High Revving When the Car is Warm

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Kim Reeves
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High Revving When the Car is Warm

#1 Post by Kim Reeves »

Hello Again. I do have 2-3 more questions and will keep them separated.
So, when i start the car, it idles at 750RPM. When it warms up after 2 miles or so, she races up to 1500+RPM. When she comes home and is left a while, she will calm down to 800-1000RPM. I have tried tapping the accelerator and applied the clutch to force her to calm down, but she does come back racing.
This started happening last year after the mechanic had it but he said no adjustments to carbs were made...hmm. I will say the fuel pump is leaking at the front housing cap. See pic. I have ordered new distributor springs, fuel pump gasket kit and will try unclipping the linkage whilst its racing. But are there any other ideas?
Thank you again.
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John Brooks
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Re: High Revving When the Car is Warm

#2 Post by John Brooks »

Put a timing light on it, probably when it heats up, the distributor advance is not returning to idle timing. The addition advance timing is causing the RPM increase. Check it cold, then let it run and warm up, or after the next drive check it while hot. If the idle timing is not return to normal, pop the cap and advance it by hand CW then release it, it should spring back with no additional rotation CCW. If there is some CCW play look for something rubbing.

Some times the points screw is a little long, and touch the balance weights keeping it from completely regarding to idle. A little light oil on the felt under the rotor may also help everything loose. You can see the weights move when you turn the rotor.
John Brooks

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Kim Reeves
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Re: High Revving When the Car is Warm

#3 Post by Kim Reeves »

Thank you John! Will try, hopefully, this weekend!
Shelter Island, NY
1964 356SC Coupe

Kim Reeves
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Re: High Revving When the Car is Warm

#4 Post by Kim Reeves »

Hi, John. So i checked the static timing and it was right where it says factory. But a lot of forums say 5 degrees after - which i adjusted. Car still runs with high revs. When you say advance it by hand, are you talking about the rotor? I tried and can move that CW and it returns - i was able to move it say 10 degrees before it does not let you. Also checked to see if the points are hitting the screw - and they don't. Anything else i can try? The distributor under the points area, does look rather brown and dry.
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Mike Wilson
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Re: High Revving When the Car is Warm

#5 Post by Mike Wilson »

It has been suggested by several of the experts in our community that the best place to start is a full tune up. I agree.

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Re: High Revving When the Car is Warm

#6 Post by David Jones »

Correct static timing is 5 degrees before top dead center. Correct max advance is 35 +/- 2 degrees at 3k rpm. Depending on condition of distributor they may not coincide. Pop the carb links off and see if that helps. There should always be a little slop in both carb links with a hot engine.
If I had known I would live this long I would have pushed the envelope a little harder.
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C J Murray
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Re: High Revving When the Car is Warm

#7 Post by C J Murray »

Weak dist springs and/or dist needs cleaning and lube.
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Re: High Revving When the Car is Warm

#8 Post by Jay Darlington »

Posible air leak at the manifold head area, opens up when it gets hot ?
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Re: High Revving When the Car is Warm

#9 Post by Wes Bender »

More than likely that leaks there would close up rather than open as it heats Jay. Aluminum expands more than the steel studs would.
Some days it's just not worth chewing through the restraints.....

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Re: High Revving When the Car is Warm

#10 Post by Kim Reeves »

OK - i checked the manifolds as the carbs were overhauled 3 years ago and there were some loose (ish) nuts that have now been tightened (not to much) - you never know!
Back to the springs - is there a good step by step guide for how to replace them. Hope it does not require me to take out the distributor. I have the points plate out so i can see them and they work but look very original and it does look a little grimmy in there.
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Re: High Revving When the Car is Warm

#11 Post by C J Murray »

Some of the new springs are too long. Make sure the new ones hold the cam securely in the idle position. To clean and replace the springs use a tiny probe screwdriver or whatever to remove the visible end from the post that it is on. Then the cam will slide up and off and you can clean and lube. Do not get aggressive with the spring tabs on the cam when you spread them to remove install the springs. They can snap. Before you put the points plate back on confirm that the springs will pull the cam to idle securely, no free movement before the spring pulls against the movement.
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Re: High Revving When the Car is Warm

#12 Post by John Brooks »

Kim

after its cleaned up. Put the timing light on it check the idle 5 deg, then when hot rev it to 2500-3000 watch the mark on the pulley advance and then drop it to idle and see if it is returning to 5 Deg, I have seen a few that will retard at idle but stop at 10-12 degrees when hot. That advance in the timing is giving you the extra Idle RPM. but as you rev it the mark will move to the left and shout hit the max advance, There is a measurement in inches around the outer diameter of the pulley for the 35 degree max advance I just cant remember what it is. But returning to 5 Deg at Idle after revving it up is the thing to check.
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Re: High Revving When the Car is Warm

#13 Post by Kim Reeves »

Ok. Took the springs off the posts. But the cam does not slide off. I don’t want to force it. Any suggestions. Took a pic if anything looks out of line Again so appreciate this.
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Re: High Revving When the Car is Warm

#14 Post by C J Murray »

It should lift off. Remove the felt in the center of the cam and spray the hole full of your favorite spray such as Blaster or WD40. It is easier to work on it removed from the engine. If you remove the 13mm hex nut the clamp will stay attached to the distributor and your timing will be close to where it had been. Let the Blaster soak in and wiggle the cam relative to the drive end until it frees up. Give it time to soak in.
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Re: High Revving When the Car is Warm

#15 Post by Mike Wilson »

It looks like it could definitely use a good cleaning.

Mike
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