Results of poor valve adjustment of 409 425 hp motor?

[32witha409]

DUH, go back to post #23 and you can see the "90" from the 690 head casting number. NOW go to post #27 and take a peek at the 5/16" push rods rattlin around in the guide holes. WTF? Am I seeing things wrong? Leo

Im only asking you this because I want to give you the option to clarify.
Are you being an azz or ? You certainly have no position to come off like that to me........ Or trying be point out something you missed..

If I miss read your post I do appologize...

 

[62impala409]

Why didn't we see this earlier???? Too much googling in the "chicks" area. Leo

Im only asking you this because I want to give you the option to clarify.
Are you being an azz or ? You certainly have no position to come off like that to me........ Or trying be point out something you missed..

If I miss read your post I do appologize...

Sorry, My response was not entirely to your post. Your post woke me up! What I meant was how could so many of us other forum participants have missed something so obvious. We are up to about 80 comments and your recent post made me slap my forehead. Many of us didn't see the forest because of all the trees I guess. I sincerely apologize if I offended anyone. Leo

 

[Don Jacks]

OK,We've determined that there's a possible push rod error,but do not overlook the excessive spring pressure/wrong spring areas of concern.Leo,dont be so hard on your self.I have a feeling that there's more than one "simple" problem going on here.

 

[CDNpontiac409guy]

I have a feeling that there's more than one "simple" problem going on here.

I'm outa this one

 

[Michael Cohen]

On the first push rod break on # 2 cyl the bent rod's # was MPR 35 ab that fell into the manifold area and was severely bent The less bent push rod has a # MPR 105 or 185 it was scratched when bent right in the # on the push rod making it hard to read. Putting it in the sun light it is MPR 105

 

[Michael Cohen]

Is the push rod size diameter?

 

[Don Jacks]

Well,I did a little research on Crane's website.Turns out that there are 2 425 replacement cams offered.One is a hydraulic lifter "replacement" grind,pn.h230/3101/2s/4,the other is of their "blueprint" series,pn.383690,is a solid lifter cam.If you have the hyd.version,and you're trying to run solid lifters on it,you'll never get to sound right due to the fact that hyd.cams do not have the "take up ramps"that Aubrey mentioned.It will literally beat the valvetrain apart.The excessive spring pressure that your mechanic noted has me concerened,especially with todays oils.These parts wouldnt take that kind of pressure back when we didnt have zinc problems with the oils,today it's a recipe for desaster.This is a place wheere we need to slow down[check everything] in order to speed up ,and stay that way for a while.

 

[Don Jacks]

Yes,the push rod diameter is what we're talking about.If you're using the 5/16 dia.push rod in your 690,or 583 heads,your using the wrong one.The push rod holes in the head act as guides for the pushrod .Your heads must have the 3/8th dia.pushrod in order to work correctly,the small push rod simply would have too much clearence to stay in place.

 

[Michael Cohen]

I measured the push rods they do look like 5/16th not 3/8th. I don't have a pinch style measuring tool. Used a ruler on a web site. But in any case will have that answer soon. Thanks for the investigations! I owe dinners for all who helped when you come to LA ( Maybe at the 409 gathering coming up.) !

 

[Michael Cohen]

Man one sixteenth of an inch! wow!

 

[Don Jacks]

1/16 th in=.0625,a BUNCH in an engine where .003 can spell sucess or disaster.

 

[MRHP]

Use a 5/16 or 3/8 wrench for your measuring.

 

[32witha409]

Why didn't we see this earlier???? Too much googling in the "chicks" area. Leo

Sorry, My response was not entirely to your post. Your post woke me up! What I meant was how could so many of us other forum participants have missed something so obvious. We are up to about 80 comments and your recent post made me slap my forehead. Many of us didn't see the forest because of all the trees I guess. I sincerely apologize if I offended anyone. Leo

Thanks for clearing it up... Amazing what is lost with only text to evaluate...

The first hint on the PR diameter was when the OP said the roller rockers slid off the valve. I finished reading the thread and saw photos of the straight not necked PR's and the guide hole in the head looking like a 690 583..

 

[32witha409]

I agree also that there are possibly other gremlins running amuck..
But #1 failure mode if the lack of rocker and pushrod guidance...

 

[Bub6le 2op]

the difference between 5/16 and 3/8 is really pretty big you should be able to get close with a regular tape measure
just take the pushrod and push it thru a piece of paper then draw lines on each side of the hole then take a tape measure
and measure the distance between the lines you can also buy a set of digital calipers from harbor freight for around 15.00

 

[chevymusclecars]

I'm outa this one

Me too, he has more problems than the obvious!!

Bill

 

[blkblk63ss]

Use a 5/16 or 3/8 wrench for your measuring.

Another trick is anything you want to measure use a cresent wrench large or small ,tighten on what you are measuring and then measure opening on wrench with caliper's or tape measure!!!!, but then if you have caliper's , that's all you need.

 

[Michael Cohen]

Yup 5/16ths not 3/8s fur sure.

 

[Michael Cohen]

So new 3/8s are in order. Suggestions on the ones to get? I am sure now new springs are in order but will await testing. I think the major underlying problem was not having expert 409 mechanic building the first time then having someone with no 409 experience compounding mistakes with assumptions not experience. Building other Chevy motors I can see are a whole ball of wax different than 409's. Now with my 64 motor will check all this stuff before starting it up. It is less hp a 340hp type but will now question my builder with more exact info before problems arise. Due mainly to your all help! A devote' of the 348 409 forum. Michael

 

[Michael Cohen]

Leo I think you are spot on with insight to the problems Thanks