[gtome]

I will look and see if I still have the vid of my car doing a 600 ft burnout with 2:73 gears and a mild 455 with no brake stand. I always figured it was because there was so much tq once the tires were spinnin they were goin 150mph with the tall gears and the car never had a chance to catch up. Mine did have skinny tires on it though? I loved lighting the tires up at 30mph and scaring the **** out of ricers!

Originally Posted by 67ramair4

Not trying to be rude, but what do they already know?

I've never seen a car with 2.93 gears spin the tires let alone "boil" them, no matter what size the motor was! Many senior members have mentioned gears as the cause, and I'm on their side.

[Greg Reid]

Originally Posted by 67ramair4

I've never seen a car with 2.93 gears spin the tires...

That's strange...
As I recall, all base auto with a/c '68 GTOs came with 2.93 or something close to it and they'll certainly spin the tires with ease from a dead stop or a slow roll and no power braking.
Maybe your experience is with Chevies that have to rev to make power?

[Greg Reid]

Originally Posted by gtome

I will look and see if I still have the vid of my car doing a 600 ft burnout with 2:73 gears and a mild 455 with no brake stand. I always figured it was because there was so much tq once the tires were spinnin they were goin 150mph with the tall gears and the car never had a chance to catch up. Mine did have skinny tires on it though? I loved lighting the tires up at 30mph and scaring the **** out of ricers!

We were answering at the same time...That's been close to my experience too.

[tr709]

Not to gang up on you 67ramair4, but the mostly stock 76 350 that was in the car prior would spin the tires. A dyno run right now would only tell me how much power I wasn't making and piss me off.

[Stuckinda60s]

There must be something wrong with me, I'm considering using a 3.08 with a 200-4R for a street/strip combo.

It sounds like guys whose cars with long gears aren't quick, should be checking them out to see why not.

[PontGuy]

A 2.93 gear, 2200 stall converter of unknown origin and a cam with plenty of duration- seems to me this might not be a combination with enough bottom end grunt to spin the tires. But if not, that engine still ought to be making plenty of power up the curve somewhere!

I (like many others) keep on checking on this thread to see if the results of the cam degree check are in yet...

[performerrpm]

Originally Posted by 67ramair4

Not trying to be rude, but what do they already know?

I've never seen a car with 2.93 gears spin the tires let alone "boil" them, no matter what size the motor was! Many senior members have mentioned gears as the cause, and I'm on their side.

my tired ole 400 with a lil better than stock cam cast pistons 6x8 heads with years of abuse with 273s would not only breakem loose a bit at 20mph roll but from a stand still i could do a 100mph burn out once those tall gears break the tires with lil effort after words you can boil them pretty good. i dont see a dyno doing any good......in fact i could see how that would piss the owner off to see what amount of power he is not making...lol that comment was funny when i read it

[guccieng]

Originally Posted by 67ramair4

Not trying to be rude, but what do they already know?

I've never seen a car with 2.93 gears spin the tires let alone "boil" them, no matter what size the motor was! Many senior members have mentioned gears as the cause, and I'm on their side.

i certainly don't think your rude to ask! we have multiple people familiar with pontiac power noticing a power loss. i've got 2.78 gears and will 'boil' the (one!) tire right off the rim if i kept my foot in it. if you lack torque in a poncho, something is amiss.

[jakeshoe]

The accessories are off the front and of the engine and out of the way. I'll be degreeing it this a.m. I had to make a run to Dallas all day yesterday to get transmission cores/parts.

I'll post the cam results later today. Unless I've missed something pretty big I'm 95% certain the cam timing is off.

[1967Tempest]

Originally Posted by jakeshoe

The accessories are off the front and of the engine and out of the way. I'll be degreeing it this a.m. I had to make a run to Dallas all day yesterday to get transmission cores/parts.

I'll post the cam results later today. Unless I've missed something pretty big I'm 95% certain the cam timing is off.

I hate to ask, but IF it is wrong can you take some pictures for us. I am going to be installing a cam soon, and I would like a visual.

I have installed a couple of cams in a Pontiac, and once we had a timing chain that had a imperfection that looked like a dot. Car didn't run. SO I would like to see one that might be wrong.

Thanks

[vidguy]

I have a 2.73 posi rear out of a 71 cutlass or other Olds.. in my 67 GTO, TH400 original 400 mildly built 25 years ago, 65 tripower.. I can smoke my tires from a standstill and get some scratch going into second.

[Cliff R]

On the subject of burnouts, my old 400, with 6X-8 heads, small Crower 210/221/112 cam, stock converter and 2.73 gears would do a burnout all the way thru first gear.

It ran as quick as 13.78 @ 101mph in that configuration.

One would think a mild 455 with a roller cam and some compression would melt the tires down with a blip of the throttle?.....Cliff

[kyle_blake]

I recall somewhere on the internet was a link about how power productions change when a camshaft was installed 20 degrees off. They dyno'd the engine before and after.

Wish I had that link, that would be great to see in this thread. It had dyno chart pictures, I believe it was a buick engine.

[jakeshoe]

I'm referring back to the thread to get the cam so I can look up the specs.

Current status is that the timing mark on the balancer is within 1* of correct.

[jakeshoe]

We have 2* BTDC for .050" opening, 38* ABDC for .050" closing.

This tells me the cam is 4* short on the intake side but it's pretty close on the cam install.

We could be off 1* on the wheel easily since it's relatively small diameter.
We're going to check the exhaust side so we can confirm.

[tr709]

Jake,

Here is the link to the cam specs if needed

http://www.compcams.com/Cam_Specs/Ca...csid=1216&sb=0

[67bonnie455]

I think it would be more helpful to measure the intake center line over the initial timing events. The ICL is what is usually looked at for cam timing. Your cam probably had this information with it for installation. If not, someone familiar with your cam can probably tell you where to degree it in off the CL information over the initial events.

Make sure you have TDC and zero degrees set accurately using a piston stop. You can rotate motor back an forth and move pointer until the two values when hitting the stop average zero. Check it a couple of times to make sure. Set pointer on Zero.

Now, remove stop and by only rotating in clockwise direction (keeps the chain tight) rotate the motor and zero the gauge (rod nearly fully compressed) on the peak lift of the #1 intake lifter or lobe (4th lobe back). Now rotate again and record the 0.05 degree before peak and 0.05 after peak. Add togeter and divide by 2. This is the intake certerline. Usually at or about 108.

[67bonnie455]

Your cam should be at 106. With the initial even 4 degree off, if the CL is 4 degress off, you have your problem.

[jakeshoe]

Originally Posted by 67bonnie455

I think it would be more helpful to measure the intake center line over the initial timing events. The ICL is what is usually looked at for cam timing. Your cam probably had this information with it for installation. If not, someone familiar with your cam can probably tell you where to degree it in off the CL information over the initial events.

Make sure you have TDC and zero degrees set accurately using a piston stop. You can rotate motor back an forth and move pointer until the two values when hitting the stop average zero. Check it a couple of times to make sure. Set pointer on Zero.

Now, remove stop and by only rotating in clockwise direction (keeps the chain tight) rotate the motor and zero the gauge (rod nearly fully compressed) on the peak lift of the #1 intake lifter or lobe (4th lobe back). Now rotate again and record the 0.05 degree before peak and 0.05 after peak. Add togeter and divide by 2. This is the intake certerline. Usually at or about 108.

Yes I do know how to use a piston stop and degree wheel...
I've degree'd a cam or two
Although I mostly build performance transmissions these days I'm a Master Auto Tech, Master Engine Machinist, with other certs (L1).
I determine ICL by where the .050"events happen. There are other methods but because of the assymetrical cam lobes you get into, you can't assume it's exactly centered on the events.

Exhaust events are 3* retarded. 46* BBDC and 4* BTDC.

The cam timing is not the issue. 3* is not "staight up" but it's also not a deal breaker.

Timing chain may have stretched since initial build as well.

[jakeshoe]

Originally Posted by 67bonnie455

Your cam should be at 106. With the initial even 4 degree off, if the CL is 4 degress off, you have your problem.

I doubt it...