My Dad's car dyno'd 342 RWHP through the stock exhaust manifolds, stock cat converters and stock exhaust system with Borla mufflers and the Hot cam. PCM programming was stock as well, except a Hypertech was used to raise the rev limiter.

Since most LT4's dyno stock at around 300 RWHP, that's a 40 HP gain just from a cam change! See my sig for the dyno graph.

Sorry we never dyno'd the car when it was all stock.

 

I need to get a baseline dyno on my car before I get into any major mods.. I'm unsure of the history on the car, but it does have the CAGS disabled, cut air lid, looks like a new water pump and the opti looks very clean (new)Maybe I'll get lucky and the car has a cam already in it :p: (don't I wish)

What is the stock revlimiter set to on the LT4's? I've had mine wound up pretty high and haven't hit it yet...

From what everyone is telling me here.. the cam alone is certainly something I'm going to do. I can think of a lot of ways to spend a grand on a vette and get no wheres near 25-40 RWHP! :cheers:


[Modified by Springer's LT4, 6:38 PM 9/27/2002]

 

Stock rev limiter in 6400

 

Is there a write-up somewhere on just the cam change? I've found a couple on how to swap the heads, nothing on just the cam.

Thanks,
Sam

 

Were you able to do with out pulling the motor? Did you just remove the Rad. and shroud?

 

Right, you don't have to pull the motor. Just jack it up. Below is what I used to do my hotcam job. I just got all this info here using the search function. Many forum members are quoted below. Some of it is just notes for me.


HOTCAM JOB

Thing to replace as well
* waterpump
* plugs and plug wires
* power steering pump?
* lifters? (recommended by GM when a new cam is put in)
* timing chain and gears
* gaskets
* valve guides
new GM gasket for LT4 (part# 12367777),

The hardest part of the kit (obviously) is the cam. What makes it difficult is having to raise the engine up slightly so that when you pull the cam out it doesn't hit the crossmemeber in front of the engine. And to get the cam out, you have to take the lifters out, which means you need to remove the intake ... so it takes a little while. You have to take the radiator out to do it as well.

Jacking up the engine is not a problem, you just remove the two motor mount screws (a 1 minute job) and use a floor jack to raise it an inch or so. The major pain is getting the front hub off. Other than that it's just removing and reinstalling the millions of parts that are in the way. I managed to raise my A/C condenser up enough to get it out of the way with the lines still attached (maybe I was lucky).
_______

I'm in the middle of installing. I agree jacking up the engine is worse to think about than doing. It was probably one of the easiest things to do in the job. Just use a block of wood on the jack to prevent damaging the oil pump.
The balancer components were the difficult part. I had to carefully bend the power stearing oil line quite a bit to get access to the puller.

VERY IMPORTANT to place a smaller diameter bolt in the crank for the puller to push off on. Preferable a long allenkey bolt as it has a small head so the ballancer mount wont hit when coming off. And the puller tip fits in the allen key head and won't slip and hit the crank threads.

If you don't insert a smaller diamater bolt, the puller's center bolt will be pressing against the seat of the very thing you bolted the outside puller bolts to. So all bolts are connected to the ballancer mount, none on the crank.

Also, I renforced the the three outer bolts on the puller with nuts behind the balancer mount. Again to protect the threads.

I also did not disconnect the A/C and simply moved it out of the way. I keep dinging the condenser(SP?) fins with the airhose though.

The opti is keyed on both sides to the little drive shaft. As long as you get the shaft to line up with the keys it will be right. Warning getting the keys lined up can be painstaking. You can insert it in about half way without the keys lining up, so make sure it seats completly.

FRONT HUB REMOVAL

LT1_LT4 Balancer/Hub Removal
By following this procedure you will gain access and be able to change the three front timing cover seals (Water Pump, OptiSpark Drive, Front Crankshaft/Balancer)

Unlike its SBC predecessor, the LT1/LT4 Balancer is a two-piece assembly consisting of an (inner) hub, and (outer) balancer/pulley. Removal of the assembly can be frustrating if approached in the conventional way. By following the procedures below, you can safely and quickly remove the assembly with little or no problem.

