Engine falls on its face on hard acceleration/help???
#1
Engine falls on its face on hard acceleration/help???
OK I drove the olds today with a 455 that’s been built basically to 1970 W 30 specs. Car is been running great lately plenty of power. I picked up an extra dwell tachometer today and thought I would see if it was working. Put it on the Oldsmobile, then noticed that it was way off on the reading. Grab the wrench and adjusted dwell on the run, Couldn’t seem to get the needle close to where it should be without the engine dying, dwell should be between 28 and 32. I set back to where I thought it was close to when I started, test drove car and everything seem to be fine except on hard acceleration the car falls on his face above 4000 RPM. After several more Attempts no change, Then on next attempt to change the dwell car died and wouldn’t start, barely move Allen wrench and car started, can’t move wrench any at all One way or the other without car dieing. Cleaned and reset points with feeler gauge and car starts. 😆 test drove car and it still falls on its face on hard acceleration, then did the same just driving down the road anytime I got over 4000 RPM! Look down throat of carburetor to see if I was getting gas I noticed that one of the Jets was only delivering half the fuel it should, I’m thinking maybe it needs a kid in the carburetor? What a day! One step forward two steps back. Is there a good HEI set up for use with Edelbrock 04B intake and ram air induction breather?
#2
Dwell adjustment changes ignition timing. Ignition timing adjustment does not affect dwell. Anytime dwell is adjusted the ignition timing must be checked/adjusted. What is the dwell reading after gapping the points with the feeler gauge? Used points don't gap accurately with a feeler gauge due to contact surface pitting, it's better to use a known good meter especially on used points.
The symptom described sounds like it is running out of fuel. Is the fuel filter clean and are the hoses in good shape including the ones at the tank? Run a fuel pump test or try another pump.
Good luck!!!
The symptom described sounds like it is running out of fuel. Is the fuel filter clean and are the hoses in good shape including the ones at the tank? Run a fuel pump test or try another pump.
Good luck!!!
#3
I picked up an extra dwell tachometer today and thought I would see if it was working. Put it on the Oldsmobile, then noticed that it was way off on the reading. Grab the wrench and adjusted dwell on the run, Couldn’t seem to get the needle close to where it should be without the engine dying, dwell should be between 28 and 32. I set back to where I thought it was close to when I started, test drove car and everything seem to be fine except on hard acceleration the car falls on his face above 4000 RPM. After several more Attempts no change, Then on next attempt to change the dwell car died and wouldn’t start, barely move Allen wrench and car started, can’t move wrench any at all One way or the other without car dieing.
Second Guess: Dwellmeter set for 6 cylinder engine instead of eight.
You've ruined the points. Points come with a tungsten coating on the contact surface. You file them, you destroy the Tungsten coating. You knock-off the little cone of transferred metal, you reduce the surface area. Install new points.
test drove car and it still falls on its face on hard acceleration, then did the same just driving down the road anytime I got over 4000 RPM! Look down throat of carburetor to see if I was getting gas I noticed that one of the Jets was only delivering half the fuel it should, I’m thinking maybe it needs a kid in the carburetor?
"I" would open the carb up, and see what's plugging that passage. I've seen flecks of rust partially-plug a main jet; remove the carb top and fifteen seconds with a tweezer removes the "plug". Put the carb together and it runs great. Other times, there's crap in the passageway beyond the jet, and it takes real work to clean it out.
Sorry--no photos of the underside of the HEI where I trimmed it.
Dwell adjustment changes ignition timing. Ignition timing adjustment does not affect dwell. Anytime dwell is adjusted the ignition timing must be checked/adjusted. What is the dwell reading after gapping the points with the feeler gauge? Used points don't gap accurately with a feeler gauge due to contact surface pitting, it's better to use a known good meter especially on used points.
Last edited by Schurkey; March 29th, 2021 at 10:40 PM.
#8
#9
If you buy a MSD or Mallory Unilte, they will clear the O4B. Factory HEI wont clear without grinding intake and distributor. Pertronix makes an electronic module to eliminate points on the stock distributor
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Chris98Buffalo
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June 10th, 2017 08:00 AM