Firebird is gutless turd-pig. Help!
 

Why is my Firebird such a gutless turd? 1969 Firebird, 400 ( .030 over), M-20, 3:73 rear. Engine has strong, even compression, #62 heads, long branch manifolds, Gardner stock-type exhaust, stock 1969 intake, correct 1969 M/T recalibrated Quadrajet, Summit 2802 cam, 1.65 rockers, DUI HEI with 24 degrees @ 3000, Delco 44R plugs gapped to .050 (as per DUI instructions). Runs cool even in 90 degree weather. Total timing is/has been 32, 34 and 36 degrees while trying to find the sweet spot. Still looking for it. Sadly, it pulls about as hard as the Saginaw 3-speed V6 ’81 Malibu I had as a kid. None of that pushed-into-the-seat power I have had with previous cars. It’s embarrassing. What am I missing? Could this still be some kind of timing/ignition problem? Slipping balancer? Is the quadrajet insufficient? Way too mild a cam? Has Greta Thunberg put a curse on me? I’m stumped.

Maybe find a good chassis dyno shop around you and run it out?Tom

That should be a strong running engine. Describe how you calculated 32,34,36 total timing vs 24 degrees at 3k rpm - this is way too low. Initial timing + mechanical advance should be around 34-36 degrees and if using vacuum advance another ~10 degrees at light load. I would certainly verify the balancer hasn’t slipped. Was cam degrees-in? What is the history of the engine?

I would want to see 34* timing at 3000 if not sooner. Maybe the 24* is a typo? Anyway, the combo looks good. You say stock type exhaust. What size pipes and what mufflers? This could be a restriction. Any sign of a fuel starvation issue? Stock pump with in tank pickup/sock?

No disrespect intended, but that Gardner style exhaust could be a choke point. I know I had one and loved the sound, but taking mine off got me probably 30 hp. I had a 66 GTO that i dynoed on a chassis dyno and it made 209 hp at the wheel. I took off the Gardner exhaust and stock manifolds, added Ram Air manifolds and went to a 2.5 inch exhaust, and from a stock cam to a Crower 60916 and re dynoed at 270 hp. It's something to look at.

Watch this. https://www.youtube.com/watch?v=eLceqIoTMvo

You may want to check cam lift. Years ago they had trouble with those cams being soft. I put one in an engine and it didn't even make it thru the break in on my test stand. Replaced with another brand and it fixed the problem. I won't buy that brand again. Just saying.

I've got the same engine, 400, 62 heads, 2802 cam, 1.5 rockers. RPM intake, QF 750 double pumper, headers, 2.5 exhaust, magnaflow mufflers dumped. 35* at 3000. Loose converter and 3.25 gears with true-trac. Thing will absolutely fly, easily breaks the tires loose, fairly strong for an old worn engine. My hat is off to whoever built the thing like 30 years ago. I did the 2802 swap, replaced a 1980s Crane 284HIT cam and valvesprings that was in it. Makes 13" of vacuum at 900 .

I suspect the exhaust, the carb and the 1.65 rockers are the issue, in that order. The engine wants to breathe, and likes the gas. I suspect the stock exhaust is choking it, and the engine wants more accel pump shot and a different opening rate on the secondary flaps. Maybe the secondaries aren't really opening? The 1.65s may be hurting the low end, and are overkill for stock port 62s and that cam.

A wideband O2 sensor will tell the tale.

Thanks. The 1.65 rockers are a late addition. Started throwing parts at it after I ran out of other ideas. Had same issues with the 1.5s. Carb is recalibrated and secondaries work as they should. A double pumper is tempting though. Consensus seems to be exhaust. Didn’t even cross my mind but it makes a lot of sense since I’ve been over everything else multiple times. It’s on it’s 2nd cam, new rockers, 3rd distributor, 2nd carb, etc.
the exhaust has resonators and a transversal. Maybe I’ll give a different exhaust a shot in the spring.

Sorry, I was not clear. I meant 24 degrees mechanical with the 10-12 degrees initial. So, 34-36 degrees total @3000.

If you’re not sure if the balancer has slipped or not giving you inaccurate timing readings you could use a piston stop that replaces the number one spark plug and verify TDC.

Of simply replace the balancer if it’s old anyway.

Regarding the exhaust, honestly how bad could it possibly be? A copy of an original HO or Ram Air exhaust has to be better than the standard 400 system that used log exhaust manifolds. I had a 1969 400 4-speed Firebird with the standard 330 hp 400 and it ran just fine with the original factory exhaust, it sure didn’t feel like a slug I can tell you that.

The long branch exhaust should have 2-1/4” headpipes, a standard system only has 2” headpipes.

If you still think the exhaust is too restrictive then take the headpipes loose and run it without the exhaust hooked up, that’ll tell you right away.

Double pumper Holley carb would not be an improvement, just diminished fuel efficiency.

I'm running 16* base timing, 19* advance bushing, timing all in by 3100 or so. Another 11 degrees on vacuum advance. I run 93 octane E10 gas. Throw more base timing at it, reduce mechanical advance and see what it does.

I'm a Q-jet guy, the QF750 came with this car. Having tuned both, I do like how easy it is to get a holley apart. It's also nice to not depend on a thimble's worth of gas in the bowl with a cheap mechanical fuel pump. It's taken a LOT of work to lean it out to where it gets decent mileage. I suspect it wouldn't be as much fun if it didn't have a 3500 stall converter. A double pumper is bog city if the engine doesn't have the converter or gears to revv freely.

I agree that it seems unlikely that it's the exhaust alone. My stock RAIII ran as you'd expect it to with a basic factory style Gardner exhaust system. Your engine combo seems a bit better than a RAIII so it should run better than you describe with a Gardner exhaust..

Sounds like your timing is not horrible either. Sure, maybe it could be better, but it shouldn't be causing a major problem.

I'd be thinking more about the carb. I just had two different Quadrajets both built by "experts" that had serious problems. One was as simple as the secondary air door tensioner installation/adjustment. But even though it was a "simple" problem, the motor ran like total crap until it was fixed.

If not something like that, then maybe something worse. Hopefully not.

Agree about your Quadrajet.

Who recalibrated it?

May be time to question that work and try another carb guy like Ray Klemm (worked with Cliff Ruggles) or Shaker455:https://forums.maxperformanceinc.com...r.php?u=140343

No mention of AFR, you can be real lean or super fat and missing 40hp etc right there, I'll assume the plugs don't read black so you're not super rich.

You have not stated what was done to your #62 heads to allow them to work with the 488" exh valve lift of the 2802 Cam.

Even if you have changed valve springs to allow the use of 1.65 rockers there is not enough stock valve installed height to work with the . 488" lift no less the .536" Exh lift, or even the .516" lift the intakes will have with the 1.65 ratio rockers.

Have you checked your valvetrain geometry with the 1.5 rockers no less the 1.65 rockers to see if you need different lenght push Rods?

Are you getting full throttle when the pedal is on the floor?

Will the motor out of gear and with wide open throttle buzz right up to 5400 with no back firing?

I would start out with a vacuum gauge and do basic tune up troubleshooting. Increase the timing while watching the vacuum gauge. Let us know what kind of readings you are getting.

What is the cranking compression? Was the camshaft degreed? Did you confirm that the balancer is accurate during cam install? Does your carb have a secondary lockout?

A late addition of 1.65 rockers?

tells me the heads were not prepared for them correctly.

Good point in the above!
I forgot to mention that 1.65 rockers can be dropped on any factory cam other then the RA4 cam without running into push rod to guide hole clearance issues, but once your into higher lift non factory cams that can change.
In short you may have push rods rubbing on the rocker stud side of the guide hole.

I was scratching my head on throwing 1.65 rockers on a high lift cam;
That cam specs out at .466" & .488" lift with a 1.5 rocker;
Unless my math is wrong, that's .513" & .537" lift;
If the heads are not setup for that much lift, this may be a part of the problem.

I also know that the advertised durations make this cam appear to be a high lift 068, but the @0.050" duration numbers suggest that this is actually much larger;
It appears to me that this grind has 10(int) & 11(exh) degrees more duration than the 068;
The @0.050" duration numbers put it closer to a 744.

Wasn't the consensus that #62 heads were more around 78cc's?
If the engines details haven't all been confirmed, this could be a 9:1 (or slightly less) compression engine - and with a cam that big, if you don't have enough compression, I am told that you might have something of a pig...

This is a good point, the 2802 is very similar to a 744, much closer to a 744 than an 068HL IMO, the chart below shows that as well. I’ve been looking into the 2802 as I think it’s a cam that I want to run as well, almost every thread I’ve read on the 2802 seems to state that they run pretty good so it sounds like something else is going on with the OP’s combo that’s not related to the 2802.

http://pontiacpower.org/PontiacCams.htm

The OP states that his motor has “strong even compression “ but yet he does not state how much PSI that is.

Thanks all. I’m going to start with the basics and run with your suggestions and comments.
Starting with simple things like the balancer. I’ll use a TDC tool and see if the mark lines up with true TDC @ 0 degrees or not. If it slipped and needs a new balancer, then there’s one problem solved. From there if need be, I’ll go through your suggestions and see what happens. I’ll also drop the exhaust and make a quick run around the nearby back roads for a minute to see if it makes any significant difference.

I would think that a "Gardner stock-type exhaust" shouldn't hold you back;
Look at pure stock drags and such - I have understood that many of those people are running a Gardner exhaust.

Many times when you run an open exh the car has even less torque output up to 3000 rpm or so I don’t know how much that test out will tell you about your issue.

Your better off listening for the vacuum cleaner sound back at the tail pipes at high throttle like is done to pin down a clogged converter.

When I compared the 2802 cam specs, it is more similar to a 744 cam. The HIT-284 Crane cam I pulled out was 228/235 at 050, about 500 lift. The stock retainers had mashed the aftermarket Viton seals flat. It was a mess when I got the valvetrain apart. I put it back together with the Crower 60404 springs, short crower retainers, BBC studs and crower enduro rockers. Had juuuust enough room to clear a new set of blue vitons.

Put an AFR and vacuum gauge on it, where you can see it while driving.

That will tell you if the carb is opening all the way and what the AFR is. I have that setup on my car, really helps nail down what the carb is actually doing. I've got the DP tuned to cruise at 13.2 on the mains, it goes leaner as I add throttle until the vacuum drops below 8.5, where the PV starts to open. Then it goes richer as I go to WOT, where AFR ends up in the 12.5 range.

I've had secondaries on Q-jets that didn't open at WOT, and it will show up as vacuum gauge won't go below 6" or so of vacuum.

I'm thinking if the performance of the engine was disappointing before the addition of 1.65 rocker arms, most likely the 1.65 rocker arms aren't the culprit.

My first thought was secondary lock out on the secondaries. Then a slipped harmonic damper and then exhaust. I'm not mentioning the manufacturer but I worked on a beautiful SD TA that was down 130 horsepower because of the "correct" looking exhaust.

If your familiar with using an "in car" vacuum gauge one might notice the vacuum won't go to zero under full throttle and will have a restricted reading when you back off the throttle when the exhaust is clogged up.

Then I thought maybe the OP is used to incredibly fast cars and a twelve second car seems boring.

Side story.

Back in the day HO racing during testing dropped exchanged the stock exh system on a 74 455SD for a duel exh system and picked up 90 Hp.

Who put the camshaft in the engine? If the timing chain is one that has multiple advance and retard keyways, I would check to make sure they used the correct mark and associated keyway. I have had several Pontiac engines over the years come in my shop for troubleshooting with the same symptoms as yours. In each case it appeared that it was a good combination and should run well, but didn't have ANY power. When I inspected the timing chain installation, I have found that they incorrectly used the keyway on the crank gear to line up with the mark on the cam gear. Once corrected the cars ran like they were supposed to .

when i posted about 1.65 rockers being installed i was just planting a seed, immediately they are not a running problem but i would almost bet the pushrods are grinding on the heads and spring stack and retainer to guide clearance are very minimal if not dieing a slow death, aftermarket retainers could be giving pc seals a break, lifter faces and cam lobes are taxed under this situation

Yup, need more specific info, SCR, head info, cam degreed or not, timing chain setup, etc.

It does sound like maybe the secondaries aren't opening up.

Balancer marks/slip is a very good bet too, especially if it's OE, or even an OE replacement.

You could be 8 degrees off or more on timing if it slipped.

History of the engine would help too.


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If it was mine I'd keep loosening up the secondarys till there is a bog. Then tighten jist enough till it doesn't bog.

When I got my 455 running it didn't feel right. Way low on power. Secondary spring on the quadrajet was too tight.

Do you have full battery voltage to the DUI ignition?
What is the ‘good’ cranking compression psi ?
✌🏼

I'm in with Gary on this. That combo should be a fun rowdy little ride. I'd be checking TDC and checking timing chain/gears.

I'll cast my vote for the incorrect cam phasing and/or inaccurate ignition timing marks on the balancer.

Eric

I wouldn't go chasing exhaust. In Your case it's not an issue.

I ran Gardner exhaust on my RAIII in pure stock and ran 14 flat with it at 99 mph. While it wasn't holding the car back a ton it wasn't a pig either at a 3890 race weight

I did switch to a flowmaster transverse setup back then because 2 1/2" is legal and what most run in the class, and ran 13.70's at 102 mph with no other changes. Worth maybe 30 hp or so. Don't think that's your issue when you say it's a pig.

I know he said there was no issue with the secondaries.

Might not be running it through range of motion by hand, but I would highly suggest having someone in the car push accelerator to floor and visually verifying they open fully inside the car.

I’ve seen too many at work that didn’t make the grade in actual operation off the pedal. Carpet ,bent linkages, throttle cable issues etc.

You said that you have the correct 69 Quadrajet on there. There is alot of info on how the factory limited the secondary throttle opening on the early Firebird carbs, so they wouldn't outrun the GTO's. Just a thought. Maybe worth a check.

Sounds similar to my story. So subjective the topic is without having before and after data to compare..

Seat of pants feeling being the gauge and all.

It can get to be a downer trying so many things , going out and driving it hoping for all of a sudden some more action but hopefully it gets sorted and this is the forum that can help, that is for sure.

Of the information I've read on degreeing camshafts and performance the final word in my opinion is if it's with in +4 Advanced from LSA or -4 Retarded from LSA it doesn't ultimately change the 1/4 mile results. As one would expect. I think the torque curve moves 300 rpm forward or backwards based on 2 degree changes? I saw some deep dives on this forum where the writer literally made 2 degree changes , went out and did the 1/4 mile. Now, could the tires spin and grip, track conditions all play a role? Sure. So maybe if your camshaft is installed outside of that 8 degree range from a straight up install then it could be a turd? I wouldn't know. Knowing at least where it is installed is more beneficial then not, though!

- hook up fuel pressure gauge safely, route lines up to your windshield and do a full throttle accel from stand still up till end of 3rd gear, does the psi stay at 5 through out the full run?

- carb full throttle with pedal down to floor?

- try some different distributors

- try some different carbs

- ignition 12v feed

- wires ohm check?

- compression check, dry, wet , dynamic running


For me describing seat of the pants feel in my automatic was. From stand still.

1st gear - traction loss and power spinning fast up to 5000 rpm. just constant "freight train" feeling
2nd gear - RPM'S at shift would come down to 2600 rpm and rise, then when 3000 rpm hit , it was like push you back in seat super exciting up to next shift 5000 rpm. more than freight train!!! I looked forward to it!

Then 3rd gear would just be a constant pull .

Anyway I think Cliff said once , the butt meter can be misleading and lots of engines run down the 1/4 mile freight train with no special "hard pull" and run just as fast as engines that do have that. Something to that effect. Cliff has a lot of experience with cars coming in with owner saying our story.

In the end after all your check lists are complete, perhaps a radical cam change just to see or... in my case... I'm just gonna build another engine all together with a way different recipe.

Keep us posted!!! Excited to hear results as you go through them. Exhaust seems to be a place to investigate too.

As I recall what was the 360 hp motor in the GTO was down rated to 345 in the Firebird by means of limiting the secondary throttle opening, but that being the case 345 Hp will not feel like a Turd, nor will even 300 hp.

Oh, and if it has not been posted yet confirm your firing order.

What is your CR?

A couple of people have asked. So why not do a cranking compression test?

Stan

Cam timing is retarded.

Mystery solved. I picked up a TDC piston stop tool. Seems the balancer has slipped/is bad.
According to the TDC tool, my balancer reference mark is off by about 11 degrees. Top line is original mark, lower line is correct according the the TDC tool. If I’m not mistaken I’ve been running 10-12 degrees retarded.

Excellent news - please update after you swap in a new balancer.

Good news to hear!

That much retard is right on the edge of the motor backfiring when you mash the throttle which would have been a more definitive clue to your issue assuming your firing order was right.

Now get a new balancer and go make some rear tire smoke.

Right on!

you can go by the new mark and time it presumably correctly and enjoy how it is supposed to run while waiting on new part (sanity check)

You might want to take advantage of this service if your balancer is not cracked in the keyway area.

Well that could've gone bad if it was 12 degrees advanced, I smoked all 8 cylinders on a fresh engine all because they didn't mark true TDC on the balancer and it was 4 degrees advanced.