No power under load

[James Fraschieri]

I'm doing a resto mod on a 63 deville and I want to use the stock drive train instead of an ls swap like everyone else would. The problem I'm running into right now is I have no power under load. When cold it revs fine and sounds good but when under a load and warmed it it falls on its face and won't get out of its own way. Timing was set with a light and carb was roughed in and is close (edelbrock 600cfm) so I'm running out of ideas. Broken vacuum advance? Weak fuel pump?

[Russ Austin]

The carb is running lean, bump it up 2 steps for cruise and power. 

[Dennis P. DiBari]

Hi James,

Russ makes a great point.  You might be running too lean - open the adjusters a bit.  You can also check your vacuum advance with the timing light attached; reattach the vacuum and see if it advances with the car running.  One last thing, how is  the transmission fluid?  Make sure it's clean and at correct level.  Hope this helps.

Dennis DiBari, Cottekill, NY

[Russ Austin]

The 2 adjusters are for idle only. You will need to swap out the metering rods and possibly the jets. Go to this link as it is the chart to adjust your 600 cfm carb.  The stock carb is at #1 in the middle.  You need to go rich so go to the right by 2 steps. Depending on the number, you will swap rods or jets.  Find the number and check below to see what is needed to be swapped. You can buy a rod & jet kit at the parts stores or on line. 

Now this is very important as you will burn a piston. I worked on a 64 that had a stock 750 cfm put on it by a shop.  It was at stock calibration and ran lean and burned the ring skirt off of 2 pistons.  The engine had to be rebuilt. 

[James Fraschieri]

I changed out the metering rods, re timed and re adjusted the carb and took the car down the road again. Things started out better but when I turned around about a mile down the road it was back to the same old problems. No power, wouldn't Rev up while in gear or in park. Gonna check compression just to rule it out but I'm starting to suspect it might be a transmission issue. Could it be?

[a5c0048011b941599a2e58cc24e9eb2f]

Have you replaced the fuel filter? That's always a good place to start.  

[Russ Austin]

Check the coil, it may be going bad. Also the condenser. 

[Jason Edge]

If it seems to be starving for fuel underload, you need to check your fuel lines from the tank to the carb. At the tank are rubber lines to the metal feed lines. They are notorious for dry rotting after 60 years, with age cracks that create a siphoning effect making it harder for the fuel pump to pull gas (sort of like sucking soda through a straw with a hole in it). Check all hose clamps, metal lines, then the rubber lines at the front feeding to fuel pump and filter vapor return line (if AC equipped). Check main fuel filter, but also check the inlet screen at the carb. Where the metal line attached to the carb, there is first an inlet screen. Anything that gets past a compromised fuel filter gets trapped here and can limit gas flow. Here is a picture of one below. Also, if you have a stock glass filter, the glass jar should  stay full once the car fires up. Most cars will hold the fuel up in the bowl for a few days. If it quickly leaks back down that can indicate a problem in the aforementioned areas.

PS. This picture might have been a good "What Is It" Trivia as many might not be aware of it!  You will become aware of if it gets clogged!!

[a5c0048011b941599a2e58cc24e9eb2f]

That's the culprit!  Jason's right in checking EVERYTHING that delivers fuel to the intake manifold.

It might be a slight fix here, a slight fix there, but it adds up.