L78 Hydraulic Roller

[Survivor 69/Z28]

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 😀

[luzl78]

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]

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]

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

[WILMASBOYL78]

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]

<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]

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]

http://s113.photobucket.com/component/Download-File?file=%2Falbums%2Fn212%2Fwac_Z28%2FMobile+Uplo ads%2Fimage.jpeg

[L78racer]

http://www.yenko.net/ubbthreads/pics/usergals/2016/08/full-3824-47370-image.jpg

[Survivor 69/Z28]

Thanks for posting the picture.

[Salvatore]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: luzl78</div><div class="ubbcode-body">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.</div></div>

I would keep the M20 and the 4.10's. Will perform better.
Also, some oil on the plug threads is really no danger right now in my opinion.

[Survivor 69/Z28]

I have been using a NGK racing plug with heat range at 6 and have tried 7.
Called NGK last week and their &quot;performance&quot; guy told me that I should use an Iridium IX plug with extended tip with heat range at 6. Went and bought some but have not tried them yet.

[Salvatore]

Let us know how you make out.

[PxTx]

What problem we are trying to solve?

The Ir plugs are great, but not sure they really offer a solution to your present condition.

Don't want to sound harsh. I just was hoping to be clear on what is the 1st priority to fix. Can't wait to see more of your car!

[Survivor 69/Z28]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: pxtx</div><div class="ubbcode-body">What problem we are trying to solve?

The Ir plugs are great, but not sure they really offer a solution to your present condition.

Don't want to sound harsh. I just was hoping to be clear on what is the 1st priority to fix. Can't wait to see more of your car! </div></div>

http://i113.photobucket.com/albums/n212/wac_Z28/Mobile%20Uploads/image_1.jpeg


Was wanting to pull motor to freshen up and fix oil leak. While we are at why not try and improve what I have if possible. Like fixing my oil seepage issue on to the plugs which may not be too bad. These were my thought...... Or maybe like Sam said I should be ok the way it is.
The whole plug thing was me just trying to fine tune. When this thing heats up and when it's 100 degrees out the car is a total dog. Much more of a dog in the heat than my 454 Chevelle. The engine does not over heat it's like I am missing 50+HP in the heat. Runs really strong when it's not so hot out. I know most cars do, but have not ever owned one like this that is effected so much by the heat of the summer. Could be jetting. But was looking for a quick fix to get me through the summer so that is why I called NGK.
Hope this makes sense. To be honest I don't really know what to do. Just tired of oil leaks and and want this thing right. Have only owned it for a year and have been trying to get the bugs out since I have had it. Anyone live in the DFW area? Would love someone to take a peek at this thing that really knows motors.

[Survivor 69/Z28]

Here is what I am working on. Hope these pics populate....

http://www.yenko.net/ubbthreads/pics/usergals/2016/08/full-4016-47419-img_0333.jpg
http://www.yenko.net/ubbthreads/pics/usergals/2016/08/full-4016-47420-img_0342.jpg
http://www.yenko.net/ubbthreads/pics/usergals/2016/08/full-4016-47421-img_0338.jpg
http://www.yenko.net/ubbthreads/pics/usergals/2016/08/full-4016-47422-img_0337.jpg

[Lynn]

WTH, here's my 2 cents. Take if for what it is worth. I have never owned a BBC. Have worked and tuned them, including a 375hp 70 Nova that was raced on weekends.

1. Those are some pretty strong numbers. Don't know that you can gain 50hp with a cam swap, UNLESS you are willing to give up some drivability. Just a guess at this point, as we don't know the specs on the cam, but really, assuming those dyno numbers are accurate, you are not leaving much on the table for a driver. If you can't nail down the cam specs, I would just leave well enough alone. You can spend a lot of money, and possibly see almost no gains. Won't cost you any extra to keep what you got. If you do decide to change cams, contact Eric (vintagemuslcecar) or Straub technologies.

2. Stay with a copper core AC or Autolite (Motorcraft would work just as well, as they are made by Autolite) spark plug. Platinum, iridium, unobtanium, etc. seem to work great on late model computer controlled cars. I have seen more than one vintage car fall on its face using new plug technology. Your mileage may vary. I am sure other very informed and experienced guys disagree.

3. Might want to diagnose the &quot;runs like a dog when it is hot&quot; issue before pulling the motor. Although, it is most certainly a tune issue, and nothing to do with the cam choice. I have two turbo cars, and they REALLY suffer at 100 degrees, but that is just part of the game with those. I can't tell you if my 69 Z/28 runs like a dog at 100 degrees, cuz I never drive it in that weather. Black car, black interior and no A/C. The older I get, the less I tolerate heat (may just be grumpy old man syndrome).

