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Old 08-26-2003, 09:29 AM
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Question Pontiac Build advice

Okay, how about some help for a new guy who needs some guidance.....
I am building a 400 Pontiac from scratch. The foundation is a 77 WA block, to be punched out 0.030, and use flat top forged stock style pistons and stock, reconditioned rods. I want to use a 455 crank, commercially available with the journals already turned to 3'. On top I want to use the Edelbrock Performer intake and carb, 750 CFM. I have a set of #96 heads, which have not been touched as yet. I would like to use a roller cam, roller lifters, roller rockers, roller timing chain, etc. I'll gasket match the intake, heads, and exhaust, too.
I also plan on installing a crossover exhaust, attached to Doug's ceramic coated headers. I also have a 3.73 rear end to put in.
I guess my main concern is what work to have done on my heads. I want to do my own porting and polishing, so that's a given. How much, if any, should I have milled to avoid too much compression for high octane pump gas? I don't want an astronomical compression ratio, but I want a streetable machine with decent manners. What would be the best choice of cam, and should I ditch the thoughts of a roller and just go hydraulic, or I am I going in the right direction? Given the information I have included, and my aspirations, what do you think the potential HP would be, as well as a possible figure on the CR?
Finally, I have a higher than stock converter, but I am really unsure what the stall speed is; it's a B&M, so if you can tell me where the stall speed might be indicated in the converter, I'd be appreciative.
I am not an incredibly technically-oriented person, but I am getting aclimated little by little to how these engines can work best; obviously, I still need some guidance, and that's what I'm appealing to you folks for. I have read alot of posts, and I know you guys are out there. SO, what do you think?

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Old 08-26-2003, 10:35 AM
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I honestly don't have any experience with roller cams but you could try and contact this guy, Steve Coombs. He's got a ton of experience with them.

shc@thegateway.net
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Old 08-26-2003, 01:43 PM
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CR on current combo

You seem to be on the right track for a potent street motor. With the 400 bored .030 over and the heads being their original 96cc before milling and the 4.21 stroke of the 455 crank you'd be looking at 9.06:1 compression with 6.7 cc piston dish and .039 gasket thickness.

This is assuming the block has never been decked and the piston is still .020 in the hole. If you have the block and heads surfaced just to true up the mounting surfaces you could easily get 9.4:1 CR. I would recommend staying below 9.8:1 for iron heads and pump gas.

The cost of a full roller set up may not make the roller cam and lifters worthwhile. If you are going to be cleaning up the heads and not having them professionally ported you won't need them anyway. Are you wanting to build an all out race motor or just a potent street motor. IMO the $$$ for roller cam and lifters could be used to upgrade the rods. (build a better foundation as the factory cast rods will be your weak link in this motor)

1.65 roller rockers and a good hydraulic or solid cam will suffice.
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Old 08-26-2003, 02:18 PM
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I have to differ with drew a little.
Since you are building a street motor, I think the rods will be fine, as long as you don't twist this thing too high. I personally think a roller cam is a great upgrade, just expensive. It's an easy way of freeing up some ponies. In your post, you said you have flat tops, and drew gave a compression ratio with dish pistons of 9.06. That would mean you'd be over that and like he said, with iron heads, you shouldn't go too high. True up the heads and block (if neccessary), and you should be fine. Like drew said, you should have a nice street pounder when you're done! Good luck!
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Old 08-26-2003, 10:07 PM
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Good advice!

Guys, thanks for your input. SOunds like you two have been there and done it already....

I DO want a hot street machine; I am somewhat of a perfectionist, and a little of an egomaniac.... gotta have bigger, stronger, faster. Some guys at work have some high end machines, like 454 SS's, a 428CJ, so I want to fall in there somewhere. BUT, I don't want to have a high priced car that runs like crap. Blueprinting is a very important aspect to me, and that's what this is....... in the end, if the parts don't match up, you have nothing but a fistful of bills. In addition, I have already gone to great pains to totally redo the underside; I installed new springs and shocks, front and rear, a 1 1/8 inch sway bar in the rear, Hyperflex poly urethene bushings all the way around so that the torque and HP goes to the pavement and holds the vehicle on the road. It already has a quick ratio steering box.

