What can you tell me about this cam card?

["Turbo-T"]

First off this is the cam that was installed in my engine, before I purchased the car:

Poston GN 110T camshaft

This is the cam card I received with the car at the time of purchase:

It looks like the cam was installed advanced 4 degrees. It says it has a .478/.456 lift and a 266/258 advised duration, and I believe a 212/206 duration @ .050. I am also guessing this cam has a 112 lobe separation?

Am I reading all of this info right?

Postons says this cam pulls super hard to 6200 rpm, but if the cam were advanced 4 degrees, and ran on an engine with stock heads and a stock intake, about what max rpm would you say this cam would go to?

Thanks.

 

[charlief1]

The factory cam and most after market cams are made with a 4 degree advance in them. If you want bottom end advance it 4 degrees, but if you want to get to 6200 install it straight up or retatd it 1 to 2 degrees for better top end.

 

["Turbo-T"]

Thanks Charlie, actually the engine this cam is in is put together and running and was when I bought the car. So 4 degrees advance it is and will stay that way.

I am just trying to learn how high I can spit in before it runs out of steam. So far 4700 is the max but I can't tell if it's running too rich by then or if it's hit it's highest rpm.

 

[charlief1]

If you've already advanced the cam then you've hit your wall. Teh max of 6200 is only good if you install it strait up or advanced. If you're willing to take the cover off then put it strait up or retard it 1 to 2 degrees.

 

["Turbo-T"]

So by advancing the cam 4 degrees lowers the power band from 6200 to 4700? Because I wouldn't think a 4 degree advancement would decrease the range by 1500 rpms.

Thanks.

 

[Slow91z]

If it won't pull past 4700 1st thing I would think of is weak valve springs.

 

[turbofabricator]

If it has been in for a while, then the advance will practically dissappear. As the timing chain stretches, cam timing will automatically retard. The exhaust valve looks to be too advanced for my liking. I like to keep the exhaust valve closed a little bit longer to extract a little more power out of it before it blows the cylinder down. Opening the exhaust valve early, will (sometimes) help the turbo spool. With the more modern turbine wheels and housings, opening the exhaust valve early is not needed. In the early days we did that to help spool. Not needed today, and it will hurt power on the top end, especially if you have a big turbine housing and efficient turbo. By changing to a different cam, you might gain a little. If it is a flat tappet (which I'm sure it is) the cam might be going flat, causing your top end power decrease. Valve springs will also KILL top end power. (and cam lobes) If you talk with four different engine builders about cam timing, you will get four (or six) different theories on lobe profiles. All of them right, sort of, I think, maybe.

 

["Turbo-T"]

Thanks. I didn't notice any spitting or sputtering when it hit 4700, as in my experience was the sign of valve float. All I know is it feels like power just hits a brick wall.

In fact when I first put the alky kit in and was testing it, I still had the boost at 14 and it felt almost the same at a lower rpm, which of course turned out to be the engine suddenly getting rich at a certain rpm due to alky spray and fuel.

Since then I pulled some fuel out and it helped, I am tempted to pull more but now I'm being told I need a new 02 sensor because at WOT the 02 millivolts will jump one second from 832 to 812 to 796 to 804, etc....

Also my car has what I am pretty sure to be stock heads and a stock intake, I heard when these cars were new their power bad was only until like 4400 rpm or something like that. So I am wondering if that also has anything to do with it.

 

[scojack_2001]

I dont know if I'd be brave enough to take one of these motors to 6200rpm. Not on original parts that is. The max Ive seen is 5200rpm at the top of third in my car, which is around 112mph. Maybe with fresh valvesprings I might be able to get to 5600rpm for a bit, but not 6200.

Heck, my buddies built 3.8 with a roller only sees 6500rpm max for a redline. Id venture to say something else is wrong with the car. How many miles on the engine & cam? May be time to do a timing chain and possibly a newer cam.

Just my .02.

 

[turbofabricator]

I have stock crank and rods, with TRW forged pistons with light pins (not the factory heavy TRW pins) and a hydraulic roller. I have taken my engine to 7,000+ on many occasions . It is balanced, too, though.

 

["Turbo-T"]

Not sure how many miles my engine has, I have put almost 4k on it, the guy before me didn't put many miles on it, before him it was Richie Kibler's car (turbokid) who told me he bought the car with the engine out of it from another guy who I guess supposedly either built the engine or had it done, and for whatever reason never did get it installed.

 

[charlief1]

How many miles on it totally? It could be a factor but if you ever ran a car till it ran out of power it's like hitting a brick wall. No spitting or sputtering, just doesn't go any faster. My old car redlined ar about 5200-5300. I was to busy trying to shifr and we didn't have shift light tacs like we do now. When it ran out of steam that was it.

 

["Turbo-T"]

The car itself has 218k on it, but as mentioned the engine has been gone thru so I am told. I do know it has ARP studs holding the heads down, so at least those have been off at one time.

Of course I do believe the car has stock heads and intake, I heard factory these engines only went to like 4400 and then were done, and I'm sure the cam played a big role in it, but I'm also wondering if it was due to restrictive heads and/or intake?

I have had two vehicles that hit valve float, usually they sputtered or popped besides losing power, that's how I knew what it was.

 

[charlief1]

It doesn't sound like valve float to me. It sounds like you just hit the max the engine will do. I know if you ballance and blueprint a 231 you can get to 8K but your idle suffers a great deal. Take your valve covers off and look at your valve train while the engine is runnig out of gear. See if there is any fex that you can detece of movement in the rockers or pushrods.

 

[scojack_2001]

Ive taken my 99,000 mile original 109 to 5200rpm, as verified by my SM2.1. The only thing that isnt original inside the engine is the timing chain.

Id say there is a problem with your motor. Im no expert by any means, but something just doesnt seem right to me...

 

["Turbo-T"]

Hey...not to bring up an old post but I'm about to order a new chip and it's asking for cam specs....not sure if I'm reading this right but does it look like this cam has a 212 intake duration at .050 and a 206 exhaust duration at .050?

I can't click on the Postons link anymore, it's been taken down. :frown: