No compression

Tiny
DGRIFFIN
  • MEMBER
  • 1969 GMC C1500
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 10,000 MILES
Engine free spends. Check compression none on cylinder one and low on others. Bought this truck from someone that rebuilt this engine put a small cam with roller rocks on 350 4 bolt main. Can't seem to get any compression no matter how I adjust the valves. Anybody have suggestions?
Tuesday, July 6th, 2021 AT 1:00 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi,

It sounds like the timing is wrong. Have you checked that? Do you know what year the engine is?

Either the timing is off or the valves are not closing. Since you have adjusted the valves, you should have noticed if they are not closing fully, so the next thing is to check timing.

If you look below, I attached a pic of the timing marks and how they should be aligned. I don't know for sure what year the engine is, but the 350ci has been consistent.

Check this and let me know what you find. Also, if you could record it cranking so I can hear it, that may help me.

Take care,

Joe

See pics below.
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Tuesday, July 6th, 2021 AT 7:56 PM
Tiny
DGRIFFIN
  • MEMBER
  • 2 POSTS
Thanks Joe, I will check that next. I bought this engine already put together never know what some else does. I will let you know. Thanks.
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Wednesday, July 7th, 2021 AT 5:08 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Hi,

You are very welcome. If you have a chance, let me know. I'm interested in knowing if that is the issue.

Take care,

Joe
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Wednesday, July 7th, 2021 AT 7:44 PM

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