[Formulas]

Skip in vacuum reading can also be the PCV valve plumbed into a single runner

7 cylinders will be slightly higher and smooth then the one cylinder will hit, it has to draw a vacuum in the PCV line then the PCV slams shut which you can also HEAR and also see on a vacuum gauge

Google how a PCV valve works to see internals

As RPM increases the frequency increases and your ability to detect it diminishes

.

[Pronto Poncho]

Originally Posted by Formulas

Skip in vacuum reading can also be the PCV valve plumbed into a single runner

7 cylinders will be slightly higher and smooth then the one cylinder will hit, it has to draw a vacuum in the PCV line then the PCV slams shut which you can also HEAR and also see on a vacuum gauge

Google how a PCV valve works to see internals

As RPM increases the frequency increases and your ability to detect it diminishes

.

Very Good Stuff, Thanks

[Va68goat]

wbnapier,
No updates...been out of town for a week for work. Jeff and Paul reached out to a guy that lives near me thats going to check out the motor. I spoke to him a few times. Hoping he can come take a look this weekend.

[dataway]

It would be weird if it ended up being something like the valley pan flexing under fluctuating vacuum signal ... like popping the bottom of a tin can back and forth.

[Formulas]

Originally Posted by dataway

It would be weird if it ended up being something like the valley pan flexing under fluctuating vacuum signal ... like popping the bottom of a tin can back and forth.

The PCV valve by virtu of being in the pushrod cover helps to make the sound bigger like a drum skin

This isn't a theory or guess circa 1982 I put a p4b intake on my 1968 GTO removed the q'jet intake I totally forget what carb I used but i plumbed PCV through a front runner and thought i hurt my engine by foreign debris because it was making noise and idle was not as smooth

Since I am not in front of original poster's engine I won't go as far as to say this is his problem but its soooooo EASY and cost nothing to check to eliminate.

.

[STEELCITYFIREBIRD]

Originally Posted by dataway

It would be weird if it ended up being something like the valley pan flexing under fluctuating vacuum signal ... like popping the bottom of a tin can back and forth.

I could only see that happening if there is no or inadequate source of air in to motor.

Just pull PCV valve and cover with your thumb. No noise reduction or smoother running... move along.

Compression tester is nothing more than an air pressure gauge with a check valve inline. (motor is an air pump your testing). A quick check with your shop air from a rubber tip blow gun will verify your gauge and integrity of the hose and check valve against shop compressor line regulator gauge psi output . The only thing you can't check is how well it will seal to the spark plug hole.(without some fabrication).

Any info/pictures on which crank pin/s the problem occurred on or pics of crank and damaged/replaced rods/parts?

Take all the spark plugs out when doing compression test on an entire engine!

[Va68goat]

STEELCITYFIREBIRD,
I'm hoping for that.

Steve C.,
Collusion or conclusion? Hahaha

[Steve C.]

Carnac suggests no secret cooperation or conspiracy, especially in order to cheat or deceive.


.

[Va68goat]

Well...I do have an update but I think it would be best to hold off on posting anything until I see how this plays out.

[tom s]

Mike,I have a QJ,Holley and a pair of AFBs in my cabinet that are dyno carbs and also 2 dist,one with a std gear and one with a poly gear.The last thing I want on a dyno or test stand is a issue!Tom

[HWYSTR455]

The carb that is on there now is the carb it was last on the dyno with. But it's unclear at what the adjustments were on the dyno. Kind of doesn't matter, simple carb adjustments shouldn't cause the 'noise' issue, but it is one factor that will eventually be addressed.

I was informed the carb, due to elevation concerns, was jetted up 2 steps prior to shipping. Not a deal breaker, also wouldn't cause any 'noise', and that will have to be revisited once running properly and road tests can be accomplished.

Yes, the objective is to resolve the rough running issue with the next effort, then the 'noise'.

My comments of 'theorizing' is a reach as well as some wishful thinking thrown in for good measure. Also to point out a potential cause that can easily be eliminated. (Following the process of elimination approach).

.

[mgarblik]

Originally Posted by HWYSTR455

The carb that is on there now is the carb it was last on the dyno with. But it's unclear at what the adjustments were on the dyno. Kind of doesn't matter, simple carb adjustments shouldn't cause the 'noise' issue, but it is one factor that will eventually be addressed.

I was informed the carb, due to elevation concerns, was jetted up 2 steps prior to shipping. Not a deal breaker, also wouldn't cause any 'noise', and that will have to be revisited once running properly and road tests can be accomplished.

Yes, the objective is to resolve the rough running issue with the next effort, then the 'noise'.

My comments of 'theorizing' is a reach as well as some wishful thinking thrown in for good measure. Also to point out a potential cause that can easily be eliminated. (Following the process of elimination approach).

.

OK, so my misunderstanding. To be clear, the engine ran smooth and fine with this carburetor on it on the dyno. Got it. Sorry to take this off track. I agree with your approach of getting it running right first, then address any noise issue. Again, best of luck.

[64speed]

What’s the deal with this engine? He has reached out to me about mine and caster1 engine builder. I gave him the contact info but I know my builder and unless it’s just a simple fix he isn’t gonna cobble it together. He is gonna tear it down and completely redo it using new parts in place of anything he feels is unworthy.

[GTO JONES]

My guess intake vacuum leak.

