Author Topic: 1986 305 to 350 Vortec Swap  (Read 3726 times)

Offline Jeff86inMS

  • Newbie
  • Posts: 44
  • Newbie
1986 305 to 350 Vortec Swap
« on: January 14, 2019, 02:51:28 PM »
Hello all,
I have a 1986 C10 stepside custom deluxe that originally came with a 305 V8.  I'm getting ready to swap it for a 350 Vortec V8 with Carb.  My question is, will the exhaust manifolds from the 305 swap over to the 350 Vortec?  I know the intake manifold is different.  Need to know about the exhaust ones though.  Thanks!

Jeff

Offline VileZambonie

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 19114
Re: 1986 305 to 350 Vortec Swap
« Reply #1 on: January 14, 2019, 04:40:32 PM »
Yes but why not run headers? Exhaust manifolds will choke that thing right out
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Jeff86inMS

  • Newbie
  • Posts: 44
  • Newbie
Re: 1986 305 to 350 Vortec Swap
« Reply #2 on: January 14, 2019, 05:04:39 PM »
I will probably run headers later on, but trying to just stick to the items I have to have to get it installed.


Sent from my iPhone using Tapatalk

Offline Ronno6

  • Frequent Member
  • **
  • Posts: 290
  • Elder Student
Re: 1986 305 to 350 Vortec Swap
« Reply #3 on: January 14, 2019, 10:24:52 PM »
Exhaust manifolds should oughta bolt right up.
You can lead a man to water, but yoiu can't keep him from pissing in it.

Online JohnnyPopper

  • Senior Member
  • ****
  • Posts: 2662
  • Old Goof
Re: 1986 305 to 350 Vortec Swap
« Reply #4 on: January 15, 2019, 12:46:27 PM »
Unless you need a manifold spreader tool.

I just had my 350 swapped out, and the mechanic showed me a tool to spread the the outer manifold ports away from the center ports.

Wish I had known about them the last time I changed the manifold gaskets, would have been a lot less &&%$#(!!!@#^%$#!!????!!
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline zieg85

  • Global Moderator
  • Senior Member
  • ****
  • Posts: 7567
    • 73-87 GM squarebody extended cab and conversions up to 91 R/V series
Re: 1986 305 to 350 Vortec Swap
« Reply #5 on: January 15, 2019, 12:57:23 PM »
The only caution would be the dipstick location clearing the manifolds. 
Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
https://www.facebook.com/groups/248658382003506/

Offline 75gmck25

  • Frequent Member
  • **
  • Posts: 439
  • 1975 GMC K25 Camper Special, 350/TH350/NP203
Re: 1986 305 to 350 Vortec Swap
« Reply #6 on: January 16, 2019, 09:10:21 PM »
I had to use a manifold spreader tool to get one of the manifolds back on my new heads, so I actually read the directions.  It worked very well.  They recommended also using the tool before you remove the manifolds so that you can remove sideways pressure and get the bolts to come out without binding.   The only local parts store that had the tool on hand was NAPA, but lots of places sold them online for $11-12.

Bruce
« Last Edit: January 16, 2019, 09:12:19 PM by 75gmck25 »

Online JohnnyPopper

  • Senior Member
  • ****
  • Posts: 2662
  • Old Goof
Re: 1986 305 to 350 Vortec Swap
« Reply #7 on: January 17, 2019, 06:26:25 PM »
It's the little things...
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline fitz

  • Senior Member
  • ****
  • Posts: 2085
Re: 1986 305 to 350 Vortec Swap
« Reply #8 on: January 17, 2019, 06:52:55 PM »
It's the little things...

1 more thing to look into is the distributor gear. You might need a different gear with the roller cam.