C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette

'69 427 Bent Push Rod

 
Old 03-09-2019, 03:44 PM
  #41  
derekderek
CF Senior Member
 
Member Since: Jul 2015
Location: Westville NJ
Posts: 4,467
Thanked 558 Times in 523 Posts
Default

Yes. There are 2 measurements you have to check. One is coil bind. The other measurement is the distance from the bottom of the valve retainer to the top of the valve seal. As the coil might not bind but the valve itself might. Or the valve might have plenty of travel if you had a different Spring in there. So call my you could actually put the valve retainer back on with no Spring or with a tiny little flimsy went be Spring I rotate the engine and watch what the rocker and push rod does with the valve travel if it comes too close to bottoming out on the valve seal.

Last edited by derekderek; 03-09-2019 at 03:50 PM.
derekderek is online now  
The Following User Says Thank You to derekderek For This Useful Post:
Z06CE (03-09-2019)
Old 03-09-2019, 03:57 PM
  #42  
derekderek
CF Senior Member
 
Member Since: Jul 2015
Location: Westville NJ
Posts: 4,467
Thanked 558 Times in 523 Posts
Default

derekderek is online now  
The Following User Says Thank You to derekderek For This Useful Post:
Z06CE (03-09-2019)
Old 03-09-2019, 05:22 PM
  #43  
jackson
CF Senior Member
 
Member Since: Sep 2001
Location: Timmonsville SC
Posts: 4,762
Thanked 95 Times in 89 Posts
Default

measure lobe on its heel or base (minimum) -- record it
roll motor over about one full crank rev OR one-half cam rev
measure lobe on its top or nose (maximum) -- record it

subtract base from nose = lobe lift

lobe lift x RAR (seems yours is 1.7) = valve lift (theoretical)

Use a dial indicator fixed perfectly square (No sine error) to retainer --- to determine valve lift (measured) ... a 6" caliper will do for what you need.

Critical to know if any coil bind/how much gap between coils when valves FULL OPEN.
Without info, I lean toward too big cam for too scrawny springs ... inspection & measurement will tell the tale.

Again, look for witness marks on RA studs & RA slots.

What you need to accomplish is to find WHY & HOW the failure so you can correct. Measurement alone may not solve this. Don't buy any parts until you've identified any & all damages and you're certain of root cause.
jackson is offline  
Old 03-09-2019, 06:37 PM
  #44  
HeadsU.P.
CF Senior Member
 
HeadsU.P.'s Avatar
 
Member Since: Aug 2017
Location: Cool Northern Michigan
Posts: 2,006
Thanked 346 Times in 327 Posts
Default

Originally Posted by CanadaGrant View Post
I'm still of the opinion that this is straight coil bind because somebody cheaped out and didn't replace the springs with the new cam. If you look at Comp Cams website for example, even with one of their fairly mild cams whether it's a roller or flat tappet hydraulic, you must replace the stock 427 valve springs in stock heads or risk coil bind. I think that's what's in the pics, not pistons hitting valves. It isn't a valve timing issue. When you're changing the springs (throw in some valve seals at the same time) and using compressed air to hold the valves up on that cylinder you will know right away if you have a bent valve. You will hear it and it won't hold pressure. Your main problem is figuring out what cam you really have and what or whose springs to use.
If it is coil bind, why not all 16? It appears just intakes are bent? That would indicate valve timing / piston strikes wouldn't it?

And on BBC, doesn't the intake valves have to have block clearance (notched)? H-m-m-m-m-.

Last edited by HeadsU.P.; 03-09-2019 at 06:42 PM.
HeadsU.P. is offline  
Old 03-09-2019, 06:55 PM
  #45  
Jebbysan
CF Senior Member
 
Jebbysan's Avatar
 
Member Since: Mar 2012
Location: New Braunfels Texas
Posts: 3,089
Thanked 354 Times in 319 Posts
Default

Originally Posted by Z06CE View Post
What is the rope trick?... I have used air pressure to hold the valves in place on a 347 ford a while back
The rope trick is to carefully thread a bunch of rope into the cylinder to fill the cavity and keep the valves from dropping.....it sounds crude but actually works pretty well if you use the right rope....soft 1/4 rope.
It is how it was done in the prehistoric times!!!

