I need the vacuum hose diagram for a 1978 chevy. el camino 350 eng. 4-barrel crb.

https://www.autozone.com/diy/repair-guides/gm-full-size-trucks-1970-1979-repair-guide-vacuum-diagrams-repair-guide-p-0996b43f80cb0d10

215 75 14 is the original size for a 1978 Chevy el camino Larry b

www.gmheritagecenter.com/docs/gm-heritage-archive/vehicle-information-kits/El-Camino/1983-Chevrolet-El-Camino.pdf

1979 chevy C1500
the vacuum setup varies,
by (california, Federal (USA) and export models)
where are you, or if in USA the under hood sticker shows if calif.or not.

if in usa, use the FSM (buy one used) or use alldata.com
on USA cars , (not sure starting year, this one is old) the vacuum
map is on the underside of the hood. (not not painted over,etc)

Wow, quite an undertaking. I had an '81 El Camino and wish I had never sold it. Originally it had a 267 c.i. V-8 with a Rochester 2bbl carb. I put in a Chevy 350 4-bolt main crate engine, Edelbrock intake and carb, and Hedmann headers (it ran like a scalded dog LOL). My advice is to look for a Haynes manual covering the '71 model year. They have complete wiring diagrams in their manuals, but the wire routing will be up to you. Good luck.

the parts store or the chevy dealer with a service center can print one out for you

Yes, the engine will swap fine, for the vacuum lines Go to Autozone.com, become member, will give you repair manual,location of parts,diagrams.

See if this is a match.

http://www.impalaforums.com/garage-image-3621-1255907788.jpg

OBVIOUSLY U HAVE FOUND THE DIAGRAM U NEED. TAKE IT TO A PRINT SHOP AND HAVE THEM ENLARGE THE DIAGRAM SO U CAN SEE IT.

Fig. Fig. 17: 1977 305 V8 engine-2bbl 49 states