[guccieng]

Originally Posted by tr709

Also looking to replace the performer intake with a factory cast iron, Thoughts?

good move.

[Billz428]

I,d also look at freeing up the exhaust too, gotto breathe.

[jakeshoe]

I think we got it all sorted out.

It seems to have been a combination of things. It will definitely break the tires loose now, seems to pull well going down the road.

The issues we found and addressed:
Cam timing 3* retarded, set for straight up.
Valve adjustment sounded loose, re-adjusted valves.
Air valve on carb was too stiff. We took some tension out and that really seemed to help the off the line response after all the other changes.
Modified trans governor for higher RPM WOT shifts.


It feels like a different car now. I think Tony will like it

I agree,
some gears and free flowing exhaust would make a profound improvement again.

I'm not all that familiar with the Pontiac specifics but why is the Performer considered such a bad choice for intake? Any links to some testing? I'm curious.

[grandville455]

[QUOTE=jakeshoe;3827535]I think we got it all sorted out.

It will definitely break the tires loose now,

We don't Believe you Jake! we will need to see video

[guccieng]

Originally Posted by jakeshoe

I'm not all that familiar with the Pontiac specifics but why is the Performer considered such a bad choice for intake? Any links to some testing? I'm curious.

http://www.classicfirebird.com/hand/jhand14.html

http://psp.aquacomp.net/topic.asp?TOPIC_ID=429

[Stuckinda60s]

I definitely thought the cam might have been retarded, but thought it might have been more so. I'm surprised. How much difference did it make in idle vacuum?

Not trying to second guess you Jake, you've done well, but I'm curious as to why you didn't advance the cam. Doesn't Comp recommend 4* advanced?

I'm assuming the air valve was too stiff after the cam was re-installed? If that's true, how bad must it have been before?

[jakeshoe]

[QUOTE=grandville455;3827545]

Originally Posted by jakeshoe

I think we got it all sorted out.

It will definitely break the tires loose now,

We don't Believe you Jake! we will need to see video

I took the car on a test drive tonight to see if the last carb adjustment made any difference. I had my wife follow me to the gas station and car wash.

I rinsed the car off and my son was asking about the races (I live about 5 miles from the local drag strip). I occasionally go to the drag strip in my wife's Trailblazer SS and clean up some of the local Mustang GT's with a 4700 lb SUV

http://www.youtube.com/watch?v=y8SSexNfguM

The kids get a kick out of this.
I jokingly told my son Josh, "we could take the Firebird to the dragstrip!"

He was game for it.

I'll take video of Tony abusing the tires.

[Stuckinda60s]

Jake:

If I remember, right, you went with ported vacuum, right? Have you tried it both ways since you got everything sorted out?

[jakeshoe]

Originally Posted by guccieng

http://www.classicfirebird.com/hand/jhand14.html

http://psp.aquacomp.net/topic.asp?TOPIC_ID=429

Good info. I just got done reading all of it.

[jakeshoe]

Originally Posted by Stuckinda60s

I definitely thought the cam might have been retarded, but thought it might have been more so. I'm surprised. How much difference did it make in idle vacuum?

Not trying to second guess you Jake, you've done well, but I'm curious as to why you didn't advance the cam. Doesn't Comp recommend 4* advanced?

I'm assuming the air valve was too stiff after the cam was re-installed? If that's true, how bad must it have been before?

I'll have to check the idle vacuum. I haven't put the vacuum gauge back on the car. I think we achieved our goal. I'll have to install it though because I'm curious now that you mention it.

The valve adjustment would also have effected the vacuum.

I think the combined effect of several factors was the reason it felt so weak.
The air valve felt "OK" if you tipped them open, but I felt they were a bit tighter than I usually set them up. However I haven't really been doing a bunch of Q-jet tuning since I was playing with the one on my Chevelle a few years back.

The valve adjustment made the engine sound as if it was a solid roller. We lashed them down to 1/2 turn past no lash. It's still noisy (roller rockers always are IMO) but better.
Maybe it was losing some effective duration?

I could spend another full day just tweaking small things, but Tony has mentioned wanting to possibly change intakes and other combo changes, so there is no reason for me to spend his money perfecting the tune on this setup.

I notice a slight "burble" in the part throttle steady rpm cruise that I would want to work on.

I do feel like there is better throttle response at cruise rpm, when you slightly accelerate.

I'l let Tony drive it and get his thoughts, I have pretty limited drive time behind the wheel so he'll be more likely to notice the minor things.

[jakeshoe]

Originally Posted by Stuckinda60s

Jake:

If I remember, right, you went with ported vacuum, right? Have you tried it both ways since you got everything sorted out?