Jebby
Jebbysan is offline  
Old 03-09-2019, 07:03 PM
  #46  
Jebbysan
CF Senior Member
 
Jebbysan's Avatar
 
Member Since: Mar 2012
Location: New Braunfels Texas
Posts: 3,089
Thanked 354 Times in 319 Posts
Default

Just do a leak down on the engine right now.....
You can buy an OTC leak down tester for $65.
It will tell you immediately if the valves are bent....
If all is good....you have a spring or retainer crash.
I would pull the intake at this point to take a look at everything....it is also much easier to lash with the intake off so you can stare at the lifters....

Jebby

Last edited by Jebbysan; 03-09-2019 at 07:03 PM.
Jebbysan is offline  
Old 03-09-2019, 07:38 PM
  #47  
CanadaGrant
CF Senior Member
 
CanadaGrant's Avatar
 
Member Since: Apr 2006
Location: Blind Bay BC
Posts: 3,687
Thanked 262 Times in 232 Posts
Default

Originally Posted by HeadsU.P. View Post
If it is coil bind, why not all 16? It appears just intakes are bent? That would indicate valve timing / piston strikes wouldn't it?

And on BBC, doesn't the intake valves have to have block clearance (notched)? H-m-m-m-m-.
Block is not notched. Same as a 454. I would think it's a small installed height difference on that motor between the intake and exhaust valves. Might be machining. Might be different cam intake vs. exhaust lobe height/lift. If you are close to coil bind anyway, it doesn't take much to start bending pushrods. Those stock springs are not meant to take any more lift and intake and exhaust valves are also different lengths and sit at different locations in the head so a little tighter on the intake vs. exhaust is easy to see happening.

Last edited by CanadaGrant; 03-09-2019 at 08:06 PM.
CanadaGrant is offline  
The Following User Says Thank You to CanadaGrant For This Useful Post:
HeadsU.P. (03-09-2019)
Old 03-09-2019, 07:39 PM
  #48  
jackson
CF Senior Member
 
Member Since: Sep 2001
Location: Timmonsville SC
Posts: 4,762
Thanked 95 Times in 89 Posts
Default

Perhaps First, rule in or out the typical.

Perhaps maybe speculate maybe the intake lobes are ground for higher lift than exhaust ... maybe not ... maybe cam timing maybe not ... first do the obvious/most likely ... in or out.

so far the heads are on it ... perhaps first check everything you can with heads on. Little by little the root cause will reveal itself.
jackson is offline  
Old 03-09-2019, 07:45 PM
  #49  
CanadaGrant
CF Senior Member
 
CanadaGrant's Avatar
 
Member Since: Apr 2006
Location: Blind Bay BC
Posts: 3,687
Thanked 262 Times in 232 Posts
Default

Originally Posted by Jebbysan View Post
Just do a leak down on the engine right now.....
You can buy an OTC leak down tester for $65.
It will tell you immediately if the valves are bent....
If all is good....you have a spring or retainer crash.
I would pull the intake at this point to take a look at everything....it is also much easier to lash with the intake off so you can stare at the lifters....

Jebby
Don't pull the heads unless you know you have a valve problem or want to rebuild everything. A compression or leak down test will confirm. Pulling the intake is a very good plan as it's not much work and only some gaskets.
CanadaGrant is offline  
Old 03-09-2019, 09:09 PM
  #50  
Z06CE
CF Member
Thread Starter
 
Z06CE's Avatar
 
Member Since: Apr 2013
Posts: 89
Thanked 0 Times in 0 Posts
Default

Originally Posted by Jebbysan View Post
Just do a leak down on the engine right now.....
You can buy an OTC leak down tester for $65.
It will tell you immediately if the valves are bent....
If all is good....you have a spring or retainer crash.
I would pull the intake at this point to take a look at everything....it is also much easier to lash with the intake off so you can stare at the lifters....

