Vista Cruiser suddenly developed a miss! ={

There's one other thing that popped into my mind while thinking about HEI: is this HEI the older style with vac advance? Or is it the C3I computer-controlled style? I ask because on the older vacuum-controlled advance setups, the two wires for the pick-up coil get worked back and forth over the years, and I've had customer's (and my own) pick-up coils stop working because the vacuum advance can pulls on the arm of the pick-up coil, which causes one or both of the wires to open. As soon as the engine begins to die, the vacuum dies off, the can relaxes the arm, and the ignition fires back up. Just disconnect the connector from the module, hook up an ohms tester, and if the ohms are in spec, wiggle the wires back and forth in the direction of advance and watch the display for loss of continuity. And: if you hook up and the coil's out of spec, it needs replacing anyway.

 

I have a little bit more to add to this.

Over the weekend, brother in law came over and we turned the engine a few times and shot some compressed air thru the spark plug hole for each cylinder at TDC. (Quick tip: for some reason, it's easier to rotate backwards by hand and you can just follow the reverse firing order) Everything was fine until we got to #7 cylinder. My brother in law Ryan said he could hear the air coming thru the exhaust, but I could hear nothing.

We then took a look at the rocker arm assembly for #7 and noticed that both arms were quite tight against the pushrod and valve stem and had no slack at all. We then rotated to where one of the valves were open and the other should be closed and on both turns, pushrods and arms had zero slack when valve should be closed. We then noticed that the pushrods were also not centered in the middle of the bore like the others were, but both were kind of closer to one side. So we took the rocker arms off and did some thinking.

Yesterday, with the rocker arms off, I did the compressed air test again, only this time, using incense smoke at the tailpipe and could detect ZERO air leakage. I also (like an idiot, but very carefully) held the smoke over the carb with throttle plate open and could detect zero leakage. I guess I probably should have done that test with the rocker arms installed and torqued down. I may do that today.... after I install my 442 grilles that will arrive this afternoon!!! (Some good in all of this)

Any ideas why those rocker arms and pushrods are so tight?! These are NOS pivots and arms and I could go buy a new set and try that. When we rebuilt the engine, many of the rocker arms were tight against their valves, which is was fixed with the NOS parts. I realize that if the valve stems are tight up against the rocker arms, they may not be closing all the way and there's my miss. But what could cause this? And so suddenly?!

New pushrods, rocker arms and pivots for #7 is my next step I guess.

 

Would it be tacky of me to suggest that it is better to suddenly develop a Miss that to suddenly develop a Mrs.? OK, yeah, it would be... I'll shut up now and take my medication.

Best of luck. The smart guys no doubt have you on the right track.

mike

 

That's odd if all the new parts came together! Could you possibly take off another set and side by side compare them? You could of gotten "bad or incorrect" new parts BUT if both rockers are hitting the same(to tight) way on #7 maybe the hold down tower is the culprit?(possible the contact points are off justa tad? minor error in manufacture? I have bought new parts that were not "right" before, it happens

 

Can you shine a light down through the pushrod holes and look at the lifters? Since it's likely no Rocker Arm Gremlin came by and swapped out those parts, I'm wondering if the cam and/or lifters may be causing the tightness.

 

Ok, so check this. I took that pivot off, turned it around, torqued it down, and that tightness is no longer there! I fired her up, and this tapping sound that I could hear thru the exhaust (as heard on the video in the op) was no longer audible.

I'm thinking a brand new pair of rocker arms and a pivot and pushrods for this cylinder will do the trick. Hell, at Napa, that set comes with TWO pivots. I'm assuming because a pivot can, in fact, go bad in some way and cause some tightness there. It's just weird that it would happen so suddenly like that. But... I just went thru having to purchase a brand new ignition coil on my Monte Carlo to replace a 2 year old ignition coil! So... stuff like that DOES happen.

Anyway. It did seem to idle better, but I couldn't get a good reading because in all the hustle and bustle of taking off some of the top end parts of this motor, I lost ALL of the vacuum port caps, but even so, and with the vacuum gauge hooked up to the carb, I could tell that the rythmic drop in vacuum had decreased since over the weekend dramatically. I couldn't leave to go get caps for the vacuum ports because I was waiting for Fedex to come with my new grilles...

And THAT... is a different story altogether. Long story short on installing grilles on a Cutlass, you have to take off the entire front end. Bumper, headlight housing, stoneshield and all! Jeeez. It was like the never ending barrage of nuts and bolts, tiny ones and big ones stuck with 42 years of rust, and impossible angles! UGH. At least I can rest assured that no one can possibly just sneak up and steal my grilles without wasting hours of their time first.

Regarding the miss, when I get my front end back together, install a new set of rocker arms, pushrods and a pivot on #7, I'm putting the top end back together, dumping some Marvel Mystery Oil in the crankcase and in the gas tank and I"m gonna run that sucker and see what that does.

So here's to hoping I don't have to pull the cylinder heads for sure in the near future!

 

If you have set the valves recently a smidge of a turn too tight could cause the valve to not seat and runs like a plug wire is off. A compression test will show a dead cylinder. I suspect it would cause abnormal vacuum readings.

 

These are like my Pontiac. They go down tight on the head with a torque spec and self adjust.

 

I'm pulling the heads this weekend.

I've heard that a dollar bill test will tell if there's a valve problem on OLDER cars. So that's what I did. Low and behold, the exhaust was sucking in the dollar bill every few pulses.

On BOTH sides.

I tried this dollar bill test on my Custom Cruiser to verify my results and on that car, the bill is consistently pushed out by the exhaust, like air flowing over the bill.

So...... I get to pull my heads and bring them to a reputable engine shop. This shop didn't have much good to say about the shop I brought them to when I had them reworked, so we'll see what they say.

Not too thrilled about having to do this, so I force myself to look on the bright side about pulling the entire top end of my engine apart: practice makes..... quality beer drinkin time!

Lol. Maaan. I just put her back together, too! Got my 442 grilles on (pics coming soon), and it doesn't look too bad with a painfully obvious stone shield of a slightly different color than the car. The new grilles and bumper guards look AWESOME, so I'll overlook that until I get the rest of the car the same color as the shield. I just want my dream car to look and run awesome, dang it!

....and it shall. It shall.

I'll post results and a conclusion when get the heads back and put it all back together again.

Thanks,

Buz