502 Head Gasket (I think)

[Gimme Fuel]

You gots some darn good parts there!

 

[Rcenter1]

You gots some darn good parts there!

Specs say over 500 hp stock and I don't think my cam is stock, not to get ahead of myself here but I wonder if this is better naturally aspirated or if it would look better with a blower on it this winter

 

[Gimme Fuel]

If it is a ZZ502 crate motor, the cam that came in those tends to have some reversion issues unless long tubes or dry are used.

Isn't everything better when its blown?

 

[Rcenter1]

If it is a ZZ502 crate motor, the cam that came in those tends to have some reversion issues unless long tubes or dry are used.

Isn't everything better when its blown?

I blame this forum for making me think this way, I remember a time when my freshly built 4.3 was plenty for me...lol

ZZ502
Part Number: 19201332
Displacement (cu in): 502
Bore x stroke (in): 4.47 x 4.00
Block (P/N 10237292): Cast iron with 4-bolt main caps
Crankshaft (P/N 10183723): Forged steel
Connecting rods (P/N 10198922): Forged steel, shot peened
Pistons (P/N 12533507): Forged aluminum
Camshaft type (P/N 12366543): Hydraulic roller
Camshaft lift (in): .527 intake / .544 exhaust
Camshaft duration (@.050 in): 224'c1 intake / 234'c1 exhaust
Cylinder heads (P/N 12363390): Aluminum oval port; 110cc chambers
Valve size (in): 2.25 intake / 1.88 exhaust; stain less steel
Compression ratio: 9.6:1
Rocker Arms (P/N 12368082): Stamped steel
Rocker arm ratio: 1.7:1
Distributor (P/N 93440806): HEI type
Carburetor (P/N 12366996): 850 cfm
Water pump (P/N 14058915): Aluminum, short-style
Spark plugs & wires: Included
Starter (P/N 9000852): Included
Flexplate (P/N 10185034): 14"
Recommended fuel: 92 octane
Ignition timing: 8'c1 BTDC @ 800 rpm; 36'c1 total @ 5000 rpm
Maximum rpm: 5800

 

[Gimme Fuel]

Description

This steel hydraulic roller is used in the 502/502 crate engines.
The duration at .050" tappet lift (intake/exhaust) is 224/234
Lift with 1.7:1 rocker ratio (intake/exhaust) is 527/544.
Valve lash is zero/zero
Lobe centerline is 110 degrees.
This cam is intended to be used in Gen VI factory roller blocks. It is possible to use this cam in Mark IV and Gen V blocks if aftermarket tie-bar type lifters are used along with a Gen VI timing set and thrust plate. Some early blocks may need to be drilled and tapped for thrust plate mounting.
Lifters are not included.
Cam has lobe for mechanical fuel pump
Intended for factory roller blocks - 96' and up. Use with thrust plate and Gen VI timing chain set. Can be used on some Mark IV 454's if the block is machined for the thrust plate and has the two holes under the cam gear - some blocks have this provision, some don't visual inspection is necessary.
Single valvespring part # 12462970 or 12495691 set of 16
Technical Notes: Distributor P/N 88961867 or melonized distributor gear P/N 10456413 must be used

------------------------------------------------------------


That 110 centerline (lobe separation) is where the reversion comes from. 114 usually no worries, 112 you might want long tubes, 110 you need long tubes.

http://www.seriousoffshore.com/forums/engine-tech/21687-cam-question-2.html

Lift-height wise it is mild (relative term I know), but decent overlap/centerline making it act a bit larger but also opening up door to reversion at slow speeds. Some have had issues, some havent. All depends on your exhaust setup.

 

[corey331]

Well, since you are going to have the timing cover and what not off, pull the timing chain and look at the front of the cam and see if there is a part number. Then you will know exactly what you have. If it is that stock cam with that seperation, I would suggest changing it.

And if you are wanting to Procharge.... I might happen to have something in my garage you would be interested in..... and I might be able to be talked into letting it go for a really good price......

 

[Rcenter1]

Are you suggesting that the small amount of steam I had coming from vents could have been reversion and not the head gasket slowly failing or are you referring to the cam I have in respects to putting a blower on this engine?

My headers..long or short? No sure...




I definitely don't want to damage this engine and will buy alternate exhaust if I have to.

 

[Gimme Fuel]

Those are Lightnings looks like. I couldn't tell ya. Corey might, he has experience with Lightnings. Lighnings are decent performing headers but the water is introduced fairly early compared to other longtube header makes.

If nothing else, call Bob madera and he will give you a kick-azz cam that works better than your stock one. May have to change valvesprings though with higher lift numbers.

