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455 olds, 850 double pumper, crane electronic ignition, OT headers
I recently decided to freshen up my olds motor, nothing was wrong the motor it ran great (it just had a rough summer:D )
anyway I sent the block to my builder for a re-ring and bearings. I get it back and on the water and within a few minutes two of the valves stick, I remove the heads and find 2- exhaust valves "blue" and the valves were galded. we replace the valves, put it all back together I changed the ignition tear into the carb, find an obstruction in one of the secondary passages (small metal shaving) I am thinkin I found a problem, but I install a fuel pressure guage (it is at a steady 6 psi @ 3000 rpm, retard the timing, and run it.
Within a couple of minutes it starts popping (exhaust backfire) and missing. I tow it in, find that again it got hot as hell almost burnt through the head gasket, blew a hole in the new exhaust valve and it was stuck open this time by the seat that had fallen out (not the same two cylanders as the first time). again it was obvious it got valve melting hot, the temp guage never went over 125 and it didn't seem like it had anything internally wrong with it...it ran good, keep in mind this thing ran GREAT all summer I didnt screw with anything while the engine was in the shop. I am pretty sure its a fuel issue but I keep hearing about pre-detonation, sorry I cant post any pics, my camera dock just took a dump as well :mad:
Is there something I am overlooking here?
Thanks,
John
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Sounds like a vacuum leak at the intake, or somehow you're restricting the water flow from the block to circulate thru the heads. Is this a jet? Any water valves not open?.....Or not closed?......No one messed with the heads, right? Same heads, same block, the only things that changed were the gaskets........Sheet metal or aftermarket intake gasket?........Maybe some of the Olds experts here can tell you if there are more than one type head gasket.....I know some Fords changed the water routing from block to head........Maybe Olds did too.........MP
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Hello, and sorry for taking so long to post, things are really hectic right now.
this pic is from the second time I tore it down I have a steady 125 degree temp reading on the guage, all the water valves have been checked. I really think this is a fuel issue but why is the question?, all I had done was "freshen up" the motor bolted everything back on and went for a put to dial it in. This damage happened inside of 5 minutes of running it and only at around 3 thousand rpm :idea: http://i148.photobucket.com/albums/s...dascopy016.jpg
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Water temp guages only read the temp acurately if the water is flowing. What did the oil temp climb up to? To get that hot you'd need to be running some seriously lean conditions and the temps should still climb through the roof. I'd check the guage and sending unit in a pan of boiling water. If they work right, I'd be checking to make sure water is flowing all the way through the engine.
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We used a snap on temp meter (laser light) and the temps were fine, no hotspots, no heat related issues to speak of other than the obvious. I plan on putting it back together this weekend, and I am thinking I will put a dump on the back of the intake manifold,(water jacket) just to be sure I have flow in the block itself. I am also installing a holley fuel pump with a regulator on it. A buddy of mine has a 900 holley we are going to slap on it as well. I am planning on drowning this thing with fuel then dial it in from there.........I hope lol, these heads are getting expensive.....:D
I just cant figure out what could have happened in the first place, everything was the same when it went back together. I guess it'll be one of those things you would have never guessed would happen til it happens to you.
Thanks for the input I will keep you posted
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Sounds like a vacuum leak at the intake,
I lost a valve once in a 454 after a freshen up. Went from a GM cast iron spreadbore manifold to an Edelbrock Perfomer and Holley 4150. When Edelbrock machined the manifold, they drilled the carb stud holes all the way through into the intake passages. One of the holes not being used for a stud was not sealed by the carb gasket, vacumn leak in that port and got the valve. Edelbrock offered me a new valve, BFD. Good luck on your search.
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How much timing are you running?
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I can't tell how your plug looked in that picture, did it match the other 8?
What cylinders where having issues?
Tell me you didn't use that crappy stainless valley tray/intake gasket on an aluminum intake!? Gotta use the MR. Gasket ones on the Olds with the Al intake.
Again, we need to know how the plugs looked in each chamber.
If you are using the good composite intake gasket already, and you have the timing reasonable, and you know the cam was clocked right- then I would check for vacuum leaks at idle. You should have a good vacuum gauge hooked up to the intake and idle screws for maximum vacuum. Then have your buddy soak the intake with water or soapy water or WD40 and you watch the gauge. Instal new plugs and let it idle for a few minutes. Pull plugs and see how they look.
If all that looks good, try a different carb. Maybe also ditch the Crane box for a while and slap on a stock HEI unit and see how she runs. The HEI is the best thing around IMO for a mild engine.
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I should have the heads back today and we put stainless steel valves in them, it already had the longer springs and keepers installed. the heads were warped so they were re-surfaced as well.
The plugs; in the posted picture the diode is gone and the porcelain actually looked like it had "warped" , as far as the rest of the plugs are concerned they looked like they were burning good, possibly a little lean, but they only had a few minutes run time on them so it is hard to guage off of that.
I have the "offy 360" intake and the big housing for my HEI distributer hits the intake about 1/4 inch before it seats, so I am going to see if I cant remove a little of the distributer housing (actually just ease the sharp edges) off of the distributer housing.
also I am re-jetting the carb, I have checked out some old posts and it looks like 4 size larger jets will be a good starting point.
I have been using the Fel-pro racing gsakets for the intake they are a little thicker than the standard ones, and when I pulled it apart the seal looked great, but I cant judge that by looks alone after the fact.
Where do I get the Mr gasket intake set?
The last concern is the fuel pump its a carter electric, it runs a steady 7-8 psi but when I start it or rather when the boat has sat for a while it will start off really low 1-3 psi, I thought it might just be air that collects in the high section where the guage is (guage is mounted on the top side of the fuel line) and I was getting a false reading until the air gets purged, but I am going to have to relocate the guage to be positive.
Thanks for the input and I will keep you posted.
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I think I would tear that carburetor all the way down to individual pieces and blow the passages out with serious air pressure. If there were shavings in there that you could see, there's probably some in there that you can't see.
I have seen little chunks of rubber hose clog up a carb and do similar damage.
The Mr. Gasket intake gaskets can be ordered from most good autopart stores but the felpro racing ones are probably as good or better. Just goot stay away from the thin sheet metal crap.
good luck!
