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03-19-2007, 08:04 PM
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#1 (permalink) |
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2.2 Liter ECOTEC
Join Date: Jan 2006
Drives: Saturn
Posts: 63
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1975 Trans Am
I have owned this TA since about 1979. For those of you that don't know the 400 CID V8 had a 7.6-1 compression ratio that year. And the timing is suppose to be set at 12 degrees before top dead center.
My question is, if there is anyone that has any idea about this kind of thing. I must also add that with the timing mark on the harmonic balancer at zero, the number one clylinder is at top dead center. THIS ENGINE will not run right with the timing set at 12 before. With this setting it has no power. Now if I advance it before the markings it starts to feel right but by this point I'm off scale. I have been timing it with vacume and and retarding it a little if it knocks. Does anyone out there have an idea what could be going on? |
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04-14-2007, 02:01 AM
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#2 (permalink) |
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3.9 Liter V6
Join Date: Mar 2005
Location: Fox Valley Wisconsin
Drives: 2005 Equinox,1981 Bonneville, 1985 Caprice
Posts: 833
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Re: 1975 Trans Am
I had a car that the markings were gone. They had to time it the same way you just did and with a little expirementation it worked just fine. Long as it doesnt spark knock to the point it damages the engine.
__________________
2005 Equinox LS AWD. 1981 Pontiac Bonneville. "The last full sized RWD Bonneville". 1985 Chevrolet Caprice. 2007 Sears Craftsman Lawn Tractor. |
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04-14-2007, 07:06 AM
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#3 (permalink) |
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6.2 Liter Vortec V8
Join Date: Jul 2005
Location: Southern Illinois
Drives: Silvy,
57-Pickup,
Corvair-Vert.
Posts: 2,956
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Re: 1975 Trans Am
See my signature below. This is what happens when you can't stop the spark knock.
I would try replacing all the vacuum hoses. If I remember right you remove the vacuum for the distributor, and plug it before you time the car. Have you replaced all of the plug wires, cap, plugs? Start with the simple stuff first.
__________________
 All GM since 1985. Owner of a 92 Long Roof Caprice. |
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04-14-2007, 10:55 AM
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#4 (permalink) |
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3.8 Liter V6
Join Date: Apr 2004
Drives: 2005 Pontiac Grand Prix GXP
Posts: 491
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Re: 1975 Trans Am
I suggest you stop by the forums at transamcountry.com, a site dedicated to 2nd gen Firebirds. There are a lot of knowledgeable guys there that will be more than willing to help you figure it out.
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04-21-2007, 08:09 PM
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#5 (permalink) |
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3.9 Liter V6
Join Date: Apr 2007
Location: Minnesota
Drives: 2007 GMC Sierra SLT 4x4 Crewcab VortecMax
Posts: 901
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Re: 1975 Trans Am
I am guessing your harmonic balancer has slipped. This was a common problem.
__________________
 2007 GMC Sierra SLT CrewCab VortecMax 6.0, 3.73's 2004 Chevy Impala LS (Wife's ride). |
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04-21-2007, 08:27 PM
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#6 (permalink) | |
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GMI Fixed Ops Contributor
Join Date: Sep 2004
Posts: 8,947
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Re: 1975 Trans Am
Quote:
Pontiac V8's also had timing chain issues as well....chains would stretch out, as I understand??? Nailhead425 or T-Type could answer this like nothing!
__________________
certified GM Dealer Parts Manager since 1994 GM Dealer Parts employee since 1987 AMC-Jeep-Renault Dealer Parts employee 1987-90 holder of many GM accredations, too numerous to list and not giving a damn! |
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04-24-2007, 06:13 PM
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#7 (permalink) |
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2.2 Liter ECOTEC
Join Date: Jan 2006
Drives: Saturn
Posts: 63
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Re: 1975 Trans Am
The timing chain is new and the number one cylinder is at the top at the zero mark. Thanks for the link Zabolots, I'll check there. It doesn't knock at all and it runs fine I'm just perplexed as to what is going on. I'd like to put a set of 9.5 to 1 heads on it but I'm not sure what will happen with the timing then.
John |
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