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#341
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I think you need to leave the amount of Vacuum Advance out of your total timing equation. Initial +Centrifugal = 30-32-34. I think most GM cars end up with approx 50 BTDC total at cruise.
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1968 Firebird 400 RAII M21, 3.31 12 bolt, Mayfair Maize. 1977 Trans Am W72 400, TH350, 3.23 T Top Everyone you will ever meet knows something you don't. Bill Nye. |
#342
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That’s right. I have it set to 15 degrees initial + 17 mechanical for a total of 32. I’d like to experiment with up to 36, it that would push my initial up to 18-19. Maybe that’s ok if it starts fine? I haven’t really been worried about the vacuum advance other than to make sure it’s working.
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Ken '68 GTO - 464 - Ram Air II heads - 236/242 roller - 9.5 TSP converter - Moser 3.55 Truetrac (build thread | walk around) '95 Comp T/A #6 M6 - bone stock (pics) |
#343
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I haven't had as much road time as I would have liked in the car since I got it running. I sent my distributor off to a couple weeks ago and it appears to be MIA somewhere between TN and CA right now. Hoping it gets here for the show at my son's school next week.
In the mean time, I received a new 9.5" TSP converter that Cliff specced for me. The old 13" Continental wasn't enough and while the mystery 12" I got from the trans builder was better, there was room for improvement. According to the paperwork he set this one up for 3k stall. Can't wait to try it out. Between the distributor tweaks and the new converter this thing should be pretty well dialed in. We'll see if the nodular 8.2 holds up. I did get the A/C hoses crimped up and a new drier installed. Here's a couple pics from a cruise in a few weeks ago looking all fresh.
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Ken '68 GTO - 464 - Ram Air II heads - 236/242 roller - 9.5 TSP converter - Moser 3.55 Truetrac (build thread | walk around) '95 Comp T/A #6 M6 - bone stock (pics) |
The Following 4 Users Say Thank You to Verdoro 68 For This Useful Post: | ||
#344
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Is it weird for me to like the center exhaust ports on a round port head? Is that strange?
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72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007 (cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD 1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.64 @ 87.3 mph on slippery street tires.Bad 2.25 60ft.Owned since 86' |
#345
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Quote:
Dennis |
#346
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Ken, That convertor should make a world of difference for you. The GTO is a true work of art! I love it! You may need a good 12-bolt rear in the future with all that power and a 4-speed. All it took was one rolling full throttle blast in my 462 LeMans with the M-20 4-speed to take out the original gray iron 8.2 10 bolt (with 3.23 Safe-T-Track). We were fortunate that we had a McKinnon 3.07 12 bolt rear from a '70 GP under the bench to rebuild. The gears were toast, so we replaced them with a new 3.08 Yukon gears, posi, and axles. Now the weak link is the M-20, so taking it easy on the old gal.
Dennis Last edited by SD455DJ; 05-10-2023 at 07:37 AM. |
The Following 2 Users Say Thank You to SD455DJ For This Useful Post: | ||
#347
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We'll see how long the rear lasts. It's a '69 4 pinion 3.55 HD unit I swapped in 30 years ago. I had monzaz rebuild it about 10 years ago and at the time he said "go easy on it". It may hold up on street tires around town, but I suspect if I ever I take it down the track it will probably check out. There might be a thread on a 12 bolt upgrade in the future.
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Ken '68 GTO - 464 - Ram Air II heads - 236/242 roller - 9.5 TSP converter - Moser 3.55 Truetrac (build thread | walk around) '95 Comp T/A #6 M6 - bone stock (pics) |
#348
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He built the 71 Buick 8.5" under my car and it's survived 10 years or so. Moser axles and a Tru-Trac.
Great job on your car.
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frittering and wasting the hours in an off hand way.... 1969 GTO, 455ci, 230/236 Pontiac Dude's "Butcher Special" Comp hyd roller cam with Crower HIPPO solid roller lifters, Q-jet, Edelbrock P4B-QJ, Doug's headers, ported 6X-8 (97cc) heads, TKO600, 3.73 geared Eaton Tru-Trac 8.5", hydroboost, rear disc brakes......and my greatest mechanical feat....a new heater core. |
#349
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David, I always wonder how that rear is holding up, hard to believe it has been that long since I shipped it to you. I still remember the heavy duty crate I built for it ! Hope all is well with you and your family.
