Frustrated with builder

9829 Views 458 Replies 26 Participants Last post by armyadarkness, 8 mo ago

kevin1727

Discussion Starter · 9 mo ago

I'm now on the second carburetor on my car.
Rebuilt 428 engine, TH400, long tube headers, 3.36 rear end.

The car runs like an old U-Haul truck and the exhaust pipes are loaded with black soot.

First carb was a 650cfm HP Holley dual pumper. No choke and probably 4 mpg gas mileage. Smoked like a mosquito fogger.
Second carb is now an Edelbrock 1411 750cfm. Mileage is around 10mpg but still a good bit of smoke, black soot in tail pipes, and hesitation when first hitting the accelerator.

The builder wants to try a standard 600cfm now.

My position is that if the fuel/air mixture, timing, etc are correct, then changing the max capacity of the carburetor should make little difference unless I am running at max rpm.

I can adjust the fuel idle mixture but swapping out springs and jets are not in my skill set. It's been decades since I threw out my timing light and tuning tools.

The builder says he put "milder" jets and springs in this carb but there has to be something else wrong.

I'm currently trying different accelerator pump settings and vacuum advance ports. No luck so far.

I've heard so many different things and I'm lost.
Fuel pressure too high? -the fuel is fed from an atmospheric pressure bowl, so how is that an issue?
Too many CFM for a cruiser? -isn't cfm set by throttle position? It's not always running at 750 cfm.

361 - 380 of 459 Posts

RMTZ67

· #361 · 9 mo ago

armyadarkness said:
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.

Reactions: 3

PontiacJim

· #362 · 9 mo ago

kevin1727 said:
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.

Xtreme Energy 224/230 Hydraulic Flat Cam for Pontiac 265-455

Xtreme Energy 224/230 Hydraulic Flat Tappet Cam for Pontiac 265-455. Good for street machines. 2000+ stall. Slightly rough idle.

www.compcams.com

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.

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Reactions: 5

PontiacJim

· #363 · 9 mo ago

RMTZ67 said:
What happened to the days when you set your base timing with a taillight harness and bulb?

That was pre-internet and when we were poor speed freaks! How did we ever live without cell phones? LOL

Reactions: 5

Jared

· #364 · 9 mo ago

kevin1727 said:
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.

Reactions: 5

armyadarkness

· #365 · 9 mo ago

PontiacJim said:
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).

Exactly my thought, and I suspect that this is simply being misunderstood.

Reactions: 2

armyadarkness

· #366 · 9 mo ago

PontiacJim said:
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.

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Reactions: 2

kevin1727

Discussion Starter · #367 · 9 mo ago

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.

Reactions: 5

armyadarkness

· #368 · 9 mo ago

Yes... with vacuum that low, oem springs for that Eddy would lift the needles out of the seats VERY/ TOO quickly

Reactions: 3

Baaad65

· #369 · 9 mo ago

kevin1727 said:
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

Reactions: 3

Philski

· #370 · 8 mo ago

kevin1727 said:
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".😗

Reactions: 3

kevin1727

Discussion Starter · #371 · 8 mo ago

Philski said:
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.

Reactions: 2

armyadarkness

· #372 · 8 mo ago

Like I said... easy to mask some issues with others.

Reactions: 2

Jared

· #373 · 8 mo ago

kevin1727 said:
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.

Reactions: 5

Baaad65

· #374 · 8 mo ago

Jared said:
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

Reactions: 5

Baaad65

· #375 · 8 mo ago

Philski said:
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

Reactions: 3

geeteeohguy

· #376 · 8 mo ago

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.

Reactions: 5

Jared

· #377 · 8 mo ago

Baaad65 said:
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

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.

Reactions: 5

PontiacJim

· #378 · 8 mo ago

geeteeohguy said:
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.

Reactions: 5

Philski

· #379 · 8 mo ago

Baaad65 said:
Are you trying to start a civil war with ported or non ported vacuum

Nah.🥸 I just think that if you're running a non-adjustable vacuum advance, there's no since in having full advance at idle.

Reactions: 1

armyadarkness

· #380 · 8 mo ago

Jared said:
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

Reactions: 2

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