Just bought a 1973 240Z, won't start

[Weasel73240Z]

Sorry for the confusion, they're Hitchi flat-tops. I'll pick up some 20WT fork oil and new fuel filters today, and try starting tonight. I'm pretty sure the stuck needle valve in the front carb was the problem.

I have another question. When I was working on the carbs, I noticed that one of the coolant lines (the one that exits the rear carb and appears to recirculate coolant back to the block) was pinched right near the firewall. It looks like it was done intentionally, not like it was some sort of damage. The pinch is perfectly done, almost like sombody squeezed it in a vise. But I can't seen how the coolant recirculates to the block, what's the deal? If my description doesn't help, I'll take a picture and post it. Thanks.

[geezer]

The pinched coolant line sounds like an attempt to regulate operating temperature. I will do some research. I don't pretend to know a dang thing about flat tops, but I read a lot. I have heard of this before but just can't remember where.

[EScanlon]

Hey Ron, that's interesting about MS 10-30. I'll have to point it out to Beandip as he's the one that informed me as to the 20wt info.

As far as how much, I've also been told that the excess will just flow into the airstream and be burned off in the engine. At least as I've been told.

E

[MikeW]

Hey Ron, that's interesting about MS 10-30. I'll have to point it out to Beandip as he's the one that informed me as to the 20wt info.

The diagram posted looks to be specific to flat-tops. Perhaps they require a different weight than round-tops?

[geezer]

Enrique, I wouldn't doubt a recommendation from Beandip for a second. Both you and he know what works and it's got y'all this far. I noticed that illustration and found it interesting also. It pertains to only flat tops, in the context intended in the manual maybe?

[Weasel73240Z]

So I got my 73 240 to start and idle pretty well last night. It seems that the gunked up Hitachi flat-top carbs were the problem, that's the good news.

The bad news is, when it was running, I was getting coolant through the exhaust system. Not a little sweet smell like I've seen before, but actual (unburned, clean) coolant. I assume the head gasket is gone, and the coolant is getting directly into the exhuast manifold. If it were going into the pistons, I don't think the car would run as well as it does, and the coolant coming out of the exhaust wouldn't be so clean. Is there anything else that I could be missing to explain coolant (a lot of coolant) in the exhaust system, before I pull my engine, and rebuild it?

[hd240z]

Hopefully its only a head gasket, but it sounds like it could be a cracked head around an exhaust port, so be sure to look closely when you pull it apart. You might want to do a leak down test before tearing it apart to see what shows up. If its the gasket it will leak air into the cooling system. If its cracked down stream of the valve seat it will not show up during the test.

Good Luck

[JimmyZ]

Let's hope it's not a cracked or coroded head casting allowing coolant to pass. Great to hear that you got it running otherwise though.

As part of a hobby I do metal casting and end up cutting a lot of cylinder heads up to make ingots. It's amazing how thin some of the jackets are inside these castings. Of course the heads I obtain are scrap heads from the local engine shop so this helps explain why they were on the "way out". I've found a few heads which exhibit exactly what you seem to have... A nice crack in either the exhaust or intake runner. (emphasis on "seem")

Hope it's just a head gasket.

Jim

[thor]

To desmog or not to desmog. I am revitalizing a '71 that I would guess had the smog pump belt removed very early in its life. I am desmogging it now. The plumbing of the smog system is is about 20% full of corroded material.

On my '71 the emmision stuff was quite simple. A pump that injected fresh air into the ballance tube of the intake and into the exhaust manifold at each port. My system had a leak on the common rail for the exhaust injection which prompted me to go ahead with the desmog project.

If there is now visible corrosion or leaks, you aren't forced to remove or repair.

I would suggest that if you have the time, ambition and can fight the urge to keep your machine off the road, desmog it. It will tidy up that side of the engine nicely.

It may take a little bit of grunt work as the nuts and hose clamps are *stubborn and a *little tough to get at. I also am using a reciprocating saw on the exhaust section to allow a box wrench or socket to loosen the nuts on the exhaust ports.

Wall of text to you :classic:

thor

thor

[SteveJ]

Thor,

You do realize [your comment is to a] post that is over two years old, don't you?

Edited September 16, 2009 by SteveJ
Just trying to remember how to phrase things in English.

[thor]

Oh my ! :stupid:

Thanks Steve

[mgmoreau]

Good original thread though!