broke91firebird

I recently tore the motor in my Firebird all apart. The rod bearings were almost new so thr bottom end just got the oil pan gasket. I then swapped in a 252 grind cam with 206 duration and .425int./425exh vs the stock 195 duration and 195 int./196 exh.
I also replaced the timing chain and sprockets, lifters, distributor seal, water pump and gasket, timing cover gasket, front seal, intake gasket and all the plenum gaskets. Also has 6 new plugs

With the stock chip it will only run with the electronic timing unhooked and at roughly 25 degrees of spark advance. Is that because the distributor is a tooth off or the lack of a tune?

fasteddi

iTrader: (2)

25 degrees of base timing with the Est wire unhooked??? You just need to set the timing to 10 degrees btdc.

broke91firebird

That's my problem. It won't run at 10 degrees btdc. The closest to a nice running motor is at roughly 25 and even then I have to rev it a little to keep it running.

cosmick

The new cam isn't wild enough to need the timing changed from GM spec.

dmccain

iTrader: (2)

broke91firebird

That was my thought too. Could it just be that I am still using the stock tune? Or is there something else it could be?

cosmick

If the cam was the only mod, then it might go a little lean at higher RPM, I'd guess above 4000, but maybe closer to 3000. But other than that, stock spec should idle like stock.

project89

iTrader: (1)

yeah that 252 is super mild u have something else going on.
dbl check u have the plug wires on in the right order.

im willing to bet when u did the timing chain the marks werent aligned properly

broke91firebird

I was wondering if the distributor could be off. Could be a problem with the new lifters being set too tight? The marks on the timing gears were lined up with the top dot facing down right at the bottom dot. I will have to check the plug wires.

midias

If you crank the car until the rotor is pointing at cylinder 1 is the timing mark lined up?

broke91firebird

No. Ill look when I go out but I know that with the marks lined up the rotor is nearly at number 2 plug wire

midias

When #1 is at the compression stroke get the mark lined up and put the distributor with the rotor pointing at cylinder 1. You may need to align the oil pump with a screwdriver.

broke91firebird

Than with tge timing marks aligned and the distributor at #1 it won't idle, it dies as soon as I let off the gas. Wiith approximately 20° or so of timing it will run with no ESP. It will not idle anywhere with the ESP hooked up. All spark plug wires are right and im sure the timing marks were lined up (bottom mark up top mark down). Both me and dad checked them at least a dozen times.
Anyone gave any other ideas?

fasteddi

iTrader: (2)

It's definitly not the computer or the cam itself. I added a delta 260 back in the day. With no tune it worked just fine idleing at 10 dbtdc With the est wire unhooked. this was on my 3.1l. So rest assure you have something mechanical going on that is not right. The ecm and cam I'm sure are fine.

Could be the timing sprockets aren't lines up right. You are looking at the fat notch on the balancer and not the narrow one right, when checking timing?

broke91firebird

Would the fact that its as 2.8 timing chain make a difference? And im looking at the notch that had paint on it when I pulled it apart. Itwas also on 0 when the marks were lined up. Im not sure if its the fat one or not. Would these sprockets have multiple marks on them?

broke91firebird

Here is a video of the motor running tonight

project89

iTrader: (1)

that does not sound like a 252 cam , either that or u have the cam timing way off

broke91firebird

By cam timing you mean the marks on the timing chain sprockets right? Are they supposed to both be vertical or one up and one down?

cosmick

Ignition timing being off can make a mild cam sound more like a wild cam.
Unless you ordered the cheapest Chinese timing set, it should have come with instructions. I've seen many sets want dot to dot, with the cam down at 6 and the crank up at 12, but I've also seen sets that call for both up at 12.
I'd remove then re-stab the dizzy, and did you re-use your original damper and timing tab?

broke91firebird

Yes to the original damper and timing tab. I will have to look and see what they say, when I replaced it I went by the Chilton manual which just said to line them up.

cosmick

Chiltons' are based on the one car their mechanic and photographer team tore down, and factory service manuals. So their instructions would be correct for re-using the GM timing set, but that would be dumb because the GM timing chains were cheap, so they stretched alot. That's why aftermarket "double-roller" timing sets sell so well, but I've seen the cheaper versions of those stretched also.

Six_Shooter

iTrader: (2)

Cam sprocket up or down is the same thing.

Install which ever way you want, then rotate the crank 1 revolution and bam, the dot will be 180* from where it started, rotate the crank another revolution and bam back where it started. This is why I usually install cams with the dots facing each other. It's easier to ensure that the dots are perfectly lined up when they are closer together.

fasteddi

iTrader: (2)

project89

iTrader: (1)

alot of timing sets have a built in 4* advance , alot of cams are also ground with 4* of advance as well.

this is why its important to know what u have and to also use a degree wheel

and as stated it dont matter how u line up the marks but dot to dot is easiest

broke91firebird

Everything I put in was Comp Cams stuff that someone else bought for a project he didn't finish. All I know is its the 252h cam the model 3201 timing chain and gears for the 2.8 and a set of flat tappet lifters

broke91firebird

Side note the timing is still way off but I got it running much better by re-adjusting the valves now that tge lifters are pumped up

fasteddi

iTrader: (2)

Yea lashing in the valves wrong would definitly make it run weird.

Do you remember how you lashes them in?

broke91firebird

The first time I turned the pilgrims slowly till the resistance started then gave them 3/4 turn more. The problem was that the lifters weren't pumped up yet so once got oil pressure they were about 1.5 turns too tight.
the second time I only gave them 1/4 turn and its running loads better. Though the timing mark on the damper is still at 12o, clock when it's running

broke91firebird

So yes, the cam is most likely built with a 4° advance. Does that change how it should be installed?

willexoIX

Whole issue sounds like timing off and tight valves. Just having one valve too tight on mine made it run like crap. Then with the base timing set at 0* (Don't do that), made it even worse.

You were right to re-do the valve lash, now all you should have to do is sort your timing out. I would start from scratch. Pull the timing set off and reset everything to TDC compression and line the marks up again and go from there.