Low power

All Models and Years
Post Reply
topless65
Posts: 5
Joined: Sat Aug 09, 2014 6:05 pm

Low power

Unread post by topless65 » Wed Sep 13, 2017 3:05 am

I can get my 66 Monza 140 4spd to start right up, idles good. When pressing the gas the motor revs up good. The choke coils work and I think i did ok on carb syncing. Timing seems to be on point. Pertronix 2 and flame thrower 2 are good. Here's the problem. When I go to take off the car barely moves unless I am at almost full throttle. Car makes no power until further up the rpm range. It feels like you are starting in 2nd gear. Problem is also present in reverse. Car doesn't make enough power to drive it up onto car ramps. Secondary carbs do not have the linkages to them installed. Any thoughts as to where to start looking. Thanks in advance.

Sent from my SM-G955U using Corvair Forum mobile app


Wagon Master
Posts: 188
Joined: Thu Jul 28, 2011 6:36 pm

Re: Low power

Unread post by Wagon Master » Wed Sep 13, 2017 7:09 am

1. Not enough initial ignition timing.
2. Vacuum advance on side of distributor is not functioning.
3. Disconnected secondaries are not completely closed causing a vacuum leak.

User avatar
bbodie52
Corvair of the Month
Corvair of the Month
Posts: 7272
Joined: Mon Aug 06, 2012 12:33 pm
Location: Lake Chatuge Hayesville, NC
Contact:

Re: Low power

Unread post by bbodie52 » Wed Sep 13, 2017 7:38 am

:think:

Here are a few things that I would suggest checking…
topless65 wrote:...Car makes no power until further up the rpm range. It feels like you are starting in 2nd gear. Problem is also present in reverse...
TIMING ADVANCE

Did you check to verify that the vacuum advance mechanism appears to be functioning? The centrifugal advance does not come into play on the 140 hp engine until the rpm reaches 2800 RPM or more. If the vacuum advance is not functioning, it's potential of adding up to 22° of ignition timing will not be available to the engine at lower engine speeds. You should be able to see the vacuum advance mechanism physically move the breaker plate on the distributor as you begin to rev the engine.

Image

There have been some instances where the distributor had been dismantled and reassembled with the centrifugal advance mechanism flipped upside down — creating a centrifugal retard mechanism. You can verify the action of the centrifugal advance by disconnecting the vacuum advance hose and plugging it. Then observe the timing mark using a timing light and increase the engine speed. You should be able to observe the timing mark moving correctly to add more advance to the ignition timing as the engine RPM increases. I accidentally created a centrifugal retard when I overhauled my first distributor back around 1970. The engine seemed to run fine at idle, but when I test drove the car it felt like I was throwing out an anchor as engine speed increased and power disappeared. Higher engine RPM just made things worse! When I rechecked the ignition timing with a timing light, the base setting was correct. But when I reved the engine I noticed that the timing mark went in the wrong direction! That was when I discovered that it was possible to reinstall the centrifugal advance weights upside down — creating a centrifugal retard mechanism.

Image
topless65 wrote:...Pertronix 2 and flame thrower 2 are good...
You should confirm that the Pertronix components have been properly installed, and that the source voltage and supplies the high output Pertronix Flame-Thrower II coil and the Pertronix Ignitor II electronic ignition module is a full 12 V DC. This means that the ballast resistor wire (labeled 20 W/R/B in the wiring schematic below) should have been bypassed when the Pertronix upgrade system was installed. If it was not bypassed than the source voltage feeding the coil and electronic ignition system may only be a nominal 7 V DC. Keeping the ballast resistor wire in the circuit cancels much of the advantage of the high output coil and can introduce a malfunctioning electronic module in the distributor by providing it with an inadequate source voltage.

Image

Image

Also, I would recommend that you carefully check your system to ensure that there are no vacuum leaks that could be introducing a very lean fuel/air mixture that could rob your engine of power.

Image
Brad Bodie
Lake Chatuge, North Carolina
Image

64powerglide
Posts: 1199
Joined: Tue Mar 25, 2014 9:18 pm
Location: Kalamazoo Mi..

Re: Low power

Unread post by 64powerglide » Wed Sep 13, 2017 8:29 pm

What do you mean by "timing seems to be on point"????????? What does your timing light say???
64Powerglide, Jeff Phillips

Kalamazoo, Mi..

topless65
Posts: 5
Joined: Sat Aug 09, 2014 6:05 pm

Re: Low power

Unread post by topless65 » Wed Sep 13, 2017 9:23 pm

Thanks. This is the info I need to start with. I have an old timing light that isn't adjustable. I estimate base idle to be about 16*. Distributor is adjusted to where engine runs smoothest at idle. The marks on the balancer look like they are lined up. I'll do an actual TDC check and compare. This is the first carb car I've actually messed with. I need to go back to school. I'm used to fuel injection. I'll check over all this hopefully this weekend and get back with results. Thank you again.

Sent from my SM-G955U using Corvair Forum mobile app


Post Reply

Return to “Ask your Mechanical Questions here”