Idle problem on C15 261 CU IN

[Bob Carriere]

The Oaks Brothers..... now seem to be operating from the same location under the name....

Carburetor Rebuilders Company Limited
60 Eugene St
North York, ON M6B 3Z4, Canada

The Dad was in is 80 when I last saw him a few years ago.....

They now seem to be offering machine shop services for milling heads, manifolds, ect.

cheers

[TCLARK]

So far the fuel pump tests at 4 psi and holds so its good. The plugs are
AC R43S They all look nice and orange so there is not one misfiring.
Next I will warm up beast and test vacuum numbers 18 psi ??

[TCLARK]

So i set the plugs to 40 and reinstalled. I then hooked up a vac gauge
and got 18 inches at 1000 rpm but only 6 at idle. The minute I hooked up the vac gauge to the carb the idle seemed to smooth out. I put a different brASS
fitting into the carb for the vac line and hooked it up to the distributor..seems to idle nice. It had a slight bog when doing a gentle rev up from 500rpm to 1000rpm, so I retarded the timing and that got better.
The engine runs very nice now not really sure why as I still only have poor vac at idle. The vacuum did not change by adusting the timing??

[Bob Carriere]

Hi Terry

How steady is the reading at 18 inches........?

If she is steady but looses vacuum slowly as you lower the idling speed..... you may have a small air leak that is easily overcomed by more rpm..... now a small leak may be hard to find but an un-ignited propane torch or a spray can of ether should work.......

You say that moving the distributor by hand did not affect the vacuum reading?? It should make it stumble in either direction and you aim for a middle point..... then drive it ... if it pings or stumble it needs to be either retarded or advanced slightly...... I now use the vacuum gauge to set the timing.

Now the idle mixture screw ...... have you played with that yet......

How are you controlling the engine speed right now.... do you have a manual throttle cable installed yet????

Try setting the rpm at around 800 then go in and out no more than a full turn on the mixture screw and watch the vacuum gauge.... aim for the highest reading..... slow the rpm down a notch to 700 rpm using the idle screw on the bell crank and repeat the process.....

You may have to find and cure the leak before the final adjustments.

Don't quit now you are so close.....

.... at worst stay up late Xmas night and ask Santa for advice.

We did our home Xmas yesterday as we are travelling to the inlaws on Xmas eve on the far side of Toronto.... so already all turkeyed out.

All the Best for the NEW YEAR and a very Merry Xmas to finish 2016.

Bob C

[Lynn Eades]

The Pertronix requires resistance leads and the correct coil. If your leads are copper wire then your resistance plugs are probably important.
Have you checked for an air leak at the inlet manifold (at the head)?

[Bob Carriere]

Solid copper wire are mentioned in the Pertronix instruction as being potentially deadly to the module.

Some how, on looking at Terry's modern ignition wires, I suspect that they are the modern 8mm carbon fiber of today.

I was using a set of carbon wire from the 50s when I installed my Pertronix and had to upgrade to a 7mm modern black set up as I was getting shocks whenever I handled the old NOS wires......that Pertronix high voltage 40 thou coil sure puts out a hot spark. Once I regapped the plugs it ran noticeably better.

I lucked out years ago, when plugs were still cheap on Ebay, and acquired a lifetime supply of various NOS AC plugs in assorted heat range.... now they advertise the same plugs as fitting early Corvettes and increased the price accordingly.

[TCLARK]

Hi Bob
The vacuum reading was about 6 at 500 rpm. It went up to 18 at 1000 rpm.
The vacuum held steady at both rpms so that is good. I took it out for a run
and it ran so nice I m almost afraid to touch it. I set the idle jet to 1 3/4 turns
as per factory spec (Chiltons). I will go out and play with the idle screww at 800 and then at 700 and see if I can fine tune. This morn I barely touched the starter and she fired up instantly; never done that before. This is the pertronix and the big spark plug gap doing its thing. I may also get the ether out, some guys use acetylene as a final leak check

Hi Lynn
I did check the manifold and all looks good, I am using noncopper leads
from a hot rod shop they were expensive but leakproof as the wires are so close to the firewall . My coil is a Baster II 8802 I have it powered through the 12-8 volt resistor. I was wondering with pertronix if I need that resister
or maybe its a coil spec?

Thanks everybody for the help and excellent advice . Merry Christmas to all!!
Cheers Terry

[TCLARK]

Thaqt is a Blaster 8202 not 8802

[motto (RIP)]

Originally Posted by TCLARK

I have it powered through the 12-8 volt resistor. I was wondering with pertronix if I need that resister
or maybe its a coil spec?

Cheers Terry

The rationale behind the 8 volt coil as I understand it is that it only has 12 volts applied whilst the engine is cranking on the starter. They are normally used with a key ignition that has OFF, RUN & START positions. In the start position the resistor is bypassed, in the run position the coil only gets 8 volts. Applying 12 volts full time may do it no good at all.

David