I got the head back. I will post some pictures this weekend. Completed: - Valve Job - Surface Head - (1) guide installed - Removed (2) broken exhaust manifold bolts - (6) guides cut for PC seals - (6) PC seals installed on intake valves - (1) intake valve replaced - (3) exhaust valves replaced The PC seals were only installed on the intake valves. Not necessary on the exhaust valves????
Craig At this you are maybe $200 - $300 or maybe less from doing a inframe ohaul. So drop the oil pan pull all 6 pistons and rod assembles out hone all 6 cyl. clean all piston ring lands ( make sure all drain holes in oil rings are open and clear ) Replace rod bearings .replace oil pump and pan gasket . Reassemble head and so on . Than drive the wheels off it
Just adding to the discussion. If a thermostat gets stuck open or too cold of a thermostat is installed, the head runs cold and it will allow oil to gunk up on the valve instead of being burned off like at normal temperatures. Same thing with the plugs. Too cold of a head will translate into too cold of an operating temperature for the plug. Just a thought .......
Probably 95% or better of lost oil through the valve guides are on the intake, this is due to manifold vac sucking it through the guides... The exhaust has some pressure pushing up the stem so doesn't allow much if any oil to pass...
I have nothing more to add that hasn't already been stated, but I can say that every ford small block 6 cyl. head I've pulled apart so far has had that heavy crusty build up on the back of the valves, including a 200 that had 29,000 original miles on it at the time. I just knocked it off with a scochbrite wheel in a grinder. Like was said, I've yet to get more then 30-40k out of a set of valve stem seals before the tell tell puff of smoke at start up comes back. In the past few years, I've always gotten that same white buildup. I think it has something to do with the ethanol in the low grade gas. I never used to get it back in 2005-2006 before the 10% ethanol became common around here. I jetted my carb a little richer and went a range colder on my plugs and it helped some. I usually get 15-20k out of a set of plugs before I get the occasional miss, but I have MSD 6A ignition as well.
Just as Crazy Comet already mentioned.. no.. not for a low compression street engine running full exhaust. On an engine that makes substantial amounts of scavenging vacuum with racing type cam/exhaust?.. you betcha! The amount of depression the closed exhaust valve see's right before it comes off its seat is usually extremely misunderstood by most and is actually far greater than the forces created by piston pumping simply because the piston hasn't moved very far at that point. This fact combined with intake ramming is what gives high performance motors such high VE. This is also somewhat true even for a lo-po motor too because overlap and high depression still exists on initail exhaust opening(yes.. even with full restrictive factory type exhausts).. but isn't really significant enough on smaller/low powered motors to warrant spending the extra cash for positive type seals.. for most people. However.. I still run them on ALL valves(as does the factory these days) because it makes for a cleaner running motor in the long run as things start to wear out. "Overkill right now".. can make for "just right later on" and extends service life. If you do enough of these projects like I do.. the stem cutting tool pays for itself on the first set of head/s(they run about $75 bucks and are worth their weight in gold). I use one that also cuts the valve spring seat while I'm at it too.
Here are some pictures of the head fresh from the machine shop. Yesterday I painted it blue. Hope to get it installed tomorrow. In the last picture one can see the positive type valve stem seals on the intake valve. Behind that valve one can see the standard unbrella type valve seal on the exhaust valve. I can't wait to drive this thing and see if there is a noteable improvment.
I got the car put back together last Monday and have driven it about 50 miles in the last week. It needs some "tweaking"...but runs excellent. I see no puffs of smoke at start up anymore. Cost a total of about $300 for all the head work, gaskets, etc...plus my labor to do the remove and installation of the head. I should have done this years ago...like before I drove it to Washington D.C. or Dearborn, Michigan. I will report back my finding as I continue to drive the car this summer.
Drove the car about 350 miles this weekend back and forth to the Ohio Mini-Meet, so that makes about 500 miles since the rebuild. Used absolutely NO oil. Cruise control only kicked off 3 or 4 times (still don't know why it is doing that). Running a lot better. Checked the gas milage.....got about 18 mpg, which is what I was getting when I drove the car to Washington, D.C. and back. I was hoping the gas milage would get better since all the head work. Of course....I was driving 65 mph and had the AC on. Probably would do better at 55 with no AC on.
Here is an update 5 years later...and lots of miles. Still not burning any oil. Running excellent. So glad I did this.
Craig, After reading through your whole post, it reminded me of a 250 rebuild I did and had the same issues. Like you, I removed the smog equipment and the EGR. I kept the stock carb. It was jetted for the EGR and ran lean without it. After a couple years, it roasted the stem seals and I had to redo the head. Micah
the extra ethonal content in todays fuels is a double edged sword too. Ethanol is excellent at reducing deposit buildups.. but also runs slightly hotter(even moreso if that added ethonal content has not been factored into the air fuel ratio which leans the mixture out the higher the content becomes(10% vs 15%, etc). This often leads to increased valve and therefore higher guide temps which thins the oil, increases wear and leakage.