Jebby
What is a retainer crash?
A spring crash is when the spring can't compress...
The coils are bottomed out correct?
Z06CE is offline  
Old 03-09-2019, 09:14 PM
  #51  
Jebbysan
CF Senior Member
 
Jebbysan's Avatar
 
Member Since: Mar 2012
Location: New Braunfels Texas
Posts: 3,089
Thanked 354 Times in 319 Posts
Default

Originally Posted by Z06CE View Post
What is a retainer crash?
A spring crash is when the spring can't compress...
The coils are bottomed out correct?
Retainer crash is when the bottom of the retainer hits the top of the valve guide boss....in some cases this can happen before the spring reaches bind.

Jebby

Last edited by Jebbysan; 03-09-2019 at 09:15 PM.
Jebbysan is offline  
Old 03-09-2019, 09:25 PM
  #52  
Z06CE
CF Member
Thread Starter
 
Z06CE's Avatar
 
Member Since: Apr 2013
Posts: 89
Thanked 0 Times in 0 Posts
Default

The C retainers that hold the springs can hit? Wow.

I know what the crap push rods were used...
They are Sealed Power
Exhaust part# RP 3103. 9.2540"
Intake part # RP 3104. 8,2810"
3/8 dia. .060. Wall
It might have been a blessing that the PR's bent before anything else!
Z06CE is offline  
Old 03-09-2019, 09:31 PM
  #53  
Jebbysan
CF Senior Member
 
Jebbysan's Avatar
 
Member Since: Mar 2012
Location: New Braunfels Texas
Posts: 3,089
Thanked 354 Times in 319 Posts
Default

Originally Posted by Z06CE View Post
The C retainers that hold the springs can hit? Wow.

I know what the crap push rods were used...
They are Sealed Power
Exhaust part# RP 3103. 9.2540"
Intake part # RP 3104. 8,2810"
3/8 dia. .060. Wall
It might have been a blessing that the PR's bent before anything else!
It is a blessing and now you need to figure out why.
Yes the retainer can hit....but on a Big Block not likely but still could happen....
SBC Vortec is limited to .465 lift due to retainer crash and there is a boss machining tool designed for it....very well known thing.
But go back to my post #19 and follow my instruction and you will know for sure!

Jebby
Jebbysan is offline  
The Following User Says Thank You to Jebbysan For This Useful Post:
Z06CE (03-09-2019)
Old 03-09-2019, 11:18 PM
  #54  
Z06CE
CF Member
Thread Starter
 
Z06CE's Avatar
 
Member Since: Apr 2013
Posts: 89
Thanked 0 Times in 0 Posts
Default

Well I was wrong about the head casting Numbers
The heads should be 3931063
I have:
336781 used in the 454 vette in 1974
The block is correct 3963512
Z06CE is offline  
Old 03-09-2019, 11:34 PM
  #55  
CanadaGrant
CF Senior Member
 
CanadaGrant's Avatar
 
Member Since: Apr 2006
Location: Blind Bay BC
Posts: 3,687
Thanked 262 Times in 232 Posts
Default

Originally Posted by Z06CE View Post
Well I was wrong about the head casting Numbers
The heads should be 3931063
I have:
336781 used in the 454 vette in 1974
The block is correct 3963512
The 3963512 block used in the 69 427 was also used for 70 454's. Exact same block right down to the casting number. Different crankshaft gave it the additional cubes.

