Have a tick sound im trying to pin point and it doesnt seem like valve is opening enough. I have a dial indicator and plan on measuring the spring. Was wondering if that number will be the same as came lift??? I also read you should take that number you measure off of the spring and divide it by the rocker ratio. So would a reading of say .850 be about right for a .530ish lift cam with a 1.6 rocker? Thanks for the help!

PS also the lifters are hydraulic flat tappets. With them being hydraulic this might change the number as well though... Just dont want to tear motor down and replace lifters and I find out I have a wiped lobe because if im going through that hassle I will switch over to a big solid roller cam but the money part stinks lol Any way to no for sure if its a lifter or a lobe that is wiped? Thanks again

 

You have it backwards, divide the lift at the rocker by the rocker ratio to come up with cam lift, so if you have a .500 lift cam with a 1.5 rocker then it would be:.500/1.5=.333 lobe lift.

 

Are you sure because that would make a 1.6 rocker open the valve less then a 1.5 because with a .500 lift cam and 1.6 rocker your looking at .3125 valve opening opposed to the .333 with the 1.5??? Thanks again for the help and quick response.

 

He has it right and you have it entirely wrong. If you have 1.5 rockers, you divide the valve lift by 1.5 to get the lobe lift. Lobe lift never changes unless you change the cam. Once you calc the lobe lift, then multiply that by 1.6 to get valve lift with 1.6 rockers.

If you have a dial indicator and the cam specs, measure the cam or off the pushrod and forget about the valve side. The ratios especially on factory parts is not that accurate.

 

Thanks for telling me I have it entirely wrong lol I knew what you and him said I think terminolgoy was messed up between us because he was having me find lobe lift in which I am not looking for. What you said I know how to calculate what a 1.6 rocker does over a 1.5 rocker. I was just wondering if I measured the spring what would be the number im looking for.For instance if one had a .500 VALVE lift cam would that be what you read on the retainer of the spring when it moves with a dial indicator? You also stated factory parts are not that accurate in your response in which I dont have one single factory part on the motor lol So thanks for the help but dont just respond with a smart comment and talk down to me like im running some stock junk. Thanks

 

The cam card will say what the valve lift is with a specific rocker arm.

Cam card that says .500 lift with a 1.5 rocker means if you measure at the valve retainer you should see .500 lift if using 1.5 rockers

IF the cam card says .500 lift at valve with 1.5 rocker and you have 1.6's, you will see higher lift at the valve since 1.6's open it up more.

So you have to know what the cam is spec'd at. Some cams give valve lift with 1.6 rockers but more than likely its gonna be with 1.5's.

But you will not see full lift at the valve with hydraulic lifters because with motor off, there is no oil pressure in the lifter body so they will collapse under spring pressure. Thats why you need a solid lifter to check valve lift when degreeing cams..or check springs which have low pressure and wont collapse the hydraulic lifter assembly.

IF you let the engine run and get lifters pumped up and then try it, the lift may be close to what cam card says it should be but i doubt you'll see 100% of the lift so you wont know it anyhow.

If the valvetrain is ticking it may be a loose rocker and you wont need to measure valve lift

 

Thanks for the help. The part im interested in is the part about the lifters not being pumped up because I thought that would be a problem. Does anyone know how much a lifter will compress so I can take this into account when measuring valve lift with a hydraulic lifter? I also dont think its a rocker because I readjusted them and they all seem to be fine.

 

Its going to vary depending on how much if any the lifter is leaking down fluid pressure. So you cant assign a number to it. If its 'pumped up' then it will be like a solid lifter and nothing will change. If you have a lifter you're questioning then start the engine, let it run 10 seconds or so, shut it off, and turn the motor until that valve is open and see how fast the valve closes. Usually a bad lifter the valve will close almost immediately.

What rockers do you have? The aftermarket stuff is supposedly accurate but I've never checked one vs the other. The factory rockers are known to be widely varying in ratio so while you may have .300 lift at the cam and supposedly .450 at the valve with factory 1.5 rockers, it might be less like 1.4 and you only have .420 lift.

Cam specs are generally listed by valve lift so if you know its .500 lift then thats what you will get measuring off the valve tip, end of the rocker, the retainer, anything on the valve end side.

Only way to find out if a lobe is wiped out is to look at it. You could do this with the intake off at a minimum.

 

youll need a few basic tools and a good understanding of what your doing, but its certainly not all that difficult.
lobe lift is simply the distance the lifter moves from the cams base circle to its max lift on the cam lobes nose, valve lift has the rocker ratio added , example
if your cam lifts the lifter 0.345inches in its bore and you've got a 1.6:1 ratio rocker, your valve at least in theory moves to open to a full 0.552 inches lift





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The simple way:
Measure another cylinder's valve travel (intake and exhaust may be different)
Compare to the valve travel of the questionable cylinder.
If a lobe is going down there will be a BIG difference.

 

ok, i am trying to figure out what cam is in my car,r u saying that i can use a dial indicator and measure one of my springs? need to find this out without having to tear into the motor or remove the timing cover.

 

you can do that to get an idea of what lift the cam has. If you put a degree wheel on the crank and checked the open points/close points of the valve at .050" lift, you can get the duration of the cam.

 

ok, but how would i go about checking the open points/close points of the valve at .050" lift? explain further please.

 

Buy the degree wheel and read the directions basically find TDC by putting a piston stop into the #1 sparkplug hole and using the degree wheel. once you locate TDC, setup the dial indicator on the valve retainer and then rotate motor til valve opens .050". That will give you the valve events at the valve. From those you can calculate the durations.

