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Discussion Starter #1
Hello i'm Giulio from Italy , i recently builded a Big Block ford 390-432 FE on a Ford Mustang 1968 , engine run very good and very fast but valve floating at 4700-4900 rpm , i read that this engine family FE bear this problem , but the strange thing is why Eddy rpm heads and rpm cam combo can get 6k rpm ?? and after this valvetrain is not able after 5k rpm ??? i will be happy for any advice !! thank you very much ...Giulio from Italy

this is my engine specs
390-432 scat stroker kit all balanced
Edelbrock RPM heads ( out of box) number 60069 with our springs
Edelbrock RPM camshaft and lifter kit
Edelbrock timing set ( with correct degreeing)
comp cams roller rockers ( with 1 turn preload )
single plane intake manifold
milodon oil pan and windage tray
ford racing oil pump
750 cfm holley double pumper
comp ratio is 11:1
transmission is manual 4 speed

Thanks !!
 

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Hello i'm Giulio from Italy , i recently builded a Big Block ford 390-432 FE on a Ford Mustang 1968 , engine run very good and very fast but valve floating at 4700-4900 rpm , i read that this engine family FE bear this problem , but the strange thing is why Eddy rpm heads and rpm cam combo can get 6k rpm ?? and after this valvetrain is not able after 5k rpm ??? i will be happy for any advice !! thank you very much ...Giulio from Italy

this is my engine specs
390-432 scat stroker kit all balanced
Edelbrock RPM heads ( out of box) number 60069 with our springs
Edelbrock RPM camshaft and lifter kit
Edelbrock timing set ( with correct degreeing)
comp cams roller rockers ( with 1 turn preload )
single plane intake manifold
milodon oil pan and windage tray
ford racing oil pump
750 cfm holley double pumper
comp ratio is 11:1
transmission is manual 4 speed

Thanks !!
I have never heard of an FE specific issue with valve float

If you are sure it is valve float, I would recheck your preload, if not, consider looking for other areas that can cause a fuel issue, a high rpm misfire or cross fire.

It would be a very sloppy/weak spring to float at that low of an RPM, my hunch is something else is wrong.
 

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my first thought was valve springs .

you spec your springs are installed .

what type - single , dual plus do they have a damper(flat looking spring)
whats the spec of the spring ? installed height , closed pressure and open pressure.

now there are other things that can look like bad spring like My427stang said , you could back off the one full turn to a 1/2 turn . then check carb settings/fuel pressure and the spark plugs. I'd do these first , then check the springs on a tester
 

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Discussion Starter #4
Hello!! Thanks for your answer !! my springs are EDL 5792 and this is the specs from summitracing site

Number of Springs Per Valve:Single
Outside Diameter of Outer Spring (in):1.550 in.
Coil Bind Height (in):1.070 in.
Damper Spring Included:Yes
Inside Diameter of Outer Spring (in):1.120 in.
Inside Diameter of Inner Spring (in):1.120 in.
Installed Height (in):1.885 in.
Seat Pressure at Installed Height (lbs):130 lbs.

Fuel pressure is 8 psi and spark plug look like a little bit rich , AFR gauge at WOT is rich … im sure at 99 % that have valve float…

Danh , why you advice me of turn back ½ the adjust ??

Thank's
 

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If it is valve float, it will miss at exactly the same RPM in neutral. If it misses at slightly higher RPM then look at ignition. A fuel issue should not appear at all (or the same) in neutral. Rev it in in the driveway.
:tup:
David
 

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Hello!! Thanks for your answer !! my springs are EDL 5792 and this is the specs from summitracing site

Number of Springs Per Valve:Single
Outside Diameter of Outer Spring (in):1.550 in.
Coil Bind Height (in):1.070 in.
Damper Spring Included:Yes
Inside Diameter of Outer Spring (in):1.120 in.
Inside Diameter of Inner Spring (in):1.120 in.
Installed Height (in):1.885 in.
Seat Pressure at Installed Height (lbs):130 lbs.

Fuel pressure is 8 psi and spark plug look like a little bit rich , AFR gauge at WOT is rich … im sure at 99 % that have valve float…

Danh , why you advice me of turn back ½ the adjust ??

Thank's
your first post said out of the box heads with Our Springs ..
The our spings made me believe you didnt use the Edelbrock springs but some other springs .

The Edelbrock springs are know to fail on 429/460 heads very quick.
 

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why Eddy rpm heads and rpm cam combo can get 6k rpm ?? and after this valvetrain is not able after 5k rpm ? !!

I would be pissed off too if I bought the whole edelbrock kit and it did not come close to what they claimed!
 

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Discussion Starter #9
If it is valve float, it will miss at exactly the same RPM in neutral. If it misses at slightly higher RPM then look at ignition. A fuel issue should not appear at all (or the same) in neutral. Rev it in in the driveway.
:tup:
David
Ok , today we make some other test considering all your advice:

"David Test" : Right in neutral no have floating or esitation and no problem , try first up to 5500k.

Then try to decreased secondary jet form 80 to 76 and try the car on street but a few km because is very bad :) for sure now is too little fuel ...

Then we have increased jet and put 86 , and we go on street to test , really not sure 100% that not valve floating what happens at 4700 but conforted that there are not in neutral we go.....and .... with more fuel and surpassed the strange vibration, after 5200k the cars go up to 6200

NOT IS VALVE FLOATING , first is a combination of strange vibration and too lean carburation...now have only the vibration..

Good News but ... the vibration ??

So now vibration at 4800 to 5200 that little restrain and after 5200 go down , in all speed , and only with gear engaged...
I do not think is responsable the driveshat... could be the trasmission ??

Trasmission is a 4 speed revised form original 390GT with 3.25 corrier 9" traction look...

