That engine should be removed and completely redone by a competent 409 engine builder. Sorry for the downer opinion but every thing else is just a band aid.
Results of poor valve adjustment of 409 425 hp motor?
- Thread starter Michael Cohen
- Start date
CDNpontiac409guy
Banned
I'm inclined to agree. What seems to be "surface" wrong here, is something that even a novice high performance engine guy would never have let happen. Lift, spring travel, rocker arms, are extremely simple mathematics.
At the very least, start with having a high performance engine mechanic look at... someone who is as comfortable with valve train geometry, as others are with installing a hub cap.
Any suggestions in L.A. Ca. area?
That's along way away! Got to be somebody good in So Cal? I did speak to him months ago. Very helpful.
It is a tough pill to swallow 
Not trying to be inconsiderate Michael but...........what would it cost to drive up and see Jack if the next guy you have build your engine ends up not knowing what he's doing? Jack is a PRO...you know what you will get with Jack's experience.
People ship their engine's thousands of miles to Jack for his expertise.
He's built hundreds of 409's.
As close as you are to him, it would be crazy not to take it to him !
Pease of mind.
I own a motor built by Jack.
Randy
He's built hundreds of 409's.
As close as you are to him, it would be crazy not to take it to him !
Pease of mind.
I own a motor built by Jack.
Randy
Well did get some new info today. I was wrong about not installing a new cam. The man who built my motor put a new stock Crane 409 425 hp camshaft. Hydraulic stock lifters. I do know the 425 hp was to have solid lifters but we discussed this awhile ago (fading memory refreshed) and we decided because of not racing the motor, low or no zinc oils, less problems to go hydraulic. But I did find out that the valve springs were not changed from the Michigan build. They could be BBC springs because the Michigan builder used a stronger more aggressive Iskendarian (sp) cam with roller rockers. So they are stronger than stock 409 hp springs. We are planning to take one set off and test them. If they test too strong will replace all springs. Also going to look for notched rocker arms so they will not slip off the rocker arm stud (see I am learning the nomenclature).Any help where to find them? I cannot afford at the moment to do a Jack Gibb rebuild. I hope these more simple modifications will make the motor stop throwing push rods. I feel that with the stock cam and hydraulic lifters and possible new springs the motor will last. It is a numbers matching setup at the moment. So I think of the car more as a collector car rather than a cruiser. I've got the 6 cyl green 63 pictured for cruising. Get the good looks and thumbs up just as much with the green 63 6 cyl as the brown 409 cause most people don't know the difference. The motor was compression checked after 409 was started. Around 175 to 185 average.
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Make sure your motor still has the original 3/8" push rods that the heads were machined for and not the wimpy 5/16" push rods. Big springs and a oversized guide hole WILL throw push rods. :eek Leo
CDNpontiac409guy
Banned
Hydraulic lifters on an "out of the box" Crane 425 HP solid profile ???????????
This has to stop. The more I hear, the worse it gets
.
Solid lifter cam profiles, have an opening and closing ramp. Averages about .020" in lash, which acts as a "cushion" for the valve train. That profile, with hydraulic lifters, is a "ticking bomb" ( pun intended
).
The "ramp" on the solid cam, will cause the valves to float out of control.
Anyhow, if nothing is wrecked yet, that cam requires about 115-120 pounds on the seat... maybe 280-290 open. No more than that.
As Leo just mentioned... the push rods. It REALLY does sound like a case where 5/16" were use where 3/8' were supposed to be. With what I've been seeing here, it would be just more in the pattern.
This has to stop. The more I hear, the worse it gets
. Solid lifter cam profiles, have an opening and closing ramp. Averages about .020" in lash, which acts as a "cushion" for the valve train. That profile, with hydraulic lifters, is a "ticking bomb" ( pun intended
). The "ramp" on the solid cam, will cause the valves to float out of control.
Anyhow, if nothing is wrecked yet, that cam requires about 115-120 pounds on the seat... maybe 280-290 open. No more than that.
As Leo just mentioned... the push rods. It REALLY does sound like a case where 5/16" were use where 3/8' were supposed to be. With what I've been seeing here, it would be just more in the pattern.
No Aubrey,Crane sells a "replacement" 409-425 cam that is designed for hydralic lifters.You are,as expected,right on the needed spring pressure,if in fact that's whats in Micheals engine.I just hope that he's not trying to solid lifters on a cam ground for hydraulic lifters,just wont work for long.
I also questioned the pushrods in the photos. The ball is 5/16 and the tube looks like the same size. Those are the wrong rods if theheads are hipo. They should be necked down at the tips.
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. Am I seeing things wrong? Leo
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