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  #16 (permalink)  
Old 06-13-2012, 05:46 PM
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Ok, so from what ive gathered from yall
Xtreme Energy 274H Cam
Edelbrock 7156 Intake
Quadrajet

This would be suitable for a street build? What type torque convertor? how about this
http://www.ebay.com/itm/ACC-1600-220...8af2f1&vxp=mtr

also im having a little confusion with the fly wheel.... i dont have the stock flywheel.... it was lost before I got to the car.... I there are a couple different ones.... and I just dont know which one I need. I do know I need one with the 2 3/4" hole... how do i know about the balance and such?
http://www.ebay.com/itm/67-75-326-40...82c036&vxp=mtr would that be what i needed? what bolt pattern would i need to be able to bolt up a th350 torque convertor?

also, this quadrajet should do the trick? http://www.autozone.com/autozone/par...ier=52642_0_0_
the part number matches a 78 ta with the 6.6l and a 1970 gto with a 455.... the autozone part number is ND4631 or reference number c9477

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Last edited by kcscott11; 06-13-2012 at 06:10 PM.
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  #17 (permalink)  
Old 06-14-2012, 08:33 AM
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That converter is for a TH350. I must have missed that. TH350 is not well suited to 455 Pontiacs. The low-end torque the engine makes is very "hard" on them. While there ARE success stories, there are also failures. TH400 is a much better choice. Would you use a TH350 behind a 500 HP 454? That's about the same level of raw power we're talking here, at a lower RPM.

But the rev range of that converter is okay for the cam. Understand, too, most converters "off the shelf" are rated based on 350 Chevy as a "base line". Bigger (higher torque) engines raise the stall speed proportionally.

An AutoZone reman carb is probably a decent basis, but remans can be problematic. They aren't necessarily kept "together" during the process. You COULD get the same base, body and top that Rochester orginally shipped, but you COULD get a mish-mash. It's a bit of a "crap shoot". Even if a "good one", it will need to have the upgrades outlined in Cliff's book to really perform well. Later (post '72) carbs are "emmissions" carbs and the idle circuits won't properly support a "big" cam. If you were lucky enough to find a '73 or '74 455SD carb, THEN you'd have something! Very rare and very expensive today.

The best option may be to find a good "core" locally, and send it to one of the Q-Jet builders. Many Pontiac guys are very proud of their Q-Jets. It's easy enough to make an Olds or Buick carb work on the Pontiac, too. Chevy and Caddy versions are a little more difficult, but not insurmountable.

Jim
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Old 06-14-2012, 07:41 PM
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Hmmm got a th400 tranny today from my uncle. Its a good transmission, and he gave it to me for 100 bucks, just lucked out on him having that! anyhow I came across a guy local who may have some other parts, I should be getting my flex plate and possibly an intake from him, although I may hold off on that because he doesnt know if he has any intakes worth a crap. He said at one point he had 12 455's, knew quite a bit about these motors, so He is going to call me and tell me what all he has tomorrrow. I think this thing might come along a little bit. I need to order my cam soon, thats the next step to getting this going! just having so many problems deciding what to get.... I know my heads are supposedly set up for a "big cam" they are 6x heads.... i dunno. I just know i want as much cam as i can use. Then I will choose my intake accordingly..
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  #19 (permalink)  
Old 06-14-2012, 08:48 PM
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Heads/cam

Quote:
Originally Posted by kcscott11
I know my heads are supposedly set up for a "big cam" they are 6x heads.... i dunno. I just know i want as much cam as i can use. Then I will choose my intake accordingly..
Check the spring installed height to be sure it is equal between the valves. The spring's seat and open pressure is also important but all but impossible to measure unless the springs are checked w/a spring gauge. There are spring gauges that can be used on an assembled head. You might ask for a receipt for the parts including the springs so you can verify they are appropriate for the cam you want to use.

Often, modified Pontiac "X" heads have 1.77" exhaust valves installed in place if the stock 1.66" and this is obviously going to be very easy to determine. As far as the rest of the work that may have been done to the heads, you can visually look to see if they both have at least 3-angle seats (that won't tell you if the seats are concentric, though), the valves can be inspected to see that they have adequate margins, seat widths, and if they've been back cut or have undercut stems. I would suggest you measure the valve guide clearances, too.

