 bhp at the wheels, all i did was get 2 sheets of 600 emery paper, stuck them to a FLAT board & rub the face until almost polished then cleaned the piston tops of crud & thightend 'em down to factory spec BUT re-tightened 'em to 5lbs over 100 miles later,.. PS, to get 100% more miles per gallon take the thermostat out, flush the rad & turn the dizzy to 22 degrees ABOVE top dead centre, (she'll run run hot if you leave the 'stat in), then watch out for the cops 'cos you'll increase your bhp, i played with my Serville for a couple of years & finally sold her running with 425 ponnies, you should hear how i got 660 bhp from my '65 Buick GS 2 door coupe, wicked. have fun.
 

old-git

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. PS, to get 100% more miles per gallon take the thermostat out, flush the rad & turn the dizzy to 22 degrees ABOVE top dead centre, (she'll run run hot if you leave the 'stat in), then watch out for the cops 'cos you'll increase your bhp, i played with my Serville for a couple of years & finally sold her running with 425 ponnies, you should hear how i got 660 bhp from my '65 Buick GS 2 door coupe, wicked. have fun.

I assume you mean 22 degrees after TDC. If the timing is set to this, the ignition happens on the piston downstroke with the exhaust valve opening so the compression will be low. Can't see how this will work, let alone double the mpg. Please explain how this works.

The thermostat is there to control the speed of coolant through the radiator giving it a chance to do its job. With no thermostat the engine will take longer to get to operating temperature increasing the risk of wear and can actually run hotter due to the radiator not being able to remove heat from the coolant effeciently. Again, I would be interested in hearing your reasons for believing this works.

With regard to getting 660bhp from your Buick, this would make an interesting new thread as are short on V8 tuning tips on this forum.
 

yankfan101

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ok old firtly i do mean ATDC, junk the thermo 'cos it'll run Very hot but will also increase bhp , but the downside,drinks gas, i was the 3rd owner of my Buick gs pillarless coupe '65,the first was the wife of the boss of Buick, in '66 he got a shiney silver conv gs, she asked for one aswell but he said no, so she gave it to the Buick race "boys" & had it serverly beefed up , now i got that info from the GS club in Chino, Cal: as i was a member,the car was no: 17 of the line & i sold it to a guy in the states for $20,000, as seen, back in '86, & where it is now i dont know , but god was it fun to drive.
 

old-git

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Are you sure you mean ATDC? Every internal combustion 4 stroke engine that I know of has an ignition point somewhere BTDC. My friend's 500bhp+ Cleveland engine, for example, runs 28 degrees BTDC.
 

ninjasta

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The SBC 350 (Small Block Chevy) with a mild tune is usually set for Static Timing advance of 10 Degs BTDC.
I think yankfan101's post is probably refering to setting the static timing advance to 22degs BTDC. Though without other mods this may be too much advance.
This would be done by setting the engine to TCD on cylinder 1 and then rotating the distributor further than the standard setting.
 
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old-git

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I agree, but he confirmed that he meant ATDC :) If he means BTDC then fine, but simply changing the timing won't improve BHP.
 

yankfan101

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IT was nearly 30 years ago, so you are both more than likley right, but i rember doing it whilst the engine was running,,,and stalling alot,,,BUT ,,one thing i forgot to mention ,, i did have re-worked heads on-board aswell as fuel injection and 3, yes, 3 no-board computers to play with,, but being Cadllac i also got a fuel injection manual and computer manual, i also did somthing to a small plate INSIDE the distributer,,but dont ask me what, i just cant remember that clearly that far back...
 

ninjasta

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IT was nearly 30 years ago, so you are both more than likley right, but i rember doing it whilst the engine was running,,,and stalling alot,,,BUT ,,one thing i forgot to mention ,, i did have re-worked heads on-board aswell as fuel injection and 3, yes, 3 no-board computers to play with,, but being Cadllac i also got a fuel injection manual and computer manual, i also did somthing to a small plate INSIDE the distributer,,but dont ask me what, i just cant remember that clearly that far back...

I was going ot that 425 BHP classic SBC 350 would require more than than spark timing adjustments.
In general all "Otto cycle" spark ignition engines need to fire the spark in advance of TDC which is defined as 0 degrees. So the absolute timing point is negative degrees relative to TDC. In most ECU's this be quotes as realative timing in tems of absolute advance meaning before TDC.
 

Rollsraceteam

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I think you might mean 22 degrees before TDC. That's a lot of advance plus that will increase further when you take in the mechanical and vacuum advance added by the distributor. Not sure that's a good idea.

As for the thermostat, It not only controls the temp by opening and closing but is also a restricter to control the flow. Most race cars have no thermostat to reduce mechanical failure but still have a restricter in place. If you don't then what happens is that the front cylinders have too much flow and so can have damaged cylinders due to blow past scoring and the rear cylinders are too hot and so wear out the rings and bore due to over expansion of the rings.

As an ex parts salesman I would say that if thermostats were a throw away item, then the manufacturers could save billions globally by not fitting them in the first place. Be very cautious of removing them except in an emergency on the road.
 

TCJBOLDIE

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Not heard of them TCJ - do they sell them in the UK? What are the plusses of these gaskets over other similar ones?

Not aware of any advantages over other Multi Layer Steel gaskets and I guess that I mentioned Cometic as I thought it was a well known brand.

http://www.performanceunlimited.co.uk/brands/cometic-gaskets/

PS to seal properly they need a finer surface finish to the head and block than the standard type fibre type head gasket.
 
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