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  #1  
Old 07-09-2002, 10:18 PM
Mr. Cuda Mr. Cuda is offline
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Default Carb selection

What would be a good carb choice for a 451 stroker? The engine has a 230/236 cam, 10:1 pistons, aluminum heads and the Edelbrock Performer RPM intake. The car is primarily a street car with maybe the occasional trip to the strip.

I was thinking about a Speed Demon 750 CFM with vacuum secondaries.
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  #2  
Old 07-09-2002, 10:35 PM
bubby440 bubby440 is offline
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that would probably be a very good choice, but you might make a little more h.p. with a larger carb.
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  #3  
Old 07-09-2002, 11:26 PM
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Default carb

I would agree go with the 850cfm. you have to feed that lion or it won`t roar. I would use an edlbrock myself. In my opinion ,I would say as I read the title of someones post Danm holley. Just my opinion.happy trails.
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Old 07-10-2002, 02:16 PM
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How heavy the car? How steep the butt gears? Stick or auto? Cam? Headers or not?

I think the newish Edelbrock 800 might work on an A or B body, auto with 3.56 or steeper gears and headers, and a fairly agressive cam with stock valve train.

I might make a different recommendation for a different car set-up.
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Old 07-10-2002, 03:42 PM
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For the street the Edelbrock will be fine. I personally think the Holley is the way to go and nothing will beat it in stragiht line. You will have to figure out how to set one up, but I think that a serious stroker motor will need a serious carb. I think I would lean towards an 830 DP with the 4-corner idling without the choke. Costs around $420 new from Summit and has the annular boosters which do better with a low vacuum signal which you will have with a large lift cam.
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Old 07-10-2002, 06:19 PM
cuda367 cuda367 is offline
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You should have an 800+ carb but with the manifold you chose 750-800 it will run the same.
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Old 07-10-2002, 06:29 PM
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Tell me some more about this cam...

Sounds a bit small...
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  #8  
Old 07-10-2002, 09:32 PM
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Vehicle stats:
70 'Cuda
A833 4-speed
~3400 lbs
3.23 posi
Hooker long tube headers going to 2.5" dual exhaust.
Hydraulic flat tappet cam 230/236 @.50 with .5" lift.

This cam provides more low RPM torque with a very flat curve at the expense of high RPM horsepower. I'm not planning on racing the car much so I don't want/need max hp numbers in the 6500 RPM range.

Bumping the cam up to 240/246 without changing anything else yields a higher peak HP at a higher RPM (especially with a single plane manifold) but sacrifices low end torque.

Realistically this engine is going to spend most of its life in the 2000~4000 RPM range. I don't think a 750 CFM carb would really hinder this engine's performace at these RPMs and its smaller size should provide great throttle response.

I don't know if this matters in carb selection but where I live is 5000 feet above sea level and it was 105 degrees today.

Thanks for the input, everyone!
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  #9  
Old 07-10-2002, 11:21 PM
Doug Wilson Doug Wilson is offline
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With your cam specs, I agree with the 750. Holley or Edelbrock shouldn't make much difference. In the RPM range you're going after, you should have a helluva runner, assuming the suspension and brakes match the engine.

Right on for canyon carvers!!!
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  #10  
Old 07-11-2002, 04:41 PM
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I don't want to argue just to argue, but I think the cam you are running is a bit small. That lift/duration @.050 is right between the MP .455/.268-.272 and the .474/.280. For the displacment you have I think the cam won't be big enough.

The basic RPM band on the cams are as follows:

.455/.268-.272 (1500-5800)

.474/.280. (2000-6000)

.484/.284 (2600-6000)

I think the last listed cam would be a better choice. The cam you listed if it is advertised for .5 lift is fairly lazy. Who is the cam manufacturer and what are all the specs?
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  #11  
Old 07-11-2002, 05:52 PM
Doug Wilson Doug Wilson is offline
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For a canyon runner, using the RPM range you state, the cam should be great, and might even give you decent fuel mileage. You can always stick in a bigger cam.
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  #12  
Old 07-11-2002, 06:04 PM
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Agreed on putting in a bigger cam later. Why bother building a stroker in the first place if you want it to run a like a warmed up 440? My thinking on the 452 stroker was to get better rod angles, more cubes for more power. Building a stroker to make 400 horse is like throwing an extra $2000 at a mild 440 build just because.
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  #13  
Old 07-11-2002, 10:23 PM
Mr. Cuda Mr. Cuda is offline
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Using Dyno 2000, my engine with that cam calculated a max hp of about 540 and a max torque of about 590 lb/ft. I'll get the exact numbers from work tomorrow. According to the program, this cam produces a torque cruve that doesn't vary more than 20 lb/ft from 2500~4000 RPM. I memory serves, the max hp is about 5500 RPM. Unfortunately, these numbers represent sea level and I live in Reno, which is at around 5000 ft so I'm not expecting to see these figures.

