[petes67bird]

What are some ways to add horsepower to my setup? 1972 Luxury Lemans, 455 bored 0.030 over, #96 heads 3 angle valves, flat TRW pistons, 9.3:1 compression estimate, Melling 26308 cam was set at zero, iron intake, quadrajet by Cliff, curved ac delco hei(sun machine reading attached, not sure what it means), ram air manifolds, 2.5" dual exhaust, 3.73 gears with Eaton posi, 200r4 transmission, 10" billet 2800 stall. Downside, I am not sure if my rods are forged. The paperwork says 496453 crankshaft, polished standard sized rods and mains, rods resized with ARP Bolts.

Not looking to rebuild my motor as it has about 3k miles, but it's not as fast as I was hoping when I put it together. What would be the best way to get rid of the laziness on the line?

My ideas and questions.

1. Advance cam to 109, 4 degrees or
2. Boost compression by adding kre heads if it really would make a noticeable difference over the 96 heads. I was thinking the 74cc heads maybe at 290 or 310cfm ported.
3. Have my 96 heads reworked.

[RocktimusPryme]

How are you measuring, "Not as fast as I was hoping?"

Do you have disappointing track times or low dyno numbers? Im wondering if you just have a really well-sorted out combo that's running smooth and doesn't feel fast. If you just want it to feel more violent, put a manual in it. It will feel faster. If you are comfortable with the money for new heads you arent that far off of a TKX kit.

If on the other hand you have disappointing measurables, like the track times, then I would pull the trigger on the heads and go with a bigger cam. All the other stuff is likely going to be small gains (if any) that you wont be able to discernably notice. You could probably make some numbers with exhaust, longtubes and 3" exhaust. Maybe more depending on your mufflers, but even if you made an extra 25 Hp I don't think you would feel it.

Im all for people getting faster, I just want to make sure you are having an honest assessment with yourself about what you are disappointed in. If you don't have track times, go make a pass. You might surprise yourself.

[petes67bird]

Originally Posted by RocktimusPryme

How are you measuring, "Not as fast as I was hoping?"

Do you have disappointing track times or low dyno numbers? Im wondering if you just have a really well-sorted out combo that's running smooth and doesn't feel fast. If you just want it to feel more violent, but a manual in it. It will feel faster.

If on the other hand you have disappointing measurables, like the track times, then I would pull the trigger on the heads and go with a bigger cam. All the other stuff is likely going to be small gains (if any) that you wont be able to discernably notice.

Im all for people getting faster, I just want to make sure you are having an honest assessment with yourself about what you are disappointed in. If you don't have track times, go make a pass. You might surprise yourself.

It's just in daily driving and getting on it, it doesn't feel fast off the line. I chatted with cliff today and he said that the cam I have is doggish when it's at zero, and recommended advancing it. I am not sure if the shop who did my sun machine curve/timing set it incorrectly, or if I just need to tweak my combo a bit. I just want launch to be better.

[chiphead]

Ah, RAIV style copy camshaft. Rhodes lifters would provide some additional low end torque. The best way to increase power everywhere for a given cam and engine size is to increase compression to the limit of the available octane. Rhodes lifters would increase dynamic compression at lower RPMs due to earlier intake closing provided by the fast bleed down. It would pull about the same at high RPM.

Increasing static compression to the mid 10s with high flowing aluminum heads is the nuclear option.

3.73 and 2004R's 2.74 first gear and a 2800 stall should let it spin up. It should blow the tires off. Surprised it feels lazy. How much timing at idle? Did you and cliff discuss secondary opening speeds?

Knowing base timing, compression test and vacuum at idle would help us understand what it's doing now.

[RocktimusPryme]

I guess a bad timing curve could be a culprit. I would also be surprised that its not blowing the tires off.

Whats your initial timing set at? What are you getting all in without the vacuum advance plugged in? I might put a light on it and see before I started spending money. You might be able to wake it up just with some more timing advance.

[petes67bird]

Thanks, I do not know the timing as i had a shop do it for me. The shop is a well known gto restoration shop, so I am guessing they would know how to set it. Are you talking about cylinder compression? The builder provided me with those details.

Regarding Rhoads lifters would replacing that now cause a risk to my cam as everything is running smooth and broken in? I have sealed power lifters right now.

[AJ-]

I would agree with what some are saying with checking the basics first or have someone knowledgeable help you. Check that the throttle is actually getting pulled all the way open, make sure the choke isn't staying on or the secondaries being otherwise prevented from opening or opening all the way, and check your timing situation.

