Head Lift

JD1964

there is enough sticking out to grab on to
15 Year Member
Jun 28, 2013
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Maryland
I'm over the depression of not yet solving the problem I'm having with head lift. I'm in the solution mode now.

I'm thinking the chamber pressures are just too high. Nothing wrong with the heads or the installation, just pressure spikes. For good measure, I'll be adding an extra 10 ft/lbs of tq to the upper row of head bolts. Then I'll be cutting the timing back to 6 degrees initial and mixing in some cam2 race gas to get the octane level up. My AF ratio is good in the mid to low 11's WOT so there is enough fuel getting in.

Maybe the tune in the chip needs to be adjusted to cut back on timing under boost. My chip was tuned by All Out Automotive. But, I changed the game after the fact. My SC kit came with a 6" crank pulley but I changed to a larger 6.87" pulley. So, I'm not criticizing All Out. Just pointing out that I changed the game. I figure by cutting back on my initial timing, if the lifting stops, it's something I can have corrected in the tune.

BTW, my setup does not use the FMU that came with the kit. I was told to omit it since everything needed is programmed into the chip tune. I have a question on the chip tune and how it gets info. How exactly does the computer know when the intake is under boost in my setup? What components is the computer getting info in order to adjust fuel under boost? I have no vacuum line referencing the intake for boost information so how does it do it?

I can run this thing all day under normal driving conditions no matter what with no problems. Only pukes under boost.
 
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I can read the AF ratio on my wideband. But the timing curve is still a mystery. If the tune setup does not have a reference for boost, how does it know when and how much timing to pull? It must be fixed based on things other than boost. Is it possible that this could be part of the problems some of us are having with head lift?

And if I need schooling, hit me. I don't mind being told I'm wrong if the end result is understanding how things work.

Boost may not always be relative to rpm. It takes longer to get through 3rd than 2nd, and longer to get through 4th than 3rd. So, can't the pressure build up more at a given rpm if the force is being applied for a longer period.

So, without a true reference to actual boost levels, how do you precisely control the critical perimeters of fuel and timing?
 
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The temperature of intake air is another thing that will affect boost levels. How do our setups make timing adjustments on the fly for this?

We either need to accurately in real time make finite adjustments or detune fixed settings to a level where they won't cause problems under all the variable circumstances.

As far as head lift is concerned, it will probably continue to happen. The 9333's blow coolant under head lift because the seal ring gets bypassed. With Cometic, the cylinder seal ring is basically continuous across the entire gasket. So, the head can lift but the pressure is more likely not reach the water jacket.

I'm going with Cometics next time. For now I'm not taking it apart. I'm going to detune by pulling timing to see if it stops the puking. I like jricker's idea about pulling the spout to fix the timing at a set point. I'm going to try this and see if it changes anything.
 
The MAP sensor would be the boost reference point, or should be. The IAT sensor should be referenced as well. The real problem is pump gas. It can vary tank to tank. Adding octane booster is a bandaid as the mix will never be the same from tank to tank. When using Cometic head gaskets it is extremly important that the head and deck surface are perfect. I also spray a few coats of Copper Coat on both sides of the head gasket before it goes on.
 
MAP sensor, ok. Just to be sure, the MAP sensors original design was to reference vacuum in the stock NA setup. Can it also accurately read and send boost levels to the computer?
 
I've learned on a Foxbody its called BAP, not MAP.

Anyway, on MAF cars (89-93) there's no vacuum line on the BAP. There's a wiring harness but the vacuum line connection is plugged. The ones with vacuum lines are the earlier speed density cars.

So, I'm still wondering how we get a reliable reference on boost levels on MAF equipped cars.
 
I dealt with the same issue its probably the thin deck height. The last time I blew a head gasket with 9333pt1 and gt40s, and arp head studs they lasted 2 days! That was with 16 degrees timing and 15 pounds of boost. I have since upgraded to edelbrock performer heads and felpro mls head gaskets no more issues with a pressurized coolant system.
 
I dealt with the same issue its probably the thin deck height. The last time I blew a head gasket with 9333pt1 and gt40s, and arp head studs they lasted 2 days! That was with 16 degrees timing and 15 pounds of boost. I have since upgraded to edelbrock performer heads and felpro mls head gaskets no more issues with a pressurized coolant system.

Thin deck height? You mean deck height of the heads?
 
I've learned on a Foxbody its called BAP, not MAP.

Anyway, on MAF cars (89-93) there's no vacuum line on the BAP. There's a wiring harness but the vacuum line connection is plugged. The ones with vacuum lines are the earlier speed density cars.

So, I'm still wondering how we get a reliable reference on boost levels on MAF equipped cars.
There was a reason EEC4 engines that were supercharged had an FMU. They had no boost reference outside of the FMU to be responsible for fuel enrichment while under boost. Take away the FMU and the ECU needs to see boost reference. One could tune based off of IAT, but that is a dangerous game because the temp rise could be due to a number of things besides boost.
Rethinking this...the tune must be based on total mass air flow, not boost. Thus if the meter is undersized it can get pegged and the tune can be way off due to lack of accurate information about total mass air flow.
 
