Opened 'er up and this is what I found

[HotRodPC]

HotRod,

Thanks for the tip on the #93051 dial indicator from HF. Got it for 26 and some change out the door after the 25% discount and taxes. This tool will come in handy.

Not a problem. For the money you can't beat it for it's intended purposes. As said, I wouldn't trust it's accuracy for the tightest and most critical of measurements, like for firearms, but for things we do to our squares, like comparing valve lifts, end shaft plays on transmissions, and setting up ring and pinions it's great. Glad you got down there today and able use the 25% off. Usually when I get those, I don't need anything, or I have to spend $100 to get 20% off and don't need $100 worth of stuff or can't afford $100 worth of stuff.

 

[BADAZ chevy guy]

I don't know for certain, but I believe vortek heads require a push rod guide plate to keep them from sliding sideways. Something like the pic below.

 

[Driver4r]

I don't know for certain, but I believe vortek heads require a push rod guide plate to keep them from sliding sideways. Something like the pic below.

Nope, I have a set of 906's that ive turned up to 5k on and have roughly like 300-400 miles on them, I average 3k rpm. No guide plates, just the Gen1 pushrods with the vortec rockers. They stay lined up(the rockers have the cup to hold the pushrod, and the tips have a slot that the valve stem sits in. Have had no issues and havnt opened the covers since we set up the lash on initial startup. Now I might have to upgrade my rocker studs eventually cause im running around 112-120 LBS seat pressure(installed, not compressed) on .489/.504 lift and eventually they will probly start sliding out, But other then that, vortecs don't really need any added hardware.

Just looked it up, compressed the seat pressure is around 325lbs.

 

[cbrodine]

Vortec heads do not use guide plates...

 

[DoubleDingo]

Cam Question

This is where I sit until I get my rocker arms.

After doing some research, the 12364051 cam/lifter kit I mentioned that I bought from GM Performance Parts years ago, replaced the P/N 3896929 cam that apparently was used for many years in Chevy engines. They call it the 300hp cam for 327 engines, but it was used in everything from 283 up to 400. My research has led me to realize that most everybody is looking for big cams and high rpm horsepower, whereas I am looking for low-end torque and to get better mileage. I don't race my engines so high rpm's are not what I am looking for.

The information I have found about this cam are as follows:
Dual pattern, blueprinted replacement for factory P/N 3896929 with 300 hp and 327 cu. in. camshaft.
Technical Notes:
Basic rpm range is 1000 - 3500; cruise rpm at 60 mph is 1600 - 2200 and compression ratio is 7.75 - 8.75. The duration at .050 lift (intake/exhaust) is 195/202 degrees, and the valve lift is .390"/.410". Lobe centerline is 112.
This camshaft kit is designed and manufactured by Crane Cam Co.®. It contains one camshaft and 16 tappets.
I attached additional information from the grind sheet.

My truck is a 1981 Chevy C20 with a 350/TH400 and 4:10 gears but I would like to have a higher gear for lower highway rpm's, so when money comes available for such a swap, I may go that route. I replaced the heads with vortec heads, I am replacing the rocker arms with self-aligning 1.52 rockers ( http://www.summitracing.com/parts/cca-1417-16/overview/ ). I have the GMPP 12486570 dual plane intake that is an inch or two higher than the stock cast iron intake. Everything else is bone stock, exhaust manifolds, single 2.5 inch diameter exhaust pipes, no frills.

Could somebody please tell me if they have had experience with the 300hp cam. From your expertise, and the information I provided about this cam and my application, do you think it will work with the vortec heads regarding the limited lift of the vortec head design? Do you have any power band information about this cam? Any information you can provide will be much appreciated. If you need additional information, please let me know. I don't want to go through the extra labor to replace the cam, only to have it screw up my heads, engine, etc. I like to do things once, preferably the right way, and to have a low maintenance rig that runs really good. I got this specific cam because my stepdad used to be a mechanic for race teams and he mentioned a track grind cam, and this seemed to fall within the rpm range he mentioned. I am more worried about exceeding the lift limitations of the vortec heads.

 

[Driver4r]

This is where I sit until I get my rocker arms.

After doing some research, the 12364051 cam/lifter kit I mentioned that I bought from GM Performance Parts years ago, replaced the P/N 3896929 cam that apparently was used for many years in Chevy engines. They call it the 300hp cam for 327 engines, but it was used in everything from 283 up to 400. My research has led me to realize that most everybody is looking for big cams and high rpm horsepower, whereas I am looking for low-end torque and to get better mileage. I don't race my engines so high rpm's are not what I am looking for.

