Timing frustrations

[Stanglover]

That's a lot of ugly pictures!! I can't comment on this issue other than somethin ain't right somewhere.

 

[jpaz]

Wow, that doesn’t look good. You can bend the baffle so the rockers don’t hit them. Looks like the poly locks are set to far down? Or they aren’t the correct ones for those rockers? Not sure, one of the more knowledgeable guys here will let you know.

 

[Big Red Mach 1]

I PM'd Eddie (the previous owner) on Facebook Messenger to ask him if he had some sort of previous issue that caused this, and he just chose to keep them this way and not replace them. Or if this is new damage that he has not seen. We'll see what he says.

 

[Big Red Mach 1]

Wow, that doesn’t look good. You can bend the baffle so the rockers don’t hit them. Looks like the poly locks are set to far down? Or they aren’t the correct ones for those rockers? Not sure, one of the more knowledgeable guys here will let you know.

I thought they looked very recessed also! :-/

 

[Big Red Mach 1]

If you look at the one that has been replaced, it looks perfect. The Polylock is also slightly different. I can get a set of 16 on Summit and I think I'm headed that direction.

 

[jpaz]

Check to make sure the rockers are ok. If they weren’t put in correct then they could be damaged. Look at the swivel part where the poly locks seat on them.. The locks should be setting on the flat machined side, not the round side. I would also inspect everything in that valve train closely, which I’m sure you will.

 

[boilermaster]

Big red mach 1,

That looks like geometry 101 to me,

Suggest that you start doing some measuring.

I would start by checking rocker arm to valve stem contact pattern and see where you sit.

check pushrod length and then the length of your rocker nuts.

Obviously your rockers are contacting the adjusting nuts when the valves are closing

your contact pattern (should) reveal that your pushrods are too long or the rocker studs are wrong.

Shorter pushrods will gain you some threads on the rocker nuts (perhaps the rocker nuts are NOT too long)

Too long of a pushrod length could also explain the rocker to rocker cover contact.

check the part# of those rockers too and see if they are right for your application.

Boilermaster

 

[boilermaster]

1 PLUS on Jpaz's last post.

Don't know how the crane cams rocker arm is configured.

I guess there could be a round and flat on the trunnion.

meaning they could be installed 180 and therefore cause the nuts to be so backed off.

that would also give the impression that the pushrods (look) too long.

Boilermaster

 

[Big Red Mach 1]

Valve-train geometry looks good. The wear line is pretty tight and runs right down main street on the valve tip. Pushrods look good.

What does not look good is that the underside of the rocker arm. They obviously have some wobble to them. And upon further inspection there is play in the rocker arm shaft.



About this time, FastE PM's me back and let's me know that he's used this particular set of rockers in many engines since the 1980. Not the 80's. 1980. Good enough for me to replace them. Hell, the old part number doesn't even yield results.

The one single new rocker looks great. No play in the rocker arm shaft. No damage whatsoever. Mint. Pushrod on that that one looked great as well, and geometry also.

Seeing as how these old rockers have served their purpose well, it's time I retire them.

 

[Big Red Mach 1]

It should also be noted that on the one good newer rocker arm the Poly Lock is 1/16" taller. And right now that 1/16" is probably making a lot of difference.

 

[jpaz]

That’s why I couldn’t find that part number.

 

[Big Red Mach 1]

That’s why I couldn’t find that part number.

You and me both!!  lollerz

 

[Hemikiller]

The rocker studs appear to be too short, ARP offers different lengths.

For my current build, I'll be running Comp Cams Ultra Pro Magnum XD steel rockers. My engine builder says he won't even use aluminum anymore. The XDs are lighter over the tip and have less clearance issues.

 

[Big Red Mach 1]

The rocker studs appear to be too short, ARP offers different lengths.

For my current build, I'll be running Comp Cams Ultra Pro Magnum XD steel rockers. My engine builder says he won't even use aluminum anymore. The XDs are lighter over the tip and have less clearance issues.

Yeah, when I ordered the new rockers today I also ordered 1.90 studs. The ones installed are 1.7's definitely too short which is why the allen head is buried so deep. 

