Pontiac GTO Forum banner
361 - 380 of 401 Posts

·
Registered
Joined
·
1,140 Posts
I suppose that's a round about way. The piston at TDC should put the timing mark at zero. The cam couldve been degreed? It's hard to imagine that anyone with the skill to degree a cam, would install rockers without verifying clearance.
Not sure what Kevins reference for timing is but, when I bought a new balancer from butler the timing mark was not close to tdc. They offered to send me a new one but I settled for the piston stop and timing tape,,,,the rest is history.
 

·
Registered
Joined
·
6,878 Posts
My paperwork doesn't show 4 degrees. It only says specs are for the cam installed at 106 Intake Center Line.
Not sure how that correlates to 4 degrees.

4-degrees is typically built right into the cam by the cam grinder. So the spec used when dialing in the cam is the 106 degrees Intake Center Line (ICL).

To determine if a camshaft has ground-in advance, subtract the Intake Centerline from the Lobe Separation Angle.
For example, a camshaft has an intake centerline of 106° and an LSA of 110°.

110° - 106° = 4° ground-in advance

Not trying to discourage you or throw in the towel, just trying to sort through some of the issues that are not making sense. Seems like a number of inaccurate motorhead locker room chatter that is not based on facts, but buddies getting together at the track and passing along bad info and no one knowing any better to call them out on it.

Not a big deal IF you had to go in and dial in the cam, BUT, I would try and speak with the actual engine builder and see if he has any notes or remembers what he set the cam at. He may also have a reason as to why he retarded the cam if he indeed did retard it. But at this point, I would not assume the cam was retarded and it may just be a wrong assumption altogether. It would have to be for a specific reason that a builder would retard a cam rather than install it per the cam card.

So find this out if you can and then report back and we can go from there. If everything is on the up and up, then we can go back with the carb adjustments and/or timing to see if we can get the engine more responsive and crisp.

(y)
 

·
Registered
Joined
·
1,183 Posts
Isn't it the coil that determines the energy?
Yes. Figure that the original coil used would have less power going to it than your HEI does. I am no expert at this but did a lot of reading on this before I set mine up. Everything I could find indicated a larger spark gap for HEI. I found reference to gaps as small as 0.040 and as large as 0.048. I split the difference and called it a day. Car seems to like it. I have not played around tweaking the gap to look for very minor improvements.

This all being said, I will not speak for folks running other forms of electronic ignition. Their needs could be different. I was gearing up to run HEI so that's what I focused my research on.
 

·
Premium Member
Cameo Ivory 1967
Joined
·
4,209 Posts
Not trying to discourage you or throw in the towel, just trying to sort through some of the issues that are not making sense. Seems like a number of inaccurate motorhead locker room chatter that is not based on facts, but buddies getting together at the track and passing along bad info and no one knowing any better to call them out on it.
This is what I was referring to yesterday. Learning anything requires practical, scientific, theoretical, and working knowledge. No one of those things is going to bring you full circle, because you need them all.

It's one thing to read something on the internet, it's another to understand it, and it's another to be able to conduct it.

When I picked my cam, I spent days on the internet, studying famous Pontiac cams, then I spent day on the internet and Butlers website researching, then I spent weeks going back and forth with @PontiacJim about them.

But then I had to sort through all of it and use the advice and options, to determine what was best for my needs. I didnt arbitrarily pick what someone else recommended... but if I didnt spend so much time learning first, then I wouldve had no choice but to do so.

Let me tell you, I still dont understand 75% of it, but Im wise enough to only take on what I can handle. You have to have a plan, a method, and persistence, and learn from your mistakes. If you do, you'll achieve your goals, and if you don't, it wont just be a GTO that you suck at.
 

·
Registered
Joined
·
263 Posts
Discussion Starter · #367 ·
I've got to take a break for a while to spend time with the other half and try to get more information from engine builder.
Going to get the front end aligned and the windshield checked out in the meantime.

My plans for the hesitation:
lube the accelerator pump (need to know what kind of lube).
measure total timing and maybe adjust spark timing.
try lighter springs for carb jets.
 

·
Premium Member
Joined
·
2,355 Posts
I've got to take a break for a while to spend time with the other half and try to get more information from engine builder.
Going to get the front end aligned and the windshield checked out in the meantime.

My plans for the hesitation:
lube the accelerator pump (need to know what kind of lube).
measure total timing and maybe adjust spark timing.
try lighter springs for carb jets.
Don't know if you bought a new timing light but I have an Innova digital light and really like it. And yes keep the other half happy, that's way more important than cam shaft problems (y)
 

·
Registered
Joined
·
16 Posts
I've got to take a break for a while to spend time with the other half and try to get more information from engine builder.
Going to get the front end aligned and the windshield checked out in the meantime.

My plans for the hesitation:
lube the accelerator pump (need to know what kind of lube).
measure total timing and maybe adjust spark timing.
try lighter springs for carb jets.
Hory smokes! I started reading this with Frustrated With Builder. I couldn't put it down until I got here... I should be out in my barn welding and grinding on my own project! I've seen all the excellent advice and tips by knowledgeable people on here. So glad to see you get your car corrected to this point. One thing bothers me though. I may have missed it, but has anyone asked where you're hooking up the vacuum advance hose from the distributor ? It needs to be hooked up to the port above the throttle plates to work correctly. I may be stating the obvious here, but I'm following the basic rules of troubleshooting, "never assume anything".😗
 

·
Registered
Joined
·
263 Posts
Discussion Starter · #371 ·
Hory smokes! I started reading this with Frustrated With Builder. I couldn't put it down until I got here... I should be out in my barn welding and grinding on my own project! I've seen all the excellent advice and tips by knowledgeable people on here. So glad to see you get your car corrected to this point. One thing bothers me though. I may have missed it, but has anyone asked where you're hooking up the vacuum advance hose from the distributor ? It needs to be hooked up to the port above the throttle plates to work correctly. I may be stating the obvious here, but I'm following the basic rules of troubleshooting, "never assume anything".😗
Glad it's been a page turner. It was for me too.

