High Vacuum / Burns Oil

check the vacuum hose from the valve cover to the back of the carb plate make sure it isnt collapsed. If it idles good i dont think it is a intake leak unless the whole gasket has moved internally/ or broke apart.Do a compression check make sure its not a cracked ring although that will usually cause high pressure in the crankcase pushing oil not a vacuum issue.Verify all vacuum hoses are in good shape . good luck

I have not checked with a vacuum gauge, however when I remove the hose with the PCV valve and place my hand over the opening on the valve cover it will suck your hand down pretty good. Same when I remove the oil filler cap.

As far as what was done to the heads... They were replaced prior to the rebuild new. I do not believe they actually worked on them. I will have to check. Is there something I should look for ? to verify this. My understanding is there should be no vacuum activity in the valve covers. Is this correct ?

Thanks for your help and coments.

when you remove the pcv valve from the valve cover there should not be any vacuum in the crankcase(valve covers)to cause the amount of vacuum you are talking about you definitely have an intake leak or possible plug from bottom of manifold missing,very possible if plug was removed and not tigntened properly,if high vacuum is occuring with pcv installed but not when installed check crankcase breather for restriction,including spark arrestor especially if aftermarket

the action of the piston moving down the cylinder creates the vacuum,if the rings were installed improperly and not sealing this cylinder would be able to create any vacuum and could not cause this problem,problem is definitely upper end,intake manifold and gaskets,or very bad valve guides and seals,my money would be on the intake.

If you have vacuum at the oil fill,with the pvc disconnected,then I'd like to know is it intermittant like coming from one cyl. or is it equal at all times.This should be checked at extremely low idle.If its equal all the time I think ya got a manifold problem,if you feel a change in it then its probably just one cyl.and could be several things.I think by what you said I'm leanning towards cracked intake.

Good luck Munday

Thats a possibility 92, you never know thats why i made the statement ( i always wanted to build a motor) the old addage is true.... you pay for what you get. A good rebuilder and i stress a good rebuilder would catch a problem on a$$embly,
I dealt with a guy this summer that had his engine rebuilt by our local qaulity rebuilder, he had a problem and they chicken danced for the entire season. the engine was buried and a m-fer to get out, I did a trans for him in which by the way worked better than new ha-ha... anyways we found a head bolt missing, that was causing the block to fill with water and they had him doing all kinds of things... change this...change that... try this try that. I guess the moral is check them out before you buy and ask for references and call the references.
Back to this guys problem, it was rebuilt with 50 hours on it, it smoked from the beginning... thats not normal for the first 10 hours as you were probably told, see my point. get your rebuilder invovled and make him stand by his warranty.... if you got one

before pulling the engine remove valve cover on that bank and inspect valve train for proper movement(both rocker arms and push rods moving approximately the same and no missing pieces).

not good

especially the guys were running the boat hard and it was leaning out at the higher rpms, on problems like this in the beginning the first thing i do is pull the plugs and inspect, if one looks suspicious you know you may have a problem on that cylinder, then do the compression test, then at this point it will determine which way to go next.
the first thing a doctor does is checks your blood pressure and checks your weight, this is the same concept.then if the doctor determines low blood pressure he has to figure out why. in this case now you have to figure out did the piston burn from a lean mixture? if so you must also fix the problem once you've made the cure

Eric-- If it is a hole in the piston can just 1 piston be replaced?, where do i go from here if this is what i find?

Thanks for the continued help. Going to garage now to start checking things out.

It is Sunday maybe someone from above will help on this one !!!

Morning update.

1. Pulled valve covers and rotated engine by socket on front of cam. All valves and rockers appeared to move top to bottom the same by the eye.

2. Pulled the intake off then head on side of # 6 cylender o compression test.

3. Hole in the piston !!!

4. I then pulled other head and things look ok to the eye ??

I can not believe the engine ran with a hole in # 6 piston ?? Have you ever come across this ? Where do I go from here?? I know I need to finish pulling the motor but should I go back to the engine shop that did the rebuild? They are what I believe to be a reputible shop (Gustaffengines.com) Rebuilds and sells rebuilds and builds race engines.

I a$$ume more thorough inspection will need to be done but I really don't know what to expect especially after spending around $2,000 just 2 years ago.

After talking to my son who was driving the boat he said they put some octane booster in the fuel... Would this have caused this? Is this a no no ??

I appreciate all your help. I am not real up & up on the internal engine building process but not afraid to dig in. I pulled and stripped engine last time and am now ready to pull again ???

Thanks

another possibility,were the spark plugs the correct heat range and reach?also saprk plug wires can crossfire and cause detonation,especially common on Ford engines.

Can you guys help me here?

Should I buy a long block / short block? where is the best place to purchase something to get me going again ?

I will contact the shop that did my rebuild but do not know what to expect >>>

these guys should be able to identify these heads, the plugs are also a possibility, Im not the one to identify ford stuff, did you look at the rest of the block? check each cylinder wall for scuffing from the pistons expanding. How does the hole look on number 6?
your valves too may have taken some heat. Is there anyway you could take some pictures for us in detail and post them?
we'll get you out of this cheap as possible
Eric

the heat range of the spark plugs should be close to the originals,you should be able to cross reference both numbers to check,a quick way to check reach is to thread the plugs into the head and check the reach,should not have alot of/or any threads exposed,also check electrode lenght with original plugs,I have seen alot of holes in pistons from this problem.