Last edited by CanadaGrant; 03-09-2019 at 11:35 PM.
CanadaGrant is offline  
Old 03-10-2019, 04:53 AM
  #56  
Little Mouse
CF Senior Member
 
Member Since: Apr 2006
Posts: 4,678
Thanks: 0
Thanked 12 Times in 10 Posts
Default Cant go to big

BBC with its really long pushrods and even worse angled at 4 degrees, you can never have to stiff a pushrod and weight of the pushrod means nothing. Worst thing i ever saw suprised me was a new 78 3/4 ton pickup i bought with a 454 had 5/16 pushrods in it. Everytime i think about that peice of **** all the trouble i had with it. Someone should take a baseball bat to someone that would put a 5/16 pushrod in a bbc.

Last edited by Little Mouse; 03-10-2019 at 04:55 AM.
Little Mouse is online now  
Old 03-10-2019, 08:06 AM
  #57  
derekderek
CF Senior Member
 
Member Since: Jul 2015
Location: Westville NJ
Posts: 4,467
Thanked 558 Times in 523 Posts
Default

OK, your CR is lower than originally was. Big diff in chamber size. Of course we don't know if pistons were also replaced. Or whether they are 2.06 orig valves or 2.18 or larger. 781 is also a 454 truck head from 73 to mid-80's. And most got bigger valves and port work when they were installed on anything but the truck they came out of. Maybe get a borescope and try to get a pic of a piston top. Closed chamber pistons rarely have an issue with open chambered heads as far as clearance goes, but if somebody put big valves above pistons whose reliefs only clear small valves they can hit.
derekderek is online now  
Old 03-10-2019, 08:37 AM
  #58  
Z06CE
CF Member
Thread Starter
 
Z06CE's Avatar
 
Member Since: Apr 2013
Posts: 89
Thanked 0 Times in 0 Posts
Default

Originally Posted by derekderek View Post
OK, your CR is lower than originally was. Big diff in chamber size. Of course we don't know if pistons were also replaced. Or whether they are 2.06 orig valves or 2.18 or larger. 781 is also a 454 truck head from 73 to mid-80's. And most got bigger valves and port work when they were installed on anything but the truck they came out of. Maybe get a borescope and try to get a pic of a piston top. Closed chamber pistons rarely have an issue with open chambered heads as far as clearance goes, but if somebody put big valves above pistons whose reliefs only clear small valves they can hit.
What is CR?
Z06CE is offline  
Old 03-10-2019, 08:56 AM
  #59  
derekderek
CF Senior Member
 
Member Since: Jul 2015
Location: Westville NJ
Posts: 4,467
Thanked 558 Times in 523 Posts
Default

compression ratio. this was about 10.5 to 1 when new. if these heads are on that orig 427, it is about 9 to 1 now. not an issue until you are trying to get into the 11's.
derekderek is online now  
Old 03-10-2019, 09:19 AM
  #60  
cuisinartvette
CF Senior Member
 
Member Since: Oct 2004
Location: Valencia Ca.
Posts: 67,847
Thanked 1,106 Times in 1,017 Posts
St. Jude Donor '05
Default

Originally Posted by Little Mouse View Post
BBC with its really long pushrods and even worse angled at 4 degrees, you can never have to stiff a pushrod and weight of the pushrod means nothing. Worst thing i ever saw suprised me was a new 78 3/4 ton pickup i bought with a 454 had 5/16 pushrods in it. Everytime i think about that peice of **** all the trouble i had with it. Someone should take a baseball bat to someone that would put a 5/16 pushrod in a bbc.
haha
Pushrods are kind of a fusible link, op you are probably fine put some good ones in and motor on.
I bent a few on a brand new motor somehow got ahold of some knockoff Manley pieces it screwed teh valvetrain up (ALL of it) in 60 mi
Guy overat Manley sent me the real deal no issues since.
Gearheads sometimes convince themselves pushrods and old springs "are fine"
cuisinartvette is offline  

Thread Tools
Search this Thread
Sponsored Ads
Vendor Directory

Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: