[k.c.]

I'm putting a 744 cam in my 389. I've been told that I need to remove one of the valve springs on each valve for cam break-in. Why and which one? Is 2000-2500 rpm for 20 min. about right?

Thanks
k.c.

[Ron Landis]

Originally Posted by k.c.

I'm putting a 744 cam in my 389. I've been told that I need to remove one of the valve springs on each valve for cam break-in. Why and which one? Is 2000-2500 rpm for 20 min. about right?

Thanks
k.c.

I never have on a cam of that size. Do you have legit double springs or just dampners inside the single spring? Just make certain you have the proper adjustment and lubricants. You are correct on the rest. Doesn't hurt to have a fan up front to aid cooling. JMHO. Good luck. Ron P.S....you HAVE gone to an adjustable valvetrain...right? That is a must!

[k.c.]

I have what came on the engine. There are two springs.

[BVR421]

Is it a 744 or a high lift version like the Summit 2802? That might be pushing the limit for stock springs not only for clearance but for control. 40 year old stock springs may give up and float the valves far in advance of the optimum shift point of the 744 cam.
As mentioned 3/8" locknuts will be a good swap for the stock torque down nuts on the rockers so you can set the valves for about a 1/2 turn past zero on the preload.
Set them and double check and double check clearances as well.

744 cam timing will sound nice but in a stock 389 it might be a bit much.
I used a 2802 in my otherwise stock 428 and its great. I used a 2801 (068GTO cam) in my otherwise stock 389 and it sounds and runs sweet.

To directly answer your question: If the springs are used stock springs on an early 389 they will have very low tension so no dont worry about it. If they have been replaced with very stiff aftermarket springs then yes it is beneficial to remove the outer springs during breakin.

Have a known good and ready to run ignition and carb ready to go. The engine must start and go to about 2000rpm on the first or 2nd crank. Cranking the motor to get gas up to a dry carb or to find timing will wipe the breakin lube off the cam before it even starts so have it ready to run.

good luck you can do it!

[k.c.]

I hope this isn't a stupid question, but how do you set ignition timing before starting a new or rebuilt engine?