Help with engine problem
Le Mans Master
Joined: Jan 2002
Posts: 8,913
Likes: 283
BTDT with the nylon gear set. Failed at highway RPM on an 82 chevy suburban. Engine died like you shut the key off. In my case, the failure was gross and very apparent.
If the engine seems rich, it probably is. Failure to idle, but runs good at higher RPM, is either too much fuel at idle or not enough.
Timing. If you rev the engine, and only have 8* advance, you have a problem there.
Your base timing (vacuum can unhooked and line plugged) should be set at 8*.
If you cannot set timing because it will not idle, then set it at 36* BTDC at 4000 RPM. I do not know the advance weight characteristics of the 300 hp motor, but someone here can post the specs. The above procedure will get you in the ballpark for a base timing. You will need a dial back timing light or mark the damper.
Get your timing verified, then move on to carb.
- Mark
If the engine seems rich, it probably is. Failure to idle, but runs good at higher RPM, is either too much fuel at idle or not enough.
Timing. If you rev the engine, and only have 8* advance, you have a problem there.
Your base timing (vacuum can unhooked and line plugged) should be set at 8*.
If you cannot set timing because it will not idle, then set it at 36* BTDC at 4000 RPM. I do not know the advance weight characteristics of the 300 hp motor, but someone here can post the specs. The above procedure will get you in the ballpark for a base timing. You will need a dial back timing light or mark the damper.
Get your timing verified, then move on to carb.
- Mark
Pro
Joined: Jul 2006
Posts: 556
Likes: 4
From: North of Spokane WA
Wow, sounds super frustrating to still have the problem after all you have done. The good news is that these motors are relatively simple and your problem has a solution.
One thing that comes to mind is the old saying that 90% of carburetor problems are actually ignition problems. Seems like replacing the points, condenser, rotor, and cap with quality new parts would be something I would try......and as others have said look over all wiring very carefully. Do you have ignition shielding? If so, checking where wiring might be in contact with it would be another place to look.
Hang in there and let us know how you solve it.
Good luck, Doug
One thing that comes to mind is the old saying that 90% of carburetor problems are actually ignition problems. Seems like replacing the points, condenser, rotor, and cap with quality new parts would be something I would try......and as others have said look over all wiring very carefully. Do you have ignition shielding? If so, checking where wiring might be in contact with it would be another place to look.
Hang in there and let us know how you solve it.
Good luck, Doug
Thread Starter
Racer
Joined: Oct 2013
Posts: 251
Likes: 24
Today I dropped the spare tire tub, and then removed the fuel sending unit. There was no strainer on it, so no restriction there. I may have blown it off when I blew 10 psi of air thru the line from the fuel pump flex line back to the tank. The flex line to the sending unit was old and somewhat kinked, but not enough to cause a fuel restriction. I cut it into 2 inch sections and found no internal defects. I ordered a new strainer, O ring, and backing cam. While I await their arrival I will install a new set of points and condenser, as several of you have suggested. Thanks for your input.
Melting Slicks
Joined: Aug 2004
Posts: 3,078
Likes: 101
From: Riverhead New York
Today I dropped the spare tire tub, and then removed the fuel sending unit. There was no strainer on it, so no restriction there. I may have blown it off when I blew 10 psi of air thru the line from the fuel pump flex line back to the tank. The flex line to the sending unit was old and somewhat kinked, but not enough to cause a fuel restriction. I cut it into 2 inch sections and found no internal defects. I ordered a new strainer, O ring, and backing cam. While I await their arrival I will install a new set of points and condenser, as several of you have suggested. Thanks for your input.
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
I'll guess that you have an ignition problem. Recall that as the engine goes from no vacuum to good vacuum when started and that the vacuum advance canister is moving the breaker plate. With an old distributor, years of vacuum changes can flex the ground wire a LOT, breaking down the wire strands inside the insulation. Of course, this will be likely intermittent - sometimes they'll connect, sometimes they won't. Test all wires for continuity and wiggle them around to see if there's a problem.
Good luck!
Good luck!
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Thread Starter
Racer
Joined: Oct 2013
Posts: 251
Likes: 24
The fuel strainer and O ring arrived this morning. They're installed now. I installed a new set of points and condenser, set the dwell, and checked the timing, which was right on 8 degrees BTDC, as before. When installing the points I checked the primary wires for tight connections and bare spots. They appeared to be fine, but I didn't check for continuity. (I hadn't read that post until just now). The engine started right up and ran normal in the garage and there were no gas leaks. I'll start driving the car tomorrow and I'll report back in a week, unless I have more issues. Again, thanks to all those who took the time to respond to my request for help...Brian
Thread Starter
Racer
Joined: Oct 2013
Posts: 251
Likes: 24
I've driven the car on several occasions over the last week, and changing the points & condenser appears to have solved the problem. Thanks to all those who suggested this repair. I should have followed your advice sooner...Brian
Team Owner
Joined: Mar 2003
Posts: 26,118
Likes: 1,874
From: Greenville, Indiana
Check the timing again in a 1000 miles or so. In your first post you indicated the timing changed 10-12* with the dwell virtually the same.
Thread Starter
Racer
Joined: Oct 2013
Posts: 251
Likes: 24
Mike M. I'm having the engine overhauled this winter and I'll mention to them to check the vibration damper. While the engine is out, I'm going to have the transmission overhauled, and will also replace the torque converter.