# motor pinging on 69 goat



## clarkaim (Jun 10, 2009)

Ok, I bought this 69 GTO judge clone, bad ass liberty blue perfect in every aspct except that it's an ac car needing a comprossor and maybe some slight clean up.. as I'm driving it home, about 20 miles, I notice a pronounced pinging when goosing the throttle. I take it by my mecnahnic, he thinks maybe the timing has too much advance, also it struggles to turn over when starting hot. Could be that I had to put 91 octane in it, as that's all available. Also the gen lite comes on, tho he tests it w/ a meter and it reads ok on the battery and the alternator, maybe the regulator? or maybe old stators? anyway the battery is charging so no problem. Well, I go to buy some 104 to boost the octane ( no Klotz made anymore? been awhile since I ve had one of these) I put it in and meet this gear head who calls his buddy ( an ase mechanic by the way) says he'll check the timing and set it for me for free. They invite me to join their cruisin club by th way. Then he covers the carb w/ his hands and the car runs normal, he determines a vacuum leak.. then he sprays around w/ carb cleaner and when he hits the intake manifold near the heads, changes in rpm/running/idle. Says I have a vacuum leak at the manifold. I call the guy I bought from, he agrees to pay for it if its reasonable, get an estimate, etc. Gearhead guy says he'll fix it and make it purr like a kitten for just cost of parts, but don't drive it, your'e running too lean and you'll burn a cylinder. Now I'm pissed, even though the guy I bought it from has so far agreed to pay for it. I take it home, at least wash it up, but I can't enjoy it until it's repaired. maybe a week or two? So someone has got to die at this point. t least it's gonna be repaired at no cost to me. Well, she sits for a couple hours, my buddy shows up, we take it for a little cruise thru the neighborhood. NO PInging. Has the octane boost in it now, by the way. We take it onto the local interstate, rack it up to a very fast speed very quickly, NO PINGING.. 

MY question, is it a manifold gasket leak? Is it timing? Could the leak not be there until the motor gets hot? If so, wouldn't just tightening down the nuts fix it? It's a rebuilt XF code 455 HO w/ 64 heads on her. Factory manifold w/ and Edlebrock 4 barrel. Not cammed out, very streetable. What do you guys think, try tightening things up tomorrow? It's a rebuild w/ maybe 1000 miles on it, I'm thinking some loose nuts causing things to show up when hot? Or maybe it just needs better octane gas? 

No pinging tonight on teh run. Also if it's that loose an sitrep, i.e. not so bad that teh pinging can stop w/ octane boost and it being cool (it started up quicker cool by the way)

Is it ok to drive around? Oh I did a great burnout at my buddies tonight he took a pic of.. He's sending my way via email, so I can post. very cool, even tho am a 44 year old guy that doesn't drive like that normally nor intend to.


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## jetstang (Nov 5, 2008)

Mechanic said it has a vacuum leak and don't drive it because it's lean and will burn a cylinder but you drive it around anyway? Then do high speed runs and burnouts? When you build a motor sometimes a gasket will pinch or the intake is warped and that stuff happens, not the guy you bought it froms fault, more of a buyer beware item. Old cars need work, even really nice ones. Pull the intake, put a new gasket on it, seal the leak, then burnout time. My 66 389 had the wrong base plate gasket on it and it had a huge vacuum leak. 
455 w/64 heads might have 10.5:1 compression, you will need a racing fuel mixed with 93 octane to make it not ping or take a bunch of timing out. Also, does it have hardened seats installed or do you have to run instead of lead? Guy I bought my 66 from said he still puts moth balls in his 69 428 Grand Prix to control ping and raise compression, he was pumping race fuel into it and a tunnel rammed big block pulled up and asked if he had forgot everything from the day and reminded him about moth balls. I may use them in mine, never did it before.
Hot starts slow cranking- that's timing and starter heat soak, also directly related to the high compression. Get the best starter you can for the car. For my 468 BBC I bought a gear reduction starter and it never hard cranked again, but did it as soon as it was warm with the new stock starter.
Have fun with your new PROJECT, these cars are never done, always need something.


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## Rukee (Feb 8, 2007)

It's like 3 minutes to set the timing and a half hour to replace the intake gaskets.
Get it fixxed before you drive it anymore, no reason to be pissed! :cheers


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## clarkaim (Jun 10, 2009)

Thanks guys. Not pissed, just frustrated. I got this car from a classic car vendor/dealer, so it's gonna get fixed, just wondering how seriuous a problem it is. I just talked to my mechanic, he thinks it does not have a serious vacuum leak, its a timing issue and it's ok to drive just not race it what do you guys think?


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## geeteeohguy (Feb 2, 2008)

I think that the harder you are on your car, the harder your car will be on your wallet.


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## Rukee (Feb 8, 2007)

If the RPMs increase spraying carb cleaner ANYWERE other then into the carb, you have a vacuum leak. If you are spraying the intake to head gasket area and the RPMs increase, then you have a problem and it NEEDS to be corrected. Driving like that will cause whichever cyl is closest to the leak to run lean and could cause damage. Half hour or hour max and 25 bucks worth of gaskets and you'll be done. Burn the piston and you could be looking at over a grand. Your choice. :cheers


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## jetstang (Nov 5, 2008)

The classic car dealer explains a lot of your issues. Many cars are built, but not driven much. Issues like this show up when driven. Swap intake gaskets because they may be leaking, you don't even have to pull the distributor on a Pontiac, drain the water, 15 bolts later it's off. Get a timing light and move back the timing off a couple degrees, or move the distributor 1/4" counterclockwise and see if that fixes your timing issues. I time cars by ear, advance it til it pings-clockwise, then back it off a little til pinging stops, or has real light ping under heavy load. Good luck and have fun.


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## clarkaim (Jun 10, 2009)

Yeah, I know what to do w/ the gaskets if I do myself. Went to another mechanic who did a look over, said there was NO vacuum leak, closed the flap on the carbuerator and it died. Nope, no leak, also said that my manifold, being an aftermarket Holley, is aluminum it's not unheard of for them to need occasional re-tightening. Then we went thru the vacuum advance, disabled it, said no reason for it as my distributor weights work fine. He tweeked the carb a bit, told me any exaust leak was around this removeable plate that sits on that portion of the intake that feeds back exaust to the intake stuff. Not sure the name of that thing. Anyway, after all that turns out it may need a touch of a retime but there was NO pinging when I drove it home and it ran perfectly.


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