Cams & Rockers

Good points, Rick. Also, it should be noted that rockers will not hurt fuel economy any more than a SC pulley in our (SC 3800) engines.

AA wrote:

Was your boat motor supercharged? That changes all kinds of rules... Re-writes them. Installing rockers in our engines is comparable to installing a mild cam, or VTEC in a Honda. All else being the same, your tach will move noticeably faster above 4kRPM. If anything, it might seem as if you lose a tiny bit of bottom end torque, but it's relative due to the extra top end gained.

No, the boat was a normally aspirated 350 Chevy with a mild aftermarket cam. With the rockers I could pull up an extra skier or two, I'd be on plane from standstill in about 75 FEET, but it couldn't break 50 MPH with any propeller.

What cam would be get to get for the build that I am working on? Myabe the ZZP VS cam? I dont want anything too crazy.

yes a VS cam is a mild grind and has the r&d to back it up. not as easy to install as rockers, but your gains will be across a wider power band.

I am running a VS cam and like it, but if I were to do it again I'd do an S1X or XP cam. You can make an XP cam idle nice, so there's no good reason not to do it. Go any bigger and you need a double roller, then you lose the balance shaft and that's when I don't like them for street use.

Derek,
With the installation of a ZZP XP cam, do you know if you need to check piston to valve clearance due to the higher lift.???

Have you installed one of these in your car at one time or someone elses car before.?

Also, ZZP says that you don't need a timing chain tensioner if you use a Rollmaster timing chain. That sounds like BS to me. I would say that at some point in the future the chain is going to stretch and could benefit from a tensioner.
What do you think.?

could i safely get away with an XP cam without the double roller? will just getting the 105s and the mod'd retainers be fine?

Ask ZZP for clarification but I know plenty of people running XP cams on the stock timing chain with 105 springs.

Rick, I don't know the specific valve lift or timing of the cam. The specs are out there though. I don't think the lift is too much higher than the stock/VS cam though, the biggest change is duration.

I installed an Intense S1X cam in another 3800 and didn't have any clearance issues, but it was a few years ago - I didn't source any of the additional parts, and the guy I was helping assemble his motor - he didn't want to measure anything. It is still running great today. If it were my motor I would have had the degree wheel and mic out and been checking everything.

deekster_caddy wrote:

Ask ZZP for clarification but I know plenty of people running XP cams on the stock timing chain with 105 springs.

Rick, I don't know the specific valve lift or timing of the cam. The specs are out there though. I don't think the lift is too much higher than the stock/VS cam though, the biggest change is duration.

I installed an Intense S1X cam in another 3800 and didn't have any clearance issues, but it was a few years ago - I didn't source any of the additional parts, and the guy I was helping assemble his motor - he didn't want to measure anything. It is still running great today. If it were my motor I would have had the degree wheel and mic out and been checking everything.

Thanks Derek,
I am asking for another guy in the hood with a Riviera and when you mentioned an XP cam earlier, I did look at ZZP's site and it calls for clearance checking, but they may have to say that to cover their arse or it may be true.
Was just trying to cut through the chaff if possible.

I can always call Bill and see what his experience has been with these cams.

SCbuick010 wrote:

could i safely get away with an XP cam without the double roller? will just getting the 105s and the mod'd retainers be fine?

Do Not get ZZP's modified retainers , the rocker arm to retainer will hit each other and make metal that can cause you some further problems. Get the LS Type retainer AND Do Not use your OEM retainers with a 105# spring, they will further compress the spring an additional .080" and cause premature Timing chain and tensioner failure. From what little research I have done up to date it seems like a good single roller chain is OK with the XP cam.
The modified ones rockers hit the modified spring retainers on more than one car on here, mine being one. I had to remove and replace them with the LS retainers, I think I got those from Intense and all other parts had been purchased thru ZZP.
If you don't mind disconnecting the Balance Shaft by removing the gear
and a couple of other things, then you can use a double roller chain.
I don't know how much vibration or
imbalance it causes as I have never done one or ridden in a car with one
disconnected or removed.

deekster_caddy wrote:

Ask ZZP for clarification but I know plenty of people running XP cams on the stock timing chain with 105 springs.

Rick, I don't know the specific valve lift or timing of the cam. The specs are out there though. I don't think the lift is too much higher than the stock/VS cam though, the biggest change is duration.

I installed an Intense S1X cam in another 3800 and didn't have any clearance issues, but it was a few years ago - I didn't source any of the additional parts, and the guy I was helping assemble his motor - he didn't want to measure anything. It is still running great today. If it were my motor I would have had the degree wheel and mic out and been checking everything.

When you installed this cam did you re-index the cam gear or run it at 0* settings or what.
I noticed it was capable of +/- 8*.
Thanks,
Rick

I've never heard of anyone offsetting the timing gears on this application. Personally, I wouldn't do it, especially when running an aftermarket cam. Whatever possible gain can be had by changing that characteristic has already been done and probably wouldn't be good to screw with.
just my 2c

The reason you degree a cam is because the cam grinds are usually off by a few degrees. You use the degree wheel to see how far off the grind really is, once your gears and all are bolted together. Then you can correct it to 0 if that's what you desire.

Rick, like I said the owner didn't want to spend time measuring ANYTHING. I should have insisted we degree the cam, but we didn't.

I have driven a few 3800s with no balance shaft, and it's not nice at all. Very rough at idle and low RPM cruise IMO. Get it under power and up to speed and it doesn't really matter, but for most driving situations, I did not like it and Rick, I am sure YOU won't like it

deekster_caddy wrote:

I have driven a few 3800s with no balance shaft, and it's not nice at all. Very rough at idle and low RPM cruise IMO. Get it under power and up to speed and it doesn't really matter, but for most driving situations, I did not like it and Rick, I am sure YOU won't like it

Is that totally fair to say about the balance shaft? What cams were these cars running? Usually, you don't delete the B.S. unless running a big cam (causing rough idle and cruising)
I'm just asking because I wanna know for my own future mod choices.

Considering the intended purpose of the balance shaft, I think it's fair to say removing it would cause very rough idle at low RPM and cruise, as derek claims. Personally, I would not consider that to be a "nice" quality. That's the very reason GM included the shaft, right?

AA wrote:

Considering the intended purpose of the balance shaft, I think it's fair to say removing it would cause very rough idle at low RPM and cruise, as derek claims. Personally, I would not consider that to be a "nice" quality. That's the very reason GM included the shaft, right?

Unless i'm remembering what I read wrong, the balance shaft has virtually no affect on the running characteristics of the engine, but rather the outside vibrations so therefore, deleting it doesn't cause a rough idle or cruise. A big cam causeing a rough idle is a side effect of the engine actually running roughly. I guess my question was to clarify the symptom thats being felt, particularly, because most people who I've heard from who removed the balance shaft didn't report much vibration but Derek is saying otherwise.

Overall point, I wanna make sure we are all on the same page as far as the difference between a rough idle and vibration. My xp cam has a rough idle, especially with the idle speed slowed down but I wouldn't say I experience any notable vibration from it.

I'm just tripping over words here but I want to know if Deek is talking about actual rough idle or vibration that's purely because of the balance shaft. If it's as bad as Derek says, I don't think I'd ever want to do that on my DD.

turtleman wrote:

AA wrote:

Considering the intended purpose of the balance shaft, I think it's fair to say removing it would cause very rough idle at low RPM and cruise, as derek claims. Personally, I would not consider that to be a "nice" quality. That's the very reason GM included the shaft, right?

Unless i'm remembering what I read wrong, the balance shaft has virtually no affect on the running characteristics of the engine, but rather the outside vibrations so therefore, deleting it doesn't cause a rough idle or cruise. A big cam causeing a rough idle is a side effect of the engine actually running roughly. I guess my question was to clarify the symptom thats being felt, particularly, because most people who I've heard from who removed the balance shaft didn't report much vibration but Derek is saying otherwise.

Overall point, I wanna make sure we are all on the same page as far as the difference between a rough idle and vibration. My xp cam has a rough idle, especially with the idle speed slowed down but I wouldn't say I experience any notable vibration from it.

I'm just tripping over words here but I want to know if Deek is talking about actual rough idle or vibration that's purely because of the balance shaft. If it's as bad as Derek says, I don't think I'd ever want to do that on my DD.

