Originally Posted by tater

Is anyone still using the factory pressed in rocker arm studs? Any problems with them pulling out with the Hot Cam?

Originally Posted by tater

Is anyone still using the factory pressed in rocker arm studs? Any problems with them pulling out with the Hot Cam?

Originally Posted by tater

The heads are still on the motor and don't really want to remove them. I've seen many magazine builds with this very set up and they did not use screw in studs.

Originally Posted by jayblue

Hello guy's I know this is an older post, but would like to ask some questions on this matter, I have a new 350 L31 vortec that I have installed the LS6 springs and comp retainers. I also installed a Lunati roller cam, Application is for the LT1, LT4 PN 20080130, BareBones Hydraulic Roller Cam - Chevrolet LT1, LT4 276/286 , lift is .503 int/.503 ext, .219/.229 @ .050 adv. dur. 276/286 ls 112 icl 108. Is this basicly the same cam you guys are talking about here? One of my questions is did you guy's install your cams straight up or install them 2 degees advanced? The engine is carbed rpm intake and 600 holley. I'm asking because from the stock cam I pulled out, lift at .414/.428 I,m not feeling any difference in performance to speak of. that,s why i'm asking if I should have installed the cam advanced to build more cylinder pressure. Any thoughts.
Thanks jim

Originally Posted by 1986BANDIT

some cams are made with 4 degrees of advance built in then you install them straight up,i would try to email lunati directly and ask them.
this is also why everyone recommends degreeing your cam to determine everything is as advertised and setup correctly.
for comparisons sake,the gmpp 7151 cam(less aggressive than yours) takes the stock L31 from 255 horsepower to 357 with the cam alone.
gmpp sells this crate engine and all it is is an L31 with a cam swap.its sold as the sp350/357 crate engine(or was)

Originally Posted by Fast355

I tuned that same cam in a lifted 4x4 4 door Tahoe with a L31. Truck had shorty headers and a custom exhaust along with a volant cold air intake. 2,400 stall in the 4L60E. Power difference was night and day even before he put 5.13 gears in the truck. It would light up 37s after the gears.

I also ran the same cam in my Express van and it too was night and day compared to the stock cam.

Have you checked the jetting and experimented with the timing? The Tahoe and Van liked 32° of timing by 2,800 rpm with about 20° of timing at 1,200 rpm. 26° of advance by 2,400 rpm. You have dropped the dynamic compression ratio. It will want more timing especially on the bottom end. More initial timing, less centrifical advance and a much quicker advance curve.

Originally Posted by jayblue

Ok here's how the timing is set up now I set total to 32* at 3000rpm, at 1200rpm it shows 12* at 2400rpm it shows30*.at 800rpm initial is 12*, starts to advance 1400rpm. Am I correct that it needs some lighter weight springs to bring the timing in sooner?

Originally Posted by 3rdgenmaro

Well guys, I recently installed a LT4 Hotcam into a 97 vortec motor with a ton of help from Melonhead. I figured I would post up on some part numbers and such that I ran into during the swap. I searched many different forums for help on this, so this thread is meant to be a help to anyone that decides to do the install.

First off, the motor is a carburated 97 Vortec 350 from a truck. It is in my 88 camaro with a stock 700r4. From what I have read, these motors come stock with 255hp. Or atleast that is what GM claims. The motor ran great, had decent power, but I wanted more. I wasnt looking for all out horsepower, but a good streetable cam that would work well with the rest of the engine and that would wake that motor up. I decided to go with the GM LT4 Hotcam. The cam is very streetable, has a smooth idle, and a good powerband that doesnt go too high in the rpm range. The cam is listed as NAL-24502586 (summit number) http://store.summitracing.com/partde...6&autoview=sku
It is a hydraulic roller with 1,500 - 5,800 operating range, 218/228 at .050, .492 lift with 1.5 rockers and a 112 lsa.

