So...I have an '82 f150 with a 351W. I believe that I'm the second owner of it, and the PO gave the truck a lot of field time. You know, time where you park it in the field...and then forget about it. I've cut the rust out of the floor, welded in new metal, rebuilt the leaky 9", replaced/painted/cleaned up everything in the cab, installed a new wiring harness, and now I'm working on the engine.

I put aluminum heads on it, along with a new cam a few weeks ago. The cam that I bought was CRAZY!!! I had my timing set up to 30 degrees advanced, and my idle wouldn't go lower than 1100 rpm. I only wanted the truck to be strong. Not light the tires up at 45 mph. The "rapped out race cam" had to go.

I replaced the cam yesterday with an Edelbrock performer. I made sure that my marks were at 6 o'clock, and 12 o'clock. I turned the motor over by hand a couple turns to cure the gut feeling that nothing was going to hit. Then I tried turning it over. It just turns, and turns, and turns. Both of my #1 valves are shut when #1 is at TDC. The rotor is at 1 on the cap at TDC.

I'm at a complete loss. I have no compression, but I do have fuel and spark. I don't know what to do. I have too much in to this truck to roll it in to the river. Any ideas of why it ran before the cam, but suddenly has no compression?

Cheers,
Jason

 

Loosen all the bolts on the rocker arms and see if you have compression. If you do, either the valve lash is not right or the valve timing is not right.

 

If you want to check valve timing, then besides checking #1 at tdc, turn the balancer 1/4 turn and check the next cylinder in the firing order for the piston to be at the top and both valves shut. Turn it 1/4 turn again and go to the next cylinder. Keep going all the way around twice till you do all 8.

 

Ok. I finally had some time to fix/work out my problem, but I still don't know why it was a problem. I took the front of my engine apart to verify I wasn't a tooth off with my cam sprocket. It was fine. I finally then followed advice. I loosened the rocker arms on number 1, and viola! I have compression on number one. I then shimmed all of the rocker arms, and my engine runs.
My question now is why did a Lunati cam/lifters with new aluminum heads and new roller rockers run freakishly well, but the same system with Edelbrock cam/lifters has the wrong length push rods?

 

My guess the first cam was a higher lift and higher lift cams need longer push rods.
Now if the cam you pulled out was stock and reused the push rods I don't know what to say then?
Dave - - - -

 

Yep. The first cam I pulled was the original. I ordered new pushrods when I got my first batch of parts, but I believe they are for a 289/302 because they were way too short. So even though I'm somewhat ashamed to say this, I'm still using stock pushrods.

 

As long as the push rods you pulled out are not bent or have warn tips and are the right size then I would use them.
I have reused push rods in a drag only motor because they were the right size, in good shape and needed them to get the motor running for a race the next weekend.


Most of the time the cam card / install sheet will say if you need longer push rods.
I thought the Edelbrock performer cam used stock push rods but I guess not?
Dave ----

 

I just got to thinking of your set up. Mainly the alum heads & roller rockers.


Now I first have to ask how does Ford setup stock rockers? Do they get rund all the way down and torked to ft lbs OR do they get taken up till they stop making noise and then 1/4 to 1/2 turn more?


Some roller rockers are a direct replacement and installed just like the stock rockers. Others are what they call "adjustable" were you take them up till they stop making noise and then 1/4 to 1/2 turn and lock down the set screw.


So not knowing you valve train setup (rockers) it could of been you just lucked out with 1 cam and not the other on how you installed them.
Dave ----

 

Different cams sometimes have different what they call "base circles". They can have the same lift but the whole operation is offset up or down and the valve train is not adjustable on the stock engine.

Ford also had different length pushrods because they used different rocker systems through the years.

The very first 289's had a setup very similar to the small chevies and it was adjustable and took it's own pushrod length.

They then came out with the "rail rockers" and these were not adjustable and had their own length pushrods. These type are easily made adjustable with a kit you can buy aftermarket.

Around 78 they came out with the "sled" type rocker system which again, took a different length pushrod. These are not adjustable, not easily made adjustable, and they used these on up till they went to the modular engines.

 

Thanks Franklin


Being he is using alum heads and roller rockers he could have anything to have it working.


On the base circles I know that is how they get more lift, make it smaller but keep the lobe the same as the lobes will not clear the bearing, just never gave it a thought of that for same lift cams from other companies. Good call.
Dave ----

 

All right, problem discovered, and on the up and up. I have non adjustable proform pedestal mount roller rockers. They call for one torque setting; 20 ft lbs. When I installed the Lunati cam, I compared the lifters to the stock ones I was replacing, and they were exact. With the Edelbrock cam, I did not compare them. I just figured Edelbrock as a generic that would fit exactly. Wrong! Turns out my Edelbrock lifters were slightly taller than originals, which made the torque spec force the plunger in the lifter to bottom out, which resulted in valves being forced open all the time, building no compression.
I decided to look up shimming rocker arms on you tube (I did order shims), and laughed at a video of a guy using 'plumber's tape'. That was when I thought, "Hey, these washers fit around the bolt perfectly." I was right about the fourteen that I had in a pack, but the other two I had to dig through the 'ole cluster of stuff. The problem the two caused is that they were slightly thicker.
The two sloppy pushrods that bent, also caused two valves to bend. I'm currently assembling with Edelbrock cam, Lunati lifters, and no washers. I have shims if I need them. Wish me luck.

 

Good to hear you found the why but not good on the broken parts - bent valves.


I did not think the lift to be that big that the valves would hit a piston like in if the timing chain was to let go.
Unless you have hi compression pistons and if so then why such a low lift cam.
Dave ----

 

I don't understand what you mean by a low lift cam. Stock lift is .416/.416 Lunati was .472/.496, and the Edelbrock cam is .448/.472

I finally called Summit today, and talked with a guy who gave me some guidance. He told me to cut a push-rod, and thread a round head screw in to it to make an adjustable push-rod. In doing so I was able to take it to zero lash, torque it down to specs and pull a measurement. Stock rods are .150" too long for my application.

I think that if I would have known how to set valve lash with the Lunati cam, I would have discovered problems with push-rod length there too. Just not as bad.

Maybe some day I will have my masters degree in the school of hard knocks. lol

 

By low lift as a rule anything under 500 lift (on an AMC motor would think same for a Ford)) should not have valve & piston hit each other but would use clay just to make sure.


I guess with all the changes you made and mix match parts that is not so. The big one lifters from a different manf. than the cam.
Dave ----

 

I think you know what is going on but some of your wording has me worried. There is really no way to "set" the valve lash on a stock Ford, unless you have a barrel full of different length pushrods. Your comment in a previous post is another one I am worried about, you made the comment on the 20 ftlb spec for the bolt and that it had something to do with pushing the pushrod down too far into the lifter. You can't change this 20ftlb spec to set the valve lash. It should ALWAYS be 20 ftlb so the bolt will not come loose. If you use shims, the bolt is still torqued to 20ftlb.

The guy you said that was using teflon tape must have been trying to tighten the threads of the bolt up so he could set the height of the bolt, but I don't see that as a permanent solution.

Just making sure there is no confusion. Fords are great when they are stock, just bolt them together and go. Any changes and it's not too easy.