Skip to main content ↑ ↓
Topic: Valve Train Noise - How to Measure Correct Pushrod Length? (Read 3628 times) previous topic - next topic

Valve Train Noise - How to Measure Correct Pushrod Length?

My Coupe has some noise in the valve train and I just always assumed it was normal from talking with a couple of guys that build a few engines a year. I started reading Vinnie's new thread on his 88 getting a new motor and the issue came up again. Well, after searching and reading a few threads on noisy valve trains I am beginning to think that it is not common to have noise and something is up with the motor in my Coupe.

I have ran the valves on this car about a dozen times and it still has noise. From what I am reading here the noise the Coupe has is more than normal. The motor has Edelbrock Performer heads (2.02/1.60), Edelbrock Performer RPM II upper and lower intakes, Jomar Ultra-Lite stud girdles (http://www.jomarperformance.com/ultralite.php), the Motorsport tall aluminum valve covers, Manley severe duty valves, Manley titanium retainers and keepers, Isky 8005-A valve springs, Ford Racing M-6500-R302 lifters, Crane Cams 11746-16 Energizer roller rockers, and a 35-518-8 Comp Cams camshaft (http://www.compcams.com/Cam_Specs/Ca...csid=1057&sb=0).

With all of that said I followed the Comp Cams valve adjustment process that I got with the cam that is in the motor. I continue to get noise even after several attempts to adjust the preload. What I noticed in several of the threads was having to correct push rod length. I went on Comp Cams website and found these:

http://www.compperformancegroupstore...y_Code=PSHRDTL

I am pretty sure the stock length for a 85-96 5.0 HO is 6.272" so I would assume I need to get this one:

http://www.compperformancegroupstore...y_Code=PSHRDTL

I did not check the pushrod length as another person built the motor and I just assumed they would have measured them. This is starting to look like the problem but I wanted to know how to measure for the correct push rod length once I get the correct adjustable checking pushrod. Any help would be appreciated.

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Valve Train Noise - How to Measure Correct Pushrod Length?

Reply #1 –
Stock Push Rods in the Cadillac are 10.200 so 6.272 seems funny so I looked it up at 6.25 so you are correct.

Here's the tech page from comp I think it is a bit confusing to me.  http://www.compcams.com/Technical/CurrentCatalog/HTML/306-307.asp

As long as your lash is correct I don't know where the noise come from?  If the length is incorrect it could cause binding and harm, but would this cause noise?  I take it your oil pressure is good?  Also do all of them make the same amount of noise or is it just a few?

It's always good to check these things out and not that hard to do when building the engine.  It is a bit harder when it's together because you cannot make the lifter a solid and it's harder to use soft spings.  So I think the best you can do is on the base circle adjust the rocker to it hit the valve tip on the right part then measure without compressing the lifter.  Then you need to add to what you want the pre-load to be, about .030, You cannot move through the whole range because the lifter will go down and give a bit of a false reading.

Good luck and have fun.

TED

Valve Train Noise - How to Measure Correct Pushrod Length?

Reply #2 –
Darren,

There are way to many cams installed with incorrect springs and/or installed height, push rods and inadaquate lifters, often resulting in either disapointing performance or damaged parts.  Push rod length is one of the most overlooked and one of the most critical. 

Most never question the push rod length, after all it worked for the factory, right?  Yup, it sure did, but factory tolerences are just that, from the factory. 

So you just change a cam, what's different?  Well the base circle of the cam may be different from the stock cam effecting push rod length. 

You install new heads or mill the stock ones.  Are pedestals for the rockers the same height as the stock heads?  Not anymore, this affects the push rod length.

You have the engine overhauled and they deck the block.  This effects the push rod length.

Noise in the valve train is not uncommon when dealing with aftermarket HR camshafts.  The Comp Cams 274 cam and the Extreme Energy line has very aggressive ramps and often result in noise or ticking (some attribute it to the flex in the SADI cam core). 

That cam is pretty big for a F/I 302/306 combination (personal experience on that one, but not germaine to this discussion).

As Ted mentioned checking push rod length is a bit more involved on an assembled engine, but can be done with some disassembly.

Based on your concerns it definetely should be done. 

Get a push rod checker (about $15) and some light "checker" springs.  The valve covers and intake need to come off.  Pull a pair of valve springs (typcially on #1) and install the "checker" springs (if you try this with regular springs, you'll bend the push rod checker).  Convert one of your roller lifters to a solid (pull the retaining clip, pull the plunger and invert it.  Don't loose the clip!).  Mark the valve tip w/a Sharpie and install the rocker at "zero" lash.  Roll the engine over a few times.  Remove the rocker and check the witness mark on the valve.  The goal is to get as narrow a mark as possible.  Centering is nice, but correct length may be slightly off center, the focus is to be as narrow as possible.

It will take a good number of trys and adjustments to find the right length, it's trial and error.  Then order the right length push rod.

(*this proceedure assumes you have an adjustable valve train.  If you have pedestal rockers: see the site below)

If you would like to some high level engine tech dealing with performance parts, I highly recommend sbftech.com.  Get 10 posts in and a weath of information opens up.  Do some reading.  It's an education opportunity rarely available.

Mark

Valve Train Noise - How to Measure Correct Pushrod Length?