The information I have found about this cam are as follows:
Dual pattern, blueprinted replacement for factory P/N 3896929 with 300 hp and 327 cu. in. camshaft.
Technical Notes:
Basic rpm range is 1000 - 3500; cruise rpm at 60 mph is 1600 - 2200 and compression ratio is 7.75 - 8.75. The duration at .050 lift (intake/exhaust) is 195/202 degrees, and the valve lift is .390"/.410". Lobe centerline is 112.
This camshaft kit is designed and manufactured by Crane Cam Co.®. It contains one camshaft and 16 tappets.
I attached additional information from the grind sheet.

My truck is a 1981 Chevy C20 with a 350/TH400 and 4:10 gears but I would like to have a higher gear for lower highway rpm's, so when money comes available for such a swap, I may go that route. I replaced the heads with vortec heads, I am replacing the rocker arms with self-aligning 1.52 rockers ( http://www.summitracing.com/parts/cca-1417-16/overview/ ). I have the GMPP 12486570 dual plane intake that is an inch or two higher than the stock cast iron intake. Everything else is bone stock, exhaust manifolds, single 2.5 inch diameter exhaust pipes, no frills.

Could somebody please tell me if they have had experience with the 300hp cam. From your expertise, and the information I provided about this cam and my application, do you think it will work with the vortec heads regarding the limited lift of the vortec head design? Do you have any power band information about this cam? Any information you can provide will be much appreciated. If you need additional information, please let me know. I don't want to go through the extra labor to replace the cam, only to have it screw up my heads, engine, etc. I like to do things once, preferably the right way, and to have a low maintenance rig that runs really good. I got this specific cam because my stepdad used to be a mechanic for race teams and he mentioned a track grind cam, and this seemed to fall within the rpm range he mentioned. I am more worried about exceeding the lift limitations of the vortec heads.

If that .390/.410 is at the valves youll have no problem clearing with 1.5:1 rockers(which are stock ratio) Around .460 is were you start possibly contacting metal(depending on the head in discussion).

I cant personally speak for the 300hp version, but I have the L79 cam in my truck(350hp/327ci). And with the 4.11's is was a screaming machine, I loved driving it. Now it has 3.08's in the rear, and still pulls pretty good when I start in first. And I specify starting in first cause right now my 1-2 valve occasionally sticks and doesn't kick down from 2nd. Highway rpm is 2100-2500(60-70) on 32" tires and a th350. Oh and even with the 3.08's, I can still break the tires loose when I try(it just takes more effort )

 

[DoubleDingo]

Thanks Driver4r. You concurred with the info I got from Crane Cams this morning. They said the operating range is from 800 to 4500 rpm, which is perfect for what I want. I saw another cam in their lineup that has a little more lift and a hair more on the top end, but since I already have this one in my possession, I will use this one. I also have to keep emissions testing in mind, so this one should not produce bad emissions for the sniffer.

 

[DoubleDingo]

Well, I decided not to tear the engine apart for the cam swap. But I got the new rockers installed and bought a new set of pushrods. Truck is back on the road. Now I can run it to burn both tanks of gas. I will post pics tomorrow.

 

[HotRodPC]

I bet it last a bit longer this time.

 

[DoubleDingo]

I sure hope it lasts longer. I do want to change out the cam, but my goal was to get the truck back on the road. When I do the 4L80e swap I will pull the engine too to remove a back exhaust manifold bolt, that holds on some emissions things, that decided to fail when I was buttoning things up yesterday. While it's out I can upgrade some stuff, replace some stuff and have a fresh drivetrain. Then I can focus on other stuff and rock a solid truck.

 

[HotRodPC]

You'll just be taking care of all kinds of stuff.

 

[DoubleDingo]

I don't have an online photo account so for clarity of what I did, I will be posting in multiple posts...

As you can see, the pushrod on Number 7 exhaust is just a tad bent

 

[DoubleDingo]

It was just a matter of time before one or more of the rockers rotated off the valve stem like number 7 exhaust did. This really was a blessing in disguise.

 

[DoubleDingo]

Just got pulled away for a short meeting...back to posting...

Number 7 plug looks good, and so do the rest. They have been running in there since the vortec swap in November 2013. All eight are as they are situated in the block if you were to look at them from the drivers side of the block.

 

[DoubleDingo]

I checked number 1 exhaust and number 7 exhaust and the lift on each was equal, so I decided not to swap the cam at this point. New pushrods installed and new rockers about to be installed.