Yes ported.

The engine really seemed to like 18-20* of timing at idle. The distributor has ~15* of mech advance curve, and this puts it right where it needs to be as far as timing.

We may try it on FMV again but I'm afraid it will pull it out of the range it likes.
It seemed sensitive to much more timing at idle than 20*.

I've played with some combos that would barely idle at 20* (BBC with healthy solid roller) and liked 40-50 degrees at idle. However this one seems very happy at 18-20.

[Stuckinda60s]

Thanks for responding, I'm sure everyone reading this appreciates how much you're willing to share.

There's no doubt you've shown the difference between standing across the shop, throwing parts at a car and trying to get it to run well, and really getting in there, using your head and applying proven methods to make it run the best with what you have.

I'm still curious as to why you installed the cam straight up.

[Keith Vrabec]

Betcha the burble you speak of will go away with full manifold vacuum to the distributor. Then tune the idle lower.

Try it.

Like Rich said, costs nothing.

You'll be able to put the pedal through the floorboard from idle.

[1967Tempest]

My cousins stock 350 in his 68 bird LOVED FMV! Really weird. Ported vacuum, with ~12* weak, ~15* weaker-er. FMV 12* better. FMV with 18* hei all in to 38 at 3000, IT BOILS the tires in 4th gear @ 50mph!! Ask my cousin 1968 Firebird, hell tell ya.

And its free.

But every engine is different. The 80$ timing light was worth every penny.

Still one of the best threads on the board.

PS. Trailblazer beats a Rustang. "A thing of beauty is a joy forever!!"

[tr709]

going to go pick up the car in a few hours. Can't wait!

My immediate plans are to swap out the performer with a stock intake, for those of you who enjoyed this thread, want to make me a good deal on one

Otherwise I'm just going to drive it and enjoy for a bit while contemplating what to do next, possibly long branch exh manifolds in order to take more advantage of the port head porting.

I'll report in later!

[Keith Vrabec]

You have the cal customs valve covers on it? Really neat looking car. (68 Bird convert was the one that started it all for me.)

I had a very similiar problem with my 76 TA, very similiar combo too. Bringing the advance in early is good for a street pontiac. I had a stuttering wehn mashing the pedalfrom about 1400/2500 rpm. As the mechanical advance kicked in the car pulled like it's rear bumper was on fire!!!! Checked for vacuum leaks, fuel delivery, air filter, etc. 2 min switch on the vacuum allows me to mat the pedal at 25 mph in 4th gear without hesitation, stutter, or drama. can shift 1 direct to 4th if I want, and no need to downshift on hills like a SBC. (76 TA, 455, 6C, 7.6 compression, 268XE, rhoads, CR BW 4 sp, 3.23 gears, pypes exhaust, RA3 headers, 87 octane, no dieselling on shut down, no starting issues when hot soaks, runs nice and cool. Big thanks to Artie Philipp (general mechanical, exhaust, and all sorts of PITA stuff)and Rich Massee (engine combo, Rhoads lifters dealer, performance tuning, driver...can't wait until summer again to get some times) on this one)

[ta man]

Upgrading the exhaust is an excellant idea>I suggest going full 2 1/2 inch exhaust with a x pipe.This will uncork some power for sure especially since your heads are ported.

[Cliff R]

Using manifold or ported vacuum to the vacuum advance has absolutely NOTHING to do with the performance of this vehicle. The vacuum advance can effect idle quality, if MVA is used. At light throttle, cruising around at very light load, etc, ported or manifold vacuum will fully employ the vacuum advance unit. Any heavy/full throttle equalizes the vacuum above and below the throttle plates and the vacuum unit does NOTHING. In other words, any heavy, full, idle to full throttle testing Jake is doing or has done with this vehicle is NOT effected in any way by what source he is choosing to employ the vacuum advance.

All heavy/full throttle testing is effected only by the base timing setting, how quick the timing curve is, and the full throttle setting. Just wanted to clear that up, the lack of performance they have been seeing, is not a product anyplace of the vacuum advance unit.......Cliff

[gtome]

I have been switching mine between ported and manifold vac for the last few days. Manifold vac gives better idle quality, but it looses the bad ass lumpy lump sound. I havent noticed any improvents anywhere else on it with FMV.
In fact I was trying to like ported vac.... but I dont like how i can feel the vac advance come in (maybe lighter adv springs would help this?). I will miss the lumpy idle though, just love the way it sounds at the stoplights. Mine is on a Holley 3310

[guccieng]

if you're foot is pressing on the throttle, there is absolutely no difference between fmv and ported. only at idle without your foot on the gas pedal will you see a difference.