You may want to consider using Rhino Ramps or jack stands to gain additional access space and elbow room underneath the front of the engine.

1. Drain the radiator by opening the drain valve on the lower right hand (passenger side)
2. Remove the serpentine belt
3. Remove the upper radiator hose
4. Remove the water pump. When removing the water pump, it is important to remember that the LT1/LT4 water pump is attached to the engine with 3 bolts on each side, vs. its predecessor, which only had 2 bolts on each side. The center bolt on the driver side is a challenge, but can be removed without removal of the power steering pump. When removing the water pump, take care to remove the pump drive coupler along with the pump and place it on the pump drive shaft for use when re-installing the pump.
5. Mark the coil wire and all plug wires at the OptiSpark cap for easy reference when re-installing the OptiSpark unit after balancer seal repairs have been completed.
6. NOTE: There is no need to separate the balancer pulley from the hub if you intend to pull the hub off anyway. The only time you need to separate the pulley from the hub is if you are simply changing the OptiSpark. There is a match mark that is cast into the balancer assembly that allows you to mate the two pieces together in the exact orientation that they come apart. If you intend to separate the balancer pulley from the hub, locate the marks and make note for re-assembly.
7. The balancer pulley is attached to the hub with three bolts. The bolts are 7/16" SAE standard, 14 threads per inch, ¾" length (not metric). Fully remove all three bolts, and if you intend to remove the unit as a complete assembly, jump to steps 9 thru 18. If you intend to separate the assembly, continue by rethreading one bolt by a couple of turns. It is now time to separate the pulley from the hub. Most pulleys have been found to be rusted in place and require considerable effort to separate from the hub. Spraying the inside of the pulley with penetrating oil helps. Do not strike the pulley with a hammer in your frustrated attempts to remove. The best method is to position yourself under the engine with a steel rod (or better yet a brass drift) and one healthy hammer. Position the rod/drift on the inside portion of the balancer when striking it with the hammer. This step requires more than a gentle tap. Try to position yourself so you can give a good solid hit at each rotation. Rotate the crankshaft 120 degrees after every couple of heavy hammer blows. Do not hit on the outer diameter of the pulley as damage can and will occur.
8. After successfully separating the pulley from the hub, it is now time to unbolt and remove the OptiSpark module. As with the water pump, a coupler drives the OptiSpark module and care should be taken to remove the drive shaft and place with the OptiSpark module for use when re-installing the unit. When the time comes to re-install the OptiSpark unit on the engine, you should pay close attention to the Notice below

Notice
Contrary to what all the books say, in some cases, the OptiSpark drive coupler can/will go on in more than one position. When the coupler is correctly installed, the OptiSpark unit will slide in place and rest firmly against the timing cover without forcing it into position. The drive spline in the rear of the OptiSpark is keyed. Pay close attention to the key, and match it up with the corresponding slot on the drive coupler.

