new stroker build, some issues

[danimal]

compression across the board is only 100psi now..... ugh.
tried checking the gauge to my air compressor which was at 120 and the compression gauge said 100, so it is possible it is off though.

[SilverXJ]

It should be 31 psi engine running and 39psi with regulator disconnected. However, I would also check it while driving.

[danimal]

that's pretty much what it is. I have a gauge in the jeep right now, i have seen it drop to like 27 for a split second when coming to a stop or something, but always goes back to 30ish and about 39-40 on the throttle. doesnt seem very suspect.

[6TIME]

Are you positive that the cam has been phased correctly? If not I'd degree it to confirm. Low comp. #'s across the board usually point at retarded valve timing, unless there has been a major error in part selection or volume calcs.. What's your vac at idle?

[danimal]

i lined up the dots when i installed it. I pulled the cover of the other day, confirmed it was lined up, counted the pins between the dots (15) and put it back together. It seems somewhat intermittent. the amount of power loss isn't consistent. That's not to say the dots are correct on the cam i guess.... Any way to check it with the valve cover off?

The idle is a bit weird right now, it idles real low, then the iacv kicks it up to 800 or 1000 every 5 seconds or so. When it is idling at like 300-400, the vac is like 15 and jumpy with the rough idle. When it jumps to 800 or 1000, it idles smooth and the vac is at 19lbs and steady till the idle drops again.

[6TIME]

What was the compression #'s on your last motor? Did you use the same components this time around?

[SilverXJ]

I would personally degree the cam in. At one time I had a timing set dot to dot. Put it on the degree wheel and it was about 13* out, or one crank shaft tooth.

[danimal]

never checked the compression on my old motor, it was the stock tired 4.0. Oil pump seized.

Silverxj, was yours marked incorrectly? The pins were the correct amount between the dots but the cam was still off?

[danimal]

we hooked it up to a snapon scan tool yesterday, and all the sensors look fine. nothing suspicious, other than the computer is cutting 33% of the fuel for some reason. We checked it with a wideband and the a/f ratio was well within range of what it should be. it definitely makes the cam timing suspicious to me.

[6TIME]

It's very common for factory replacement timing sets to have retard built into them with the dots lined up. They have done this in the past for emissions purposes. Degree it then you'll know for sure. It should be cranking at least 150psi with that type of cam.

[danimal]

looks like its about 15 degrees off or so. i printed out a degree wheel and checked it with an indicator. intake centerline is about 96 degrees, it should be 110 according to my cam card.

[SilverXJ]

That much wouldn't be a factory retard.. thats about a whole tooth. Pull the timing set, but keep it together. Rotate the cam gear one tooth CCW, reinstall and check degree again. Also, make 100% sure you are on TDC.

In my case the dots looked like they lined up. But it was off. Set it correctly and it was dead on, but the dots still looked like they lined up.

[6TIME]

That much wouldn't be a factory retard.. thats about a whole tooth.

X2. Factory retard is typically 6* or less.

[danimal]

kinda thinking to beg borrow or steal a real degree wheel, finding out where it needs to be, and redrill the timing hole in the cam gear if needed (like if it isnt exactly where it needs to be by moving it one tooth). I have a machine shop so i can do it accurately.

[SilverXJ]

I'm thinking that moving it one tooth will get it almost exactly where it needs to be. 1-2* off can be contributed to manufacturing slack in the timing set and the comp cams cam. If that scares you then don't check the other lobes.