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I dealt with the same issue its probably the thin deck height. The last time I blew a head gasket with 9333pt1 and gt40s, and arp head studs they lasted 2 days! That was with 16 degrees timing and 15 pounds of boost. I have since upgraded to edelbrock performer heads and felpro mls head gaskets no more issues with a pressurized coolant system.
You "problem" with lifting the head gaskets was probably fixed due to the fact that you went from a cast iron head to an aluminum head. You effectively lost 1/2 point of compression due to the aluminum heads ability to shed heat and also moves the air through the combustion chamber in a more efficient manner. I doubt that cylinder head deck thickness had much to do with it.
 
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You "problem" with lifting the head gaskets was probably fixed due to the fact that you went from a cast iron head to an aluminum head. You effectively lost 1/2 point of compression due to the aluminum heads ability to shed heat and also moves the air through the combustion chamber in a more efficient manner. I doubt that cylinder head deck thickness had much to do with it.
I agree with the camber being more efficient, but how would I lose a half point of compression going from a 64cc chamber head to around 59cc head? I also had no signs of detonation upon the tear down.
 
I agree with the camber being more efficient, but how would I lose a half point of compression going from a 64cc chamber head to around 59cc head? I also had no signs of detonation upon the tear down.
It is equivalent, not actual. It is because the aluminum dissipates the combustion heat far more efficiently. This is why you can run more compression on an aluminum headed engine than the same build with cast iron heads. On that same note, if you had a set of cast iron heads that were identical to the aluminum set, you would always make more power with the cast iron headed engine. Horsepower is heat, the cast iron head retains the heat of combustion better, thus more HP. This assumes everything about both engines is identical.
 
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Update;

Even though I knew I'd eventually need to pull this thing apart again I did some testing first. It will run great and hold coolant under normal driving conditions but blows coolant under boost. I wanted to rule out excessive pressure spikes caused by bad gas or too much timing. So, I set the initial timing at 15 BTDC and pulled the spout to remove all advance. I also dumped in 5 gallons of Cam2 110 octane into the existing 1/2 full tank.

Still blows coolant. Not quite as bad but still has an obvious problem that I missed. Gotta come apart again. I'm really gonna go over it with a fine toothed comb this time.

No biggie as I love this car. Trials and tribulations are worth the learning experience. The lord works in mysterious ways sometimes. This time its teaching that my half ass attempts to cut corners wont work.

Keep you posted.
 
Well well well, I finally got around to it. That is, taking jrichker's advice and buying a machinists straight edge. Thus, my discovery is my passenger side block deck is like a seesaw. High in the center between #'s 2 and 3. I could feel the straight edge teetering even without the gauge but the .002 feeler easily slides under at the ends. Tad of warpage on the drivers side too.

Like I said before, the heads had been recently milled .012 and they are still as flat as flat can be but Ill have them shaved a few thousands, maybe.

So, I guess I'm pulling the block out to have it decked. Then I'm going back in with Cometic gaskets, probably thicker ones to make up for milling and decking.

Every other aspect of the engine is 100% fine, So, I'm planning on pulling it, disassembling, sending to shop for decking and putting back together with existing parts.

Am I crazy for not punching it out to 306? The factory 302 hone marks are still on the cylinder walls and theres no wear ridge that I can see or feel.

IMG_2420_1.jpg
 
John, sorry to hear about the deck but it's not that uncommon to hear when these cars overheat and pop a HG.. I wouldn't bother boring out the motor to 306. The extra 4 cubes are neglibible in hp and not worth the money or effort if all else is the same. If you were so inclined. I would stroke it to a 331 and change to a more blower friendly piston , rings, cam and such.
 
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I'm actually relieved in some aspect. At least its clear why it was blowing coolant.

When I pull it, how far do I need to disassemble it before I take it in to be decked? Do you think I should have the shop hone the cylinders so I can put new rings on the pistons? Should I have the crank polished and then I put new bearings in? Seriously though, I'm tempted to pop those pistons back in without even changing the rings. Bearings too. My oil pressure has always been fantastic. Obviously I would be very detailed about labeling positions of everything so everything goes back in the same place.

Cam bearings is about the only thing I don't have the tools to remove. So, I guess I should avoid hot tanking right? Wouldn't hot tanking melt out the cam bearings?

70k mile on this thing. I guess I should at least install new rings and bearings. What do you think? What is the minimum I should do while I have this thing torn down?
 
John, IMO you are at a crossroads. You have these options depending on your budget and time

1. send the assembled short block to the machine shop and have them true up the deck. Put a new rear main seal, oil pump, hardended oil pump shaft, new other gaskets and roll
2. take the block down to a bear assembly, have the shop machine it and go with an eagle stroker kit, blower cam and pistons, new bearings, timing set, yada yada
3. get a j/y explorer motor, sell the top end, put a new oil pump and shaft. new rear main seal. gaskets and slap your existing top end on and roll
4. get a Dart block and good internals and build that up.

I dont see any reason to tear your block down only to have the deck machined, and if you do tear it apart, then go and do a stroker. You already know these things can easily turn a $500 fix into a $5000 one easy.
 
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