non ford question

January 24, 2005, 02:51:46 AM

hey guys,, quick question, a girl at work has a 78 nova(6 cyl) that she is haveing problems with,she told me that it felt like it was flooding out or not getting enough gas so her boyfriend had me rebuild the carb (big ol' 1 barrel)when i was done the car would sit there and run fine, rap up real good but when you drive it and put a load on it , it nose dives when you try to give it a little more throttle,same thing before the carb was rebuilt,could it be maybe timeing, timeing advance??? reply's would be great!! and thanks :wtf:

Re: non ford question

Reply #1 – January 24, 2005, 06:34:40 AM

i would have to say timing. and im not sure but if they had replaced timing belt/chain because it broke while driving......maybe somethings bent just my 2 cents

Re: non ford question

Reply #2 – January 25, 2005, 12:24:38 AM

No timing chain or belt in those, just gears.

My '77 I-6 Nova would do a similar thing when leaving from a dead stop at light throttle. Turned out the little fuel passages involved with the transfer from idle to main systems were just barely large enough to pass enough gas when they were clean, so when they gummed up a little, it would stumble like that. A tank of Mobil super unleaded would fix it for a while. There might still be something clogging that area.

Old GM HEI distributors are pr0ne to problems in the centrifugal advance mechanism. Pull the distributor cap & then the rotor. Look at the pivot points for the two D-shaped (with a tail) weights, under the little springs. If the mechanism looks rusty, it probably is worn. There may be the remains of a little plastic bushing at the outer pivot pins. If so, you may be able to find some replacement bushings. If not, you may need to find another distributor shaft & weights. Sometimes you can just get an aftermarket curve kit & use the weights & springs from those. I lubricate mine with BreakFree CLP from a gun store or sometimes Wal-Mart in the sporting goods department.

The excess wear is sometimes caused by bad plug wires, another common problem with early HEI's. High resistance causes the high-voltage electricity to seek an easier path to ground, and it usually goes right through the middle of the rotor (check for burn marks). All that high voltage dancing around with the weights & springs makes the pivots corrode & wear out quickly. This causes erratic advance, & sometimes it will just stick completely.

Re: non ford question

Reply #3 – January 25, 2005, 03:46:04 AM

Check to see if the pump in the carb is giving a good shot when the throttle is opened. If its OK, the float level could be too low, otherwise see previous suggestions.