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Help, just dropped in 5.7, major compression shortage

S

ShaggyTX

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Messages
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Location
Dallas Ft Worth
I think I have it down to compression issues now. After ecm, fuel, spark, prom, :mad2:...are working atleast for now. Its came close to
becoming a combustion issue solver!!!:rolleyes5::hihi:
Back ground: I have a 93 c2500 5.7, nv4500 spun a main.
the motor Im asking about, I cranked and ran, in a 93 gmc k3500 5.7, auto. Bought the truck, pulled motor. Put new timing chain, oil pump, new gaskets except heads. Its whooped me for the past month since then. I think I have all that taken care now but still couldnt get it crank. If i dont turn it over for a couple hrs, 1st time as long as i got the remote pressed, or key turned its so close. Almost there, its like it just needs a lil uummfth or something and would fire right up. It kind bubbles out the tail pipes, not pop or back fire. has full battery. then release the remote for a second or an hr it doeas nothing but turn over like theres no spark, but it does have it. So i did a compression check dry & wet.
firewall
70psi 8 7 65psi
60psi 6 5 70psi
70psi 4 3 65psi
60psi 2 1 60psi
front end
Any ideas, help, insight? I need it running like 3 weeks ago fast. Thx for ya'lls time and help.
 
timing chain is dead on, match the dots up like supposed to w/ old and new. I thought about the lifters but then one in all eight cylinders would have to collapse.

Whats the min psi needed to at least get cranked?

See i live in the city limits, city is a @$$. I'm not allowed to work on my truck in my drive way. i have 2, 1 in front of house, 1 on side that goes back for enough that right now it has my lwb ex cab, donor truck also lwb ex cab, 16' trailer, stillhave about 12' in between. So its not like its an eye sore for the neighbor hood. They ve already told me a month ago I need too have it towed to a shop to have a motor put back in when i had it out & truck still hasnt moved. So Ive been messing with it after 5pm, & expecting them to show up any time.
 
you said you checked both dry and wet , I assume by the numbers you posted that there was no diff between the 2 readings? If not that would point to valves not sealing. Check the alignment dowels between the gears (old and new) mebbe wrong part or mis machined
 
I'm guessing the cam timing too but double and triple check #1 TDC again and distributor (rotor) location for #1.
 
I hope you are looking for another place to live. Supporting Nazi homeowner associations are not worth the trouble.

I go with the above, distributor is out of time. As in you have it firing on the exhaust stroke instead of the compression stroke. That is what, 180 or 360 degrees out of time?
 
Compression should be around 140 psi. Did you adjust the valves ?
 
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