 

[corey331]

It would be WAAAYYYY cheaper to change the cam. And a new marine cam would not hurt performance at all. You might even gain something.

Those look different than my Lightnings, but appear to be the same style. My lightnings don't add the water in until right before it goes into the rubber exhaust hose.

 

[Rcenter1]

Well, since you are going to have the timing cover and what not off, pull the timing chain and look at the front of the cam and see if there is a part number. Then you will know exactly what you have. If it is that stock cam with that seperation, I would suggest changing it.

And if you are wanting to Procharge.... I might happen to have something in my garage you would be interested in..... and I might be able to be talked into letting it go for a really good price......

I will keep that in mind, not planning on pulling timing cover until winter though. These inject water down by spark plugs and they don't mix with the exhaust until well after the down slope

 

[Gimme Fuel]

just check to see what your exhaust valve seats look like when you pull the head. If they are pitted, it means reversion is happening.

 

[Rcenter1]

Ok, I have them off, I will draw a line on them to see exactly where the water is entering and post a picture later

 

[slingblade]

I may be wrong but if revertion was the problem I would think you would have hydrolocked the motor by now. Stuff brakes when trying to compress water. I would be very surprized if that is the cam in your boat. you can see the seat when the valve is open on the motor to check.

 

[Rcenter1]

I may be wrong but if revertion was the problem I would think you would have hydrolocked the motor by now. Stuff brakes when trying to compress water. I would be very surprized if that is the cam in your boat. you can see the seat when the valve is open on the motor to check.

I think it is premature to even assume the stock cam is in it, he obviously had the heads off, this motor did not come with those bolts factory or those rockers. He very well may have slipped in a new cam. I will find out this winter part numbers on everything but Ron has a point, might as well flip em over and check em while they are in our hands.

 

[Gimme Fuel]

right. Reversion doesn't necessarily mean enough water to hydrolock the cylinder. just a few drops here or there erode the valve seats causing leak down/compression loss and can also ruin piston rings. I had a buddy who just had to have his Tyler Crockett motor rebuilt last year due to reversion from silent choice. Motor ran decent up top but had absolutely no torque down low. Reversion was determined to be the cause. Solution was a rebuild and weld an extension on the inner water jacket of the end of the manifold riser (in your case header) to cause the exhaust to mix with water further down the exhaust. Also meant he had to remove silent choice.

 

[slingblade]

right. Reversion doesn't necessarily mean enough water to hydrolock the cylinder. just a few drops here or there erode the valve seats causing leak down/compression loss and can also ruin piston rings. I had a buddy who just had to have his Tyler Crockett motor rebuilt last year due to reversion from silent choice. Motor ran decent up top but had absolutely no torque down low. Reversion was determined to be the cause. Solution was a rebuild and weld an extension on the inner water jacket of the end of the manifold riser (in your case header) to cause the exhaust to mix with water further down the exhaust. Also meant he had to remove silent choice.

did he have water in the oil?

 

[Gimme Fuel]

Nope. Most reversion cases are not severe to get that much water in the oil that won't evaporate out at running temperatures. A severe case of ingestion like a wave rolling up the pipe at idle would do that (that's why we have flappers and/or baffles in tips). Most likely if a motor got hydrolocked it was either a wave rolled up pipe while motor was off filling inner pipe completely or manifold/header cracked and leaked into the cylinder.

Think of average cam induced reversion as small drops of water randomly sucked back up into the primaries/manifolds from overlapping cam timing suction. Most of the water will be blown out the tip but some droplets get sucked back in. These cool droplets on the valves and valve seats cause rapid cooling, corrosion, pitting, or cracking in severe cases. The heat of the cylinder evaporates the little droplets into vapor for the most part but only after the valve and seat area have been damaged.

Speaking of that, might be a good idea to pressure test your headers while they are off. Headers are know to develop small cracks with age. Any metal object that goes through that many severe heat cycles like headers do will have issues from thermal fatigue. This should be done every few years on older headers. If a problem is found usually a good welder can fix it easily.

 

[Rcenter1]

Definitely not the intake gasket, sealed tighter than tight around all ports except where I turned it over and some oil/water ran down....


Look at this picture close.. See the pure water with no oil mixed in? this is the starb side of the boat 2nd cylinder from the front,this is the cylinder I have always thought the steam was originating from, I bet there is a hole in my head gasket right there. Between cylinders 2 and 4

 

[Gimme Fuel]

Im guessing you are going to pull that head and find your culprit.....

 

[slingblade]

This winter you need to be looking for a bowtie intake to match those cnc ports on the head. I am sure you can find one used and sell yours for the same $ . when you get the head off take a tape and see what it is from top of cyl to top of piston when it is all the way down.