I drove a 2000 Regal with an XP Hot cam, Headers and a lot of other mods and no balance shaft for about 3 weeks, regular city stop-n-go commuting. It had poly upper mounts, so I think it may have given more vibration than normal. Idle was not "rough" at all as it was an excellent running engine, but there was a lot of _vibration_. In my opinion too much, but I have always been a Buick driver and expect a quiet, comfortable, powerful car from a Buick. In a Riv, it may not feel as bad because of the transverse front motor mount soaking up more of the vibrations. Personally, I wouldn't do it. Your taste may vary. Your driving style may also vary - my commute involves a lot of sitting at light cycles, so smooth and quiet is kind of important to me. If you have a daily drive where you are moving the whole time, it may not bother you as much.

Quote :

Unless i'm remembering what I read wrong, the balance shaft has virtually no affect on the running characteristics of the engine, but rather the outside vibrations so therefore, deleting it doesn't cause a rough idle or cruise. A big cam causeing a rough idle is a side effect of the engine actually running roughly. I guess my question was to clarify the symptom thats being felt, particularly, because most people who I've heard from who removed the balance shaft didn't report much vibration but Derek is saying otherwise.

Info found at Wikipedia:

"While an inherently balanced V6 engine would have either 60 or 120 degrees angle between the two banks of cylinders, many current V6 engines are derived from older V8 engines, which have a 90 degree angle between the two banks of cylinders. While this provides for an evenly spaced firing order in an 8 cylinder engine, in a six cylinder engine this results in a loping rhythm, where during each rotation of the crankshaft three cylinders fire at 90 degree intervals, followed by a gap of 90 degrees with no power pulse. This can be eliminated by using a more complex, and expensive, crankshaft which alters the relationship between the cylinders in the two banks to give an effective 60 degree difference, but recently many manufacturers have found it more economical to adapt the balance shaft concept, using a single shaft with counterweights spaced so as to provide a vibration which cancels out the shake inherent in the 90 degree V6."

deekster_caddy wrote:

The reason you degree a cam is because the cam grinds are usually off by a few degrees. You use the degree wheel to see how far off the grind really is, once your gears and all are bolted together. Then you can correct it to 0 if that's what you desire.

Rick, like I said the owner didn't want to spend time measuring ANYTHING. I should have insisted we degree the cam, but we didn't.

I have driven a few 3800s with no balance shaft, and it's not nice at all. Very rough at idle and low RPM cruise IMO. Get it under power and up to speed and it doesn't really matter, but for most driving situations, I did not like it and Rick, I am sure YOU won't like it

I never said i had plans to remove a balance shaft or put high lift cam in it.
I was just asking some general questions regarding the type of cam you recommended. The XP from ZZP.

Degreeing an adjustable cam to O* is not the only reason to have an
adjustable cam sprocket, if anything the most desirable reasons are to
be able to retard or advance your cam timing with the adjustable
sprocket.
I don't have any dyno time with a modified 3800 to get
specific. But I do know from experience on other engines that the main
reason of having the + or - settings etched on the gear is for
performance adjustments. These adjustments will be based on an awful lot
more data than just basic running of the engine. Flow Dynamics plays a
big part along with compression ratio's and on and on.

Buick made the 3800 an even fire engine many years ago. We have the split crank and balance shaft.

"A V6 isn't balanced against inertial forces. The best layout for balance is the 60-degree engine, where a cylinder fires every 120 degrees of crankshaft rotation. The 3800 duplicates the firing position of the 60-degree engine by using a split pin on each of the 3 throws of the crankshaft, offsetting each piston to obtain the 120-degree firing angle. But with the split pins the 90-degree block doesn't match the plane of the reciprocating masses of the pistons and crankshaft weight, resulting in a rotating force.
Buick's uses a balance shaft in the center of the V, rotating at engine speed in the opposite direction of the crankshaft, canceling the tremors; this helps give the 3800 its luxury-class smoothness."

- Dan McCosh, Popular Mechanics, Jan 1991

what is Intense's comparable cam to the zzp XP cam?

SCbuick010 wrote:

what is Intense's comparable cam to the zzp XP cam?

S1X.

yeah thats what i thought

I like both - the S1X and XP cams are nice performance oriented daily drivers and you don't need to go double roller.