Tim john--- |
#350
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I want to give a shout out to SunTuned who put in some extra effort to get my distributor back in time for the car show at my son's High School auto shop. Super stand up guy, but we all knew that already. I have a full 36 degrees now without overloading the initial timing.
The new converter is also in. I had a minor issue with a broken trans line fitting on the maiden voyage that caused a smoke show and messed up my nice clean undercarriage. Nothing hurt, just a mess to clean up. I ended up pilfering a fitting off an abandoned TH400 at the school shop to get back on the road. The car drives way different with this converter. I definitely notice that it has a stall in it. Like the paperwork says, it stalls spot on at 3000. With a light foot, it will kick in around 2600. By contrast, the 13" Continental was around 2200 so this one is quite a bit higher. It keeps the engine squarely in the torque curve and it feels like I could pull a house off it's foundation. It's going to take me a little bit to get used to the higher stall speed, but this converter feels right for the power band. Blip the throttle and you're very quickly sideways - it's fun I think I'm good to just go and enjoy the car for a little while now!
__________________
Ken '68 GTO - 464 - Ram Air II heads - 236/242 roller - 9.5 TSP converter - Moser 3.55 Truetrac (build thread | walk around) '95 Comp T/A #6 M6 - bone stock (pics) |
The Following 2 Users Say Thank You to Verdoro 68 For This Useful Post: | ||
#351
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Dude, what an awesome build!!! I just read through all 18 pages so far and it's great seeing your build progress. Love the RAII heads! Look forward to seeing updates.
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#352
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Thanks! I learned a ton during this build and am really glad I did it myself rather than handing it over to a shop.
Since I updated this thread, I pulled the engine two more times to fix the rear main. The first two rope seals got shredded after a few hundred miles, I think due to the serrations on the crank. I had the crank polished and carefully installed a BOP one piece. It's been leak free since. I have about 2,000 miles on it now. Overall, this setup has been trouble free and a lot of fun to drive. The lifters are quiet, oil pressure is great, it starts easy and runs cool. The carb and distributor are dialed in and the converter was a great addition. There's no shortage of torque! It's funny looking back at the last few comments. I just did a rear end swap to a Moser 12 bolt. I kept the 3.55s but went to a Truetrac. That required a new driveshaft so I stepped it up to a 3.5" with 1350s. I also installed Global West control arms out back. This combo made a surprising difference in the way the car feels and hooks up on the road. I need to take it to the track now! I'd be lying if I said I haven't been daydreaming a little about what's next for this engine. I can't leave well enough alone. In hindsight, a set of Edelbrocks would have been a more frugal choice and given me a lot more power. Most people don't notice the setup when I pop the hood, but every once in a while I run into a Pontiac nerd like me who appreciates it.
__________________
Ken '68 GTO - 464 - Ram Air II heads - 236/242 roller - 9.5 TSP converter - Moser 3.55 Truetrac (build thread | walk around) '95 Comp T/A #6 M6 - bone stock (pics) |
#353
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Very cool thread to have followed ❗️❗️👍
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#354
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I love the iron ram air heads, to.me.they are what makes this build special. I know its hard to say if it hasnt broken, but are you happy with the cast crank decision, we're you happy with the quality of it or do you wish you went forged?
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#355
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The RAII heads are part of what makes a 68 GTO special.
Along with the GTO fender emblems, the vent wings and the ignition key in the dash. Modern Endura styling with old school GTO features.
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1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
The Following User Says Thank You to b-man For This Useful Post: | ||
#356
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No issues with the cast crank, but I dont really beat on it daily. I suspect it will be perfectly fine at this power level. I suspect Butler went over it before they shipped it because all the journals were really uniform in size and the rod bearing clearances were spot on. Overall I dont have any regrets in my choices for this build.
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Ken '68 GTO - 464 - Ram Air II heads - 236/242 roller - 9.5 TSP converter - Moser 3.55 Truetrac (build thread | walk around) '95 Comp T/A #6 M6 - bone stock (pics) |
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