I did look at those Ultra Pro Mag XD's. I damn near added them to my cart, but stuck with aluminum. Based on the one good one he had in there, it should be just fine, but yeah those steel rockers looked pretty attractive.

 

[Big Red Mach 1]

Anyway, I have growing confidence that by the time I replace the studs, and rockers, get preload set, and replace the intake manifold gasket, I'll be in super good shape. Fingers crossed, but we definitely seem to be on the right path here.

I still may need to replace the power valve in the carb. Eddie believes he had a 8.5 in there which would really require 17Hg of vacuum to work optimally. I don't expect to get anywhere near that. If i got 14-15Hg and had a 6.5 Power Valve, I think I'd be happy.

 

[jpaz]

I never thought that the studs would be too short. That sure would explain the problems you experienced. Hopefully that’s all it was. Probably a combination of everything that was done wrong.

 

[TommyK]

Anyway, I have growing confidence that by the time I replace the studs, and rockers, get preload set, and replace the intake manifold gasket, I'll be in super good shape. Fingers crossed, but we definitely seem to be on the right path here.

I still may need to replace the power valve in the carb. Eddie believes he had a 8.5 in there which would really require 17Hg of vacuum to work optimally. I don't expect to get anywhere near that. If i got 14-15Hg and had a 6.5 Power Valve, I think I'd be happy.

Not to derail your thread because I know this can be a controversial subject, but...

...since the power valve provides fuel to the main circuit, whether it is open or closed it has no effect on idle a/f mixture. My advice is don't get sidetracked with the power valve. Focus on the other issues you have identified.

 

[boilermaster]

Anyway, I have growing confidence that by the time I replace the studs, and rockers, get preload set, and replace the intake manifold gasket, I'll be in super good shape. Fingers crossed, but we definitely seem to be on the right path here.

I still may need to replace the power valve in the carb. Eddie believes he had a 8.5 in there which would really require 17Hg of vacuum to work optimally. I don't expect to get anywhere near that. If i got 14-15Hg and had a 6.5 Power Valve, I think I'd be happy.

Um, ahhh,

Perhaps Eddie WAS experiencing 17'' of vacuum @ hot ldle, thus the 8.5'' power valve ?

That should be your new target.

Boilermaster

 

[Stanglover]

Anyway, I have growing confidence that by the time I replace the studs, and rockers, get preload set, and replace the intake manifold gasket, I'll be in super good shape. Fingers crossed, but we definitely seem to be on the right path here.

I still may need to replace the power valve in the carb. Eddie believes he had a 8.5 in there which would really require 17Hg of vacuum to work optimally. I don't expect to get anywhere near that. If i got 14-15Hg and had a 6.5 Power Valve, I think I'd be happy.

 I can comment from my own experience on power valves. My engine produces 18" Hg at 800 rpm idle ( 4 speed manual). That indicates the need for a 8.5 P/V, so I installed one and the car ran like crap. So, talking to "my guy" at the speed shop, he suggested that was the wrong move and to go back to the 6.5 P/V, which i did and it ran like a champ thereafter. I think it will actually depend one YOUR engine's needs, so be prepared to experiment. Buy a couple of extra primary bowl gaskets and bolt seals just to be prepared. You probably won't have to pull the carb to change it as long as you have room underneath to pull the bowl bolts. Lots of paper towel to soak up the gas.

 

[Big Red Mach 1]

Guys, Excellent advice as always.

Tommy - Agree that I definitely don't want to get sidetracked by the power valve. Just mentioned that after all is said and done with my primary repairs, it still may need to be looked at. Definitely bottom of the heap until the vacuum issue is fully resolved. : )

Boilermaster - 17Hg would definitely make my day. Sounds like a good target to me based on that logic.

Geoff - For sure. I've already got a 4.5 and 5.5 which are probably too small, and I will hopefully never need to use. I'll get a 6.5 and some new gaskets and seals coming. In the worst case scenario I have some extra parts I don't need, but I never mind that too much either.

Have a great rest of your weekend guys!