Compression report, photos, questions. Please look!

http://www.utahstangs.org/boat/boat/boat.htm

Okay there are 2 wires hanging off the ignition box. Where do they go? they arn't hooked to anything. Its the picture that has a red circle.


I'm trying to get my 2500rpm "limited bog" figured out. I cleaned the plugs and did a compresison check.

They go in order starting from the top.

All cylinders but one are 145, the other (the top) is 130psi. But that spark plug was very clean.

Re: Compression report, photos, questions. Please look!

does your primer bulb get hard? do your butterflies stay open all the way?

Re: Compression report, photos, questions. Please look!

I havn't checked the bulb yet. I have read the on the forum that its common for the fuel pump to require a rebuild so I ordered a rebuild kit and will be doing that.

I checked the butterflys on the carbs today and they do fully open.

The rebuild kit for the fuel pump better help this thing out.

Any idea's on what the 2 wires are??

Re: Compression report, photos, questions. Please look!

just a guess, revs counter or temp sensor?

Re: Compression report, photos, questions. Please look!

The temp sensor works and so does the Tach.

The only gauge i have that dosn't work is the tilt.

I don't want to plug these wires into each other because they are both marked differently and don't want to fry anything...

Re: Compression report, photos, questions. Please look!

I can't help you with those two wires.
However, the low compression coupled with a cleaned plug is often indicatative of a leaking head, or manifold gasket. One confirmation (actually just another inication of a blown gasket) would be durring the compression test, that one jug will give a lower reading than normal, and also leak-down faster than the others do. When water escapes the cooling circuit and enters a hot cylinder, it "steam-cleans" the plug.
The combination of all three symptoms would have me ordering gaskets and pulling the head and manifold.
I could be from outer space too, but that's the direction I personally would take if it were mine, NOS.
I do not steer you in that direction lightly, because I have personally never pulled a head on a Force of any HP and not wrung a head bolt off... or two .. I HATE when that happens.

Also, the pics, while excellent , do not show the port side of the head. Anyhow, look for a white substance in the crack between the head and the block, and manfifold/block. This is called "salt-creep", and seen on many motors that have been used in salt water. Salt creep causes aluminum oxide to form in between the surfaces, and it can literally lift the two mating surfaces appart.
I mention this because that one picture (with the two wierd wires) shows what might be a very minor spot of it.

Re: Compression report, photos, questions. Please look!

Changing the head gasket dosn't scare me much. I've built several small block Ford race engines. Wrenching is definatly the one thing I do well.

Pulling the head off.... can this be done with the engine still attached in the boat or do I have to remove it? Also are the bolts torque to yield or can they be re-used? Whats the average time frame for a head gasket to be changed?

Should I take the manifold off first or the head?

Also the boat has never been in salt water, only fresh.

With just a 15psi difference you really think its the head gasket? I'd hate to do all the work for nothing. I've seen differences like that before on brand new freshly built engines. Modular fords specificly.

Re: Compression report, photos, questions. Please look!

Nitrous SSC said:

With just a 15psi difference you really think its the head gasket? I'd hate to do all the work for nothing. I've seen differences like that before on brand new freshly built engines. Modular fords specificly.

Click to expand...

A leak down test will tell you for sure.

Re: Compression report, photos, questions. Please look!

Alright I'll do a leakdown test today if I have the time.

OH, how do I keep the engine from turning when I throw the air into it?

Re: Compression report, photos, questions. Please look!

It's a fun dance of getting it RIGHT at TDC so the rod is pushing straight down with the crank facing straight up... start with a lower pressure and make tiny adjustments in the crankshaft position till it just doesn't want to move any more.

Good Luck!

Re: Compression report, photos, questions. Please look!

I just ask because last time I did a leak down test on a car the 90psi in one cylinder actually pushed the car forward!