Author Topic: 74 GMC K25 engine swap.  (Read 4004 times)

Offline Nomar85

  • Newbie
  • Posts: 11
  • Newbie
74 GMC K25 engine swap.
« on: August 10, 2015, 10:52:02 am »
Ok, so over this past weekend I found out the the rings were shot in my newly aquired truck. Oil was dripping out of my header while the engine was running. I found a running 350 on craigslist for $175 bucks and went to pick it up. After getting the engine home and taking the heads off, I found out that it was recently rebuilt with TRW .040 forged pistons and it looks like it was balanced. I pulled the cam only to find a flattened lobe on one cylinder. So, I put in an Edelbrock perfomer plus cam and new lifters along with a gear drive timing set i had laying around. Reassembled the motor and I am now ready to paint and install the new ( to me) 357 SBC in the truck after work today. I cant wait to hear what the little beast is going to sound with my headets and flowmasters. Picks will be uploaded later.
74 K25 350/350 D44/14bolt

Offline enaberif

  • Junior Member
  • ***
  • Posts: 810
Re: 74 GMC K25 engine swap.
« Reply #1 on: August 10, 2015, 10:56:52 am »
The gear drive will probably annoy you after awhile.. and if that is a brand new cam I hope your going to break it in... as well as using proper zddp oil to prevent future wiped lobes.

Offline Nomar85

  • Newbie
  • Posts: 11
  • Newbie
Re: 74 GMC K25 engine swap.
« Reply #2 on: August 10, 2015, 12:00:56 pm »
Yes, It might get annoying but it figured why not. It is a (wuiet) version. I do have the break in lube and I know I have to start it and run it between 2000-2500rpm for 30 mins. Any other tips would be greatly appreciated. Ive built boat motors before just never a motor for the road.
74 K25 350/350 D44/14bolt

Offline LTZ C20

  • Senior Member
  • ****
  • Posts: 3795
  • "I'm here for a good time" -George Strait
Re: 74 GMC K25 engine swap.
« Reply #3 on: August 10, 2015, 01:40:40 pm »
Sounds like good fun. Pictures?
LTZ Cheyenne C20

Offline bd

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 6600
Re: 74 GMC K25 engine swap.
« Reply #4 on: August 10, 2015, 01:48:16 pm »
If you're using dual (inner/outer) valve springs on the heads, remove the inner springs during the initial break in period.  To be clear, in addition to coating the cam lobes with the special lubricant that shipped with the cam, run ZDDP enriched break-in oil, or add a bottle of ZDDP supplement to the engine oil during break in as enaberif recommended.

It does sound fun!
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Nomar85

  • Newbie
  • Posts: 11
  • Newbie
Re: 74 GMC K25 engine swap.
« Reply #5 on: August 10, 2015, 02:09:41 pm »
If you're using dual (inner/outer) valve springs on the heads, remove the inner springs during the initial break in period.  To be clear, in addition to coating the cam lobes with the special lubricant that shipped with the cam, run ZDDP enriched break-in oil, or add a bottle of ZDDP supplement to the engine oil during break in as enaberif recommended.

It does sound fun!

So only remove the inner springs during break in? After how many miles of driving would it be ok for me to put the inners back in? And thanks for the tip.
74 K25 350/350 D44/14bolt

Offline Nomar85

  • Newbie
  • Posts: 11
  • Newbie
Re: 74 GMC K25 engine swap.
« Reply #6 on: August 10, 2015, 02:11:16 pm »
Sounds like good fun. Pictures?

Its been a blast so far. And ill post sone pictures after work, my phone dorsnt like posting them.
74 K25 350/350 D44/14bolt

Offline bd

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 6600
Re: 74 GMC K25 engine swap.
« Reply #7 on: August 10, 2015, 04:44:19 pm »
So only remove the inner springs during break in? After how many miles of driving would it be ok for me to put the inners back in? And thanks for the tip.

To ensure we are on the same page, the inner springs to which I refer are actual wire springs that look like small versions of the outer springs, not flat damper springs.  Excessive lobe pressure during initial break-in will wipe the lobes off the camshaft and destroy the lifters, no matter what lubricant is used.  The idea behind removing the inner springs is to decrease lobe pressure to the minimum amount required to maintain zero lash in the valve train below 3,000 RPM.  Following the 30-minute break-in period, after the lifters have seated onto their lobes, the inner wire springs can be reinstalled.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Nomar85

  • Newbie
  • Posts: 11
  • Newbie
Re: 74 GMC K25 engine swap.
« Reply #8 on: August 13, 2015, 11:58:26 am »
So only remove the inner springs during break in? After how many miles of driving would it be ok for me to put the inners back in? And thanks for the tip.

To ensure we are on the same page, the inner springs to which I refer are actual wire springs that look like small versions of the outer springs, not flat damper springs.  Excessive lobe pressure during initial break-in will wipe the lobes off the camshaft and destroy the lifters, no matter what lubricant is used.  The idea behind removing the inner springs is to decrease lobe pressure to the minimum amount required to maintain zero lash in the valve train below 3,000 RPM.  Following the 30-minute break-in period, after the lifters have seated onto their lobes, the inner wire springs can be reinstalled.

ok, Thanks that would have been a lot of work for no reason. I have thew flat damper inner springs. So, I'm just going to paint her up and throw her in. Any recommendations?  On fuel, Should I run 91?
74 K25 350/350 D44/14bolt