I have built what I believe to be a 1968 Ford 428 block. I have a 1U crank and had it bored .030 over.

Here's what I'm playing with:

I got the Edelbrock Performer RPM Intake and the matching Performer RPM Cam. The specs on the cam are:

DURATION AS ADVERTISED INTAKE: 296° EXHAUST: 296°
DURATION @ .050 INTAKE: 236° EXHAUST: 236°
LIFT @ CAM (Lobe) INTAKE: 0.325" EXHAUST: 0.325"
LIFT @ VALVE INTAKE: 0.572" EXHAUST: 0.572"

I used stock length 9.59" pushrods. This is Edelbrock suggested with the stock heads I am running. They are D2TE-AA heads that have been ported, polished, and had the cobra jet sized valves (2.090 intake,1.650 exhaust) installed. I am also running the suggested Edelbrock springs which are part number 5767.

I started the truck up and broke the cam in following Edelbrock's directions which were 2000-2500 RPM for 30 minutes.

Upon getting exhaust ran so I could actually hear the engine over the open headers before, it was ticking in the valve train. Pulled the valve covers and found that both exhaust and intake of the cylinder #5 pushrods were bent. I checked all of the other pushrods and none of the others were bent. I am using stock rocker arms...

I am putting it back together today with new pushrods and am going to turn it over and watch the valvetrain with the covers off to see how everything looks.

My question is with a .572 lift cam do I really need adjustable rockers? From everything I've read some folks say that they are required while others are running a cam of up to .600 lift and not having any issues with the stock rocker shaft assemblies.

Any help would be great.

Thanks, Jay.

 

You need adjustables with that lift. Need end stands too. But with bent pushrods, I'd pull both those lifters and see what the bottoms' look like. You could have wiped a couple of cam lobes.

 

If you did not check for lifter preload, then that is where I would start. Loosen them all, then start at #1 and put at TDC compression. Then snug the rocker shaft down slowly and watch valve tips. Likely see them sneak open when the lifter bottoms out.

I would carefully inspect all the lifters to be sure they are okay and recheck all the push rods. Even worse, you could have bent a valve or two. Might want to do a compression check with the rocker shafts off. Visually inspect to see all the valve tips are at about the same height(hopefully when machined they did try to keep them all the same).

 

All the lifters looked fine. I will check everything. I really don't have much money left over after building it and was wondering the exact reason for adjustable lifters. It doesn't make much sense to me. Especially with hydrollic lifters.

It would take a little bit of time but I really like the ease of the stock rocker set up. Would using different length pushrods for each valve do the same thing as adjustable rockers? Just a thought. Anyone ever done this?

 

The only reason for adjustables was for solid lifter motors. BUT, if you run a hydraulic cam with more lift then stock then USUALLY the base circle of the cam is larger and the very limited amount of preload is overrun if you use non adj rockers. Yes, you can get different length pushrods and get away from the adjustables. You can buy an adjustable version to check the length you need(check Summit racing or Jegs). You set it to the proper preload on the lifter(check multiple places to make sure they are all okay), then measure and buy the length you need. Very common practice.

 

The stock rocker arm shafts are good for about 5200 to 5500 hundred rpm any more than that your risking breaking the ends of them with the springs and lift your running

 

Well, I wiped a cam lobe or two. I am now in search of a different cam and lifter set. The motor is in a '76 4x4 truck. It will mainly be driven on the street with an occasional trail and muddy road. I am looking to get as much power as I can but would like to keep my non-adjustable rocker arms. Any cam recommendations?

Thanks, Jay.

 

Wow...I've run stock length pushrods with a .575 " lift cam without problems...But I also made sure the lifters were pumped up...ran them down til I heard til I didnt hear any clicking then back them off til I did again..then tightened just enough for the click to go away.. JMO.... Good luck..