A Road Draft Tube?
 

so i bought a 283 block and crank from a guy the other day(got a flame to my butt cuz i thought it would be cool for a future truck, or ratrod, now i realized ive clogged the garage and now its on craigslist), and was confused as to what the heck a black canister was doing in the lifter galley. he said it was a primitive pcv valve. someone want to explain to me whats so great about it? he said they are desired by people with old engines....i just figured it was just like a pcv valve, it just vented the internals....am i right?

Re: A Road Draft Tube?
 

Pretty much just venting, there were no vents in the valve covers. There was a "blow by" pipe that vented off the back of the eng that was connected to the valley canister thingy. in stead of feeding the vent gas back into the carb it just dumped the fumes. Primitive PCV pretty much sums it up, The valve covers look so much cooler with no vent holes in them ;)

Re: A Road Draft Tube?
 

:wop: Im interested to see what it looks like if its not too much trouble

Re: A Road Draft Tube?
 

This do it for you.

http://www.google.com/search?q=gm+28...w=1070&bih=674

Re: A Road Draft Tube?
 

The canister in the valley in plugged into a casting in older blocks that comes out between the dist and oil sensor, another pipe plugs into that hole and vents the fumage down the road. I had one on my '67 and a '64 Impala both 283's.

Re: A Road Draft Tube?
 

If you look at old pics of the highways in California, and see all the black streaks down the center of the lanes. It's the black oil slick left behind from road draft tubes. :)

Then when it rained... the roads were like a skating rink.

Gary

Re: A Road Draft Tube?
 

roaddraft tubes were better than undercoating

Re: A Road Draft Tube?
 

Ha ha!

Re: A Road Draft Tube?
 

Only the small-journal blocks (pre '68) have this provision.

Re: A Road Draft Tube?
 

Thanks for the pics :metal:

Re: A Road Draft Tube?
 

Yea its a oil separator for a road draft tube. Road draft tubes were bad about puking oil droplets along with crankcase fumes at highway speed.

Re: A Road Draft Tube?
 

Yes, the movement of the vehicle created a vacuum at the end of the draft tube to draw fumes out. Fresh air entered the engine through the oil fill "breather cap" at the front.

I can remember every parking space in every parking lot having a giant oil stain at the front end of it from dripping vehicles back in the 60's and 70's. These days, if you spill a quart of fluid somebody will call out the HAZMAT team.

Re: A Road Draft Tube?
 

Just an FYI:

I believe the road draft tube was ended after 1962. My 63 Impala is equipped with a pcv valve that goes into the back of the carb.

Just in case anyone wanted to know. :D

Re: A Road Draft Tube?
 

I'm pretty sure that the road draft tube continued until 1967 with the end of the small journal cranks. Some earlier ones may have been converted to PCV-maybe for California emissions-but now I'm reaching. I am pretty sure all small journal blocks at least have road draft provisions.

Re: A Road Draft Tube?
 

That may be. Here in CA, a lot of the emission laws were based on GVWR, so the "open" crankcase ventilation likely continued on trucks after cars went to closed PCV systems.

I had a '65 Chevelle that somebody had put a 327 truck engine in. (Solid lifters, long canister oil filter, etc.) It seems like it had the draft tube setup, but I could be mistaken as that was 30 years ago.

Re: A Road Draft Tube?
 

my block was a 68

Re: A Road Draft Tube?
 

Are you sure? Was it a warranty block? I thought that '67 was the last year for 283 and that in '68 it went to 307. I thought '67 was the last year for small journal cranks and that all '68 engines were large journal. Not that it matters, but that has been what I have always thought to be true.

Re: A Road Draft Tube?
 

mark your right. i confused dates. i stand corrected.