But you will need to find the intake centerline and exhaust centerlines to determine LSA of the cam. Do similar method but I believe its recording degree wheel numbers at .050" before max lift and after max lift. From those you average the values and thats the installed intake centerline. Do same on the exhaust valve. Average the 2 values to get LSA.

 

all i'm after is either duration or lift specs. That will give me an idea of which factory cam i have,because IIRC,the guy i bought the car from years ago mentioned something to the effect of how his friend wanted the cam that was in the new 350 motor that was just swapped in, and that it had the tbi cam in it now. That is,if IIRC.

 

So basically i need a degree wheel and also a dial indicator too? I dont have to remove my intake right?

 

naw, dont have to remove the intake, but you do need to attach the wheel to the crank somehow and they make a socket type fitting that slides over the keyway and holds the wheel. May need to pull the balancer off, i'm not sure. Atleast the main crank pulley..

It is possible to turn the motor over by cranking down hard on the crank pulley bolts but you'd need to take the spark plugs out and loosen all the rocker arms and remove pushrods except on cylinder 1 where you are checking to make it easier to spin.

 

They used to make an aluminum part that bolts on with 3 longer bolts that hold it and the pulley on.
You bolt it and the pulley on and leave it. It had a big fat hex to put a socket on and a 1/2" square inside it. I was gonna get one but didn't.
Now I can't FIND it anymore. A little help please...
This, some degree tape and a "southern engineered" pointer (bent welding rod) would do the trick for him.

 

I almost made my own bracket to do that with but bought the crank snout socket connection since 99% of the time you will be doing a cam with the balancer off when using 1pc timing cover.

 

Yea, there's a ton of them that slip over the crank key but pulling and pushing the balancer can be a PITA in frame. I wanted the one that bolted on so I could bar the engine over with the serpentine setup and electric fans.
Mr. 'oldschool is used to just putting a thumb on the belt and giving the fanblade a tug which don't work anymore.
I guess I'll just have to go into bussiness making them... (hmmm)

 

If the balancer's on and the accessories are all assembled, I do the thumb on the belt thing, and crank on the alt pulley nut with a socket in a long torque wrench (plugs out of course). Gives a fair degree of control.

 

Clearly you don't have #$%@&in' headers...
I have to bar over diesels at work that have a big fat bolt that takes a 1-1/4" or 1-1/2" socket (take the sparkplugs out ain't happenin').
How can we have come this far without a bolt-on for the SBC to do the same thing is beyond me.
Here's how it should work: Put 15/16" deepwell socket on 1/2" drive pull handle and turn the crank all you want.
I'll sell 'em, myself dammit
p.s. loved the Southpark tree-fiddy episode BTW, can't say 350 anymore, always comes out "tree-fiddy"...

 

Heh yep no headers yet, it's almost impossible to find a set that over here that will clear the relocated steering column...

I saw one of those socket drives that bolt on over the pulley in a speed shop once, like you I didn't buy it tho, must revisit that one.

Yep - Treefiddy comes from Southpark, and also when I joined I had just pulled my heads to discover my 305 in fact had 4" bores. I think I'm the only guy ever who accidentally bought a 350

 

Well, dear lawd(pc) if you find one please post back.
I know that we live in a lawsuit world today and several of us "southern gentlemen"(pc) have left the socket and ratchet on one and started the engine. After pulling the ratchet handle out of his head, his next thought was:
I'll get a check for this! and then, "damn this hurts".

 

P.s. I ain't often when we get to celebrate seeing a big hole huh?

 

LOL another person who saw that episode. Hilarious!

 

I once left the torque wrench unsecured in the alt pulley while doing a leakdown, and forgot to chock the crank. Applied air pressure and BAM, piston disappears down the hole, wrench handle whips around 180 degrees and slams me mid forearm - hurt so much I though it was broken for a minute

Yeah seeing a big hole can often be cause for celebration, depends on personal taste I suppose

I got to celebrate with my username, and also a new set of head gaskets to replace the 305 set I had already bought.

 

i have heard that you can use a ruler to measure and get an idea of the lift. is this true?

 

You can, but it's not going to help identify the cam since the factory TBI cam and the factory TPI cam have almost the same lift (differ by less than .010" valve lift; 1/16" on a ruler=.0625) but differ much more in duration. That's why we bother with the degree wheel and dial indicator.

 

what? I thought the tbi cam had like .350/.385 lift and the L98 cam was .413/.428

 

I think that the difference is pretty great. I know that you could definately hear a difference in exhaust note with the cam that has the greater lift.

 

Ruler method will be hard to accurately determine lift.

 

Sorry, but this needs to be said..

http://www.youtube.com/watch?v=4qcbgclG4_A

 

Again, the difference in the exhaust sound and HP is from the duration not so much the lift.
Here are some specs for you:
TBI: lobe lift exhaust= .269" X 1.5 = .403"
TBI: lobe lift intake= .257" X 1.5 = .385"
TPI: lobe lift = .273" X 1.5= .409"
Even if you went with the .428" lift verses the .385 lift you are looking at .043" difference which is much less than the 1/16" (.0625") on a ruler (about 2/3rds of a sixteenth of an inch).
̥[
The distance from the vertical line above to the end of the bracket is about .045".
That's more than the difference in valve lift between the TBI cam and the TPI cam.
Can ya measure that with a ruler?
p.s. DeltaElite121: Love it! always have. (OT flag withheld)