Measure cam specs without pulling the cam?

[Tram]

Drove the Bronco to church tonight and a friends asked if it had an aftermarket cam.



"I'm not sure." I told him.



The guy I bought it from, thinks he was told by the guy he traded into it with, that it had a cam put in it. I've attempted to contact the PPO (previous-previous-owner) with zero luck. I got his son, his son didn't know anything about the truck. I've called his father "who built it" and he won't return my calls nor have I been able to get him to answer the phone.

Sooo..

I was thinking about pulling a valve cover, putting the dial indicator on the top of a pushrod and measuring the lift.

Anyone done this? Should at least get me in the ball park, I'd think?

 

[DirtDonk]

Yep, should do the trick. You probably need to remove a rocker arms from one cylinder so you can put the indicator on either a lifter or a pushrod, since the valve spring pressure against the rocker arm can compress a lifter with no oil pressure to hold it up. That would often (always?) give you a skewed reading.

That would only give you the total lift at the cam. You'd need the full degree wheel routine to get all the exact duration and other specs.
But lift alone should actually tell you what you need to know. Not what exact cam it is, but whether it's stock or aftermarket.

Good luck.

Paul

 

[Tram]

Yeh, that's what I was thinking.

It'll at least narrow it down some in terms of what has been done to the engine.

 

[Broncobowsher]

Readings may not match actual specs due to lifter bleed down as you turn it over. But it will give a good idea of what is going on.

 

[rguest3]

I have seen Cam Part numbers before stamped somewhere on the Cam.

Front end of the Cam??? Maybe???

 

[BR549]

Lot of work to find the cam specs, but the grind numbers are stamped on the front end of the cam.

 

[Broncobowsher]

Not front of the cam. No room with the machined area for the timing chain. Numbers (if present) are on the back of the cam. That is where I always found them.

 

[Tram]

As long as I can figure if the lift is different than stock, I'll be satisfied. At least I'll know if I should consider another cam.

 

[73azbronco]

Unless you have some special tool to get into the lifter bore and can hold a measuring device within .0001 of an inch, I'd say you will be waisting your time. Only reliable way to determine lift is with heads off and access to cam lobe, If you get that far along, you might as well put in the cam you want to be sure you have what you think you have.

Oh, once you do get the numbers, now you have to sift through countless cams to determine what you have...

 

[BR549]

Why would the cam manufactur put the grind numbers at the rear so you would have to pull it to find it? They are etched or engraved in. No additional clearance needed. Figue out that one.

 

[73azbronco]

They are usually at the back though...

 

[Mountain Ram]

Why would the cam manufactur put the grind numbers at the rear so you would have to pull it to find it? They are etched or engraved in. No additional clearance needed. Figue out that one.

There is no other place to etch it on the cam... If you think about it- you only really care when you are looking at a cam to put it in. Once you bought it and stick it in, you should keep the paperwork with the rig.

As said before trying to measure at the rocker is very tough with hydraulic lifters and likely wont be right. You could measure it at the lifter itself if you took the intake off and that would be as accurate as measuring the cam for lift. replacing the intake gasket is all ti would cost you unless you broke a bolt off in the head... and that is pretty common...

 

[DirtDonk]

While getting it down to the the exact thou of an inch by using the pushrod is sketchy due to monkey motion, the OP was really only trying to ascertain whether he had a stock cam or a slightly hotter one. And that should be easy enough to determine without getting too precise. Granted, if it was even a modestly big difference you could just tell by driving it, but if it's a slight upgrade and you're not familiar with how a stock one works as some, it could be useful info.
Besides, with lift numbers all you're getting is a wide range of individual cams that it could be. Even with a full degree wheel run and reading from the lobes might net you a couple of different possibilities, as some are very close, and some cheap ones might even be clones of more well-known brands.

As said the only way to know which exact cam is to get the part number off of one of the ends. But that's not what he really needed. Just the basic info he could work with.

So I'd say that just a quick test on the pushrod end of things would get him the answer he's looking for.
Is it a lot of work for a little gain? Maybe. But pulling a valve cover and a couple of rocker arms isn't that bad for getting a quick answer to a question that might be bugging him with a new engine of unknown heritage.

Paul

 

[Tram]

While getting it down to the the exact thou of an inch by using the pushrod is sketchy due to monkey motion, the OP was really only trying to ascertain whether he had a stock cam or a slightly hotter one. And that should be easy enough to determine without getting too precise. Granted, if it was even a modestly big difference you could just tell by driving it, but if it's a slight upgrade and you're not familiar with how a stock one works as some, it could be useful info.

This..

Sometimes, it sounds like it's been cammed. Sometimes it doesn't.

I've never driven an EB with a 351W, so I can't judge there either. I'll say this, it doesn't have any issues getting headed down the road.

I wish I could just get the guy who built it to talk to me. However, there were a few sketchy decisions made here and there that make me think that may be why he doesn't want to talk. LOL