Any way to simplify the vacuum lines under the hood...

[Todd55]

I am helping my buddy rebuild his 84 SWB truck and alot of the vacuum lines have been removed by the previous owner.He replaced the core support so it has a diagram from an 82 which may or may not be the same....It is running the stock Rochester carb and a 305 w/EGR. Which lines are required to make the engine run correctly? Can some of the extra ports on the carb just be capped off? The truck will be inspected in a non smog county so the smog stuff may get removed but he would like to get the motor running well before we put to much time into it.

I know this is a lot of stuff for one post but I am not sure what "needs" to be there to make it run well.

Thanks in advance,
Todd

[stan79chevy]

i have caps on most of my ports on my carb. i think the brakes are the only thing that is hooked to mine. transmission to i think? for the kickdown or something.

[79BIG10]

He might watch it being in a non-smog county as DFW is getting worse and worse on smog tests. I used to live down there and luckily passed but I went to a place that they were really easy to pass other than the sniffer test which you can't "fix".

On the hoses I eliminated alot of mine. First I had the EGR already blocked off from the engine swap. Next I changed the thermostat housing out for a aluminum one without the "tree" hose hook up. I now only have the PCV valve hose, hose to the HEI, and the brake booster hooked up on the carb. I have a T behind that on the intake itself for the heater vacuum line and tranny (automatic).

[Todd55]

Will the the carb functioning properly if I cap off all of the unused ports on the carb? He has already purchased a new thermostat housing with out the TVS holes so that may be the route we go. As far as inpection it will be 1.5 hours out of Dallas in east Texas so it is not a smog county at all.

[SSC's76]

You only need a max of 4 lines. Assuming you have a tq converter switch (that works) on the firewall full manifold vacuum from the reat manifold tree, a ported source on the carb for vacuum advance, the full manifold source on the back of the carb for power brakes and the rear manifold tree on the back intake for the TH350 trans. This will allow the truck to operate properly. Since you friend eleminated the temp switch on the Tstat housing which is hooked into the EGR system you can T the ported carb source for vacuum advance and run the T to the EGR. Most EGR passages are too plugged up to work anymore.

EDIT: One more vacuum line for the PCV valve but thats usually a given.

[piecesparts]

Run a larger vacuum line to a spot on the firewall and then branch them out to what you need (heater controls, tranny, cruise control, and brakes). That way you can clean up the motor. I have an 84 and the tranny is now a 700 R4, so it doesn't need a vacuum line, the distributor has one line from the carb, the brakes are connected to the back of the carb and the other stuff is fed from a tap to the firewall and then it branches off of that point. The PCV is fed to the front of the carb, also.

[87 STEPPER]

Auto zone has the diagrams on line if you go to

www.autozone.com

Then on the left side click Repair Info then click Vehicle repair guides also on left side then cilck on Driveability & emissions controls in the center of the page then click on Vaccum diagrams at the bottom on the right side.

Then scroll about half way down and you'll see '84 305 auto and manual trans.
im not shure how you will determin what diagram will be effictive for that truck.

I tired to link to it but it didn't work sorry.

hope this helps

Good luck

[Todd55]

Those diagrams are great.....The truck has a 4 speed manual so the tranny stuff is not important. Thanks for all the help guys.