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Discussion Starter · #1 ·
how does the oil reach the valve guide to lubricate the valve stem as
it moves up and down? or does it? talking BBC
 

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If you are asking how the valve stem on a BBC gets the lubrication at the contact of the guide, it doesn't take much oil and it is mostly just residual oil and a semi porous guide (wether they are iron or bronze) holds a small amount of oil. There really is no supply of oil going to the valve stem (if that was the question)..

GT :)hand
 

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Discussion Starter · #3 ·
what happened and the reason for my question is the exhaust valve in my #6
cylinder was stuck open- had a new valve guide and valve put in and put it together- now no oil out of the pushrod onto the rocker arm-should have checked the lifter but I didn't-it was a low $ (fix valve and guide) and I'm hoping it will blow out the obstruction when I run it ......be interested to hear
what you guys think- should I not risk running it?
 

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what happened and the reason for my question is the exhaust valve in my #6
cylinder was stuck open- had a new valve guide and valve put in and put it together- now no oil out of the pushrod onto the rocker arm-should have checked the lifter but I didn't-it was a low $ (fix valve and guide) and I'm hoping it will blow out the obstruction when I run it ......be interested to hear
what you guys think- should I not risk running it?
Have you checked the p-rod for a restriction or damage?, could have mushroomed a tip....sounds to me like you killed a lifter....

GT :)hand
 

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Discussion Starter · #5 ·
yep blew air threw it and then swapped it out how does a lifter fail ? thank you for your replies GT
 

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yep blew air threw it and then swapped it out how does a lifter fail ? thank you for your replies GT
Well if a valve stuck, it could be a chicken before the egg thing, the lifter could have either pumped up or collapsed before the valve sticking, or there could be a piece of debris lodged in the oil cavity or even a scored lifter bore..., the holes in most hydraulics (assuming hydraulic now that I think about it) are pretty small and it does not take much to plug them up....

GT :)hand
 

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Sit N' Spin
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I call valve float. Piston could've struck the valve and bent the stem.

As far as what could've caused it, without getting oil to that rocker, there's nothing cooling the valve spring, which could easily cause it to lose tension. Spring no longer holds the valve closed, piston comes up and hits it, bends the stem, thus the valve sticks.

Just a possibility. Like GT Jets mentioned, it very well could be a "chicken before the egg" thing that you'll never figure out.

DO NOT RUN THOSE LIFTERS!!! If they're flat tappet lifters, a new set is only $100. You'll have to run the motor through the cam break in with a break in additive (for the zinc).

What cam are you running? Is the cam solid flat tappet, hydraulic flat tappet, solid roller, or hydraulic roller?

Also, what pushrods and rockers are you running? Are the rockers the OEM stamped or are they roller?
 

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Discussion Starter · #8 ·
I will get the specs on the cam- it has stamped lifters and chevy pushrods I am assuming hydraulic flat tappet- I will pull the head and get you a pic of the lifter- thanks- will not run it -Cant I get one lifter?
 

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Sit N' Spin
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I will get the specs on the cam- it has stamped lifters and chevy pushrods I am assuming hydraulic flat tappet- I will pull the head and get you a pic of the lifter- thanks- will not run it -Cant I get one lifter?
To answer your question...not recommended on a performance engine (since marine engines see much higher RPMs and for longer lengths of time than they do in an automotive application, IMHO ALL marine engines are "performance engines"). Replace the whole set. However, from what you're telling me you may need a bit more than that.

Usually on a performance camshaft, due to the increased lift and heavier springs you have to run roller rockers and 3/8" chromoly pushrods are required. The bigger pushrods will require 3/8" guideplates. Due to heavier spring pressures than stock, I also recommend upgrading the rocker studs to the ARP chromoly studs.

If you are running stock springs on a performance cam, this very well could be your problem. With increased lift and higher ramp speeds on the cam, a stock spring cannot close the valve fast enough and does not have enough pressure to keep the lifter down on the cam. Thus, you run into valve float and the lifter pumps up, not allowing the valve to close all the way. Piston hits it...bends the valve stem, and causes the valve to stick in the guide.

The valvetrain is a very critical part of the engine and when not set up properly, can reak major havoc in an engine when it fails. Broken lifters, bent/broken pushrods, bent/broken valves, broken springs, broken rockers, broken studs...it's even possible to break a camshaft. That's just in the valvetrain...not counting all the other shit that it breaks with it. YOU CAN'T JUST SIMPLY INSTALL A PERFORMANCE CAM & LIFTER KIT AND GO!!! You gotta use the right parts (cam, lifters, springs, pushrods, rockers, rocker studs, guideplates, timing set)!!! At minimum you'll need a quality double roller timing set (i.e. timing chain & gears),the valve stem has to be long enough to give adequate retainer to guide clearance at full lift, the spring cannot bind (i.e. when the spring coils "stack" on top of each other and the spring goes solid), the cam has to be "degree'd in", pushrod length has to be checked/measured for proper valvetrain geometry...there's a whole tedious setup process involved to ensure max performance and valve train reliability. Not something I recommend for a novice.

Furthermore, the valvetrain is something you definitely DO NOT want to go cheap on.

To summarize, if you have a bone stock motor and decide to upgrade the camshaft, the whole entire valve train must be upgraded as well.
 

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Boat Nut
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what happened and the reason for my question is the exhaust valve in my #6
cylinder was stuck open- had a new valve guide and valve put in and put it together- now no oil out of the pushrod onto the rocker arm-should have checked the lifter but I didn't-it was a low $ (fix valve and guide) and I'm hoping it will blow out the obstruction when I run it ......be interested to hear
what you guys think- should I not risk running it?
The valve guides on marine motors do need to be clearanced, extra clearance, on the extreme end, otherwise your looking at hanging the exhaust valve. Even brand new heads need to be gone thru, and clearanced for life as a boat motor.
 

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Discussion Starter · #11 ·
thanks to all for your replies- this is a new to me engine- I have put it on the water once-I believe the valve was stuck from the beginning based on the way it ran I will get the thing torn down and some pics of what I find- It will be set up with logs to give some preheat to the cooling water that enters the engine
 

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Discussion Starter · #13 ·
pumped up fine this am when I ran it- guess I got lucky on this one- thanks again everyone
 
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