Good evening fella's, I've been in the garage with Lucy all day (my '67 GS400), and a compression test revealed no compression in the #4 and #6 cylinders... so here's a little background. I had a restoration shop re-wire the car with a harness from Todd (Lectric Limited) and replace the distributor with a brand new unit with a Lectric conversion. However, when I picked the car up, she was down on power. I've driven over 500 miles in the past week since getting her back and have been noticing a decline in power, and increase in backfiring. I advanced the timing (stupidly) by ear a couple of days ago and was happy to feel a big improvement in throttle response. But no changes otherwise. However I started to develop a blue smoke at idle. So today, I put on a digital timing light, and a vacuum gauge to get the ignition timing and fuel mixture dialed back in (15* initial // 32* total). I used ported vacuum and have not changed the springs that came in the new distributor. However, while timing it, I had a LOT of blue-ish smoke out of the passenger tailpipe. A compression test then revealed the following: #1 - 138 #2 - 178 #3 - 130 #4 - 5 #5 - 120 #6 - 0 #7 - 134 #8 - 135 You can see that 4 & 6 have got an issue. There is also oil staining on the header flange at cylinder 6, and both of those spark plugs had a lot of oil on them. The test was conducted with all 8 spark plugs removed, a rented vacuum gauge (EverTough) that was brand new, Wide-Open throttle, and approximately 5 seconds of cranking per cylinder. -A wet test bumped my Cyl #4 compression up to 18. I guess I'm just looking to share my information with everyone and hopefully confirm with the gurus here that my piston rings have gone out in those two cylinders? Or if there are other variables that I should look into before I pull the motor? Any insight is always appreciated. Thanks! -Jared
4/6 right next to each other. Maybe a blown head gasket between the two? I'd say pull that head but be prepared to yank the engine. With a cracked piston or broken rings there would be a ton of smoke puffing out the crankcase through the oil fill or breather. Maybe start there? Obviously it's hurt though.
Remove the rocker shaft asm, put shop air into either cylinder, have the other spark plug out, and see if the air comes out the other hole confirming a blown head gasket.
only way to fix it is to completely disassemble the car,..buy a bunch if parts that have nothing to do with what's wrong,...then start piling parts to other cars on top of it,....oh wait that's I do nevermind
Thanks for the insight guys. Just to be clear, I've got a couple more days at home for diagnosis, but then am going back overseas for a few months which means that no major repairs are going to happen immediately. I'll keep this thread updated as I go, but for now I just need to know what parts to shop for while I'm deployed. As for the problem being a head gasket, I will try the trick that Bob suggested. However, I have never found any water in the oil, and have never had any water consumption. Still though, I suppose stranger things have happened. And as for the broken rings, I don't have any smoke coming out of the oil-fill cap or anywhere else in the engine bay... just from the tailpipe. I've already started compiling a parts list. Anyone have a line on any engines for sale? Especially any '67 400's!
Here's a little media. It's not the most helpful but I everyone likes pictures right? The engine picture is of the passenger side and shows the oil on the header flange at #6. I also attached a picture that attempted to show the condition of the plugs right after I pulled them out, although the lighting didn't really cooperate. And finally a picture of the car when I got it home from the electrical job a few nights ago... Just because.
Blown head gasket, otherwise if you had 2 Pistons that where cracked and or had broken rings you would have unbelievable blowby! Ask me how I know this, lol!
A blown fire ring between the two cylinders wouldn't necessarily mix the fluids. I'd diagnose it before ordering anything. Chances are a head gasket kit will get you back on the road. If you want to use this as an excuse/catalyst to build another engine then go for it!
Check these videos out, he blew the head gasket and it smoked like crazy. I think that is probably your problem.
Update: From all of your advice (and that compressed air in the spark plug hole trick) I determined that the head gasket has split. Just posting an update that I’m tearing it all down tonight. Everything is disconnected now, and I’m about to pull off the intake and then the head. The gaskets are supposed to arrive in the morning, so reassembly will be tomorrow. If anyone has any advice for the job I’d be greatly appreciative.
Just clean clean clean,...i use a sanding block with 180grit and sand tge surfaces after they have been scraped with a razor and wiped down with Alchohol,..thinner,..or .brake clean on a rag make sure its all dry,.. clean the bolt holes out well,..they are all blind so just blow them out and chase them,..you can use a bolt with a few grooves cut in it Lite oil on the threads Lubriplate under the bolt heads Silver or gold metallic spray paint dusted on both sides of gaskets
Holy S*** that went faster than expected BUT you’re right... Those parts were heavy. That intake//carb combo must weight 100 lbs. Good news is that I didn’t waste my time... the gasket was blown right between the dead cylinders. THANK YOU for all of the advice.
I would only use spray paint on steel shim head gaskets, never on composition head gaskets. They don't need any sealer at all. The rest of the info I can't argue with. I'll add that I like to install hardened head bolt washers on just about any build. They probably took it out and got on it a bunch with way too much timing which popped the head gasket. Or the previous builder didn't re-torque the head gaskets. That engine was rebuilt with the low compression pistons as evidenced by the dish and the compression check. Except for #2 which seems oddly high. Did you do the compression test hot? Maybe the lifters in that cylinder were collapsing a bit when you got around to it. Or worst case a cam lobe is worn on that cylinder. Eyeball the lobe and make sure it doesn't look oddly worn. Crank the engine around while the intake is off and make sure that cylinder's lobes are moving up about the same as the others. Just an added $.02. Get rid of the hose from the intake to the water pump that replaces where the heater used to be hooked up to. All that is doing is allowing the water running through it to bypass the radiator. Just plug both ends. The little hose under the thermostat is all you need.
Spraying felpro blues with paint is just the old school way,...when Gene Fulton and the old fellas do it I do it,..ha its done primarily on reseal deals and not fresh seal up on not on graphite gaskets just the felpro blues On the old shim gaskets I was told a lite coat of copper coat on them
