SPONSORED LINKS

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?
SPONSORED LINKS
Tuesday, July 6th, 2021 AT 1:00 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 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.
Images (Click to make bigger)
Thumb
Thumb
SPONSORED LINKS
Was this
answer
helpful?
Yes
No
+1
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.
Was this
answer
helpful?
Yes
No
Wednesday, July 7th, 2021 AT 5:08 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 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
Was this
answer
helpful?
Yes
No
Wednesday, July 7th, 2021 AT 7:44 PM

Please login or register to post a reply.

Related Engine Compression Content

Engine Compression Test
VIDEO
Engine Compression Test
Instructional repair video
Compression Test
GUIDE
Compression Test
A compression test is a valuable diagnostic procedure that helps determine the health of an engine by measuring the pressure generated in each cylinder. The following is a...
VIEW MORE

Sponsored links