I think the stock rods ought to be good up to 600 HP or maybe better; the question to me is at what treshhold will my HP and CR exceed good streetability, and climb into the higher fuel demands, as well as more intensive maintenance. If it means cutting back to a milder cam, I might consider that. I would like to achieve 450 - 500 HP, which given this combination, I think is reasonable. Maybe more on the 450 side, anyway.......

Once again, thanks for the input... it will be helpful in the long run of this project!
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Old 08-26-2003, 11:13 PM
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As far as streetability is concerned and cam choice, roller will free up a few ponies, but nothing that you'll really feel. A good strong cam will make the best difference. First, you don't want to buzz any Pontiac too high, but with the pressure distribution on 3" journals, you could look for a cam with a little higher range. Honestly, the new Crane blueprint cams are great. I'm running the "068" grind Ram Air cam in my Pontiac 350 and it's great, just wild enough to be fun, but streetable. The next step up, and what I'm considering for my 400 is the Ram Air IV cam which crane also has. It would be in the perfect power range for your intake and heads, and would still keep a good amount of torque available down low.

As far as heads are concerned, I would mill only what you have to to make sure they've got a level deck. If you're running flat top pistons you'll decrease compression area quite a bit (approximately 6cc). Using the CR calculator and a .042 crushed gasket thickness (slightly larger than common, but helps you be optimistic), I got a CR of 9.33:1. That's pretty decent for a street car, and with the Ram Air IV cam, you'd be able to run pump gas easy. I also had some flow number for your heads and just plugged all your specs into Desktop Dyno, using the Ram Air IV cam and 9.33:1 CR and got about 415hp and about 480ft-lbs @ 4500RPM. Now Desktop Dyno is not the do-all-end-all by any means but it gets you into the ball park, and this ball park would be a quick, torquey little 400.
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Old 08-27-2003, 04:25 PM
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adryan - would you be willing to desktop dyno my combo? I'd like to know roughly what hp I have.
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Old 08-27-2003, 06:05 PM
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Thanks again!

Thanks Adryan.... that is some good stuff. And, the info from your desktop dyno is very helpful too. Thanks again to all who have responded.
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Old 08-27-2003, 09:29 PM
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PONTIAC POWER

I think you are on the right track for your Indian. I personally would prefer just a flat tappet hydraulic cam for your warrior due to economics and the low rpm nature of a Pontiac. Your combination, with a modern flat-tappet hydraulic will easily produce the power you are looking for with some tremendous low speed torque. Of course, the fast ramps of a roller cam , albeit it's the proper grind for a big inch Poncho would make more power, but the horsepower per dollar return will not be that attractive. Also keep in mind the valvetrain improvements you will need to make to use the roller cam. You will more than likely need longer than stock valves to get away from the very short installed height of the stock type Pontiac valve springs and all of the roller cam orientated stuff will need to be top notch, so expect to spend some $$$$$.
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Old 08-28-2003, 03:23 AM
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being a pontiac guy and after reading tons and tons of set ups in the hpp magazine, the experts always say, keep compression ratio's low... 9.5:1 is lots in a big block, keep in mind that a 400 inch big block has gobs and gobs of torque, and stroking it with the 455 crank may not be the best way to go, you'll gain a bit of torque but the hp numbers will be very very simalar... you just have to think which will be the best hp per dollar way to go, keep in mind my 67 gto stock makes 366hp... it's a raIII enigne however, most are rated 335hp... mines "rated" 366hp... however it's more realistacally around 400hp... stock... look for a good set of heads, 670's are desirable, raIII heads and need little or no port work to flow decent numbers simply smooth them up with a dremal and they'll flow pretty decent,if you want to port your stock heads however the power isn;t found in gasket matchning the heads, the power is found mopstly in unshrouding the valves... do that a long with gasket matching and polishing the chambers and you should see a significant increase in power... the main thing to consider is camshaft selection... i'd reccomend just going with a flat tappet style hydrolic cam, sure the roller is nice, but not neccesarry, the extra cost is rediculous, if you use something like the edelbrock performer rpm camshaft and performer rpm intake, with a decent carb, you should see some respectfull numbers somewhere around 410hp and 420ftlbs of torque... thats providing you stick with 400cubes... if it's stroked with the 455 crank maybe 420hp and 440ftlbs of torque... but it's hard to say, just keep in mind, how much is 10 hp worth? and another thing you'll have to cinsider is how often your going to drive it, and what you intend to do with it, you may have to make comprimises with it, the long stroke may not be good for a often driven vehicle... if you want a bit bigger cam you can go with a edelbrock torker plus cam, it's got a bit more duration and a bit more lift than the performer rpm cam, and if used with a torker 2 intake you could see 450hp.... thats personally the set up i'm going to be using on my new enigne that i'll be building this winter is the torker plus cam and the torker 2 intake, along with flat tops and my 670 heads it should make a decent street machine and gobs of torque... keep in mind big blocks don;t need a lot of lift to make big power...
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Old 08-28-2003, 07:23 AM
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the long stroke may not be good for a often driven vehicle... if you want a bit --- KLRS10