Thank's to all ...

Giulio
 

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OK - to make sure I understand:

  • NEUTRAL, CLUTCH ENGAGED, it will rev to 6200. NO vibrations.
  • DRIVING, IN-GEAR, it will rev to 6200, but vibrations from 4800-5200.
If that is true, answer these questions:

  1. DRIVING, IN-GEAR, rev above 5200, DECELERATE IN-GEAR = vibration stays or goes away?
  2. DRIVING, IN-GEAR, rev above 5200, PUSH IN CLUTCH to DECELERATE = vibration stays or goes away?
David
 

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Discussion Starter #11
Hi , David , yes you understand correct

Unfortunally today go for make test as you ask me , but once i have put in temperature the motor and go to hightway , i have had a problem ...

I tried to speed up slowly for see exacly at what rpm stard vibration and when start at 4500 rpm , stop the gas and go down rpm and little push again for check rpm , always 4500 .... after 5 sec i have heard a "BANG" and a bad noise in the engine and I stopped ...

I do not tell you what happen in my mind , but i tell you only what i see 2h later ... i have broken the Rocker Stand , the one on the end .... seed attached pic

ok furtunally is not a big problem to repair but ....sxxt

So now have any suggestions for an upgrade for this part ?... i have found this :
Ford 390 Rocker Stands
Price is resonable and is like COM CAMS design ...
Thanks ..
Giulio
Repared this i try to make your test , plase can you explain what you think can do with result ?
 

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Strange...

Did you speak with EDEL TECH about the failure?

Are you sure you are using the correct supports and they are rated for your spring(s) pressure? Did you check compressed spring height? Valve clearance(s)? Proper lash (procedure) set (no-pump up)?
 

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Hi , David , yes you understand correct

Unfortunally today go for make test as you ask me , but once i have put in temperature the motor and go to hightway , i have had a problem ...

I tried to speed up slowly for see exacly at what rpm stard vibration and when start at 4500 rpm , stop the gas and go down rpm and little push again for check rpm , always 4500 .... after 5 sec i have heard a "BANG" and a bad noise in the engine and I stopped ...

I do not tell you what happen in my mind , but i tell you only what i see 2h later ... i have broken the Rocker Stand , the one on the end .... seed attached pic

ok furtunally is not a big problem to repair but ....sxxt

So now have any suggestions for an upgrade for this part ?... i have found this :
Ford 390 Rocker Stands
Price is resonable and is like COM CAMS design ...
Thanks ..
Giulio
Repared this i try to make your test , plase can you explain what you think can do with result ?
simple part for a machine shop to make- Out of Steel .
..
add- the way the stands broke , there was also a bolt failure .
what grade bolts are being used ?
 

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So now have any suggestions for an upgrade for this part ?... i have found this :
Ford 390 Rocker Stands
Price is resonable and is like COM CAMS design ...
Thanks ..
Giulio
The rocker shafts for FE engines are not supported on the ends, so they flex. This often leads to broken shafts and stands when using aftermarket cams/springs. The cure is to buy a set of end stands. These are marketed by a few companies, and support the end of the shaft to prevent these problems.

$129, and problem solved! I've dealt with Doug at POP, and have had great experiences. Top notch guy to do business with. Click the link below.

Precision Oil Pumps

If you also need the center stands, you can order these from Barry R at Survival for $195. But generally, the end ones are the cure for rocker shaft problems.

http://store.survivalmotorsports.com/rostsetbialw.html

Good Luck!
 

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This often leads to broken shafts ... $129, and problem solved! If you also need the center stands, you can order these from for $195!

Shaft is not broken, you just need another rocker stand. No need to spend $300 at a performance shop, probably someone here would give you one if the shipping was not extravagant.
 

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Shaft is not broken, you just need another rocker stand. No need to spend $300 at a performance shop, probably someone here would give you one if the shipping was not extravagant.
The problem with FE shaft rockers, is that the end of the shaft is not supported. This leads to broken shafts and stands. Every time the rocker is pushed, the shaft flexes, putting a load on it, as well as the stand.

It's pretty much MANDATORY to install end stands on an FE when upgrading the stock cam/springs to anything aftermarket. The stock setup is incredibly weak without the outer rockers being supported on both sides.

 

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All good advice here, but the original problem has to be addressed before going to end stands. There was something that caused the stand to fail (performance problems before failure - no excessive spring pressure/RPM).

And why it is popular to go to an adjustable hydraulic valve-train on a street engine I will never figure out... :confused:

Assemble and adjust to specs and drive it.
 

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the aluminum stands won't hold up to spring pressures in the high 300' lbs
the factory iron med. and hi rizers iron stands gave no problem at 385lbs open pressure .

todays 850lbs and up roller springs the end support stands make sense
 

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the aluminum stands won't hold up to spring pressures in the high 300' lbs
the factory iron med. and hi rizers iron stands gave no problem at 385lbs open pressure .

todays 850lbs and up roller springs the end support stands make sense
All the rockers on an FE are supported on both sides, except for the ones on the end. Those are only supported on ONE side. This flexes the shaft. It also forces ONE stand to carry all of the load for that rocker, and it's a leveraged load. This works okay for stock cams with weak, stock springs turning stock rpm. For ANY street/strip engine using aftermarket cam/springs, extra support is needed. A $129 set of end stands is the cure.

For a dedicated race setup using solid roller cams, etc... A fully aftermarket shaft/rocker system is highly recommended... Way more expensive than the end stands.


 

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Which stand failed? The problem has to be diagnosed correctly before throwing parts at it.

The use of end stands is not the issue but the cause of the actual failure is.

Of course end stands should be used (along with solid spacers IMO) but this failure was caused by something other than excessive spring(s) pressure (again, IMO).
 
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