Comp Cams issues

[Jeepedo129]

posting this here hoping to get some advice or experience.

I'm currently having some installation issues with my comp cams 68-232-4. This is the second 232-4 cam that I've installed into my stroker. last time I just installed it the factory way, dot to dot. Engine ran fine, however this time around I went ahead and degreed the cam when I installed the second time. I also made some solid lifters to check the cam.


With the stock timing set, I checked my ICL, and I came out with 114*. The Cam card says installed ICL is 110. So that would be 4* retarded correct? next just to see where my timing events land I went through and degreed them. Cam card says timing events are measured @ .050. When I measured them @.050 all my timing events were off by 25+ degrees.

I called Comp about this and their tech specialist says the card should have been printed with timing events @.006 not .050. So the card was wrong. I went back and measured the events again and everything was -4* retarded.

So I bought a JP performance adjustable roller timing set and advanced the crank gear +2* to get my 4* on the cam.

Rechecked my ICL and timing events and im at 110* installed, and all my timing events were within 1* +/-. all is good right?

But now it runs like crap. low vacuum, only 12in hg at idle, and im missing hard. tried adjusting the distributor to see if that would help but no joy. ( i know, computer controlled ignition)

Called Comp again and told them what I had done, and the only thing they had for me was "its impossible for you to get 114* ICL if you install the cam dot to dot, you will be happy with the cam if you go and install it that way."

My complaint is right now is, why even have a cam card then if they just want you to install it the factory way? Their instructions say right in the packet to degree the cam to get optimum performance out of the cam.

I went and ran the numbers on the cam through a cam calculator and they don't add up with the correct ICL, or duration.

Anyway, long rant, but im wondering if anyone else has had an issue with this cam as far as degreeing it vs the cam card. maybe I'm off in left field but I think someones numbers are wrong.


This is the specs of my cam from the cam card


valve timing.050 ( actually .006)
-------OPEN ------- CLOSE
INT 13 BTDC -- 56 ABDC

EXH 62 BBDC -- 13 ATDC

Duration: @.050
INT -- EXH
206 -- 212

Lobe Seperation: 113*

 

[RCP Phx]

When I degreed my 68-232-4 cam it came in "dead nuts" with the timing card. The cam has 4* built into it so it should install straight up.

 

[RCP Phx]

There are a lot of things that could cause things to not "read" perfect.

The accurate determination of TDC
The size of degree wheel/pointer
Lubricants used during testing
Dial indicators w/ less than .0001" readings
Any slack in the timing chain

I may have missed some............but besides the do's/don't(s) for actual degreeing it, you should get good readings

 

[Jeepedo129]

And I can understand those variables, but I measured several times and got -4 all around, not just ICL. I didn't want to drop the dough on the timing set, so I made sure I double and triple checked my ICL. But this is why I got the adjustable set to bring the cam to the card.

From what comp told me, that cam has a 3* advance, which is noted by the difference in the 113* lobe separation and 110 degree ICL. (didn't make sense to me either).

But again, why have a cam card, or go through the process of degreeing the cam, or adjustable cam gears or any of that, if the cam only supposed to be installed dot to dot.


This was the INT open @.006. measured with the dial indicator right on the lifter which was also a solid lifter. 9* BTDC instead of 13* BTDC.

 

[RCP Phx]

I was going to ask what set-up you use? What about the possibility of ECU/wiring issues?

This was what I used - 18" Degree wheel and a good square and firm piston stop.

And a cut down pushrod w/ a washer welded on for a soft spring below my pushrod guide.

 

[Jeepedo129]

My deck clearance is .010" so I used an indicator right on the center of the piston to verify TDC on my wheel. unfortunately the wheel I ordered ended up being a 13" wheel and not a 18" wheel like i hopped.

your push rod set up is better. I placed a push rod in the hold and placed the pointer of the DI on the center, then eyeballed it straight inline with the pushrod, then took several zeroing measurements to ensure I was inline with the lifter travel.

For ICL, I measured to the highest point on the intake lobe, then .010" either direction then divided the number of degrees in between the two points in half to verify the exact top of the lope. Exactly the same method as timing Aircraft magnetos and PMAs on B757s.



I thought about the wiring issues, and so I went and ran through my wiring prints again and checked continuity on all my pins. I also ran through electrical tests for the crank sensor, cam sensor, coil and checked my injectors with noid lights. everything checks out.

If you still have it, what were the specs on your cam card?

I'm tempted just to tear into this stupid engine again and just put the cam Dot to dot and be done with the numbers, because Comp didn't seem to care anyway.

 

[RCP Phx]

I looked but my cam card is long gone. I didn't use it as I printed off the website spec sheet. http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=12&sb=2
Is it possible some of your injector wiring got mixed up? Have you done a pin-out from the ECU?

 

[Jeepedo129]

Yeah I rang out the wires to each of the injectors to the ecu. And I went back and used the factory fsm prints just Incase my wiring print had a mistake on it. The engine did run with the new wiring harness before I tore the engine apart for the new cam. That’s whats kinda pushing me toward the cam for my engine woes right now.

 

[RCP Phx]

How about the injectors themselves?

 

[Jeepedo129]

had about 12-13ohms across all of them, I even swapped out my bosch set and put the stock ones back in, just to see if there was a change, but no joy.

also ran through the vacuum lines with carb cleaner and didn't find a leak anywhere under the hood.

 

[RCP Phx]

Your not leaving much! I am curious what this meant?

minor valve job

 

[Jeepedo129]

The machine shop put in new valves and lapped them to the seats, new seals, springs,(not sure which springs, which ever spring he recommended with the cam) caps and retainers, and he checked the guides, i think he cleaned and honed them? So nothing fancy, Basically a stock head, just freshened up.

 

[RCP Phx]

That takes us back to the beginning. You had a cam failure which you didn't determine the cause. So..........

What are the springs that your using?
Did you run (once fired) for 30 min straight @ 2000-2500 rpm?

 

[Jeepedo129]

on the old cam, yes I did the 30min break in with comps break in oil. the new one, I haven't been able to pull 2500rpm because of the misfires and no power. which makes me uneasy about the longevity of this new cam.

The old cam failure was on one lobe, #4 exhaust. This same cylinder had the injector wires melted and crossed with cyl #3 and my coolant temp sensor wires that run through the rail. My thinking is #4 had erratic injector firing causing detonation while the exhaust valve was off its seat, causing excessive pressure on the cam lobe and lifter causing them to fail.

none of the other lobes or lifters had and wear on them, however #4 lobe was nearly flattened and the lifter caved in.

I went back to my engine build sheet, and it just says new springs. The machinist is the one who got me the first cam, and he said he would match the springs to it. So unfortunately I don't know what exact springs I have. However, I feel like if it was a spring or pushrod issue, it would be across more if not all the lobes.

 

[RCP Phx]

I would definitely take a good look at those valves. Very unlikely the wiring had much to do with it since the injectors are fed with a constant B+ and only switched thru the individual grounds.

 

[RCP Phx]

I forgot to say, when my wiring shorted out it took out the ECU.

 

[Jeepedo129]

I have a spare ecu I was planning on sending out. Maybe Ill through that in there and see what happens.

 

[Jeepedo129]

What should I look at with the valves? Before I put the head on I went through and lapped each valve to make sure the seats were still good and clean. As far as the springs go, I could call the shop and see if he remembers what kind of springs he installed in there, but that was almost 2 years ago now.

When I get a chance, Im going to take the timing cover off and set the cam to the dots. Ill re degree it and record my findings and then talk with comp again about it. Ultimately, If the engine runs and makes power, I'll just leave it alone.

 

[RCP Phx]

Something in the valve-train caused it. A good mechanic will have records showing what he did/used(it's only just over a year) but critical to know. Where they single springs, single springs w/ a damper, or dual springs and what weight? I built mine almost at the same time! How many miles did you get on it?

Did by chance you miss lubing that lifter?
Did you spin the pump up and get full oil pressure "before" cranking it over?

Sticky lifter bore?
Galled rocker/pivot?
Spring bind?
Sticky valve/guide?
Did you put a straight edge across all the stems to check the stem heights?

You should have noticed something early on as this didn't happen over-night and way before you got any codes.

 

[Jeepedo129]

I got almost 8k out of the engine, before it threw a code. And on installation of this cam and my last cam, I used comp cams assembly lube liberally on every moving part, primed the oil pump with a flat head screw driver in a drill motor. Push rods were brand new out of the box, and double checked with a straight edge and verified the length to ensure correct lifter preload. The springs are a single spring, no damper or anything like that. engine build sheet says "valve springs 926" stock rockers, and valves. However again, if it was a spring, valve, lubrication, or installation issue, I feel it's safe to assume that it would present itself on more than 1 lifter, and I feel like it would be quite the coincidence that lifter was on the same cylinder bank that had a shorted injector.

The engine ran fine, however there was a vibration to it. I attributed that to the brown dog motor mounts and didn't pay attention to it, my mistake. I should have found the back wires before any of this happened.

Again though, This all comes back to the cam, and the degree wheel. The last cam was identical to this cam, I know because when I first started degreeing the new cam the numbers didn't make sense, so I put the old one in a checked it, and got the same numbers.

So, again, When installed per the factory method, ICL shows 114. and that is verified multiple times. I even counted the pins between timing marks on the chain (factory method) after aligning the dots. I then followed the cam card and advanced the cam 4* to match the card, and verified again multiple times I had an ICL of 110.

This was the only thing I did different between the two engine setups. Last time I installed it dot to dot, engine ran fine, now I match the cam card, and do it the right way, engine runs like shit.

I'm not a professional auto mechanic, however I am an Aircraft Mechanic by trade, and timing and measuring by way of dial indicators, and micrometers is defiantly something I'm proficient at since it is something I've had to do on many occasions.

All I want to know is why. I like to have my sheet, that says, install it this way, measure it this way, verify it, and correct it if needed. everything else is just a guess.