72 TA : New Project

[njsteve]

Full part # is UR4GP 2869 G Power.

[VintageMusclecar]

(edit* you posted your above reply while I was typing this one, hence some redundancy)

The 2869 is also numbered as a UR4GP. A Platinum that's one step colder would be a UR5GP. A "standard" NGK that's 1 step colder would be a UR5. (Personally, I've never had any luck with platinum plugs in anything other than late model EFI stuff)

Loosely translated, the 2869's appear to be the equivalent of a R45TS and the UR5's would be the equivalent of an R44TS.

I would expect the engine to be done by 5K if it's in stock form. All of the "stock" Pontiacs I've ever worked with liked to be shifted <5K for best performance. I also recall that most of them liked a total timing figure of 30°-32° as well. (FWIW, I'm referencing some of these figures from a friend's `76 TA with a `69 RAIII 400 in it that's dipped into the high 12's in factory trim on more than one occasion)

Phil did your carb, didn't he? If so, I believe he normally richens them up just a tad, so the carb should be good to go. You might try richening up the trim screws maybe 1/8 turn and see if that makes any difference on the plugs.

Eric

[njsteve]

Yes, got the carb from Phil at Custom Rebuilt Carburetors in Middlesex, NJ about 6 years ago.

I set the idle mixture to the highest vacuum reading i could get which was something crazy like 23 inches. Probably running a bit lean then. I will richen it up and maybe back off the timing a degree or two. As for the rpm range it's kind of hard to be accurate since the factory tachs are slow and rather inaccurate. So the nosing over could be earlier in the power range.

I will tinker with it this weekend and report back.

[68 Vert]

Steve, my former WW5 HO car would nose over around 4,500...I ended up changing the metering rods and adjusting the secondary air valve. Problem solved.
To start, make sure you have the correct metering rods, hanger and cam. I would start with 3/4 to 1 full turn on the air valve and go from there.

I'll see if I can find which rods I used...

Mike

[njsteve]

What you describe is exactly it. It seems to run out of gas at that rpm. The secondaries open very smoothly and without any bog or hesitation so hopefully it's a metering rod thing. I don't have much experience in tuning quadrajets. Any recommended websites for info (or local NJ people in the area).

[68 Vert]

Some info here: http://www.florida4x4.com/tech/quadrajet/ Download the Q-Jet tuning paper...the writer is a little over the top but you'll get the idea.

Checking/adjusting the air valve is pretty simple. I would tighten the spring by a 1/4-1/2 turn and see what kind of change you see/feel. This alone may fix the problem.

[njsteve]

Drove her over to my buddy's garage this morning and got some underside shots, since all I have to this date are the ones taken from a creeper 6" underneath the car when it was on jack stands.

[mockingbird812]

Swell underside Steve. Very nice!! [img]<<GRAEMLIN_URL>>/beers.gif[/img]

[x Baldwin Motion]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mockingbird812</div><div class="ubbcode-body">Swell underside Steve. Very nice!! [img]<<GRAEMLIN_URL>>/beers.gif[/img] </div></div>



yeah, I can hardly see any AC comp fluid [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

[njsteve]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 68 Vert</div><div class="ubbcode-body">Steve, my former WW5 HO car would nose over around 4,500...I ended up changing the metering rods and adjusting the secondary air valve. Problem solved.
To start, make sure you have the correct metering rods, hanger and cam. I would start with 3/4 to 1 full turn on the air valve and go from there.

I'll see if I can find which rods I used...

Mike </div></div>

I checked and the metering rods are the stock CR rods. Just out of curiosity, what would the recommended change be from there?