[yragat]

Anyone know what the total timing (with vac disconnected) should be on a Caddy 390 and at what rpm should it all be in by?
Thanks

[T-bucket23]

What year engine. Are you looking for base timing at idle?

[yragat]

Its a 1960 390 ci Cadillac----Want to know what total timing (with vac disconnected) should be and at what RPM it should all be in by

I know a sbc is usually good at around 38 degrees all in by 2500 rpm
But don't know what the Caddy likes

[T-bucket23]

I have a few old motor manuals, I will see if I can look it up tonight

[Frisco]

Originally Posted by yragat

Its a 1960 390 ci Cadillac----Want to know what total timing (with vac disconnected) should be and at what RPM it should all be in by

I know a sbc is usually good at around 38 degrees all in by 2500 rpm
But don't know what the Caddy likes

Most gas powered auto engines will perform best in the 32-38 degree total mechanical timing range with the vacuum advanced disconnected and plugged. The 'all-in' should also be in the 2500-3000 RPM range for street driven vehicles.

The idea is to use the highest degree of advance timing that you can without getting any detonation. This will yield the best overall performance. Keeping the 'all-in' RPM in the 2500-3000 range will also help the performance because you will normally be close to that RPM when cruising and should be in the peak horsepower and torque band for your engine.

A simple test to check for pinging is to drive at a steady speed (around 35 MPH) in high gear up a slight incline (a freeway overpass will work). If any pinging occurs, lower the timing 2 degrees and re-test. If no pinging occurs, increase the timing 2 degrees and re-test. What you are looking for is the timing set at the highest degrees with no pinging.

Some will suggest going to the dragstrip and adjusting the timing to yield the highest MPH going thru the final set of lights. This is great for a drag vehicle, but not so much for a normally street driven vehicle. You do not normally drive on the street at max RPM (which is closer to what you would be attempting on the strip).

[yragat]

Only problem is I have lakes style headers and even with baffles I can't really hear if the engine is pinging

[Frisco]

Originally Posted by yragat

Only problem is I have lakes style headers and even with baffles I can't really hear if the engine is pinging

Here are three links to the stock info that might help. Link one

Link two

Link three

The stock timing without the vacuum advance connected is 5 degrees BTDC. This should be able to be safely increased to at least 12 degrees BTDC for additional performance without any pinging.

Looking at the HP RPM values and the torque RPM values, I would still suggest the all-in between 2500-3000 RPM for the best street performance.

That engine (even in stock configuration) should be great for bottom end torque. Compression is high and will require a higher octane gas. ENJOY!!!

[yragat]

THANKS
Played with it today,put one light and one medium spring in the Dist. Set at 10* at idle and have 32 total in at 2500 rpm (without vac connected). Sounds pretty good,probably will fine tune in the spring. Not really roadster weather in W.Pa right now,although it was pretty nice out today.

I told my wife it looked so nice out that maybe I should leave it out all day LOL

Thanks again
Gary
Oh yeh---she does like premium fuel!!

[Custom10]

How much timing is the vacuum advance adding? what is the total total, just curious.

What is the car? big sled caddy or that sweet rod in the pic? all in by 2500 would be too much for a heavy caddy IMO but OK for that hotrod.

[yragat]

The vacuum adds 15
This is the car

[Frisco]

Originally Posted by yragat

The vacuum adds 15
This is the car

Great looking roadster!!!!

[Custom10]

Yeah that is very nice! What is on there for intake/carbs?

[yragat]

Offy intake Stromberg 97's---Only run the 2 in the middle-----For now

[Custom10]

Really nice, I think the carb stacks are facing the wrong way

[yragat]

Thats a matter of opinion----I remember reading somewhere that if you face them the other way it will mess with the air flow into the carb throats-- at high speeds it can cause the gas to swirl up out of the carb