Why NOT to do the cam timing and much more!

[OldSkoolGP]

Wow, it's been so long since I've been in here. But I felt I needed to bring these things up. If you've considered doing the retarded exhaust timing on your 3.4 DOHC, consider these things first.

1) Rough idle. If you're using stock idle speed you should expect occasional instances of your computer losing control of the idle speed and the motor stalling, especially in stop and go traffic.

2) Lost fuel economy. I don't care what anyone says about it. If you drive a lot of city, you're going to lose some. It's not so bad on the higway cuz you're in the power band then.

3) Vibration. I speak from experience on this one. It goes along with the rough idle. The fact is the motor shakes horribly with the retarded timing set. I just found out last night when we had to replace my coolant pipe on the pass. side (which we somehow did in 2.5 hours), and while we were in there we found that 2 of the 3 pulley bolts had spun themselves out of the pulley and were gone, and one was gone from the crossoover engine mount bracket and another one was working it's way out.

I'm not saying you shouldn't do the retarded timing. Do I wish I hadn't? Yes and no. I do love the lopey idle and the nice snap of power from 3 to 4 grand, but at times it is very annoying and considering what happened with my bolts, I'll be changing it back next time I do a belt change. Keep these things in mind before you go ahead with the retarded timing.

[SappySE107]

You lost 2 of the pulley bolts? Um, thats crazy and unrelated to the timing unless you can show me how those will work themselves out when properly torqued down under any circumstances at all. I agree, the stock idle speed is pretty low for 13 degrees, but its smooth with it raised to 800 or 850. For a 5 speed car though, idle is probably the only real issue. For an auto car, I will be testing out some different cam timing most likely cause they would probably do much better with a cam change to give better low end and limit power to 6000 instead of trying to push it to 7k.

I never said there wasn't better timing possible, but 13 degrees has been the best power gain I have found so far. Feel free to experiment and relay what you find.

[dohcfiend]

has ne1 tried to mess with the intake cams?

[SappySE107]

Yup, and it never did me any good. We tried setting both cams 6 degrees advanced and it sucked, and the intake alone 6 degrees didnt do anything performance wise either. Plenty of other combinations to try though.

[dohcfiend]

the only other place that made cam changes on the net i could find so far was this place. he went 8* on intake and 18* on exhaust for 10*of "overlap". can u break that down into lamens terms? but that might only work for his extreme high rpm style intake he built.

http://fiero.cc/fiero-tdc/members/mws/intake/index.html

[jmgtp]

The 96-97 cams had different specs to begin with. The page you are looking at is Mike Smiths. He had a very different custom intake setup and very nicely built headers so his results arent really comparable to anything were doing here. The 'overlap' is the duration that both the intake and exhaust cam are open at some partial lift.

[dohcfiend]

well while i am at it. a "retarded" exhaust cam means valves opens later and closes later? and an "advanced" cam means the opposite?

if so what do u think would happen if u were to advance one and retard the other?
for ex if i were to retard the ex. the usual 13* and advance the intake between 3 to 5?

i know what u are thinking buy a book on pushrod and ohv cams. well i will. after my car decides to behave itself. or maybe i should put a block under the throttle or something.lol.

[SappySE107]

Try it.

[dohcfiend]

maybe later. i am going to go with what is proven to add performance. i might try some alterations later when i get access to a dyno.

cause u know how it is if i go through the trouble of trying it a different way, of course i will say it rocks even if it sucks. that is just the way the human psyche is. naturally i will be biased towards my own work.

[Anonymous]

You are right about that, I am the same way about my headers. Sure the power gain is awesome, but below 3000 they made the car sound a lot more raspy. But I still think they are great!

As for the timing mod, I probly won't do it for a while, I don't have the tools and have never done more than check my belt before. Maybe after I install my 96 injectors, which should fix my idle, then i will consider it.

[dohcfiend]

i am still going to do the 13* on the exhaust cams, but i will decline messing with the intake cams for now. i think it will compliment my stall nicely.

[jmgtp]

I did not notice any drop in my average miles per gallon.... and the DIC in my car doesn't lie. Ran the car with exhaust cams retarted 16* for 6 months and never noticed a drop in mileage, with about 80% city driving. I think people noticing a drop in mileage is due to a 'heavier' foot afterwards. I got nothing bad to say about retarding the exhaust cams.

[Mitch DOHC]

my gas miledge went up concedribably when i did the 13 cam timing...... here is the reason i think any way...... the way it was tmed up befro i re set it was the back cams were at the stock setting and the front intake can was advanced about 20 degrees..... i dont recomend that setting.. whoever had the car befor me had no clue what they were doing when they set the timing...... befor the timing i was getting about 17-18 on the highway and now 20-21..... and about the same increase on city driving... i like my 13 retard timing... .and thus far have had no bolts come loose

[jmgtp]

befor the timing i was getting about 17-18 on the highway and now 20-21..... and about the same increase on city driving... i like my 13 retard timing... .

Sounds like you need a serious tuneup if your only getting 21 mpg on the highway. I get 21-23 city driving!

[pocket-rocket]

I averaged 14.4 mpg to the last tank in the 92 due to HFS (heavy foot syndrome), and that car is in tip top shape. You said your car sounds more raspy, Aaron? Personally as long as it doesn't sound like one of those fart cannons on the Civic next to me at the light, I don't care what my car sounds like as long (in the way of exhaust that is) as it's making power, lol. I would rather not have it sound like total ass, but I really don't mind raspy. I haven't checked underhood of the 91 for a while, but I am sure nothing on it has come loose or it would have all come apart a while back. I am not calling you a liar, Josh, so don't take that the wrong way, I am just trying to figure out what pulley bolts came loose and why.