Chassis / Suspension & Steering Other When accelerating Not applicable
Q: I am building a sand rail (race car) from custom parts and a 79 Caprice. The four link suspension is supposed to rock back and take the weight of the car and press down on the rear tires when launching. Instead, the wheels spin for the first 75 feet before the car finally grabs.
How should I adjust the suspension so that it will take off more smoothly?
A: it sounds to me as if there isnt enough weight to actually grab... another way to go is traction bars
Ignition System Tuning Not applicable Not applicable
Q: Greetings,
I just purchased a 1967 chevy caprice with the original 283 2bb. It has a/c and a pg trans. Can you give me the tune-up specs for the car? Information on plug gap, timing, point gap, tach/dwell, and idle speed would be most appreciated.
Thanks,
Dennis
A: Plug gaps.035.timing 6btdc.Dwell 28 to 32 degrees.Idle speed around 750RPM. Steve
Q: There's a subtle "knocking" sound coming from the engine at idle, or under load. The intesity in the same in both cases.
This is when the engine is cold. When the engine warms up, the noise goes away. And in the summertime, it never occurs at all.
This has been happening for the last year and a half.
It's is a 1966 Chevy Caprice 2dr Hdtp with the original 325hp 396.
There is no rattle when the engine first lights off as one would hear in a worn engine just before the oil pressure picks up.
A friend suggested it may be a worn cam bearing - the engine had been rebuilt before I bought the car in '96. To follw up on that, I pulled the valve covers off and loaded up, then unloaded each lifter with the rocker nuts.
When I got to number 3 exhaust valve and tightened up the rocker nut a half turn, the knock jumped out at me. When I backed it off again, it went away.
Tapped an analog oil pressure gage off the block and found I have adaquate oil pressure, about 65 psi at idle, slightly higher above that, and the engine doesn't burn any oil.
I haven't had any problems as such with it, but any noise like that coming from an engine always bugs me!
Since I haven't been able to specifically locate the source, even with a stethoscope, I'm hoping you could shed some light on this.
Long winded as this email is, I thank you in advance for your help!
ANDY BOEHLKE
A: Andy... first of all, thank you for the detail...
You may be chasing a wrist pin (upper end of connecting rod to piston) problem.....
All pistons are cam ground... slightly out-of-round. As the whole engine warms up, they grow or expand to become perfectly round.....
Two things happen... the wrist pin hole grows tighter, or smaller - depending on how you look at it - and thereby "tightens" it's grip on the pin.
Or, when the piston is cold - and not yet round - the extra clearance makes a noise called "piston slap" .....Ed
This way to the live technicians