Man, this is disinformation at it's best. How can stroking the engine make it less streetable? The longer stroke will build more low-speed power and just all around power for that matter. This is the best mod he can make aside from supercharging or nitrous oxide for power.
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Old 08-28-2003, 10:57 AM
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455 = more torque. The more torque the better.
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Old 08-28-2003, 04:06 PM
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Smile

I think if diferenntial is higer than stock, make more torque from engine and use 6speed AT/gearbox(richmond gear).use little bit more rpm cam that mid range
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Old 08-28-2003, 05:09 PM
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i was looking at it from a hp per dollar standpoint... as we all know aftermarket cranks like he is talking are very expensive... i know cuz i had one in my s-10 i used a lunati 3.5" crank and it just wasn't worth the money for what i was doing with it (yes i know that stock stroke is 3.48 on a 350) and as we all know the longer stroke engines generally heat up a lot more too, and if you think that the 400 alone isn't gunna create lots of torque.... think again, they make AWESOME amounts of low end torque with a very streetable set up..
how come when somone strokes their enigne they think they are god? i don;t know but personally i've seen lots of strokers and ridden in many strokers and they just don't impress me... there's this one guy i town that swears his truck is the fastest thing in the wodls because it has a 383 stroker in it... and i know for a fact even with my low compression and turbo grind cam that my truck would destroy it, but he won't let me prove it.. and i run mid 14's with the set up i have now... my gto with the bone stock enigne that is completely original still pulls down 13's... and thats a 4000+lb car... i'm simply stating that he does not need to stroke the engine to make respectable hp numbersand turn awesome times...
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Old 08-28-2003, 06:21 PM
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A reconsideration.....

One thing that is helpful in reading other's opinions, and factual information, about engine building is that it gives one time to examine the options for a bit. One thing that I was thinking, is that since the 400 block is basically the same block as the 455 (the stroke is different, and the main journals are beefier in the 455), outside the gain in torque, what am I to benefit by the stroker concept? I COULD just drop in a 455 and be done with it, but the versatility of the Pontiac block enables one to make this choice, depending upon what the plan for the auto is. I would like to be able to drive it whenever I want, and I don't plan to baby it because of fuel concerns (but hey, at today's prices, we might ALL have to make that consideration soon!) or wear and tear on the valvetain, etc. , but I don't want to consider it a daily driver, either. I'm a hot dog by nature, and a show off, plain and simple, so I'll be flaunting my TA and all it's HP in front of all the Chevy nuts I work with at every opportunity.

If the power gains from the roller are so minimal, I may want to scrap that plan, and maybe the crank too, but regardless, a new crank is going in, so why not the 455? Same price (check the seller "gofaststuff" on ebay.... they sell Eagle cranks, both sizes, same money), same deal to balance, same rods, etc., so I guess I have somewhat rationalized myself into the stroker, but what's anyone else's opinion on the cam selection? Still stick with all the roller components like lifters, timing chain, rockers, etc? My thought is possibly the Comp Cams S Kit in an appropriate combination with a Performer intake (because I DO want to keep the rev's low, rather than the RPM Performer and the 1500-6500 range). Also what do you all think about the carb? What do you think is the best option there?
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