[RocktimusPryme]

Originally Posted by AJ-

I would agree with what some are saying with checking the basics first or have someone knowledgeable help you. Check that the throttle is actually getting pulled all the way open, make sure the choke isn't staying on or the secondaries being otherwise prevented from opening or opening all the way, and check your timing situation.

This is actually a good point. I recently had a deal where my air cleaner was interfering with choke linkage on a quadrajet. Made it run terribly. Make sure your throttle is opening all the way when the fun pedal goes all the way down and make sure your choke isn’t hanging closed.

As far as the timing goes, that’s something you could verify pretty easy. There isn’t much to it. Buy a cheap timing light, plug off the vacuum advance temporarily and just see where you are at. It’s not that the shop doesn’t know how to do it, but if they weren’t given specific instructions on where to set it who knows what they did.

[steve25]

First and foremost what is the motors hot cranking compression?

Larger port higher flowing heads will not help at all in terms of better acceleration below 4000 to 4500 rpm so strip that notion out of your mind.

Your leaving too much in hands of so called experts when it come to distributor timing, and not being able to check it yourself is leaving you behind the 8 ball .


You car set up right and with those rear gears should anniilate the rear tires at will!.

Here’s how your HEI should be set up.

[HWYSTR455]

Your total mech advance, if I'm reading it right, is only 12 degrees total. I would try making your initial timing around 16-18 as long as it cranks over ok. Then see if it's an improvement.

If so, you need to have the distributor recurved to have about 16-18 total mech advance with 16 degrees initial advance.


.

[petes67bird]

Originally Posted by HWYSTR455

Your total mech advance, if I'm reading it right, is only 12 degrees total. I would try making your initial timing around 16-18 as long as it cranks over ok. Then see if it's an improvement.

If so, you need to have the distributor recurved to have about 16-18 total mech advance with 16 degrees initial advance.


.

Thank you, I plan on taking it to another shop once it warms up in the spring to get it looked at once again. I am hoping that timing adjustment livens up the motor a bit.

[petes67bird]

Originally Posted by steve25

First and foremost what is the motors hot cranking compression?

Larger port higher flowing heads will not help at all in terms of better acceleration below 4000 to 4500 rpm so strip that notion out of your mind.

Your leaving too much in hands of so called experts when it come to distributor timing, and not being able to check it yourself is leaving you behind the 8 ball .


You car set up right and with those rear gears should anniilate the rear tires at will!.

Here’s how your HEI should be set up.

When you are asking about cranking compression, do you mean per cylinder. If so, they all measured between 159-166psi. The only reason I started thinking about heads is because that is what I was being told by people more knowledgeable than me. Butler, KRE, and Cliff all said that changing my heads would give me more air that the motor needs and generate the power I was lacking. I was told that the 96 heads do not flow great ( I only have the 3 angle and milled a little) and that I want to increase my compression for my cam. 2 of those three mentioned that the cam needs to be put 4 degree forward to 109, and that on center, it will be sluggish. I asked the builder about my concerns and he sent me videos of the same build in a Firebird and it seemed very lively.

I will be honest, I do not know what moving the cam will do to my driveability etc, I am just disappointed in my current setup and for the spring, I would like to wake up my setup or get it set properly if it is not. I am happy to save money wherever I can obviously as I would prefer not to spend 5k on heads/rockers etc. My vehicle prior to this was a 1980 z28 with a 350 crate motor, reverse valve body TH400, 373 gears, that was feel it in your pants way faster

[i82much]

should melt your face for sure.

[steve25]

Even in stock form those 96 heads will make an easy 400 Hp with that cam.

Your issue is not air flow in terms of that motor making good power up to 5200 rpm .
Even with reworked stock rods you do not want to spin that motor passed 5500 which is something you would need to do to make good use of a aftermarket head.

Getting your needed timing right will bring in a added 25 Hp and 30 ft lbs of needed Torque.

[chiphead]

I broke out the calculator on that distributor setup. Since the dist turns half as fast as the crank, you double the degrees and RPM stated on the Sun sheet to calculate the timing at the crankshaft.

I get
16 degrees advance at 2000 RPM
20 degrees at 2600
24 degrees at 3400

Assuming the typical Pontiac engine wants total timing to be 36 degrees (which includes base timing) you subtract 36 from the 24 degrees of dist advance to get 12 degrees at idle. So the base timing would have to be set at 12 degrees BTDC to give 36 degrees at 3400 RPM. Base timing (which you set) plus dist advance curve (calculated above) gives the total timing the piston will see at a given RPM.

The total timing at those RPMs with 12* base would be
28* at 2000 RPM
32 at 2600 RPM
36* at 3400 RPM

So take a timing light and verify you have 12* of base timing. This is your starting point for tuning. What's interesting to me is that there is a decent amount of timing from 2000-2600 RPM, but it takes another 800 RPM for the curve to come all in. I assume they did this to provide a safe tuning window that won't rattle the bearings due to too much timing too early.

At low 9s static compression, on 93 octane gas, I would think it safe to quicken the second half of that curve. Basically have all the timing in at 2900-3000 may increase some power in that range. Maybe 15-30 HP depending on what the engine likes.

But that's not going to provide a world of difference unless the actual timing is vastly different from what I estimated above. For comparison, my 400 motors tend to like 14-16* of base timing and 34-36* at 3200. So shoot the timing with a light and report back.

Cranking compression is a decent estimator of how an engine will behave, if engine size, compression and camshaft is known. Manifold vacuum at idle will help tell if an engine is tuned properly, at least at idle. You put the two together to estimate an engine's power potential and if the tune is in the ballpark.

Edit- I just saw that your cranking PSI is in the 160s. That's not bad. My 400 with 2802 and 9.7:1 compression pumps 165 and it's no slouch. I'd look at ignition timing and carb settings first. How about shift points? How long does the 2004R hold 1st gear at heavy throttle?

I do think that the biggest gains would be heads. Its not just airflow. Going from 9.3 to 10.3 compression is going to pick up power everywhere. The power production above 4500 is going to benefit from headers and 3" exhaust, but down low, cylinder pressure rules.

[HWYSTR455]

Ok I see the hand written notes now.


.

[Bill S]

Fuel supply could be an issue. Read your spark plugs. Are they too clean (lean mixture) ? Setup a temporary fuel pressure gage (tape it to the windshield). Do you get a pressure drop when accelerating ? A wide band A/F gage can help, or putting the car on a chassis or hub dyno. I just did the overkill approach with the Tanks INC electric fuel pump setup. Car runs strong now and I will put in on a hub dyno in the spring.

[Holeshot71]

Also make sure when you put the go pedal to the floor you’re getting full throttle at the carb.

[petes67bird]

Originally Posted by chiphead

I broke out the calculator on that distributor setup. Since the dist turns half as fast as the crank, you double the degrees and RPM stated on the Sun sheet to calculate the timing at the crankshaft.

I get
16 degrees advance at 2000 RPM
20 degrees at 2600
24 degrees at 3400

Assuming the typical Pontiac engine wants total timing to be 36 degrees (which includes base timing) you subtract 36 from the 24 degrees of dist advance to get 12 degrees at idle. So the base timing would have to be set at 12 degrees BTDC to give 36 degrees at 3400 RPM. Base timing (which you set) plus dist advance curve (calculated above) gives the total timing the piston will see at a given RPM.

The total timing at those RPMs with 12* base would be
28* at 2000 RPM
32 at 2600 RPM
36* at 3400 RPM

So take a timing light and verify you have 12* of base timing. This is your starting point for tuning. What's interesting to me is that there is a decent amount of timing from 2000-2600 RPM, but it takes another 800 RPM for the curve to come all in. I assume they did this to provide a safe tuning window that won't rattle the bearings due to too much timing too early.

At low 9s static compression, on 93 octane gas, I would think it safe to quicken the second half of that curve. Basically have all the timing in at 2900-3000 may increase some power in that range. Maybe 15-30 HP depending on what the engine likes.

But that's not going to provide a world of difference unless the actual timing is vastly different from what I estimated above. For comparison, my 400 motors tend to like 14-16* of base timing and 34-36* at 3200. So shoot the timing with a light and report back.

Cranking compression is a decent estimator of how an engine will behave, if engine size, compression and camshaft is known. Manifold vacuum at idle will help tell if an engine is tuned properly, at least at idle. You put the two together to estimate an engine's power potential and if the tune is in the ballpark.

Edit- I just saw that your cranking PSI is in the 160s. That's not bad. My 400 with 2802 and 9.7:1 compression pumps 165 and it's no slouch. I'd look at ignition timing and carb settings first. How about shift points? How long does the 2004R hold 1st gear at heavy throttle?

I do think that the biggest gains would be heads. Its not just airflow. Going from 9.3 to 10.3 compression is going to pick up power everywhere. The power production above 4500 is going to benefit from headers and 3" exhaust, but down low, cylinder pressure rules.

If you did heads, do I go edelbrock or kre? Also I was thinking either 72 or 74cc.

[petes67bird]

How do you find a good shop to tune everything and dial everything in? I spent a good chunk already at the other shop that got everything running smoothly to where I can drive anywhere with zero hesitation, only problem is it's feels sluggish.