9. Finally, it is now time to remove the hub. The center bolt that holds the hub on the crankshaft snout is 7/16" fine thread (not metric). I have found that I can generally break the center bolt loose by placing a 6 sided socket on the bolt, with a ½" breaker bar attached. By striking the breaker bar with that healthy hammer you just used in step #7, you can break the torque on the bolt.
10. Fully remove the bolt, remove the washer from the bolt, then re-install the bolt by 3 full turns.
11. Re-read step #10. If you skip this step, you are a screwed pooch.
12. The "General" was thinking when he installed the power steering rack hydraulic lines as he has installed a loop in the lines that allow the use of a balancer puller without interference of the puller jack screw. Check it out, you will be glad that he did this.
13. Use a standard balancer puller that requires the use of 3 puller bolts that fit into 3 slots on the crab portion. Make sure that you use a tip on the jack screw end that is a flat rotating plate, not a sharp point, because you will eventually place the jack screw end directly on the head of the center bolt of the hub and you don't want to damage it.
14. Next, select three new (or used) 7/16" bolts that are of sufficient length to slip thru the puller and fully thread into the hub where you previously removed the 3 bolts in step #7. If you do not have 3 - 7/16" bolts that are the proper length, you can use bolts that are slightly smaller than the tapped holes so you can slip them completely thru the hub. Make sure that the bolts are of sufficient length so that you can insert them completely thru the puller assembly and the hub, with a flat washer on each end, and a nut on the backside.
15. Rotate the entire hub assembly until the (^) mark is at the 12:00 position before removing the hub. When re-installing the hub, make sure that you install it back in the same orientation. This is a balance mark, and although it really won't make too much difference if you fail to do this, it is there for a purpose, so try to do the right thing here.
16. Position the puller onto the front of the hub, with the jack end of the jackscrew slid thru the power steering line loop, and attach as mentioned above.
17. You are now ready to slowly remove the hub from the crankshaft snout. The crank may start to turn as you apply force. Placing a 2x4 against the puller and left wheel "A" frame will stop the rotation. If you have access to a micrometer (click style) torque wrench you will find that it will take about 70 - 85 foot pounds of torque before you will see the hub start to move. As you continue to turn the jackscrew in a clockwise rotation, the hub will slide off the crankshaft. Keep doing this until you feel the hub come loose, or until you back it out against the shoulder of the center bolt. It may be beneficial to purchase a 3" x 7/16 grade 8 fine thread bolt and continued the removal with that. Without the 3" bolt you might not be able to get the hub all the way off.
Plan to use the 3" x 7/16" bolt when re-installing the hub back on the crankshaft after your repairs are complete. Just slide the washer over the bolt, start the bolt in the crankshaft, and mechanically pull the balancer back onto the crankshaft snout.

18. You have successfully removed the balancer hub. Now, time to R&R that front seal assembly.

---------------------
I just did this Sunday and Monday. I basically did what you described however I removed the radiator to get me some room to work, since my A/C lines were empty anyway.
One thing I noticed, yes the balancer has a mark that lines with the hub, but it doesn't matter. You cannot bolt it up the wrong way. The 3 "fingers" on the hub are not evenly spaced. The only way the bolts will line up is if it is installed correctly. I've also found that it's easier to just go ahead and seperate the hub from the pulley, it makes getting the hub off easier.

Reinstallation is pretty straight forward. Occasionally if your balancer hub is off for a little while it can decide it doesn't want to fit when you put it back. I think it oxidizes somewhat. You can solve this problem by taking a piece of scotch brite around the crank a few times, then for the hub you can use another trick. A brake cylinder hone works wonders. Hone it out just enough to "smooth it up" and remove any contamination. You might also want to lubricate the inside of the hub before you try to re-install it. You should be able to push the hub on by hand far enough for you to start to thread the bolt. Tighten the bolt to pull the hub onto the crank. It should be firm, but not impossible. If you feel it is too tight, remove the hub again and hone it some more. The last thing you want to do is strip the threads out of your crank or break a bolt off in it.

-------------------------

Something else to add is that I didn't take the balancer off all the way when I did mine. It just seemed like something not necessary. I undid/redid the 3 outter bolts by sticking a metal rod (12 " or so) between the block and front cross member. I just losened them and was still able to get my opti on/off.




[Modified by ericcer, 9:03 AM 9/29/2002]

 

Jim, did you call Vern about this?

 

Nice write up Eric... thanks!

Jason... I have, but he hasn't gotten back to me with a quote yet. Norris quoted me the $975 price without the springs. I'm also going to try and find some non corvette speed shops that work on camaro's, etc to see what they'd charge.. it is only a cam swap.

I'm pretty sure the rear of my intake has an oil leak... so I may need to that soon, I can get away the intake gaskets in my garage... but I don't want to pull the intake to fix the leak just to have it pulled again to do a cam.

