58 Poor Acceleration
Thread Starter
Intermediate
Joined: Mar 2009
Posts: 28
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From: Aguadilla PR
58 Poor Acceleration
I have been troubleshooting a 58 270hp trying to fix a poor acceleration problem. Originally thought to be the carbs so these got rebuilt. Then the spakplug cables were replaced. Then moved onto ignition and replaced a suspect pretronix II module, went back to the old dual points (891 distributor). Up to this point the acceleration improved a little in the part-throttle range but if you hit it to the floor the car just doesn't go! Checked timing and initial timing is as far as it can be and still be able to start the engine. Still doesn't go. The other suspect is the ignition coil. It does get hot (160F after 20 min and then I shut it down worried about frying it). I switched to another coil but it also gets hot, about the same as the other one. Both coils hace a primary resistance in the 2 ohm range, secondary 7.5-10 Kohm range. I tried bypassing the ballast resistor (0.8 ohm) but still gets hot. The sparkplugs show black as if the mixture was rich. The engine idles well and seem to rev well. Any ideas worth trying or experience with a similar situation?
Le Mans Master
Joined: Feb 2001
Posts: 8,017
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From: The problem is all inside your head she said to me.
283? Does it rev up to say 5700-6k? What are you used to? I've never ridden in a 270 hp 283 but my fathers 327/300 is slow if you ask me but that's just my opinion. I drove his car to a 14.5 1/4 mile with 3.55 gears. What rear end ratio do you have. Is there anyone around with a similar build to compare it to?
Team Owner
Joined: Aug 2007
Posts: 58,061
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Army
An original 270hp doesn't have vacuum advance...dual point all mechanical distributor instead.
Not enough symptoms. Is it missing at idle, "breaking down" on acceleration, "bogging" or just plain lacks oomph ? I have the same motor and it won't nail you back in the seat at full throttle but it should move straight up through the RPM range pretty darn quick and pull out strong.
Check fuel filter; check passenger side exhaust heat riser valve is not stuck shut, check for blocked or crushed exhaust pipes. Make sure your accelerator linkage isn't sloppy (I've seen cases where the second 4-bbl would never cut in). Check timing and make sure distributor is not loose and the mechanical advance weights are moving OK. If all else fails take a compression check...maybe the old girl is just tired and needs freshened up internally.
Make sure your clutch isn't slipping.
Ignition coils do get pretty warm but usually they crap out all together or cause misfires.
Finally, I've had more than one batch of bad gas (water in the gas) cause similar problems years back...
Not enough symptoms. Is it missing at idle, "breaking down" on acceleration, "bogging" or just plain lacks oomph ? I have the same motor and it won't nail you back in the seat at full throttle but it should move straight up through the RPM range pretty darn quick and pull out strong.
Check fuel filter; check passenger side exhaust heat riser valve is not stuck shut, check for blocked or crushed exhaust pipes. Make sure your accelerator linkage isn't sloppy (I've seen cases where the second 4-bbl would never cut in). Check timing and make sure distributor is not loose and the mechanical advance weights are moving OK. If all else fails take a compression check...maybe the old girl is just tired and needs freshened up internally.
Make sure your clutch isn't slipping.
Ignition coils do get pretty warm but usually they crap out all together or cause misfires.
Finally, I've had more than one batch of bad gas (water in the gas) cause similar problems years back...
Last edited by Frankie the Fink; Sep 19, 2011 at 04:23 PM.
Thread Starter
Intermediate
Joined: Mar 2009
Posts: 28
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From: Aguadilla PR
It sure is a 283, recently rebuilt, 4.10 rear, original T10 trany. It doesn't backfires but slowly accelerates but never seems to go... It simply lacks the kick you would expect when you floor it! I will look into the fuel filter and the exhaust heat riser, this is a good one I didnt look into. Mechanical advance moves freely and I can see it working with the timing light hooked up. At idle it doesn't miss, spark looks strong and uniform( looking at it by unplugging one cable at a time at the distributor) that is something that was a problem before with the pertonix module installed where two cylinders were not getting a good spark.
Good suggestions guys! I will look into them in the next few days. I remember earlier days when this old car did his pull when you floor it, but I will agree nothing like my 67 L71 or my 69 Z28 !!!
Good suggestions guys! I will look into them in the next few days. I remember earlier days when this old car did his pull when you floor it, but I will agree nothing like my 67 L71 or my 69 Z28 !!!
Team Owner
Joined: Aug 2007
Posts: 58,061
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Army
I have a 3.70 rear and I can spin tires on demand...with the rear you have that car should have a quick "hole shot" for sure. Definitely something wrong somewhere...
I was ignoring carbs since you said they were rebuilt but it might be worth it to take the little front covers off the carbs if they are WCFBs and, with the car running, make sure:
1) the metering rod hanger moves up and down nicely when you blip the throttle and the rods are attached properly, and,
2) the small arm that actuates the WCFB's equivalent of an accelerator pump is tight and properly adjusted and gives you a nice squirt in the primaries when blipped.
I've seen either of these cause poor performance -- a real quick check and then you can eliminate that area.
I was ignoring carbs since you said they were rebuilt but it might be worth it to take the little front covers off the carbs if they are WCFBs and, with the car running, make sure:
1) the metering rod hanger moves up and down nicely when you blip the throttle and the rods are attached properly, and,
2) the small arm that actuates the WCFB's equivalent of an accelerator pump is tight and properly adjusted and gives you a nice squirt in the primaries when blipped.
I've seen either of these cause poor performance -- a real quick check and then you can eliminate that area.
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Burning Brakes
Joined: Mar 2004
Posts: 1,006
Likes: 163
From: Grand Harbor in South Carolina
Also check your rotor in distributor. If you are using a repo of just a few years back , the tip is 1/8 inch too short. Replace this (as I did) and my performance improved noticeably.
Thread Starter
Intermediate
Joined: Mar 2009
Posts: 28
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From: Aguadilla PR
Checked WCFB carbs: the squirter shot of rear carb is much better, meaning longer and uniform, after I followed your suggestion to check into this. I adjusted the linkage/lever as it was a bit out of adjustment (per the book). Before it was very short squirt with just a few drops. This did make a difference. The metering rod mechanism is working nice on both carbs, The squirter on the front carb looks good. Tried also the hot wire to ignition (+) but did not make a difference. Checked the exhaust riser valve but it's wide open, I forgot I intentionally welded in the open position from the inside of the valve during the last rebuild. So overall a little bit better but now onto the compression test and the rotor. What should the rotor/ignition post clearance be? or otherwise the rotor length (center to tip)?