The main problem with the vortec heads as many people know is the lift restriction of .480 If you have the heads off the engine, I would recommend having the correct machining of the valve guide done and have screw in studs installed. However, you can make these heads work with larger lift cams without removing the heads. This is where Melonhead was a lifesaver for me. If you use the GM LS6 beehive valve springs (GM PART # 12499224), Comp Cams retainers 787-16, and change the umbrella valve seals to Sealed Power Part # ST2015, you should be able to get up to 0.550 lift. (I am currently only running .492 lift with this combination with no problems, however in the next couple months I will be swapping to 1.6 full roller rockers giving me a lift of .525.)

***5-27-14 Update: Had issues with the car smoking at idle. Suspected the valve seals. Ordered Fel-Pro SS72861 stem seals. While replacing them I found a couple of the old ones had popped up and were just riding the valve stem. Clearance with the retainer is still good, atleast with the 1.5 rockers I am running.*****

Swapping the valve springs is simple. Im not going into the details on how to swap valve springs on an assembled engine, you can find that elsewhere. I will say that the new seals go on fairly easily and if you put some oil on the inside it will help it slip on. Using an old retainer from a spring you just removed, press down on the seal until it fully seats on the bottom. you dont need to buy one of those installer tools for $30. The ls6 valvesprings are alittle tight to install sometimes. I had to put some of them under a hairdryer for a little bit for them to slip on. It was tight, but not tight enough to warrant a concern.

One of the huge downfalls of doing this swap with the engine in the car is the stock plastic timing cover. I first started by removing several of the front oil pan bolts. Most of you have pulled a timing cover in car before, so not much detail in that respect. The stock oil pan gasket is a one piece rubber style so be careful. While I was working the cover off, the bottom corner broke. Cheapest place I found was summit for replacement NAL-12562818 $23. The summit piece is built by GM and comes with gaskets and bolts. The crank position sensor holes are in the cover, but if you are using one, you must cut it out yourself.

The crank position sensor trigger wheel is pressed onto the crank in front of the crank sprocket. A screwdriver was all that was needed to pop it off. Gently pry on one side then the other until it comes off the keyway. The rest of the cam change is straight forward, pull spider, pull lifters, pull cam, reinstall cam, reinstall lifters, reinstall spider, reinstall timing gears. For reference the timing set I used was Cloyes CLO-9-1157. Also from summit.

If you take your time, you can reinstall the timing cover with the engine in the car, without dropping the oil pan. It just takes time, patience, and a steady hand. Do not get too forcefull or you will break it. From here on out it is basic reinstall. I set the hydraulic lifters at 1/2 turn.

Distributor gear. That is the big question I had. Do you have to run a bronze gear? No. Since these motors come originally with a roller cam, the stock gear will work with this cam. GM cams use a melonized distributor gear on the cam. However, if you go to an aftermarket cam, you might have to change out since they are billet. But for the GM hotcam, your old distributor gear will work.

I am running an Edelbrock Performer RPM intake with a holley 600 with vac secondaries. I have alot to do under the hood when money allows. Full roller 1.6 rockers, custom wires, custom air intake, and a basic cleanup of stuff under the hood.

The idle didnt change much. It almost sounds exactly as it always had. After some linkage issues I had, I could tell a huge difference in the motor. That cam really woke it up. I have realized now I need to change out the governer in the transmission to let first gear turn higher before shifting. I havent been able to do any tuning to it lately. The first couple of hard runs has given me a nice little noise somewhere in the driveshaft or rearend. Got to fix that first. I am running a stock converter. The only issue I have with it is that at times when you are coasting around a turn or down the road, you can feel the car want to "buck" alittle.

http://www.grandsportregistry.com/dyno.htm This is the registry for the 96 LT4 cars and the mods done with dynos done. Most show atleast 300hp at the wheels. I have not been able to dyno, but I can say it is alot more than the 255 the motor started out with.

All together I am completely happy with the swap. I have around $600 in the swap and it is definately worth it.

I will post up more as I get the time to tune. Here are a few pics.

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