Valvetrain issue

[Anders]

After a succesful breake in procedeur with single springs I installed the inner valve springs. Then it all started...
First thing that happend whas that the polly lock got loose. I limped home a few km with a massive clatter. Cyl No. 7 intake. I checked out for damages and reinstalled the parts and set the lash.
After a while I found out that there was a huge different between left and right cylinder raw (AFR gauge/senders) each side. I then meassured the intake air draw (ID throttle EFI) and No. 7 draw less air. Out with No. 7 spark plug and it was moore black/wet than it should be.
Now it was time to inspect the valve train. The No. 7 intake was loose again. Now even the rocker bolt was unscrewed (just a few threads was holding it in place). The push rod was bent and the roller rocker was damaged by the push rod outside the seat.

What occured this and how can I prevent this from happening again?
Could there be somethings else that could have failed, Lifter for ex.

Fontana block, AFD heads, solid flat tapped cam, no coil bind and lifters with a little hole in them, meassuerd push rods for the right lenght.

Thanks in advance
Anders

 

[Jim Cowden]

Is the inner spring coil binding.

Jim

 

[Robert May Eng.]

After a succesful breake in procedeur with single springs I installed the inner valve springs. Then it all started...
First thing that happend whas that the polly lock got loose. I limped home a few km with a massive clatter. Cyl No. 7 intake. I checked out for damages and reinstalled the parts and set the lash.
After a while I found out that there was a huge different between left and right cylinder raw (AFR gauge/senders) each side. I then meassured the intake air draw (ID throttle EFI) and No. 7 draw less air. Out with No. 7 spark plug and it was moore black/wet than it should be.
Now it was time to inspect the valve train. The No. 7 intake was loose again. Now even the rocker bolt was unscrewed (just a few threads was holding it in place). The push rod was bent and the roller rocker was damaged by the push rod outside the seat.

What occured this and how can I prevent this from happening again?
Could there be somethings else that could have failed, Lifter for ex.

Fontana block, AFD heads, solid flat tapped cam, no coil bind and lifters with a little hole in them, meassuerd push rods for the right lenght.

Thanks in advance
Anders

It might pay to get the gauge out and measure lift on all the cam lobes, you may have wiped one off on break in . Have you also checked spring pressures at installed height? There are many spring combos that require the pockets in the heads machining.

Bob

 

[Anders]

No coil bind, I use valve stem locks with an offset. Have spent a lot of time finding the right valvespring, rocker ratio and push rod length.

Thank you for sharing your thoughts
Anders

 

[dave harris]

In your initial post you mentioned "Poly lock" nuts? I've never seen those used on the rocker arm nuts - I've only seen a oversized nut with "internal" set screws to lock the nut tight after adjustment (or on older stock engines a "deformed" nut that self locks).

Maybe Jac Mac will jump in here - but I'm not sure I'd trust "poly lock" nuts under those heat cycles on the valve train? Just a thought?

Dave Harris

 

[Anders]

Sorry for that. It shuold be rocker studs
Anders

 

[Jac Mac]

I would suspect that you have a problem with that #7 intake valve/ guide, possibly seized that may have tweaked the pushrod and set this issue up, getting worse with the increased spring load. one other possibility is you may have installed the #7 rocker with the pivot 180° out of position and the posi lock therefore not seated, but in order to force the stud loose in the head there has to have been some extraordinary forces in action..... whatever given those thoughts strip the cam/valvetrain out and start again.... cleveland heads need some provision/care in getting oil to guides like spray bars or riser tubes at drainbacks to create a oil level up to base of spring coils while running.
Hope you have the correct cam for that Fontana Block.

 

[Anders]

Springs removed, valve moves freeley. The inner spring sat tight inside the outer spring. Have to take apart/together several time then the inner spring lined up in the ends with the outer spring. No other damage was found.

Just have to wait for spare parts, roller rocker and push rod.

Now, how could this happend? Could there have been a coil bind between inner and outer spring?
Could I have done any wrong during the assembling, souch as;
Set the lash when the lobe not was on the "close side",
missed the lifter seat with the push rod, they have strange angel I think
or could I have done anything else...

Anders

 

[Anders]

Jac!
You asked about right cam shaft for Fontana block, I have not heard about anything else than a Cleveland cam.

Anders

 

[Jac Mac]

Good to see your up to speed & correct on the cam! Problem can arise if the cam grinder thinks its a Windsor with the different lifter bore angle.

Cleveland pushrods do require a little extra care at assemby due to the compound angles.
When setting valve lash you can only get the lash too loose as long as the feeler gauge fits, so a quick check is to sit a straight edge along the top of the posi locks after setting the lash, they should be all at the same approximate height ( although this is assuming that the components are new and pushrods/base circle of cam etc are equal.)

Since you had no problem when using the single springs it would appear that the issue has happened since or during the spring change. Few things to check:
1. Did the motor ever spit back thru the intake in the initial run in phase ( might have bent pushrod at this time if so.)
2. Your valve spring set- is it Outer/Inner or Outer/Flat Damper/Inner ( Outer/Inner should be RH wound on one/LH wound on other.... Outer/damper/inner should have both springs wound same with reverse on damper....... if this is incorrect inner coil can interfere with outer.
3. I would still check the lifter face and camlift for wear / damage as that #7 intake lobe must have had some extra loads placed on it during the time the damage was happening.
4. I would suggest a leakdown test on that cyl to verify the condition of that #7 intake valve

Don't feel too bad about this, had similar happen to me on a 351c once when the flat damper did not sit properly on the spring seat on one valve, pushrod got shoved thru the rocker arm on that case due to the coil bind incurred.

 

[Anders]

Valve springs are double without damper.

Yes there where a batch fire and the air filter caught fire...
but that happend after the initial start up.

I will try to remove the lifter trough the head and inspect it.
Anders

 

[Jac Mac]

Yes there where a batch fire and the air filter caught fire...
but that happend after the initial start up.


Anders

This is quite likely to be the source of the misplaced/bent pushrod, happens quite often on Cleveland due to large dia/area of intake valve- lean mixture/ incorrect timing etc causes explosion of fuel mix in inlet port runner which lifts the inlet valve off the seat, angle of pushrod allows it to leave the lifter or rocker arm socket, in your case with it being at the rocker end the valve now wont be able to return to the seat & next time around the cam will try to open the valve even further with coil bind or valve to piston contact resulting.... when running in cam with soft springs you must ensure timing/mixture are close to optimum to avoid this, along with avoiding any rapid throttle opening events until you have those points correct.

 

[Anders]

Such power in that sneezing. Probably the push rod came out of its seats...?
Can you imaging that I have been driven almost 50 km with this. Could this even have affected the oil pressure, a little low?

Thank you, I will be back when the motor is assembled
Anders

 

[Keith]

You may have junk in the pump. I would flush the motor out completely. Better still, I would tear it down.

 

[Jac Mac]

Such power in that sneezing. Probably the push rod came out of its seats...?
Can you imaging that I have been driven almost 50 km with this. Could this even have affected the oil pressure, a little low?

Thank you, I will be back when the motor is assembled
Anders

" 2.17" dia inlet valve.. area approx. 3.2 sq in.... ~ 120lb seat pressure with the single spring.... only needs a pressure spike of ~60lb x 3.2 to lift valve off seat.

If lifter was out of bore you could/might have pressure drop if you don't have lifter oil restrictors.

Good Luck & look hard for stray bits of metal!/COLOR]

 

[Anders]

New parts received and valve train assembled, Progress. Push rod dance the way round and round.
Then it fired up and it draw air equally and the AFR looked the same.

Thank you all!:thumbsup:
Anders

 

[Jac Mac]

Anders, in the GT40 Replica Manufacturers corner- Superformance GT40- section there is a thread titled 'Tracking an SPF'... check out posts #129 &133 with regard to setting your valve lash with that alloy block/head combo..