[pastry_chef]

Originally Posted by Stan Weiss

Maybe of interest.

David Vizard's PowerTec 10 EP 17 Big lift rocker shootout
https://www.youtube.com/watch?v=aOco86KPzEU

Stan

Great timing Stan, love his videos.

[TransAm 474]

Here is a picture of the timing chain marks, I guess it is completely normal for the crank gear tooth and the mark on the camshaft gear to not line up when you advance the camshaft, like they did when they are installed at "dot-dot"?

[pastry_chef]

Your cam degree measurements take priority over what the markings on the gears may say. I'd ignore them.

[TransAm 474]

Originally Posted by pastry_chef

Your cam degree measurements take priority over what the markings on the gears may say. I'd ignore them.

Thanks Pastry, that is exactly what I was thinking, I just wanted to confirm... you would think with the technology that we have nowdays, they could cut the keyways in the crank gear with close enough tolerance that the marks would line up perfectly, no matter where you advanced or retarded the cam, unfortunately that doesn't seem to be the case LOL... I appreciate the help

[TransAm 474]

I seem to remember reading about a build that Paul Carter had done using one of the Voodoo's, and I'm pretty sure that particular engine degreed in at 103°, and he left it at that, because he said that was as close as he could get to his preferred 104°, but now I can't seem to find the post

[pastry_chef]

At this thread you can see a few of Harold's posts, especially post 9

https://www.chevelles.com/threads/de...ed-help.87268/

Many years ago I made a point of reading everything Harold posted. lol.

[TransAm 474]

Originally Posted by pastry_chef

At this thread you can see a few of Harold's posts, especially post 9

https://www.chevelles.com/threads/de...ed-help.87268/

Many years ago I made a point of reading everything Harold posted. lol.

Thanks, that's a great read

[Jay S]

103 sounds like a good place to me.

Cool rocker arm video and charts

[TransAm 474]

Originally Posted by Jay S

103 sounds like a good place to me.

Cool rocker arm video and charts

That's what we are thinking, I think we are gonna roll with it. I appreciate your help

[1968GTO421]

Originally Posted by pastry_chef

Your cam degree measurements take priority over what the markings on the gears may say. I'd ignore them.

I tend to agree with this. Despite my "probable dementia" on this, looking at the photo in post #22, I have to wonder about what I'm seeing as I was always taught that on Pontiacs the timing dot on the cam gear should be at 12 o'clock, not 6 like on Chevies. Unless the OP is working off #6 cylinder instead of #1. Please correct me if I'm wrong.

[TransAm 474]

Originally Posted by 1968GTO421

I tend to agree with this. Despite my "probable dementia" on this, looking at the photo in post #22, I have to wonder about what I'm seeing as I was always taught that on Pontiacs the timing dot on the cam gear should be at 12 o'clock, not 6 like on Chevies. Unless the OP is working off #6 cylinder instead of #1. Please correct me if I'm wrong.

Doesn't really make any difference, you can turn the engine over one full turn and have the dot on the cam gear at 12 o'clock instead of 6 o'clock like in my picture, only difference is it will then be on the compression stroke, instead of the exhaust stroke. We ALWAYS do any V8 engine this way when installing the timing set, just makes it a little easier to line up the marks for initial cam checking. Obviously you want to be sure it's on the compression stroke when dropping the distributor in.

[77 TRASHCAN]

Originally Posted by 1968GTO421

I tend to agree with this. Despite my "probable dementia" on this, looking at the photo in post #22, I have to wonder about what I'm seeing as I was always taught that on Pontiacs the timing dot on the cam gear should be at 12 o'clock, not 6 like on Chevies. Unless the OP is working off #6 cylinder instead of #1. Please correct me if I'm wrong.

Doesn’t matter which way...Lol, as long as the builder knows..
I freshened up a Chevy 350, a couple of years ago for a friend. Delivered it to his shop, late one evening. He and another friend installed it. I told them to try to put some gas in the float bowls, they did. I had the timing dead on. Owner calls me said it fired up immediately!! Zero hesitation. Lol he’s a car guy, but isn’t knowledgeable about engines. He’d watched too many shows where the initial fire up of an engine took hours....

[Cliff R]

I've one of the few that will respond here that has actually moved cams on the dyno and observed the results. I did this with "fast ramp" designs so it applies here.

I've also moved cams then evaluated the results on the street and backed them up with track numbers.

With a cam as big as the 704 and compression at only 9.35 to 1 I doubt if you run into any issues advancing the cam. You will however never know where it worked best unless some sort of dyno or track testing was done after each movement.

When moving cams on the dyno not one time has anything improved anyplace advancing one 4 degrees beyond the LSA, or 106ICL for a 110LSA or 108ICL for 112LSA, etc.

I even tried a 110LSA cam with really aggressive flat solid lobes once in a 455 race engine and it like 110ICL and ran deep into the 10's with a pretty "basic" engine combo, iron heads, T-II intake, HP950, etc.

I also did some street evaluations backed up by track testing moving the cam around in the 455 that powered my Ventura a few years back. It was the Crower 60919 cam and started at the recommended 109ICL. Moved it to 111, 113, then to 107, then back to 109ICL and drove the car on the street plus drag raced it several times after each movement.

Absolutely and for sure the engine "felt" strongest at 107ICL, snappy, quick to rev off idle, highest vacuum reading etc. On the street it literally shredded the tires with a "blip" of the throttle. I'd have bet a couple of pay checks it would run the quickest there. Sadly at the track it slowed down everyplace even short times and ran nearly 2mph SLOWER than it did at 109 and 111ICL. This type of testing has made me have little faith in the "butt meter" to evaluate swapping out and testing parts with these engines.

