Homing in on the problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

shuttermutt · 11-27-2003, 02:41 AM

The background story...

Tonight I finally got a compression gauge that works and ran the test. The result? The "happy" cylinders ran between 100 and 130 PSI. The "unhappy" cylinders (numbers 1 and 8) spiked the gauge, but fell immediately back to zero.

Ugh! Can you say "stuck valve" kids? Great! I knew you could!

Funny thing is that I had the valve cover off the driver's side and, with the engine running, I didn't notice anything unusual. You'd think I would have caught that, wouldn't you? Pretty strange stuff.

In reality, "stuck valve" is pretty generic and could be a bit misleading. I might have dropped a seat, got some carbon jammed in there, bent/jammed a pushrod, or burned a valve. Guess I won't really know until I pull the head(s) and have a look-see.

**old Rusty C10** · 11-27-2003, 07:11 PM

welll with the long weekend and hopefully good weather you can get it ripped down to see what happened

Hooter · 11-27-2003, 07:56 PM

well the only way you are going to know is to rip the thing apart, good luck, and with the sound of your compression ranging from 100-130 seems like it wouldn't hurt to rebuild the whole thing

shuttermutt · 11-27-2003, 11:19 PM

Well, I can live with the varied compression, frankly. At least until I can find a good 327, 350, or 400 small block core to rebuild. I ran the numbers on the block that's in there and it turns out someone has swapped in a 307 for the 327. Funny thing is, the 307 is correct for that year. Coincidence? Dunno!

Others have mentioned it and it's starting to make sense... maybe I did jump a tooth in the timing. I've been thinking about it, you see. I've got zero compression on 1 and 8. Not that it's completely out of the question, but it does seem a little strange that I'd lose two cylinders, one on each side of the engine, at the same time.

Anybody remember the shade tree method for confirming that the cam agrees with the crank? I remember that you're supposed to bring #1 up on TDC and then move the crank and watch for another valve to just start moving. If I remember, it's #5 that will start to do it's thing if everything is in order. Anyone?

11-27-2003, 07:11 PM	#2
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,283	welll with the long weekend and hopefully good weather you can get it ripped down to see what happened __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

11-27-2003, 07:56 PM	#3
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,085	well the only way you are going to know is to rip the thing apart, good luck, and with the sound of your compression ranging from 100-130 seems like it wouldn't hurt to rebuild the whole thing __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life

11-27-2003, 11:19 PM	#4
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Well, I can live with the varied compression, frankly. At least until I can find a good 327, 350, or 400 small block core to rebuild. I ran the numbers on the block that's in there and it turns out someone has swapped in a 307 for the 327. Funny thing is, the 307 is correct for that year. Coincidence? Dunno! Others have mentioned it and it's starting to make sense... maybe I did jump a tooth in the timing. I've been thinking about it, you see. I've got zero compression on 1 and 8. Not that it's completely out of the question, but it does seem a little strange that I'd lose two cylinders, one on each side of the engine, at the same time. Anybody remember the shade tree method for confirming that the cam agrees with the crank? I remember that you're supposed to bring #1 up on TDC and then move the crank and watch for another valve to just start moving. If I remember, it's #5 that will start to do it's thing if everything is in order. Anyone? __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list

11-27-2003, 02:41 AM	#1
shuttermutt Don't say "Oops!", Doctor Join Date: Nov 2003 Location: Houston, TX Posts: 677	Homing in on the problem The background story... Tonight I finally got a compression gauge that works and ran the test. The result? The "happy" cylinders ran between 100 and 130 PSI. The "unhappy" cylinders (numbers 1 and 8) spiked the gauge, but fell immediately back to zero. Ugh! Can you say "stuck valve" kids? Great! I knew you could! Funny thing is that I had the valve cover off the driver's side and, with the engine running, I didn't notice anything unusual. You'd think I would have caught that, wouldn't you? Pretty strange stuff. In reality, "stuck valve" is pretty generic and could be a bit misleading. I might have dropped a seat, got some carbon jammed in there, bent/jammed a pushrod, or burned a valve. Guess I won't really know until I pull the head(s) and have a look-see. __________________ 'Mutt 1968 CST LWB: R.I.P. 1967 Chevelle: TPI 454 beast 1967 C10 SWB: Claimed when Bumpster didn't put it on his list



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