I currently have the stock head where the plug just stick outright. Can I change this to a slant head? Did I need to take any precautions?
Changing stock head to slant head
- Thread starter Mind_Reader7
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Bump.
More info might help.
I have a 66/80cc engine that came with the head where the spark plug stick right out on a 90 degree angle. I want to know if I can buy a slant head and just whack it straight on.
More info might help.
I have a 66/80cc engine that came with the head where the spark plug stick right out on a 90 degree angle. I want to know if I can buy a slant head and just whack it straight on.
swapping them is easy, unbolt stick the new one on rebolt. some leak i think mainly due to over tightening and screwing up the gasket. the higher compression let due the demise of my clutch pads, i believe. the compression nearly stops me in my tracks when starting 
Just get the new head. I use spray copper exhaust gasket sealer on both sides of a used head gasket. Put your plug in the new head before you put it on to make sure the plug isn't too long. I use a NGK b7hs.
You should be able to just swap it, but to maintain a higher compression (in some motors anyway), take a look at your spark plug. The slant head (speaking from what I've seen) seems to come with a piston with a rounded top, and the straight comes with a flat top. In order to maintain maximum compression (usually results in more power, but a harder start), check to see you've got the rounded top one. It'l work either way.
In terms of spark plug clearence, the slant head usually has more room than the straight, so you shouldn't have any problems. But I'd check it out anyway just to be safe.
New bolts (studs) shouldn't be needed. But if you've got the nuts with the crowned tops, you might find they bottom out before actually tightening when using a head from a different manufacturer. You may need to get some standard-style ones if they are crowned, or perhaps you could space it out with a few washers.
In terms of spark plug clearence, the slant head usually has more room than the straight, so you shouldn't have any problems. But I'd check it out anyway just to be safe.
New bolts (studs) shouldn't be needed. But if you've got the nuts with the crowned tops, you might find they bottom out before actually tightening when using a head from a different manufacturer. You may need to get some standard-style ones if they are crowned, or perhaps you could space it out with a few washers.
Some folks reported pinging with too much compression my slant head motor came with two gaskets on it. Sometimes with one thin gasket it will start pinging when the motor warms up.
Ping is pre-ignition caused by low octane. Use the highest octane fuel you can find or octane booster in your premix. Some Sunoco stations sell super high octane (Corvette) fuel at a seperate pump off to the side.
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