What would allow a 4-speed in gear to roll backwards while on an incline. New clutch a few months ago. Runs good, at least I thought.
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Whats the engine compression? *NM*
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Re: Whats the engine compression?
I've never checked it. It's a '64 365hp that I've owned for a couple of years. Runs decent. My bone stock '64 300hp car will whoop it from 0-40 though so now you're making me wonder if I need some engine work. Doesn't burn oil, runs very smooth.Comment
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Re: C2 Rolls Backwwards While in Gear
A lot of SHP engines get rebuilt with what owners think ia 9.5 CR, but they are actually about 8.5-9 because the installed head gasket is a lot thicker than what the piston manufacturered used to "spec" the CR.
A high overlap cam and low compression isn't good for much unless the objective is to run regular unleaded 87 PON fuel, but fuel economy will drop more than the current percent differnce in price and you leave a lot of torque bandwith and HP on the table.
In actual fact a 30-30 or LT-1 cam engine will run without detonation on current unleaded premiums at 10.25 and will handle 10.5 with a little tweaking of the spark advance map. (Make it 10-10.25 for the Duntov or L-79 cams and 9.75 for the 300 HP engine.) The Speed Pro OE replacement domed pistons with a slightly thicker than OE gasket will get you in this range on SHP/FI engines, but "flattop" pistons and a thick gasket are a recipe for a gas guzzling dog.
DukeComment
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Re: C2 Rolls Backwwards While in Gear
If I assume the engine has't been rebuilt, is this a sign that it might need a valve job or the like. Wouldn't there be some oil burn smoke? Comments appreciated.Comment
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Re: C2 Rolls Backwwards While in Gear
any vette with a 3.08 to 1 ratio rear end will"roll backwards" off a hill more easily than a 4:56 to 1 rear. i suspect the rings/valves could be near worn out before a 4:56 rear equipped vette would "wonder backwards" . i also suspect a 3;08 rear equipped vette with a healthy engine wouldn't roll backwards. mikeComment
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Re: C2 Rolls Backwwards While in Gear
If the engine needs a health check a leakdown test or compression test is the first order of business.
Also, I'm assuming that you're using first or reverse and that the "hill" is no more than about a 3 percent grade.
DukeComment
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Re: C2 Rolls Backwwards While in Gear
That little handle above your right leg is called an emergency brake. Pull out on it firmly and see if that doesn't eliminate your problem. Since many of the disc brake cars don't have a functioning park brake, you may have to quit parking on a grade. Only park your '64 on grades since it will blow the doors off the 365 to 40 mph.Comment
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Re: C2 Rolls Backwwards While in Gear
Yes it was in first gear but it was in my driveway, not real steep but definitely more than 3%, maybe in the 5-10% range. Previous owner did change out the rear end for better mileage according to him (a real moron). I don't recal the exact ratio but I have the receipt at home.Comment
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Re: C2 Rolls Backwwards While in Gear
Dear Mike,
I use the emergency brake regularly and it works quite well. I wouldn't park it on any serious grade without doing so. In this case, I was in my driveway and ran into the house for 5 mis and noticed the car had moved towards the street. I watched it and sure as hell the thing was moving ever so slightly. Glad I was only in for 5 minutes. But my point was more to the question of whether this was signaling some other problem. I immediately thought of my clutch rebuild. Then when the comments came about the compression my mind really started racing. I will have that checked in any case.
I'm not sure I get your last sentence, seems like a bit of sarcasm but I'm not sure. Both my cars a re 64's and the 300hp car is definitely quicker at the start. I'm starting to think I have other issues with the 365 hp car though. Maybe you can clarify what you meant. Sorry if I misinterpreted anything.Comment
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Re: C2 Rolls Backwwards While in Gear
David,
If your driveway has a 5% plus slope you may not have a problem. That's 5/8"/ft and you state in the 5 to 10% range so it sounds like a steep driveway. If you decide to check the engine, follow the 1964 shop manual and check cranking compression pressure (160+- 20 pounds)and that may give a good indication of condition.Comment
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Re: C2 Rolls Backwwards While in Gear
Dear David:
You didn't misinterpret anything.Comment
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