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302 cleavo compression problem.

3K views 9 replies 3 participants last post by  V8_GRUNT 
#1 ·
302 clevo compression problem.

2500 kms ago she had new timing chain/gears, crank, bearings and oilpump. All was good till now, running like bag of s**t I have done a compression test to find, 1-100psi, 2-100psi, 3-110psi, 4-100psi, 5-130psi, 6-160psi, 7-130psi, 8-140... Stupid question maybe but could this be just from a blown head gasket or am i probably looking at a lot more of a problem. Over the last week shes fouled a couple of plugs, both in cyl 2. Sparks fine. Apparently the heads have never been off...When I get them off if its not the head gasket, how will I know whether its rings or valves??? If its the heads should I rebuild, replace, or upgrade?Anyone know prices?
 
#4 ·
Re: 302 cleavo compression problem. Heads are off.

I think the old owner was right they have never been off. most water holes corroded up to a quater of their original size. Gaskets seemed to be trying to grow into the block. I think I might just get a valve grind, plane 30 thou and slap em back on. What aya reckon???
 
#5 ·
woooooah ok before you go pullin off heads or anything, my XB was running one day on the driveway and i walked away to get something and came back and it was off, i thought straight away......"out of fuel"

So there i was trying to start it, no good, checked spark etc all good, then off came the carby, and i cleaned it several times, it ran like a bag of shit and could barely get up the driveway, so many things passed my mind, except for 1 thing.......timing chain had slipped........check that first, check your valve timing even new parts can stuff up, sounds stupid, but may save a lot of work :)
 
#6 ·
Oops to late. Their off, now what. Is checking for a timing chain slip as simple as setting the timing? If so I'd tried it, wouldn't the large difference in compression ratings = buggered valves or rings etc, Why is it fouling plugs? Is that oil gettn into the cylinders through the valves or what? It was running a bit rich?
 
#7 ·
Oh well it's all good, well it may not be the problem, but i thought i would suggest it first, all i did was take the tappet cover off and put a bit of wire down the cylinder, turn the engine by hand and watch the piston come to top dead centre.........watching the valves at the same time, in my case the inlet valve was opening when the piston was coming up!!! therefore blowing back up the carb, at that stage it wasn't running.

So a simple way to check is to just look at the valves and where they are at whilst turning over the engine by hand.........it worked for me, but obviously you have gone further with pulling the engine apart.......hope it works out well for ya, you might as well freshen up the bottom end and give the heads a little port and put a sweet cam in it...........you won't regret it.........good luck!!!! :)
 
#8 ·
Ross79xe said:
Oops to late. Their off, now what. Is checking for a timing chain slip as simple as setting the timing? If so I'd tried it, wouldn't the large difference in compression ratings = buggered valves or rings etc, Why is it fouling plugs? Is that oil gettn into the cylinders through the valves or what? It was running a bit rich?
Well my clevo's getting a bit tired it's the original engine/internals from 1973!!! and yeah compression is at about 150 - 180 which is good, but it's starting to foul up plugs as well........i have been told and it makes sense that the valve stem seals are probably deteriating and letting oil pass through them, you are probably having the same problem, i think my rings arent too bad, but that's why i am chasing a new block, so i can start to build a monster!!! :)
 
#9 ·
That sounds pretty damn close to me, How did you go about rectifying the timing chain slip??? She was spitting out the carb not so often but good and hard when it did. And I spose you cant get good compression with open valves then ay. Is it possible for that to only effect one side of the motor as only the 1-2-3-4 compression was realy down (refer to top). nice one cheers.
 
#10 ·
my timing chain was the original ford one which tend to be a weakspot on them, the gears were all chewed and had a fair bit of slop in the chain, a good way to check slop is to turn the crank over by hand an watch the dizzy rotor cap spin, then stop and rotate the crank in the opposite direction, the crank should move very slightly then the rotor will follow, i think there is a specification on that some where to detect timing chain deflection, but in my case i think the crank turned about 20 degrees or something before my dizzy rotor started to spin........was very worn, all i did was went and got a new one from repco, JP performance i think it was and it has been sweet ever since.

You may get a slight explosion from you carb and fouled plugs can do that, and gee that really pisses me off when that happens!!!
 
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