One of the most important things that you need to know about these heads is the exact chamber volumes. I'm guessing you have looked to see the secondary identifiers are the same. Even if they are, both heads need to be checked- although doing the end chambers of each head (four chambers total) will be enough to tell that the chambers are equal. This is necessary because there's no way to be sure the heads were always a pair from day one, onward. Even if they were paired from birth, one head might have had a bad head gasket that required it to be resurfaced. If both heads weren't cut an equal amount that can cause the chambers to vary. If the heads were from different engines originally, obviously they can vary due to all the above reasons plus manufacturing and casting differences from the factory.

Then there's the port volumes. Those heads have relatively small intake ports; the 6X-4 heads I used on my last 455 were 158cc "stock" (I don't know the history on them; they came on a friend's T/A he bought used), and they did not in any way look to have been ported. After porting they measured 173cc. These heads stock would be like a ~ 125cc head on a 350 SBC. The comparison isn't as bad as it sounds because of the design of the Pontiac head/ports and the 30 degree intake valve angle, but the fact remains- they ARE small.

In my opinion a stock or mildly reworked D-port doesn't need lift in excess of 0.480". That is a little past where maximum flow is reached but before any port stall occurs, given the rpm range of a 455. Combining that w/a duration @ 0.050" of around 234-236 or so will be about right. I used Rhodes on the intake side of a single pattern cam; Comp hadn't yet come out w/the XE series at the time. I'm not suggesting you do what I did, instead look into a Voodoo or XE.

With the D-port heads unless they've been heavily ported I will always recommend an RPM intake. It will hit harder off idle and gives up nothing to a single plane at the modest peak rpm the 455 is going to be turning (5000 rpm), built as described here; I preferred to harness the torque by using sticky McCreary tires (tread wear "0"). I suppose there might be an argument made for a single plane to "tame the torque". But that's for someone else to expand on, I don't do it or personally recommend anyone else do it unless all other avenues have been exhausted.
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  #20 (permalink)  
Old 06-14-2012, 10:22 PM
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I like the RPM too, but it wont fit under the stock Shaker, or under a flat hood on a 70-81 Firebird. Fits A body cars great, but on a Bird the carb vent ends up being between one and two inches above the hood line. Even worse is a Victor, the bottom of the carb is higher than the fenders.

Tomahawk intakes will fit under the shaker too, and any stock iron Qjet intake will work as good as a Performer. There are other options, but I would suggest a dual plane rather than the single plane. I never found the Torker II to make it any easier to hook up, but it did like to load up driving around at low speeds. Probably the 850 double pumper I had on it, but still a dual plane works better.
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  #21 (permalink)  
Old 06-15-2012, 03:30 AM
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Drop base for keeping the shaker scoop when using an RPM ntake. Part number WFO-1 fits 1977 to '79 T/A.

I cut my '80 Camaro hood and used a shaker scoop but it didn't 'shake'. Well, at least no more than the rest of the car.
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Old 06-15-2012, 09:01 AM
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Comparing runner volume between engine families is of no use. The Pontiac runners are about 1/2" shorter than those in a 23 degree small block. Comparing heads within a family, using similar layouts, IS a good way to understand how much port work has been done, or how one version "stacks up" to another.

Virtually all Pontiac d-port heads have the same runner volume. The bowls are a bit smaller on the small-valve heads, losing about 8-10 CCs of runner. The large valve heads all hover around the 155-160 range. Ram Air IV heads are more like 170-175. The "big" aftermarket heads are in the 210 range, capable of over 300 CFM with minor "clean up". Comparably, a "220" Dart Pro1 flows around 270 @ .600, unported (Dart heads are usually much "nicer" out of the box than Edelbrocks, so "clean up" isn't as necessary).

Another major design difference between Pontiacs and other engines is ther "venturi" port design. The intake port in the Pontiac flows about 200-210 CFM @ .450" lift "stock". This is barely enough to make 400-450 HP following conventional "wisdom" (2.2 HP per CFM @ "peak"). Yet, we've all seen 600 HP 406 CID Pontiacs in SS classes before porting was allowed. The cross-section of the port is rather small. However, due to the venturi design, the VE is VERY high, and by combining the enhancements to low-lift flow (30 deg. intake seat/face) and the longer strokes used, the stock intake port is remarkably efficient and capable of "feeding" a larger engine than one might think based on those conventions. This is the primary reason the Pontiac is so "famous" for low-end and mid-range power, and still capable of SOME high-end performance with stock components. Of course, the Ram Air, HO and SD engines are in a whole other category.

Once porting starts, if done properly, that low-end and mid-range is only marginally affected while volume at higher lifts goes up significantly. The result is a torque-monster capable of 6,200-plus RPM making well over 500 HP and 550 lb. ft. at 460-ish CID.

FWIW

Jim
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