Engine Running Rough After Reinstalling Timing Chains

[StangGrin]

Hello again all,


Man...this project (1999 GT 5-speed NA) is going to keep me always posting for help with issues.


So I got the engine and tranny back in and all together. When the engine runs it's rather rough - way down on power. I can tell it's missing. It will also backfire through the intake every so often. I'm rather certain I was quite particular when I installed the timing chains.


The chains slipped when I replaced the guides. So I pulled all the followers, put timing marks on the chains (by folding chain in half and marking each end), and installed the chains with the cams at 12 o'clock (driver's side) and ~11 o'clock (passenger side) and aligning with all timings marks. Then I put the followers back in where I could. I rotated the crank (CW as I looked at it from the front) to give me more room to install the remaining followers.


The thing I'm wondering is if I have a chain off by 1 link would it run like this?


I also replaced intake manifold gaskets - could that cause backfires?


Looking forward to sage advise...again.

 

[Musturd]

If ur not a 100% positive with the timing chains on these ur hooped.

 

[duff daddy]

Yea, if that slipped at all or moved and or you didnt have the car at TDC on #1 then you can have an issue. Also, if you did the intake gaskets and you had a small leak, on the vacuume side of the gasket, it would run rough low and smooth out on the top end, and or possibly seal once the engine is up to temp.

 

[StangGrin]

If ur not a 100% positive with the timing chains on these ur hooped.

Well...when I put the timing covers back on I was 100% positive. Apparently I didn't know enough, though.

Yea, if that slipped at all or moved and or you didnt have the car at TDC on #1 then you can have an issue. Also, if you did the intake gaskets and you had a small leak, on the vacuume side of the gasket, it would run rough low and smooth out on the top end, and or possibly seal once the engine is up to temp.

"have the car at TDC on #1" ... oh man! I didn't think that was necessary. I had pulled all the cam followers and then just put the timing chains on lining-up the timing marks on the cam gears and crank gear with the marks on the chains. I followed the procedure described here at Modular Head Shop, except I didn't bother with setting the crank keyway at "90° to the passenger side". That was because I had the followers removed; that was my logic anyways.


So at this point I'd like to find a definitive procedure for timing this engine. Hopefully one that describes the process with the followers removed.

 

[duff daddy]

Yea, if you didnt put the #1 or 6 cylinders at tdc, then you never had a beginning point to set the timing marks off of. So your timing (chains, cam and crank gears could be lined up) but remember 1 revolution of the timing chains doesnt mean that cylinder is back at tdc.

 

[StangGrin]

So far things are going okay. Got the engine at TDC and timed everything up. My engine looked just like this one (from the Modular Head Shop timing instructions) , with the crank timing marks at 180°.

I even sprung for putting some fresh white-out on the timing marks and chain links - big spender that I am; next is a KB (I wish).

The big thrill so far is that I don't seem to have bent any valves. The shade-tree-leak-down test was good on all cylinders. But as we all know, the real test will be when I fire it up.

One thing I noticed before I re-timed it was that with the crank at TDC the psngr side cam timing mark was in the right place but the drvr side was 180° out. I've read that being 180° out like that won't beak stuff which seems to be case for me...thank goodness.


So now I just need to put the timing cover on, valve covers, and other front engine stuff.

 

[StangGrin]

And it's running just like it did before I tore it apart. What a relief.

Now I can move on to the next project, the suspension. Putting in lowering springs and all that goes with that - shocks, struts, bushings, stabilizer bars, and CC plates.