Reply #3 –
Thanks Mark, you told him how to do it the correct way but do you really think it necessary?  Seems like to me if you just check it on the base circle and get the tip in the right spot it would be good enough?  This way you do not have to pull the intake or use a light spring.  At the very least it will tell you if you are in the ballpark with your old push rods.

My first cam in the Cadillac 500 was a Comp XE 274 and it was a pretty good size cam even for this engine.  It was also ground on a 110 LSA that the Cadillac did not like but I see this cam is on a 112; is this good for EFI?  I would expect a 114?

http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=1057&sb=2

I would think that this would be a very healthy engine when all the bugs are worked out.

I hate to say it buy I know very little about the 5.0 and I should not even be commenting here.

TED

Valve Train Noise - How to Measure Correct Pushrod Length?

Reply #4 –
Mark,

The heads are coming off and I am switching cams again.  I got in touch with Ed Curtis and he ground me a new cam which is very similar to this one but with a touch more lift on the intake side.  I am going to have the heads worked on per Ed's suggestion and have a guy in Oklahoma City who can do the work.

With that swapping the springs out will be no problem and I will save one of the old head gaskets to get the correct compressed thickness.

The valve train is fully adjustable so no issues there.  Hopefully this will do the trick and get the tick, tick, tick  gone.

Thanks for the info and your time.  Its going to be a month or so before I do this as I had to get in line to have the head work done but I will post back with the results.

For what it is worth the car put down 318 rwhp /323 ft-lbs of torque.  The torque came on around 2500rpm and did no let up until the pedal was lifted at 6000 rpm.  Peak was at about 4200 rpm.


Ted,

Oil pressure is 60 psig cold, 35 psig at idle, and jumps back up to 60 psig when you get in the throttle.  It has the Melling pump that has an adjustment on it to set the pressure.  It was put in a jig at Folks Automotive Machine in Norman, OK and set at 65 psig.  Charlie told me it would most likely loose a few pounds in the motor.

As far as I can tell the noise is coming from all of the valves.  Both banks have the noise and it is pretty even up and down the valve covers.

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Valve Train Noise - How to Measure Correct Pushrod Length?

Reply #5 –
Ted,  Definetely appreciate your input.  Be it a Caddy or Ford, the basics are all the same!

Darren,

Glad to hear you hooked up with Ed.  Though I have no personal experience with him, he has great reputation and many years working specifically with SBF's.  He will steer you straight. 

It's a bit of a leap of faith choosing a custom cam, but in my experience they are the best money I've ever spent on a high performance part!

When I ran the 274, it made impressive dyno numbers too and sounded bad as hell, but it was not fun to drive.  It was pretty soggy until the rev's were above 2,500 (which is all normal driving), it would buck at cruise at low RPM and the mileage was poor.  A custom cam solved all those issues (at idle it pulled in every gear including 5th [I broke a throttle cable on the HRPT] and went from 18-19mpg hwy to 23-24 mpg).

Ed will also make sure you've got the right valve springs to work the cam to make sure the valve train stays happy.  He believes in working the full combination.

I'll be interested hearing your results when it's back together.

Mark
 

Valve Train Noise - How to Measure Correct Pushrod Length?

Reply #6 –
Ed WILL make you happy ;)
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Valve Train Noise - How to Measure Correct Pushrod Length?

Reply #7 –
Ed was good to go with the current setup on the heads with the exception of getting the bowls blended and having a couple of pinch points relieved.  I just forwarded his email to Charlie and he knew exactly what Ed was talking about and said the guy new what he was talking about.  I was glad that Charlie agreed with Ed or I would have gone somewhere else:D

I do have one question though.  I am going to get a set of Comps Hi-Tech pushrod length checkers but I cannot find anywhere on their site where it mentions the low tension springs in conjunction with these checkers.  Am I missing something?  I just want to make sure that I do this right but I don't want to work my ass of if its not necessary either.  If I don't have to use the low tension springs then I can install the cam, degree the cam per Ed's recommendation, and put the heads back on fully assembled.  Once I get there I can follow the instructions on Comp's site (thanks again Ted for the link) to measure the correct pushrod length and order what I hope to be the problem solvers.

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Valve Train Noise - How to Measure Correct Pushrod Length?

Reply #8 –
Darren,

The push rod checker's are often of a lighter construction and can deflect under the load of a "real" valve spring.  Hence the recommendation of the checker springs.  Yeah, it's a PITA, but what's a few more hours into a project which has so much time and cash already invested?  Cheap!

I called Summit to get my most recent one.  It was from Comp.  My old one was a very sturdy unit, w/fine threads on the joint.  The new one's lame in comparison w/course threads and a little loose.  I know it won't take the 400+ lbs open pressure on the HR springs I use. 

I'm sure the old one disappeared into another dimension... just as I'm sure it will reappear some day, when I give up OHV engines and move into technology of the current century.

Valve Train Noise - How to Measure Correct Pushrod Length?

Reply #10 –
I kinda figured it was better to error on the safe side so I ordered the checkers and the springs.  I ended up ordering the 7705 kit as the Bird has a 351W in it and its never a bad thing to have tools.

Will let you know how it goes as soon as I can get the heads worked over.

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp