[74Grandville]

I took my Firebird to the dyno today to see what kind of power i'm putting down. I have done many modifications since my last trip. my first trip was at a different place, but my Old numbers were 261HP/365TQ. My New numbers: 322HP/386TQ.

My engine's specs

8.9:1 compression
455 0.40 over, stock rod(ARP bolts), cast pistons
6x-8 heads ported by me following Jim Hand, Pete Mcarthy and Steve25's advice, (no flow testing done)
Stock intake ported by me following Cliff R's pics
summit 2802 installed strait up following Screaming Chief's advice 224/234 .465/.488
summit headers/2.5 mid pipe 2.25 down pipe
1976 Q-jet built by me following Cliff R and Kenth's advice
HEI tuned by me following advice found on the board. 34total all in by 3,100rpm
3/4" open spacer

The session went great. The initial runs were done with a different Q-jet, it was giving me some funny readings on the top end so i swapped it after the 4th pull to a different Q-jet. I think i may have found the issue later. the 69 Q-jet did not have a positive stop and I think the secondary blades were fluttering. If not maybe someone else has an answer?

One funny thing I also noticed, no matter how many changes I made with secondary rods/ hangers the fuel curve did not change for each carb. I'm guessing it's an issue with their sniffer? The changes did make a difference in each pull.

I want to thank everyone on this board as there are many names I did not mention. I could not have got where I am with out the knowledge found here.

Old Thread: http://forums.maxperformanceinc.com/...d.php?t=635734

[hal101]

nice

[ta man]

Those are good numbers!

[Cliff R]

Problems on the top side of the pulls, and not seeing much difference from metering rod and hanger changes usually indicate fuel delivery issues (carb not full on hard runs), or fuel inlet seat too small in diameter.

Another potential issue we've seen is POE well feed holes too large, which continues to feed fuel thru the POE system for the entire pull, or run, making secondary tuning difficult, if not near impossible.

It is also nearly IMPOSSIBLE to get good/predictable A/F changes with a hand full of various secondary metering rods and hangers.

We found this out many years ago on the dyno when I swapped in metering rods with much smaller tips, and went leaner on the next pull. To get accurate and predictable results, a set of metering rods custom machined from the same cores, with the same tip length and included angle leading to the tips is required.

Almost all of our customers who drag race, and are serious about it, use custom machined metering rods for accurate and predictable changes in A/F run to run. The same hanger is used for all testing, to make things even easier with that deal.....Cliff

[74Grandville]

Originally Posted by Cliff R

Problems on the top side of the pulls, and not seeing much difference from metering rod and hanger changes usually indicate fuel delivery issues (carb not full on hard runs), or fuel inlet seat too small in diameter.

Another potential issue we've seen is POE well feed holes too large, which continues to feed fuel thru the POE system for the entire pull, or run, making secondary tuning difficult, if not near impossible.

It is also nearly IMPOSSIBLE to get good/predictable A/F changes with a hand full of various secondary metering rods and hangers.

We found this out many years ago on the dyno when I swapped in metering rods with much smaller tips, and went leaner on the next pull. To get accurate and predictable results, a set of metering rods custom machined from the same cores, with the same tip length and included angle leading to the tips is required.

Almost all of our customers who drag race, and are serious about it, use custom machined metering rods for accurate and predictable changes in A/F run to run. The same hanger is used for all testing, to make things even easier with that deal.....Cliff

Thanks Cliff, This is good information! I know the fuel system in my car is not up to par, but I plan to move the engine soon to my TA. i'll also take a look at the POE and Rods.

[steve25]

Congrats on the new HP and TQ numbers!
That size motor in its upper rev range really wants 3" tubes from the collector into the muffs, assuming that the header collectors are 3".
This can make for some lack of changes seen with jetting swaps also.

[Cliff R]

It is really impossible to effectively tune any carb with insufficient fuel delivery, even the Holley units with the huge fuel bowls.

The q-jet is much easier to tune on a chassis dyno, engine dyno, or at the track as it only takes seconds to change secondary metering rods. The rods MUST be exactly the same in taper, tip length, and included angle to the tips, or the A/F readings can be all over the map. This is why different hangers are usually required I conjunction with metering rod changes to get the desired effect.

Having a full set of custom machined metering rods take the hanger and rod tip length out of the equation. ALL of the serious racers that we support use them for class racing, Pure Stock, FAST, etc.......Cliff

https://www.youtube.com/watch?v=XMtZNOtxEec

[72LuxuryLeMansLa.]

Originally Posted by Cliff R

It is really impossible to effectively tune any carb with insufficient fuel delivery, even the Holley units with the huge fuel bowls.

The q-jet is much easier to tune on a chassis dyno, engine dyno, or at the track as it only takes seconds to change secondary metering rods. The rods MUST be exactly the same in taper, tip length, and included angle to the tips, or the A/F readings can be all over the map. This is why different hangers are usually required I conjunction with metering rod changes to get the desired effect.

Having a full set of custom machined metering rods take the hanger and rod tip length out of the equation. ALL of the serious racers that we support use them for class racing, Pure Stock, FAST, etc.......Cliff

https://www.youtube.com/watch?v=XMtZNOtxEec

Cliff,

Where would one get a set of "custom machined metering rods" these days? Would these make tuning a street car easier or would they be overkill?

[71 Goatman]

Wow Grandville,

I had almost the identical combonation and my chassis numbers from 2yrs ago were dead on with what you have. Makes me feel good that a home ported, home assembled combo can come out with decent numbers without breaking the bank. Mine is backed up with a 200r4, 3:42's/Eaton True Trac, Jim Hand Contiental convertor.

9.5:1 compression
455 0.30 over, H-beam rods, Keith Black Hyperutectics
#96 heads ported by me following Jim Hand, Pete Mcarthy DVD, (no flow testing done)
Stock intake ported by me following Cliff R's pics
Speed-Pro 1175 installed straight up following 224/234 .465/.488 (w/1.5's)
Ram Air exhaust manifolds 2.5" mandral bent Pypes system
Q-jet built by Cliff R
Stock dist. w/Pertronix kit, recurved, 36 degrees all in by 2800rpm
Thick gasket from Cliff as a spacer

Ran 102 in the 1/4 in 98 degree heat.

July 2013 changed cams to a Tomahawk TC-02-HF 236/234 .510/.505 straight up. You could really feel the increase in the top end power.

Cam change only ran a solid repeatable 109 in the 1/4 same 98 degree heat!

[Firebob]

What kind of dyno? I was told you will better numbers from a dynojet machine than a mustang. I got nearly the same HP numbers out of my 400 last year but not as much tq(356lbs) on a mustang.

[PONTIAC LARRY]

Nice numbers , very similar to a 440 RB Mopar I built for a buddy we put in a 74 Dart Sport backed by a stock 727 Torqueflite and a Ford 8.8 3.73 31 spline rear. It was std bore 440 ci, about 10.3:1 with NOS old TRW STD pop ups and uncut deck 452 casting stock valves I did decent amount of bowl work on that flowed max 269/ 192 cfm, a small pingy .465/.465 228/235 110 LSA Lunati hyd cam , Edie TQII single plane, 750 dp, 2" fenderwelll headers. It did 323 RWHP 400 RWTQ we never got to see what this could have done with much more cam and badly need stall but it was a cool car except when we talked about plug wires and plugs ..LOL

[74Grandville]

looking at dynojet.com my run in 2010 was on a 248x, Yesterday's run was on a 224x. not sure what these numbers mean, but I believe the roller was bigger on the 248x.

I have thought about stepping the cam up, but I would also want to raise the compression some if I go that route. If I pull the heads i'm going to want to go with 1.77 exhaust valves. then there's the rods and pistons... The list is never ending, but that is why I love this hobbie.

i'm going to go with 3" exhaust in my TA when I move the engine, i'm also going to upgrade the fuel system in that car. this may be the only upgrades for a while as there is a lot of other things that need to be done to get it back on the road.

[Cliff R]

Cliff,

Where would one get a set of "custom machined metering rods" these days? Would these make tuning a street car easier or would they be overkill?

Not really needed for a street driven vehicle. I don't even swap metering rods in my own carb, just run it a tad "fat" all the time, it really doesn't pick up all that much chasing around the fuel curve.

I've spent several track outings making back to back to back runs changing only secondary metering rods. Starting out "pig" rich and going up in .003-.004" increments until it leaned out enough to start surging slightly. I seldom see much over tenth from one end of that deal to the other, and under 2mph difference.

Hardly worth chasing around for a street or bracket car, but if you are trying to get the absolute most out of the combo, class racing, etc, it's pretty much mandatory....IMHO.....Cliff

[Lee]

[QUOTE=74Grandville;5164739]looking at dynojet.com my run in 2010 was on a 248x, Yesterday's run was on a 224x. not sure what these numbers mean, but I believe the roller was bigger on the 248x.

QUOTE]

The 248 DynoJets are the original versions, with 48" diameter drums. The 224 is the newest/current version, and has a 24" drum. DynoJet's numbers are typically VERY consistent, even between the older 248 and the newer 224's. I've had vehicles which I've ran on both, and had VERY similar results.

[Firebob]

"that's why I love this hobby"

74G,
You're a sick man(much like the rest of us) and apparently have too much money. That condition will be corrected shortly. Not to worry.