Depending on how agressive your ramp rate is going above .550 lift is increasing float potential. 1.8s also have more acute arc of motion and have a harder time staying on the lobe on agressive profiles.
What is your .006 (advertised duration?)
What is your ICL, meaning 114 + how many degrees advance in the grind?

 

Advertized duration in 274. Shop tells me that the ICL is 144, no added advance. Does the position of the pushrod that I noted give any clues to whether or not there is actual advance ground in? I can also advance or retard it up to 6* either way once the adjustable cam gear arrives. 1.75 rockers are another option if need be (0.580" lift). What do you suggest?

 

I'm trying to understand why you are having the clearances so tight (if you measured correctly)
AFR205s have .015 more clearance than stock, I am baffled that you are measuring .040 intake clearance.
224/224 114+0 LSA should have way more than that (if ground correctly). Is there any way you could degree the cam?

274-224 = 50 rate variance so fairly agressive, but with small durations, it should be controleable provided you have centered geometry on valve tip.

1 more Q: Do you have a cam card? If so can you post it?

 

I don't have a cam card, just a hand written note. 224/224, .563/.563 (if 1.7 rocker), 114 + 0 LSA, 274 advertized duration. Yes, I can degree w/ the adjustable cam gear.

More & more I'm thinking that the cam is advanced & not zero. I noted that the intake pushrod is on the lobe, higher than the exhaust pushrod while the piston is @ TDC. Does this indicate advance? Just before the piston starts it's downward travel, the intake pushrod/rocker has opened the intake valve a bit. Measured was .094" pushrod lift, then x 1.8 = .169" @ the valve. So, while the piston is still all the way up, the valve is .169" off of its' seat.


Also, the AFR combustion chamber measured 64cc. This suggests that .012" was decked from the heads.

 

I would degree the cam to clarify things, it just doesn't jive too well. Something is fishy IMO.
Think about it AFR 205s 59cc with .040 gasket will clear a G5X3 114 cam with better margins. That is a 234 intake duration on 114+4 LSA.

Either the cam is ground different, or install is wrong or heads are milled way beyond 64cc or you are not measuring correctly.

 

If you are using hydraulic lifters with a checker spring your measurements will be skewed because the lifter is not preloaded. You will need to subtract your lifter preload from your measured piston to valve clearance to get the actual number. The better way to do it would be to use an adjustable length pushrod to set the valve to zero lash and measure that way. Regardless of advance the intake valve should be closed at TDC.

 

I'm using a fixed lifter to check. There is zero lash during the check. I have an adjustable pushrod.

Let's discuss the intake valve. The intake valve is closed for part of the time that the piston is @ TDC. It only opens just before the piston starts to move down. So, what you have stated is that it sould be closed the whole time & not open until the piston starts to move down, correct? If this is correct, then the cam is not positioned in a way that makes dot to dot correct & degreeing the cam should fix the problem, yes?

This is also what I understand is the point that Predator is making. If I am incorrect, please explain.

I noted earlier that the cam dots separate (pass) each other by 3/8ths (0.375") of a tooth before the piston starts its' downward motion. During this 3/8ths of a tooth travel, the intake valve is opening. It is this period & distance that the valve is opening that is causing the problem. So, if the cam is degreed as to eliminate this condition, then the problem is corrected. Do I understand correctly?

I also understand the difference & example made by Predator. I have never disputed that when a more aggressive cam clears, so should mine. The problem has been trying to determine why mine does not. Am thinking that the re-ground lobes are out of position on the re-ground cam.

 

I just went out & moved the cam 1 tooth so that the intake valve would remain closed until the piston was off TDC & the problem transfered itself to the intake valve not closing early enough on the compression stroke, as it should have. Definately a f*cked up cam. Shouldn't be off as much as it is. Am gonna scrap it & buy a proven cam from a vendor or a member. If anyone has a reasonably priced cam similar to what is here, shoot me a PM. Ideally, would like a 224/228 w/ a .590 ish lift on 1.7 rockers, 114 LSA.

Thanks for the help guys. As always, I appreciate everyone who posts in an effort to help.

 

Found a TSP 231/237, .598"/.595", 112+2. Hopefully, will have better luck with this one. Any suggestions on whether I should advance or retard it a bit. BTW, will also allow me to go back to my stock 1.7 rockers.

 

Before you pull the trigger.
That 231 has much more overlap. The 224 had -4* and this one +10*
So those 2 are opposide end of spectrum.
What are you really looking for in your cams behavior, power.

 

Original cam that I had for years (no trouble w/ the install either) was a 216/220, -10*. Never had the -4* running due to the install issues. So, the +10* will be a change for sure. I want good under the curve to peak power.
How much low end torque will be lost? Should I degree it one way or another (retard/advance)?

Other thing to note is that my car is very light. So, losing some low end isn't as much of a problem. I'll just be happy to have a cam that installs properly. Price was good, as well.

 

It will lope pretty strongly, as you said with your light car, you'll not notice the loss in below 3000rpm.

Degree the cam at 110 ICL and you'll be good to go.

 

You make this way harder than it needs to be. Get a degree wheel and go through the proper steps of degreeing the cam in. Use a set of light checker springs so you do not collapse the lifters. With a degree wheel and a dial indicator you will be able to figure out how much duration and lift the cam has and what ICL you have it installed at.

 

Actually, I don't. Expected to install a small simple cam dot to dot, set up valve wipe pattern/lifter pre-load & be done with it, as many have. A bad cam made it more involved than it should have been. I have fixed roller lifters & an adjustable push rod. No need for soft checking springs. Will use a degree wheel on the modified set up........& an adjustable cam gear.




Thank-you for the input, will do.

 

A 224 XFI lobe is very similar to what you are trying to accomplish:

274* @ .006", 224 @ .050", 149 @ .200"

That lobe on a 114 ICL should hit the following specs

Opening
.006" at 23* BTDC
.050" at 2* ATDC
.200" at 39.5* ATDC

Closing
.200" at 8.5* ABDC
.050" at 46* ABDC
.006" at 71* ABDC

Before you toss this cam out, you should put it back dot-to-dot and check to see how close your regrind is. The way you are describing your valve events, it still doesn't add up. 1.8 rocker or not, you should not be moving from a "closed valve at TDC" to PTV contact in a few degrees of rotation. You should be well off the seat before TDC before you have issues. Like Predator said, 234* XE-R lobe at a 108 ICL clears stock heads and gaskets.

At present, you run the risk if buying a new cam, only to find that isn't the problem. A regrind usually doesn't have enough lobe to be ground way off of what the core cams was. Without a degree wheel and a dial indicator, you are only speculating.

 

UPDATE:

New cam is in. Of course, there's no cam card to confirm degree measurements. (TSP had no info. since it's a discontinued grind).

-231/237, .595/.598, 112 LSA

-Installed on a 110 CL using adjustable cam sprocket. 110 CL @ .050" valve lift.

-0.097" PTV clearance while using 0.030" head gaskets. Closest point is when intake valve is open slightly @ the top of the exhaust stroke.

Opening: .006" @ 11* BTDC
.050" @ 9* ATDC
.200"@37* ATDC


Everything looks OK to me & is much better. Please comment...