Are you using ethanol? Sorry if this has already been addressed, but once you start replying, hard to go back and review. Run straight 100% gas. If you can get to a small municipal airport, try putting about 1/4 tanks of 100LL in with the best 100% gas you can get. I think in the DFW area you can get 92 or 93 pretty easily, is that right? Seeing as the exhaust isn't pure stock anyway, I would highly recommend a wide band AFR meter. They are an amazing tool, and you can really dial in a Holley using one. You will always know if you are rich or lean, and under which conditions.

Lastly, I have a 4.10 and M20 in my Z. Granted, it isn't a big block (I have a motor built to 70 LT-1 specs right now) but I love that combo. Yes, 70 mph = 3600 rpm, but I don't drive it on the highway often. I also don't spend long in 1st gear. 3.55 is a pretty big jump. Frankly, you are going to just fry those street tires with either combination. You would need some drag radials to get any traction at all.

[Survivor 69/Z28]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lynn</div><div class="ubbcode-body">WTH, here's my 2 cents. Take if for what it is worth. I have never owned a BBC. Have worked and tuned them, including a 375hp 70 Nova that was raced on weekends.

1. Those are some pretty strong numbers. Don't know that you can gain 50hp with a cam swap, UNLESS you are willing to give up some drivability. Just a guess at this point, as we don't know the specs on the cam, but really, assuming those dyno numbers are accurate, you are not leaving much on the table for a driver. If you can't nail down the cam specs, I would just leave well enough alone. You can spend a lot of money, and possibly see almost no gains. Won't cost you any extra to keep what you got. If you do decide to change cams, contact Eric (vintagemuslcecar) or Straub technologies.

I definitely do not want to lose drivability nor do I want to spend a lot of money on just a slight gain or maybe no gain at all.
Just not sure if I should pull the motor and fix the oil on the plugs issue and my oil leak which appears to be the rear main.


2. Stay with a copper core AC or Autolite (Motorcraft would work just as well, as they are made by Autolite) spark plug. Platinum, iridium, unobtanium, etc. seem to work great on late model computer controlled cars. I have seen more than one vintage car fall on its face using new plug technology. Your mileage may vary. I am sure other very informed and experienced guys disagree.

Maybe I should try the long tip plugs? The guy at NGK was so convincing of that.

3. Might want to diagnose the &quot;runs like a dog when it is hot&quot; issue before pulling the motor. Although, it is most certainly a tune issue, and nothing to do with the cam choice. I have two turbo cars, and they REALLY suffer at 100 degrees, but that is just part of the game with those. I can't tell you if my 69 Z/28 runs like a dog at 100 degrees, cuz I never drive it in that weather. Black car, black interior and no A/C. The older I get, the less I tolerate heat (may just be grumpy old man syndrome).

It's probably just running too rich in the heat of the summer. I do not like driving in these temps. But was coming home from a show a few weeks ago and noticed the power issue. Then woke up the next morning and the thing was an animal. Night and day difference.

Are you using ethanol? Sorry if this has already been addressed, but once you start replying, hard to go back and review. Run straight 100% gas. If you can get to a small municipal airport, try putting about 1/4 tanks of 100LL in with the best 100% gas you can get. I think in the DFW area you can get 92 or 93 pretty easily, is that right? Seeing as the exhaust isn't pure stock anyway, I would highly recommend a wide band AFR meter. They are an amazing tool, and you can really dial in a Holley using one. You will always know if you are rich or lean, and under which conditions.

I have been using 93 pump gas with 2-5 gallons of 108 race gas for the most part. It seems to like the race gas mixture.

Lastly, I have a 4.10 and M20 in my Z. Granted, it isn't a big block (I have a motor built to 70 LT-1 specs right now) but I love that combo. Yes, 70 mph = 3600 rpm, but I don't drive it on the highway often. I also don't spend long in 1st gear. 3.55 is a pretty big jump. Frankly, you are going to just fry those street tires with either combination. You would need some drag radials to get any traction at all. </div></div>

The highway RPM does not bother me because I am not on the highway very often at all. Its 1st gear that is kind of a waste to me because I have to shift so fast. I start out in 2nd like most guys do in 1st. 2nd and 3rd are a lot of fun in this car. I am not 100% sure on the gear swap, just been thinking about it since I have these 3.55 gears sitting in my garage. Would have to get a 3 series carrier though.
My 69 Z had 373's with an M20 and I thought it was perfect! But those 302's feel totally different and just need those RPM's to get going.... IMO

Thanks for all of the tips, I really appreciate all of the input guys. That is what I am looking for is input. Maybe its just not worth pulling the motor right now for an oil leak and the oily plug issue. Having a real hard time with that.