Hey guys!

After 3 years of wishful thinking I've finally replaced my 305 with a vortec headed 350! The problem is it cranks but won't start. I went ahead and did a cold compression check and found that the #1 cylinder has no compression at all. I followed up with a squirt of oil to confirm it's not the rings.

Now, the vortec heads are used off a '98 Tahoe and I figured I could get away without rebuilding them... but I guess not. So before I take them off is there any chance that a bad valve seal or weak spring could cause a "no compression" situation or is it more likely a burnt valve/ bad seat?

BTW I did doulbe check the valve lash and the head gasket is brand spanking new (comp type).

Thanks!

 

none at all..holy cow, are you sure..NONE

 

whats a cold compression check?

 

Yep. There's no compression at all in #1. By "cold" I mean the engine is cold... I'll do a hot one once I get it running.

 

Try backing off your vavle lash completely. I mean real loose so the rocker doesnt even accuate the valve at all. Do your compression test again and see if you got compression. My guess is the lash is too tight and you actually have the valve open. If you still aint got compression, then looks like you have a head gasket leak or an issue with the heads of some sort

 

Sounds like a valve is hung open. You didn't have them rebuilt? Is there a chance that one of the valves is bent/burnt and not seating fully? That could bleed off the compression, either that or you forgot a spark plug just kidding.

 

Well, I pulled off the head and removed the #1 intake and exhaust valves. Turns out there was a pile of carbon caked on the intake seat and valve! It was just a small section in the area right beside the exhaust valve.

I'm happy to say it cleaned up nice with some steel wool and as far as my unprofessional eye could tell the seat and valve look just fine. So, I threw the head back on, set the lash, and tried another compression check... oh yeah, I gots me some compression in #1!!!

I still have to finish putting everything back on and hopefully tomorrow she'll fire up. (knocking on wooden computer desk!)

Ted

 

I got it running!!! I did have to jump it since the battery was a little run down but it's smooth and sounds awesome - a little louder than the 305. I can't wait to take it for a burn, but I guess I should put the hood on first!

Here's a pic of the problem... anyone know why it would have built up there?