L78 Hydraulic Roller

**Survivor 69/Z28** · #1 08-07-2016, 04:26 PM

Hello,
I am planning on pulling my motor out in the fall to fix some oil leaks and possibly freshen it up. It's showing a little oil on most of the spark plug threads. The motor has somewhere between 2-3k miles.
The engine was built in 2006 it's a L78 block with a hydraulic roller cam. On the engine dyno it produced 484 HP at 5800 rpm' and a little over 500 ft lbs of torque at 3500 rpm. The motor has its original 291 heads, L78 intake, Holley 4150 750 DP.
My issue is that I have a parts list and a dyno sheet from 2006 from the previous owner but I do not have the compression ratio or cam specs. So this might be kind of waste of time to discuss this until I know those 2 things.

Since the money has already been spent on making this a roller motor. I am wondering if cam technology over the past 10 yrs from when this was built will allow over 500 hp from just a cam swap? I know, without current cam specs this is kind of a dumb question.
Just looking for some advice on creeping what I have to say 525-550 hp while maintaining a stock looking appearance like it is now.
Other than headers of course. The headers are 2" Hookers going into a 3" exhaust system. The car is equipped with a Muncie M20 and 4.11 gears which I plan on going to 3.55's.
No I am not going with a 454 or 427, sticking with what I have. LOL

Or if what I have is pushing it to the limit then that is ok too. The engine currently pulls 16" of vacuum at idle and really runs smooth.
Just seeking more power like every other gear head &#128512;

**luzl78** · #2 08-07-2016, 04:36 PM

I would keep the lower rear gears.maybe you'd gain a improvement of a mile per gallon but the lower rear would keep the seat in the pants exeleration.

**Survivor 69/Z28** · #3 08-07-2016, 04:41 PM

Even with the M20? 1st gear is like granny low and Its almost like having a 3 speed because I can not really use 1st unless it's time to jump on it from a start.

**Survivor 69/Z28** · #4 08-07-2016, 04:42 PM

How concerned should I be with oil on the spark plug threads? Weird thing is it doesn't smoke at all.

**WILMASBOYL78** · #5 08-07-2016, 05:29 PM

Those are impressive figures for an L78 setup....having the exact specs on the cam and compression ratio would be helpful. Also, were the heads modified at all??

Your torque might improve a little with a smaller primary tube size on the headers...but, 500@ 3500 rpms is very good...much more than I would ever predict for those cubic inches.

As for the rear end gears...I would swap the trans for an M21 or M22 and keep the 4 series gear.

Hopefully you can post more info on this build...I'm sure we would all like to see the dyno sheet.

Good luck.

wilma

**earntaz** · #6 08-07-2016, 05:47 PM

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Survivor 69/Z28</div><div class="ubbcode-body">How concerned should I be with oil on the spark plug threads? Weird thing is it doesn't smoke at all. </div></div>

Are you sure the oil is not from the rocker boxes leaking? TAZ

**Survivor 69/Z28** · #7 08-07-2016, 06:27 PM

Wish I knew how to post a picture on here and could post the dyno sheet.
Sounds like I need to stick with my combo and just get a valve job and fix oil leaks. Unless someone has the magic recipe for more power from what I have.

I think finding an M21 would be a lot more costly then just changing to 3.55's. Mathematically 3.55's and an M20 are just like and M21 with 4.10's
The biggest drop off would be 4th gear of course.

I replaced the valve cover gaskets and they are all still wet with oil on threads.
What's strange is its every plug. Some are very slight and some have more.

**Survivor 69/Z28** · #8 08-07-2016, 07:34 PM

http://s113.photobucket.com/componen...s%2Fimage.jpeg

L78racer · #9 08-07-2016, 09:22 PM

**Survivor 69/Z28** · #10 08-07-2016, 10:13 PM

Thanks for posting the picture.