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Discussion Starter #1
I need the bullets expertise! I was running a hyd. flat tappet cam in my pontiaac 461 stroker last year with a Torker intake and this year I switched to a Victor intake and a solid roller. The cam has .688 lift and 255/263 duration @.50. The car runs the same E.T and the same mph. Do you think my carb is two small? I'm running a 950 HP. Last year I tried taller tires and the car went exactly the same and now this year the same thing. Any help or advice would be awesome.
 

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There are several threads here about the 950HP's only flow about 830 cfm. If thats the case then that's probably not enough for your 461 poncho, but I am no expert.

What kind of cyl head, and flow numbers if you got them would help
 

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Discussion Starter #5
Thanks for the replys. My heads are KRE aluminum 85cc combustion and flow 310 @ 600 int. and 248 exh. My fuel system is just a Holley street strip mech. pump. My old cam speced. at 239/[email protected] with 559injt. 568 exh. Other then the cam and intake I'm running the same combo. 3500 stall in a TH400 with 4.10 geared 12 bolt with 30" drag radials and the car weighs 3900 w/driver. The motor has 10.5 compression and is running on 93 octane.
 

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Do a vacuum check while making a pass if it's over 4" at wot then the carb would be the restriction. If its under 2" then the carb would be too big, for optimum performance. At least that is what I have been told by a few racers and it seems to work real well as a measuring stick.
 

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I would look into the fuel system also. I don't think you have enough fuel pump.
Im going to guess your car runs around 11.8?...................probably stock fuel line up from the back of the car? i would recomend at least a 140 gph electric pump with 1/2 or-8 lines up to a regulator near the carbs then -6 to the bowls I really do not think the carb is an issue yet.
 

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Discussion Starter #9
Going to try a fuel pump and if that doesn't help I'm trying a 100o HP. I'll keep you all posted. Thanks again for all the great ideas.
 

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A 1000hp is the smart way to go. Regardless of the rated cfm and actual cfm, it is the overall design of the carb. The 1,000hp will pull more fuel as well, which is what you need since you are lacking a fuel system, so I would switch to a 140 Mallory with #8 line. I do alot of Pontiacs and the camshaft you chose is alot better than the cam you had in a 10.5 compression 461..Pontiacs are over square and usually are restricted when it comes to cylinder heads, so it can actually use more camshaft than what you have. That is why they respond to duration very well. Regardless of the head flow numbers, the ports are just too small. When you make a major change, and don't really pick up, it is usually because the driver has not altered shift points, converter or changed other parts to help it work, or there is a restriction somehere else. The Victor is too large for what you are doing and although Pontiacs don't have many choices, it is a good choice if you plan on going faster later on. If not, The Tomahawk would have been a better choice, or even a rpm dual plane, which will work alot better with the gear and converter you are using.Where did you shift before and after with cam change? Intake change? I would step up the converter, especially with that intake and cam, and would go to atleast a 3.73 gear, unless you are running smaller than a 28" tire with those 3.50 gears. Converter should be in the 4,500 range as that intake comes on real late aswill the camshaft. Also, what lobe seperation did you go with and where is it installed at? Pontiacs do NOT like real wide lobes. My real basic 461's run Basic E-heads and some Kauffman alum d-ports with mild work, an RPM dual plane, hyd roller similar to yours, 2" header" 3.73 and 3800 converter with a 1,000 hp and runs 11.0's on 93 oct at 3,850lbs..Shifting at 6,500. A switch to a slightly larger solid roller, 4,500 converter, Victor intake and some head work runs well into the tens..but was a dog without the converter since the changes pushed the rpm range out of the converters limits. I would look at carb like you are doing, a higher flash converter by about a thousand, 3.73 gear, and a fuel system and that will feel like a whole differnt car. Pontiacs like the dominators, but it will be too large in this application. What size header are you running?
 

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Discussion Starter #12
I could not shift any higher then 6000 rpm when it would hit 6000 it seemed as if it feel on it's face. That night I tried rejetting and increased the timing and it made no change at all good or bad. I do have a 4500 converter that I was going to put in once I got a baseline to see the difference. I'm running 1 3/4 headers as that is the biggest I have found for D port heads.
 

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Discussion Starter #13
I end up racing last night and thanks to a good friend I got to try a few things. With a Holley blue pump on it and nothing else changed from last time out it went 1 mph faster([email protected]). I made some small changes(plugs and air cleaner w/extreme lid) and the car ran the same [email protected] mph. Then I put on the 1000 HP and the car went [email protected] then at the end of the night with it being around 50 degrees out it went a best ever [email protected]. Next I will put in the other converter. Is this looking like all the car has or am I doing something wrong? I wouldn't think a converter would do that much, but I was at leaast hoping to get a little more mph out of it and maybe a little better E.T. Any other ideas??


Thanks again Joel for lending me the fuel pump and carb I really appreciate it.
 

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I end up racing last night and thanks to a good friend I got to try a few things. With a Holley blue pump on it and nothing else changed from last time out it went 1 mph faster([email protected]). I made some small changes(plugs and air cleaner w/extreme lid) and the car ran the same [email protected] mph. Then I put on the 1000 HP and the car went [email protected] then at the end of the night with it being around 50 degrees out it went a best ever [email protected]. Next I will put in the other converter. Is this looking like all the car has or am I doing something wrong? I wouldn't think a converter would do that much, but I was at leaast hoping to get a little more mph out of it and maybe a little better E.T. Any other ideas??


Thanks again Joel for lending me the fuel pump and carb I really appreciate it.
is it still falling on its face? what do you have for fuel lines?
 

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Discussion Starter #15
No it doesn't seem to be falling off. I ran it up to 6500 rpm and seemed that it was still pulling slightly. I' running 3/8 line all the way.
 

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Run the Mallory 140 and #8 lines all the way up. Pontiacs like fuel. Headman Hustler makes bigger tube headers, even for the D-ports. Minimum I would run is the 1 7/8" header. 1 3/4" is real small. The bigger tube headers come with adapter plates to run the bigger tubes. Even 2" will be fine, especially if you are going to run spray or upgrade later on to more power. I have run the 2" with no problems. A 3" exhaust will work great on this. The converter is needed. 4500 is the lowest I would go and will help this car tremendously. The shift points are low because the intake port is on the small side. I drill the pushrod holes and use brass sleeves and move that pinch over as much as possible. Need to get the port sizes up on these for volume and the rpm will come up a bit for more power. Especially the d-port stuff. What gear and tire is on the car and what are the trap rpm's? There is alot more in the same given combination. Run an HVH SS spacer under the carb also if you have the room, it is worth it. How much does the car weigh? What distributor do you have in the car, how much timing and is it locked? LMK.
 

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Discussion Starter #17
The car is currently running 4:10s w 30" tire and weighs around 3900 lbs. w/driver. I go threw the traps at 6000 rpm and the distibutor is a Mallory Unilite at 32 degrees and it is not locked out. I was going to try rejetting the 1000 when I was out there but ran out of time. I did try the timing at 38 degrees with the 950 the previous time I was out and it made no difference from the previous run.
 
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