Degreed in my pro2's n everything was good for a couple weeks n I was doin some spirited driving one day n motor made a popping sound at high rpm, almost like a backfire. I drove easy for about a mile to get back home n the throttle response was terrible, so I did a compression test and found that one cylinder was 215 and the other three were all around 180, no c.e.l., so I pulled the head and valves all r closing all the way, headgasket looked fine, and I poured some oil on top of pistons and it stayed overnight without leaking by them so rings n cylinders should be good, no cracks n cylinders, I'm open to any more suggestions..... I'm down to thinking now it had to be something simple such as valve adjustmeant? Gotta get this car back together all help is greatly appreciated!

 

C/r is about 12.2:1 so 215-220psi is about what it should be from what I've read

 

Hows the plugs look?
A/F ratios?
Ignition system up to par?

Did you do the compression test on a warm engine, fuel disabled, and at WOT?
If so, Id suggest a leakdown test but you already got the head off so youd need to bolt it back down to do this. You dont have to install the cams to do this either. REcord the leakdown numbers with the pistons at TDC and BDC...

 

I'd recommend doing a leak down test when you can.

 

did the comp test with plug wires off, y disable fuel and y at wot? how would that change compression? the oil i put on top of the pistons didnt leak by the rings so wouldnt that mean the leak down test doesnt need to be done?

 

Disable fuel so you dont wash your cylinders out. Hold at wot so the engine can suck in the most air possible.

A leak down will tell you more than if you are leaking past piston rings. If its leaking you'll be able to tell from where. It may leak a bit from the valves or a valve. Pouring oil on top of the piston and seeing if it leaks down past it will only tell you if your rings are bad. It won't tell you if a valve is leaking.

 

yeah i knew that lol dont know what i was thinkin, i dont have anything to do a leakdown test with though. valves are closed to the point i cant see light shining from behid it using an led light. anyone know what my valve clearances should be withthese cams? just to double check that they arent too tight n not closing all the way when the cams are in

 

Bump

 

Id start with doing a compression test again.
Its unlikely that mis-adjusted valves caused you to misfire at WOT...
Was the valvetrain "ticky"?

Do you have an a/f guage that you can monitor when your car breaks up at higher rpms?

Having it all apart now may make it harder to diagnose since theres some things that could be checked when the car acts up...

What do your spark plugs look like?
Is your ignition system up to date maintenance wise?

 

dizzy has new cap,button, new ngk wires n bosch platinum 4 plugs all done in march, it only broke up that one time hasnt done it since but have had terrible throttle response since that day. thats y i checked the compression and realized it was low. i assumed that it blew the head gasket between the cylinders or cracked some sleeves thats why i pulled the head but now i see none of that. which is what led me to the rings but they r holding oil. i have skunk2 valvetrain and they have always been slightly ticky but not loud. spark plugs are pretty smutty black but not gunked up, i knew it was a little bit rich because im runnin on a phearable basemap for my setup. i dont feel it was rich enough to wash it out though

 

the deck and head r straight i checked them for warpage this afternoon, could it be possible that the degreeing of the cams is off some causing a valve to be open at wrong time and releasing some compression when it shouldnt?

 

Then all cylinders would behave the same.

 

bosch platinum 4 plugs

get rid of those, i'm surprised nobody else has said anything.


Here's what "I" think, happened. You either, tapped another valve, or tapped a piston. Enough to cause something to work fully. Car still runs, and is able to hold compression, just not like it should.
While the head is off, i'd take it to a machine shop. Let them clean it up, and reinstall a new set of valves. Allow them to reseat them and re do EVERYTHING.
Then reinstall the head. Valvelash set too tight, or too loose can cause problems, specially on bigger cams like the pro2's...

Then do another compression test, the correct way and a leak down test, the correct way. I'm thinking you touched a valve, what were your final degreed in settings for those cams..

 

I'm guessing the same. I've seen valves lightly tap a piston, bend slightly to where it is hard to see it. You typically should see "some" sort of knick/mark on the piston where it collided though.

 

No marks on pistons doesn't look like any thing touched, was plannin on swappin back to ngk plugs before tune, anyone know what the valvelash should be set at for these cams?, I'll have to check tomorrow but I think it ended up being in +2 ex -2

 

Noticed that right away also..... NGK coppers or bust!

 

Lmao..if those are ur cam settings than yes you hit something.

Pro2 and 3 require 4 degrees of seperation

You should be at +1 or 2 on the int and +3 or 4 on the Exhaust


Vl is 007 int and 008 exh cold

 

+2,+1,0,-1,-2 isnt that 4 degrees of separation?? 007,008 is what i had the valves set at. "+2or3 and +3or4" is ony 2 degrees of separation sure you didnt mean to throw a negative number in there somewhere?

 

The exhaust cam, will never be retarded on the pro series cams, unless something isn't measure correctly..ever.

 

Swap out those Boschs for some NGKs...
Your symptoms kinda sound like an ignition related misfire to me, being you have those platinum 4s in there also kinda makes me think this..

As far as compression numbers go, Id perform the compression test again (fuel pump fuse removed and at WOT..
With the throttle closed, you're limiting the amount of air going into the engine to just the tiny little idle passag way through the IAC.(nothing against your wrenching ability or skill level)

 

ok thanks for all this info guys, i havent had time to check exactly what my cam settings are but im waiting for my new gaskets to come in to put had back on n do the comp test the correct way n re-degree the cams if they r incorrect

 

Gaskets r in, the cams r set at -2 ex/ +2 in so if its true that the exhaust should never be negative then my degreeing is off somewhere. Does anyone have the settings for the pro2's? I had it wrote down but can't find it

 

Start with +1 int and +4 exhaust, see how that runs.

 

+1 and +4 isn't that only 3 degrees of separation? Not doubting you at all I'm just trying to understand better for my sake. What degree on the degree wheel should I set them to? Ex is atdc n in is btdc right?

 

Some cam gears use the method of 1 cam gear degree = 2 crank degrees
Other cam gears use 1 cam gear degree = 1 crank degree, it'll note it on the gears you use, but you "want" 4 degrees of seperation.

The drop in settings for s2, are normally listed for the gears that use 1 cam gear degree = 1 crank degree. The pro series gears are 1 degree cam gears, where as say, the AEM's are 1 degree = 2 crank degrees.

You're on the right track.. Just keep researching, you're learning.

3 degrees, 4 degrees , 5degrees seperation is all fine, opitum they say 4, but it just depends on how much is taken off the head, and supporting mods. If you measured your v2v, the rule of thumb around here is no closer then .030.