 

Eric,
Thanks for the write-up. I guess I'm still a little confused though, doesn't this car have a timing chain cover that needs to be removed too? Did I miss this part? It's been a while since I did a cam swap, and that was on a Ford, but the basics are still the same no? I mean, remove intake and lifters/pushrods, timing chain cover and everything in front of it, and pull the cam out right? All the other stuff you wrote about seems overwhelming to me, why?

Also, what can people say about the emissions for this thing in CA? I have cats I can put back on the car, so my only concern would be the cam causing it to fail the test. Anyone run this cam in CA and pass smog with no problems?

Thanks,
Sam


[Modified by LT4Sam, 5:02 PM 9/29/2002]

 

Timing chain cover, engine front cover, it is all the same and it is there. The info I posted above is unedited from varoius other posts I gathered. I did seperate searches on the different subjects involved it getting the job done. I wanted to hear about real world experiences with tips on the best way to do it. I do have a factory service manaul so I used that as well.

I recommend everyone do their own searches. Don't just assume the info I gather is all there is.

 

I also was thinking of doing the same thing. I would most likely try to get a shop to do it for me. I have acces to all the tools, but i'm sure I would screw something up. Don't know of many speed shops in the area, would give Vern a call though. You Pinellas area guys know where there are any dyno shops? Want to get a baseline before I do any thing else. If you guys are up for meeting sometime, that would be awesome, just had the vette for 1 mo and would like to meet up with others in this area. :cheers:

 

C4DC..

There is a Dyno over on in the Largo area at a Ford Speed shop... it's around the 66th/Ulmerton area. Biz or others know right where it is, hopefully they chime in. A few members have had there cars dynoed' there... and I'll be doing the same.

As far as meeting up with us.. check out the Southest section of the forums... we call ourselfs the Florida Misfits and get together often... really often... if there isn't something going on weekly, it's unusual. There are a lot of members in this area... over 100 easily. We aren't a club... just a bunch of guys (gals) that get together for vette related stuff... racing, lunches, cruis-in's... you name it.


[Modified by Springer's LT4, 11:33 AM 9/30/2002]

 

Fordspeed is just south of 118th ave on the east side of 66th st. They have a Dynojet 248H.
http://www.fordspeed.com/


There is another dyno somewhere around 62nd ave and 49th street. I am still looking for that one.


[Modified by BiZ, 4:16 PM 9/30/2002]

 

Well... I just got a quote back from Vern's.... $1200 just for the cam swap. I think he's lost his mind :)

 

:eek:

I paid $350 for him to do the clutch swap. I took him 2 hours! Good money for him. Almost sounds like he does not like those cam swap jobs.


[Modified by ericcer, 12:06 PM 10/2/2002]

 

Man, you guys are already making me jealous... if I end up getting an LT4, then I'm gonna want to change the cam out first thing, lol. Not sure if I would go with the HOT cam though....

 

And why not, that just not make enough power for ya while remaining streetable? You know you like'd your Hot Cam, it'll be mated even better to a 350 than the gone but not forgotten 383.

 

Eric, I think your right on Vern not wanting to get into that kind of work.. I called two other well known tuners in FL and they both were $975 for just the cam swap... a good bit short of Vern's 1200. I'll still use Vern for all the maintinance type work... he is a great guy to deal with.

I did talk to the Corvette Doctors in St Pete today.. he quoted me 650 to 800 for the swap... Anyone hear of them before... positive/negitive?

Glock.. I was thinking about another cam... but I don't want to change much else in the engine... going to keep the same springs and stock rev limiter. The Hotcam works really well with these motors it seems... not sure I'd want to experiment with something else.

 

yeah.. well i wouldn't be chaning it out for a while anyway. 6spd will be different than the auto, so the HOT cam may be better, we'll see.

 

Where are the Corvette Dr.'s ? I would be happy to drive down and get a feeling about the place!
:cheers: