[1969bird]

My 69 convertible 400 bird is ready for either a rebuild (yuck) or a more potent block. Since the cost of rebuilding is pretty much the same I want to try to find a short block 428 or 455 and just add it to my current combo (see list following). I need advise on what would be the better choice for a car that's driven 95% on the street with drag racing 3 or 4 times a year. Best time was 13.968 but normally it's a 14.2 car while running 26" tall M&H DOT's. I want to just drop it into the car with what I have: 62 heads "street-ported" (don't know the flow numbers), stainless steel valves, 7/16" studs, 1.62 roller tip rockers, Ultradyne Cam (223/231 @ .50, 463/486 lift, 110 lobe sep.), 1970 Pontiac alum HO intake, Rochester q-jet, MSD 6AL w/ Blaster 2 coil, long branch manifolds, straight 2 1/2" duals with Walker super turbo mufflers, turbo 400 tranny w/ L88 (?) 2100 stall convertor and B&M shift kit, 3:42 posi, SSM lift bars on the leaf springs, car weighs 3800 pounds. After ready many threads on other BB's I am concerned about the compression and need to know if forged pistons can be dished enough to bring compression down to 10:1 or less. I want to shift at 5500 (currently)to 6000 rpm. I will consider a beafier cam with Rhoads lifters (already ahve the lifters). I've read that certain year 428 cranks are hard to balance, etc. Many stories read, many questions, much confusion. Best recommendations will be appreciated. I know someone who has a 428 short block and can get it now if that's the best choice for me. I will want to add a higher stall convertor soon or even a switch pitch tranny, so my block choice needs to factor that in also. I would be happy with mid 13's but low 13's are preffered. Thanks in advance.

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JJB

[1969bird]

My 69 convertible 400 bird is ready for either a rebuild (yuck) or a more potent block. Since the cost of rebuilding is pretty much the same I want to try to find a short block 428 or 455 and just add it to my current combo (see list following). I need advise on what would be the better choice for a car that's driven 95% on the street with drag racing 3 or 4 times a year. Best time was 13.968 but normally it's a 14.2 car while running 26" tall M&H DOT's. I want to just drop it into the car with what I have: 62 heads "street-ported" (don't know the flow numbers), stainless steel valves, 7/16" studs, 1.62 roller tip rockers, Ultradyne Cam (223/231 @ .50, 463/486 lift, 110 lobe sep.), 1970 Pontiac alum HO intake, Rochester q-jet, MSD 6AL w/ Blaster 2 coil, long branch manifolds, straight 2 1/2" duals with Walker super turbo mufflers, turbo 400 tranny w/ L88 (?) 2100 stall convertor and B&M shift kit, 3:42 posi, SSM lift bars on the leaf springs, car weighs 3800 pounds. After ready many threads on other BB's I am concerned about the compression and need to know if forged pistons can be dished enough to bring compression down to 10:1 or less. I want to shift at 5500 (currently)to 6000 rpm. I will consider a beafier cam with Rhoads lifters (already ahve the lifters). I've read that certain year 428 cranks are hard to balance, etc. Many stories read, many questions, much confusion. Best recommendations will be appreciated. I know someone who has a 428 short block and can get it now if that's the best choice for me. I will want to add a higher stall convertor soon or even a switch pitch tranny, so my block choice needs to factor that in also. I would be happy with mid 13's but low 13's are preffered. Thanks in advance.

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JJB

[Blackcat]

Go for the 428. Don't believe the balancing story. You will have a shorter stroke than a 455. This will give you more RPM's than a stock 455. The Heads from your 400 will work with the 428 because of the already dished pistons used in the 428's. My old 69 GP with a 428Ho ran just fine on premium. It would run 13.02 at the track. I used to drive it 90 miles each way to the track and home. Most 428's had 4-bolt mains 67-68. The 69's only the HO's had them. Two bolts are fine If the engine is balanced.

[Metal]

I would go with the 428. It will produce less torque than the 455 and will help keep the tires on the road. You will also be able to get the added RPM you are looking for. As far as the 62 heads go, you will get about 10.75 to 1. Also, I dont think the 428 cranks are any harder to balance than any other crank.

[T Hutchinson]

Given that the 428 is available, convenience may play a big part in your decision. However, I've run both 428 and 455 in a 68 firebird with near identical components in both cases and very similar to your setup. I would prefer the 455 hands down, the added tourgue is really noticeable. Traction boils down to chassis tuning, a stock suspensioned 70 and later Trans Am would never hook because the stiff spring rates and thick sway bars but the 67-69 firebirds I've owned havent had near the trouble. Also, dont forget to tune your Q-jet for the added cubes.

[Tim Corcoran]

A healthy 455 will fry most any tire on the street especially with a higher than stock stall converter. You have that Nova sitting next to you at the light, you know he's gonna stomp it, the light changes and you both hammer it, the weak Nova jumps out in fromt? What's wrong? You look in the rear view mirror and all you can see is smoke cuz your tires are on fire. You hit second gear early cuz your engine is bouncing off the rev limiter and it's set at 6,000. Your tires continue to smoke in second and the car is going sideways so you let off the pedal for about a 1/2 second, get her a little straight and hammer it again. The tires hook hard, the the torque of the 455 is pulling real hard but the Nova has you by 5 car lengths by now, but you are cathing up quick. At about 75 MPH you fly by the Nova and he knows your there because your vortex shakes his car as you go by. That's a 455 on the street. Been there done that. I'd go with the 428.

Tim Corcoran

[1969bird]

Thanks guys for your comments so far. Keep them coming. I have a lot to learn. I'm a novice but have picked up a lot from talking with guys like you with all the experience and knowledge. So far the 428 is most favored, at least for my car. That's what I thought. Tire hookup is tough even now with the 400, since I added a 1" front sway bar and had the rear leaf springs re-arched about 1 1/2" higher that normal. The rear end sits higher now, and I suppose I regret doing that. After watching a video of my car launch at the track it is so apparent the front end hardly moves up. The 26" tall M&H DOT's spin a little before they hook, but Im feel the front should raise somewhat, but doesn't. Should I remove the front sway bar when racing? I added Southside Machine Lift bars for pretty good traction. On the street I get a lot of spin though. The 428 will make it worse, but I want results at the track when I race. As far as the q-jet, I tried a newly rebuilt q-jet from Carbs Unlimited today. So far it's junk, and I will let them know on Monday. Won't idle good at all. When I close the primary butterfly a little the idle smoothes right out, but won't last after I let go. This is when it's hot already. I think somethings wrong internally. The older q-jet doesn't do that, just has never idled the way I want it to. Once I solve my carb problems the rest should all come together. Any particular tuning needing to be done for the extra cubes, other than richer jetting?

[T Hutchinson]

Over the years I've made a fine art of enticing the race once the vehicles were under way as apposed to stoplight warfare. This has always served me well on the street and to the credit of Tim and the others I sometimes forget that real racing happens from a standstill. With your chassis setup and priorities I agree with Tim on the choice of the 428.
It would be best to loosen or completely disconct the front sway bar as well as adding some 90/10 shocks. I would definently chg those leaf srpings to a softer set. An inexpensive route would be a used set from a 68-69 Firebird that havent been re-arched. Dont use Firebird 400 or Camaro springs of any variety as they have higher rates. A few years back I pushed down on the back of Pete McCarthy's 10 second 68 Firebird race car to see how soft his suspension was and it felt like there were no shocks at all. Of course their were but chassis tuning is an extensive topic that may be covered somewhere in the archives.
As far as carb tuning goes I think it would be an excellent new topic. Their is some good information about pump shot modifications given under the topic "Super Stock Q jet mods" started by Skip Fix on p.5 in the Pontiac Drivetrain Race section, but I havent seen mention of, or suggestions for primary & secondary needle valves, secondary hangers and some of the other mods I've read about for Q-jets. It used to be as simple as calling Ken Crocie @ HO Racing and he would send out the kit. I believe he still does technical consulting as I've seen his ads in the Pontiac magazines but as far as ordering the parts I'm not sure.

[This message has been edited by T Hutchinson (edited 06-18-2000).]