[Va68goat]

ta man,
Though Paul hasn't returned any of my texts in months, it was pretty good of Jeff to find a local, respected engine builder near me. The guy has been to my house several times conducting tests and he repaired the significant vacuum leak that was at the intake. You're right, I think I've reached a point where it's no longer on me to figure out the problem with this motor. Believe me, I want this over as much as Paul and Jeff do but I'm not willing to spend any more money on making this motor right.

Paul E,
Thats a good idea.

Scott Stoneburg,
Paul says he broke this motor down after finding the bad distributor bushing. He originally said everything looked great but after closer inspection, he noticed the bearings needed to be replaced, the piston rings needed to be replaced, the crank needed to be polished and a light honing of the block was needed. Paul used Felpro gaskets for intake. The guy they sent over used Mr. Gasket gaskets and the motor is idling much better.

MarkS57,
I agree 100% with what you said about the distributor. I've found a few shops that have great reputations here that I would feel comfortable with leaving my motor. I'm just not willing to spend any more of my money on fixing this problem. I've done more than my share. As I said before, Jeff has been pretty cool with finding a local guy to me to look at this motor. Jeff is taking care of him. I do appreciate that!

[Va68goat]

scott70,
The only time this motor has been completely torn apart is after it failed on the dyno in Arizona and most recently when Paul said he replaced the bearings, piston rings, polished the crank and did a light honing. None of my buddies that have worked on the motor have taken a look at the lower end of this motor. I'm pretty sure this motor will have to come out and torn apart. There is not even a slight chance of me washing my hands of anyone....not a this stage! I'm pretty sure if my buddies that have worked on the motor tore this motor apart, I'm confident they would find something. It's not their problem though and I've already wore my buddies out with the amount of time they spent on this motor. I'm just as confident that if Jeff and Paul have their guy break this motor down, he too would find the issue.

adynes,
Paul sent me new lifters last year and I sent him the ones that were in the motor. When he received the lifters and inspected them, he said there was absolutely nothing wrong with them.

pastry_chef,
I think Paul has had a great reputation of building motors. He says he's built hundreds of them without any issues. On the other hand, people make mistakes. I think one problem is that we've been asked to spend 165 hours of diagnosing things that we could have done wrong installing the motor instead of accepting the fact that something could have been done wrong on the build. With a catastrophic failure on the dyno, something was missed. I still believe the failure of the distributor bushing could be the result of a greater issue. We have done everything that was asked and the knocking noise is still the same. This has to come to a conclusion very soon.

DOC,
We've used a mechanics stethoscope multiple times. We get a signature at the distributor and lower end of the motor. We discovered that over a year ago but I still get questions about how old the fuel is. (The fuel is only 3-4 months old)

[dataway]

I think if I had the same problem (the noise), and couldn't identify it by listening I would.

1. Turn it over with no plugs and listen ... still makes the noise ... then
2. Turn it over with no plugs and the distributor and oil pump drive removed ... noise disappears, you have a solution, noise doesn't disappear you know there is probably a part clearance issue somewhere deeper inside.
3. Only makes the noise with plugs and running ... figure probably combustion related, then....
4. Check yet again for exhaust manifold leak, crack, exhaust port leak/ crack. No luck .... now you are beyond my knowledge to diagnose.

I'd do it all with no belts installed, and AFTER any tuning issues are taken care of.

This is not a comment about this particular situation at all, just wondering if that would be the proper assumptions to make in a similar situation.

[redhawk44]

Originally Posted by dataway

I think if I had the same problem (the noise), and couldn't identify it by listening I would.

1. Turn it over with no plugs and listen ... still makes the noise ... then
2. Turn it over with no plugs and the distributor and oil pump drive removed ... noise disappears, you have a solution, noise doesn't disappear you know there is probably a part clearance issue somewhere deeper inside.
3. Only makes the noise with plugs and running ... figure probably combustion related, then....
4. Check yet again for exhaust manifold leak, crack, exhaust port leak/ crack. No luck .... now you are beyond my knowledge to diagnose.

I'd do it all with no belts installed, and AFTER any tuning issues are taken care of.

This is not a comment about this particular situation at all, just wondering if that would be the proper assumptions to make in a similar situation.

This approach makes sense.

[Mister Pontiac]

With all that you've been thru to this point, I think you've eliminated any big conspirator of major damage occurring.

If it were me (and I know it's not), I would simply start driving it, enjoy it, and monitor the knocking. If it truly is a 'mechanical' knock, it should quiet down with miles as it "self-clearances." If it's not a mechanical knock, you won't notice a change as the miles pass. It's my thought that this is your best path forward to an ultimate solution.

Good luck, and hope you get to enjoy the engine and plenty of seat time soon!

[1967Tempest]

Originally Posted by Mister Pontiac

With all that you've been thru to this point, I think you've eliminated any big conspirator of major damage occurring.

If it were me (and I know it's not), I would simply start driving it, enjoy it, and monitor the knocking. If it truly is a 'mechanical' knock, it should quiet down with miles as it "self-clearances." If it's not a mechanical knock, you won't notice a change as the miles pass. It's my thought that this is your best path forward to an ultimate solution.

Good luck, and hope you get to enjoy the engine and plenty of seat time soon!

Ditto. I wold make sure 5 and 7 wires were not backwards and drive the piss out of it!!!