I tried it ported and not-ported, and it doesn't make any difference. Seems to me it should make some difference but I don't notice it.
 

·
Registered
Joined
·
1,183 Posts
I've got to take a break for a while to spend time with the other half and try to get more information from engine builder.
Going to get the front end aligned and the windshield checked out in the meantime.

My plans for the hesitation:
lube the accelerator pump (need to know what kind of lube).
measure total timing and maybe adjust spark timing.
try lighter springs for carb jets.
Highlighted. The most important part of these projects! You gotta keep your better half happy. You know, for the next time you set off all the CO monitors in the house while breaking in a new cam shaft in the driveway with the garage door open and she's inside on a zoom work meeting. I "know a guy" that happened to and the wife thought it was funny.

All joking aside. I want to add that I respect the way you're going about this. A lot of other guys would be hopping mad, ready to throw in the towel, or both. Keep at it. You'll get this dialed in and running exactly how you want it. Like I said a bunch of posts ago, mine wasn't running that f=great when I first got it back on the road either. I slowly worked at it until I got it running the way I wanted it to. It took me a few weeks and ~500 miles to do it.
 

·
Premium Member
Joined
·
2,355 Posts
Highlighted. The most important part of these projects! You gotta keep your better half happy. You know, for the next time you set off all the CO monitors in the house while breaking in a new cam shaft in the driveway with the garage door open and she's inside on a zoom work meeting. I "know a guy" that happened to and the wife thought it was funny.

All joking aside. I want to add that I respect the way you're going about this. A lot of other guys would be hopping mad, ready to throw in the towel, or both. Keep at it. You'll get this dialed in and running exactly how you want it. Like I said a bunch of posts ago, mine wasn't running that f=great when I first got it back on the road either. I slowly worked at it until I got it running the way I wanted it to. It took me a few weeks and ~500 miles to do it.
I think I remember that guy, wasn't he on the right coast ;) He was that guy I think ready to set fire to it and I bet there's some screwdrivers in the wall too but everyone here jumped to the rescue to keep him from selling it.....I hope he doesn't regret us one day :ROFLMAO:
 

·
Premium Member
Joined
·
2,355 Posts
Hory smokes! I started reading this with Frustrated With Builder. I couldn't put it down until I got here... I should be out in my barn welding and grinding on my own project! I've seen all the excellent advice and tips by knowledgeable people on here. So glad to see you get your car corrected to this point. One thing bothers me though. I may have missed it, but has anyone asked where you're hooking up the vacuum advance hose from the distributor ? It needs to be hooked up to the port above the throttle plates to work correctly. I may be stating the obvious here, but I'm following the basic rules of troubleshooting, "never assume anything".😗
Are you trying to start a civil war with ported or non ported vacuum :ROFLMAO:
 

·
64-67 Expert
Joined
·
9,164 Posts
Most Pontiacs were set up originally with manifold vacuum to the advance on the distributor. This gave a cooler running engine at low and idle speeds and good advance at cruise speeds where the intake manifold vacuum is still high. I have always run manifold vacuum on my first-gen GTO's, as set-up from the factory. Some engines seem to prefer ported vacuum, though.
 

·
Registered
Joined
·
1,183 Posts
I think I remember that guy, wasn't he on the right coast ;) He was that guy I think ready to set fire to it and I bet there's some screwdrivers in the wall too but everyone here jumped to the rescue to keep him from selling it.....I hope he doesn't regret us one day :ROFLMAO:
I think he was on the right coast now that you mention it. I seem to remember it more of a near panic attack when he thought he wiped out a new cam because it wouldn't fire because "that guy" had the wires 180 degrees off. No screw drivers were harmed during the process. My, err I mean that guy's, kid's vocabulary will never be the same though.
 

·
Registered
Joined
·
6,878 Posts
Most Pontiacs were set up originally with manifold vacuum to the advance on the distributor. This gave a cooler running engine at low and idle speeds and good advance at cruise speeds where the intake manifold vacuum is still high. I have always run manifold vacuum on my first-gen GTO's, as set-up from the factory. Some engines seem to prefer ported vacuum, though.
The ported was a by-product as emission standards were being pushed hard on these cars.
 

·
Premium Member
Cameo Ivory 1967
Joined
·
4,209 Posts
Highlighted. The most important part of these projects! You gotta keep your better half happy. You know, for the next time you set off all the CO monitors in the house while breaking in a new cam shaft in the driveway with the garage door open and she's inside on a zoom work meeting. I "know a guy" that happened to and the wife thought it was funny.

All joking aside. I want to add that I respect the way you're going about this. A lot of other guys would be hopping mad, ready to throw in the towel, or both. Keep at it. You'll get this dialed in and running exactly how you want it. Like I said a bunch of posts ago, mine wasn't running that f=great when I first got it back on the road either. I slowly worked at it until I got it running the way I wanted it to. It took me a few weeks and ~500 miles to do it.
It took me a year and a half and several thousand miles to get it worked out
 
361 - 380 of 401 Posts
Top