[Tim Corcoran]

The Pontiac Super Stock guys, Pete McCarthy, Don Kenedy, John Angeles, Art Peterson, etc. use the Q-jet because they don't have a choice. Because of their experience much has been learned to modify the Q-jet to make it perform on the track. If they had a choice I am sure they would dump the Q-jet in favor of a Holley. There is no question that the Q-jet will perform when modified and set up properly, and sometimes it takes serious mods to the idle circuit to get a decent idle from a modified car with a weak vaccuum signal. The Holley idles much better than the Q-jet, is much easier to tune, and in the end will out perform the Q-jet. I do think a properly tuned Q-jet can get better fuel economy on the street over a Holley due to the small primary bores.

Tim Corcoran

[mike nixon]

if i were going to ditch the quadrajet personally i'd use an eldebrock on the street . there is to much maintnance on the holley for street driving. for strictly race use they work well.
if it were my car i'd take the origional quad and work the bugs out of it. once they are set up they pretty well stay set. check the throttle plates for slop in the base plate. and if it is still tight rebuild it and then worry about jetting. depending on your cam choice it may be pretty close. as for the current idle,take the idle mix screws out and run carb cleaner thru the holes in the base plate, then compressed air. if there is dirt in the passage this will clean it out. mike

[tempest455]

Some might be sick of this story but I will share again. My friend ran a relatively stock 428 in his '69 Firebird for years. We ran it under all conditions, open exhaust, closed exhaust, race gas, pump gas, different carbs, different gears etc. The 428 had a RAIV type cam, dual plane and Holley 750 vacuum secondary carb. The converter was a TCI 11" Break Away. Rear slicks were 8.5 X 26" tall. The car typically ran low 13's with open headers and slicks. The best with 3.08 gears was 13.15 @ 104 MPH. A gear change was disappointing as a switch to 3.55 gears produced 13.20-13.40's.

After adding 1.6:1 roller rockers and new valve springs, the car ran 13.10 at the same MPH. After adding a Holley 850 DP the car ran 12.97. After advancing the cam and shifting the car at 4,800 the car ran 12.80 at the same MPH.

A new 455 was built using the same drive train. Specs on the two engines were very similar and they used many of the same parts. The very first time out with the 455 on the same small slicks, the car ran 12.20's @ 109 MPH. More than 1/2 second and 5 MPH in my opinion is a HUGE difference. A 455 will get the job done with a lot less effort. The added torque did cause traction problems but the added power more than made up for the traction loss.
http://www.wauknet.com/douthitt/wayne's.htm

Eric D.

[carbking]

No comments on the 428 vs 455. As to the carburetor, go with a Q-jet on the street. Better street performance, much better economy, and practically bullet-proof once dialed in (pitch the fuel filter in the front, and install an inline filter that is easily replaceable). Very little guessing necessary as to calibrations. Just pick the original Pontiac engine that comes closest to what you are building, and build the Q-jet as Pontiac did for that engine. If you go the 455 route, the 800 CFM Q-jet does a little better because of the 200 CFM on the primaries (the 750's are 150 on the primaries). You probably will never use the full 800 (or 750 for that matter) at WOT, but the 200 primaries really seem to help the 455 on the street. When you build the carb, pay close attention to the size of the fuel valve in the kit. Rochester produced fuel valves from 0.082 inch to about 0.135 inch. The largest size isn't necessarily best, as a large fuel pump can cause overflow at low demand. Trial and error here. Vacuum piston spring choice is critical. Use the one used by Pontiac for that closely matching application as suggested above. Also, replace the secondary cam and spring AND ADJUST TO FACTORY SPECS! If you have to bush the throttle shaft as others have suggested, make sure it is done properly. Reaming through the throttle body and pressing in bushings will guarantee an internal vacuum leak, and a poor idle! Unless the throttle shaft/body clearance exceeds 0.006 leave it alone. Good luck. Jon Hardgrove.

[David Holmberg]

CarbKing, thanks for taking the time to help the people on the Pontiac Board. It's always good to have another good oppinion to help make sure our projects work out the way we want. Thanks again