Clear up at 113ICL the engine felt "soft" and a bit lethargic on the street. It ran about the same as it did at 107ICL for track numbers so the really late intake closing wasn't making it either.........Cliff

[Cliff R]

"Here is a picture of the timing chain marks, I guess it is completely normal for the crank gear tooth and the mark on the camshaft gear to not line up when you advance the camshaft, like they did when they are installed at "dot-dot"?"

Do NOT "ignore" the marks they are there for a reason.

You are lucky as they didn't used to mark them and I've seen very experienced engine "builders" screw that deal up. The little "2A" and "4A" are the new reference points to line up with the "dot" on the top sprocket.

When you move to a different keyway do NOT use the original "dot" on the crank gear to line up with the cam gear. You move up to the closest tooth then two back to the left as the new reference point. Experienced engine builders would know this even if the bottom sprocket wasn't marked.

A few years ago one of the Pontiac "gurus" built an engine for a board member here and "degreed" the cam and even test ran the engine before delivery. He told the customer it ran fine but it did NOT run well after being installed in the vehicle. Of course the carb guy was getting all the blame with comments under his breath that the "Quadra-Junk" would NOT keep up with his engine, etc. They even sent the carb back here couple of time and the distributor I did for it once. NOTHING was wrong with either so I had the car trailered here some 800 miles one way to my shop to take a look.

Low and behold the ONLY thing wrong with the engine was the "builder/guru" had used a Rollmaster 9 keyway set. He must have decided at some point in the assembly process to "advance" the cam, which he did. Problem was he used the "dot" on the lower gear to line up with the "dot" on the upper gear. Back then Rollmaster did NOT mark them for any position but "dot to dot".

Amazingly the engine ran that way, just didn't make much power. Once we got the cam lined up correctly the engine went on to push the 4000' car well into the 10's over 120mph so the rest of the build was good.......FWIW.......

[Stan Weiss]

Different cam manufactures use different lobe designs. So based on their lobe design, on their cam card they give you what they think is a good starting point for their cam lobe design.

The VooDoo lobe designer UD Harold (RIP) has said where he thinks is a good starting point. If this was my deal I would start where the cam lobe designer/ UD Harold (RIP) says.

Stan

[TransAm 474]

Originally Posted by Stan Weiss

Different cam manufactures use different lobe designs. So based on their lobe design, on their cam card they give you what they think is a good starting point for their cam lobe design.

The VooDoo lobe designer UD Harold (RIP) has said where he thinks is a good starting point. If this was my deal I would start where the cam lobe designer/ UD Harold (RIP) says.

Stan

Thanks Stan, while the Intake Centerline is 1 degree more Advanced than Harold usually recommends on the VooDoo's (ours 103° vs Harold's recommend 104°), the relation of Intake-Exhaust tappet lift at TDC seems to be right in the sweet spot however, at the 103° that is installed at, the Intake is lifted .093" and the exhaust is lifted .0612", having the Intake lobe lifted .0318" higher than the exhaust. Harold always said that he likes to see the Intake lobe .025"-.040" higher than the Exhaust lobe at TDC. When installed at 105°, the Intake was lifted .089" and the exhaust was lifted .067", having the Intake lifted only .022" higher than the exhaust.

[1968GTO421]

Thanks TransAm 474 for starting this thread. I'm learning alot here that differs from some of the shadetree methods I learned decades ago.

[pastry_chef]

Originally Posted by Cliff R

Problem was he used the "dot" on the lower gear to line up with the "dot" on the upper gear. Back then Rollmaster did NOT mark them for any position but "dot to dot".

Then the builder was shoveling BS and did not degree the cam correctly. Or if he did he moved the cam after, same end result. Dismal failure.
Only a fool would measure then try and eyeball after, change the mark and cut.

Never ever assume!

[Cliff R]

I would imagine he set everything up with the timing set "dot to dot" and saw that it needed to be advanced. Since he was using a 9 keyway timing set he simply moved the bottom sprocket, lined it up again at "dot to dot" and got lazy and didn't set everything back up to re-check his work. Each time you remove the bottom sprocket to check things the degree wheel comes off and you have to find TDC again, set up the pointer, etc.

Matters not and you are correct, take NOTHING for granted and check and re-check these things rather than just blame the carb guy when your $13,000 455 build doesn't make enough power in a later T/A to outrun a Dodge Neon with a couple of plug wires pulled off of it!......LOL

[Formulajones]

Originally Posted by TransAm 474

Thanks Stan, while the Intake Centerline is 1 degree more Advanced than Harold usually recommends on the VooDoo's (ours 103° vs Harold's recommend 104°), the relation of Intake-Exhaust tappet lift at TDC seems to be right in the sweet spot however, at the 103° that is installed at, the Intake is lifted .093" and the exhaust is lifted .0612", having the Intake lobe lifted .0318" higher than the exhaust. Harold always said that he likes to see the Intake lobe .025"-.040" higher than the Exhaust lobe at TDC. When installed at 105°, the Intake was lifted .089" and the exhaust was lifted .067", having the Intake lifted only .022" higher than the exhaust.

I'd leave it at 103. The intake lifter rise is right in the money spot and that's the most important thing. Where the ICL ends up to get it there is less important. The ICL that Harold recommends with each camshaft is a number that should get you right in the ball park for the lifter rise that he likes to see with his camshafts, but as you found out, you may have to fudge that number a pinch one way or the other to get the lifter rise you want.