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Head Gasket or What?


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My '69 Delta "88" 455 is pulling the following trick which I've never witnesed in any car I've ever owned. Bought and have been driving it for few months. Running great, getting 18mpg. Install a set of mechanical gages and notice its running at 150. No biggie... In one tank (large) of gas mileage drops to 14 and seems to run a tiny bit rough. Put plugs in, set points with feeler gage then hook up vacuum gage to manifold to fine tune. Pointer is swaying between 15-20, increasing with engine speed. Hmmm... Take for test spin, stomp on it around 75, no steam/smoke, cruising around 80 and all of a sudden gage flys up to 270 then down again. With my heart beating, pull over, doesn't seem to be hot. Gage returns to normal. Cruise back and decide to check out the thermostat. It's a 180 with a hole drilled in it. So I check the flow, seems a bit slow so the hell with it. I put a new thermostat, waterpump, hoses and had the radiator cleaned and checked. Put everything back together, filled it, started it and waited for the thermostat to open. The level dropped, I ran aroud to look at the gage and somehow it was at 180... Cool... Started filling the rest of the way, got up close to the top and noticed that the flow was still sluggish. With little bubbles.. So I reached over and gav it some gas and the level raised.. Like an idiot I blipped the throttle and the coolant literally jumped out of the radiator burning my hand in the process!I put the cap on and the hoses instantly swell hard. The hell with it, I take it for a spin and its at 180 then boom! up to 270. Within a second or two its back to normal. Take it back home, no leaks even with the hard hoses... And thats where I'm at. It's been a couple of months and I take a weekly drive of 30 or so miles at freeway speeds just to keep it up. There's no coolant in the oil or steam in the exhaust. So what do you guys think? Should I first try retorquing the heads? The engine was rebuilt 40,000 ago by the original owner. Maybe it had those gasket that needed to e retorqued and since the old man has just been pussy-footing around the last few years that I blew it? Thanks in advance for an advice/comments. It doesn't look good so can anyone recommend a mechanic in the San Diego are? I don't trust myself for this job. Thanks, RichardO.C.A. member #33154O.C.SoCal member#1301 rocket_88@webtv.net

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First off- gasoline is not what it was even a few years ago. Find out if reformulated gasoline is used in your area (and in SoCal I'd almost bet it is). The stuff uses ethanol blends, oxygenates, all kinds of rotten stuff to promote more complete combustion, but their side effect is that, as oxygenates, they force the air-fuel ratio WAY lean which makes engines run hot. You also end up burning more fuel to get any modicum of performance. Your sudden drop in gas mileage and rough running is what tipped me off to possibility of RFG.

You might try playing with the base timing, and make sure the temp gage is accurate. For the temp to go way high and straight back down like that sounds like you may be getting steam pockets in the thermostat crossover or the gage's sensing bulb may be weak and making a direct ground contact against the sender body.

If you have a thermometer that can read that high, put it in the radiator and see what the coolant is actually doing.

What actually happened when it sprayed you is the water pump pressurised the system momentarily when it sped up. Remote possibility of wrong impeller on the water pump too.

Have your coolant analysed for exhaust gas. That will be proof positive of a head gasket leak.

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