Hello I’m new to the Cadillac world and have recently purchased a 1963 2 door coupe. The car was a project that wasn’t finished by last owner so I have slowly been getting it back together. The motor was rebuilt by previous owner with a hotter cam. I thought I had it tuned but tried to drive it and it severely lacked power. After checking everything I noticed the road tube was out of its hole on the intake. I tried putting it back and the grommet started cracking and falling apart. My question is do I need this? I read the 1406 installation posted on the site and the author stated he felt the 1406 ran better without PCV. What have you guys done?

Thank you

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The terminology Road tube is not something I understand 

Can you post a picture or describe the item in different terms or its location 


I think the correct term is road draft tube it sits under the intake and drops in a hole on the “valley cover.” If I understand correctly is used for PCV purposes. Sorry new to the site trying to figure out how to post pics.

Have you done a very complete tune up  on spec —-including new  ignition wires dist cap  rotor and ignition timing  

Ignition system would be my first check for lack of power— especially timing which is 5 degrees stock after the  new points are set at a dwell angle of 28-32 

Check the dist vac advance to see if it hold a vacuum



The tube runs from under the intake into the front of the carb with a PVC valve just before entering the carb 

That tube clears the crankcase of vaporized oil fumes and would recommend you keep it stock -  the crankcase ventilation system 

I would plug both ends — the intake valley and the carbs entrance until you replace the stock hose and PCV valve in that hose 

You have a major vacuum leak if the PVC line going into the car is open preventing the carb from drawing air over its ventuires and mixing air and gas  in the carb as it should  be doing 

That much of an air leak will cause the engine to run lean and hot in the cylinders showing a whiteish spark plug when plugs are inspected ( SB the color of a paper bag ) 

Clamp all vacuum lines going to the carb 

Very high performance race engines will often block off the PCV carb port but not a good idea in my own opinion on our year Cadillac engines ( they are not a high performance engine just because they have a big cubic inch displacement ) 

The engine is a  small block and not a big block configuration 


Don't plug the intake valley as the pressure build up (very quickly) will push out gaskets or vent from the oil filler making a mess along with any gasket replacement. Check the crank to cam timing. Just a tooth off can cause problems with power. Who ever installed the cam may not have done it correctly.


There will be no pressure build up in a 64 429  crankcase as the oil filler cap is vented for the crankcase ventilation to flow air thru the engine with the use of the PCV valve and carbs help 

I think the oil filler cap being vented is somewhat unique to our engines 

Not sure about the 390 cu in engine and if it has that same feature 


I should qualify that that would be for a sound engine with no ring blow by into the crankcase which would be a crankcase pressure build up condition that can blow oil out the oil filler cap and cause a mess 


Ok, thanks so much for the reply it’s a great help! To answer your question I did replace all plugs/wires/cap etc. I have the timing set to 15 degrees as that’s where it seems to run the smoothest. With the hotter cam I’m only getting about 8 of vacuum from the carb but could also be the vacuum leak. I don’t have a dwell meter just going off the fact it’s gapped right so I have a few things working against me. I will try and get my hands on a dwell meter. I’m not the greatest mechanic trying to learn as I go here.

Thanks again!

The dwell has to be  set right  first as it changes the timing number you are looking at 

You need to do the points first then the timing 

Putting White out on the harmonic balancer and the timing plate will help you see the marks clearly 

I choose to run 10 degrees on the stock 429 engine myself ( stock is 5 degrees ) 

Any higher than that you may have a problem with the engine pinging ( detonation ) in the cylinders cause very high heat situation that can cause damage 


Pls do not try to reset a set of worn points 

Install new points - set them at 30 degrees with the engine turning 480 RPMs in drive per the service manual 

Get a Service Manual if you do not have one - a very great tool to be understanding your cars needs and understanding all about her 


Ok I’ll get back to it, thank you

A question... When the previous owner rebuilt the engine was it ever fired? With a new cam, the engine has to be run at about 2000 - 2500 rpm for at least 15 minutes, and NOT allowed to idle during that time. This is essential for cam break in, otherwise lobe damage results. That would account for the lack of power. Check the valve lift on all of the valves.

I hope it is/was something simpler, like timing or dwell, but if it wasn't, you need to check this. My 64 Caddy had a bad cam, and this was the main symptom it exhibited. It pulled the car around OK, but it felt more like a Chevy 307 under the hood than a Cadillac 429.



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