Keep in mind that this is a street car, the smaller 230/236 cam will provide great streetability and have superb idle and starting characteristics.

I agree that a larger cam making more top end power would prove better on the 1/4 mile. However, a comparably equipped car with a larger cam wouldn't catch this car until after mid track. How handy that mid track, 1/8 mile, is about the distance between two steet lights!
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  #14  
Old 07-11-2002, 10:27 PM
Doug Wilson Doug Wilson is offline
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That was exactly my approach when building HELLFISH 340.
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  #15  
Old 07-12-2002, 10:16 AM
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Mr. Cuda...

Ok don't get me wrong here. I am not trying to be a jerk I just want to think this through a bit.

I agree that the track and the street are two different things. I disagree with the statement about the larger cam not being abale to catch the smaller cam until 1/8 mile down the track.

Obvioulsy if I were to have a larger cam in the 452 for the 1/4 I would match that with some gears (4.10s?) and a converter that would get me into the powerband of my cam (2500-3500) either on the line (if I have slicks) or just off the line so I could hook and go.

With your gear you are going to run I understand the smaller cam spec, but I don't think the HP and torque numbers you calculated on your dyno program will be anywhere near 540/590. This is why I stated that a 452 stroker wasn't worth the extra money if you were only going to make 425-440 hp because that is attainable with a warmed up 440.

Some of this will also depend on how tall of a tire you are going to run. All Mopar gears are based on a 26" tall tire. If you are taller than 26" your ratio will change (lower). You may already know this. If you are going to run 28" tall tires I would suggest some 3.55s instead of the 3.23s since your final ratio will be lower will taller tires.

I also live near 5000ft and you can figure about a .8-1 sec difference between our elevation and sea level.

I also wanted to point out that a 750, in my opinon won't get it done. The stock carb on a 440 was a 625cfm and you are only increasing the CFM by 20%. I really beleive a 800-850 would be a better chioce.

Another point to make is you could advance the larger cam by 2 deg. and that would lower your powerband. The larger cam is only designed to spin 6000 anyway, but you could lower that to 5500 by advancing the cam.

Also what kind of heads are you running?
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  #16  
Old 07-12-2002, 12:24 PM
Doug Wilson Doug Wilson is offline
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I have always contended that drag strip guys have a totally different approach to the engine build than canyon carvers. If you want a cam that performs like "cam A" at 2 degrees advanced, why not buy "cam B" which is already built that way and installs straight up?

Small carbs and mild cams are great for low end and mid-range. Why buy a cam that performs best at an RPM range that you aren't going to use?

That's why it took me so long to build both my 440 tow motor and my 340 canyon carver - most guys have a "drag strip" approach that doesn't take into account other uses.

Even the "tech" people at the distributors and (most of) the cam manufacturers don't seem able to communicate well with non drag racer engine builders.

It isn't a wrong approach - it's just a different one.
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  #17  
Old 07-12-2002, 01:42 PM
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Here is why I disagree:

Cam B advanced 2 deg. will out perform cam A by a lot. You will be making more HP and more torque and taking adavantage of your 452 stroker. This has been my point from the beginning. I am not arguing just to argue, but I feel that you aren't taking advantage of the stroker attributes that cost more to build than a warmed up 440.

Why would't you want to do that with your combo?
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  #18  
Old 07-12-2002, 07:16 PM
Doug Wilson Doug Wilson is offline
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All cams do not always perform better when installed advanced.

I must not be making myself clear... drat!!

I hate it when I do that!
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Old 07-12-2002, 08:13 PM
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I actually know what you mean. The .484/.282 cam is relatively mild. I would suggest a way bigger cam for the 452 if you were all-out 1/4 drag. Heads also matter and I am not sure what kind of heads we are talking about here. I still really believe that a bigger cam would be a better deal with the set up he mentioned. Just my .02 though...
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  #20  
Old 07-12-2002, 09:54 PM
Doug Wilson Doug Wilson is offline
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If he is really building a canyon runner (sorry to speak as if you aren't here, Mr. Cuda), then he is wanting as much torque as he can get on the low end and mid range. I'd advise 11:1 on Edelbrock aluminum heads, or for high mixture velocity, shaved 452s at about 9.7:1, both with a carefully curved distributor.
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  #21  
Old 07-13-2002, 03:20 AM
Mr. Cuda Mr. Cuda is offline
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First, the stats...
Heads are Edelbrock aluminum, ported/polished, with 2.14 intake/1.81 exhaust valves. The pistons are flat top 10:1 Ross units. The intake is an Edelbrock aluminum Performer RPM dual plane that has been polished to match the intake ports on the heads. The valves are pushed by 1.5:1 roller rockers that are moved by a hydraulic roller (not flat tappet as I stated initially) 230/236 cam with 110 lobe center.

Second, the calculations (I promised these yesterday)...
According to Dyno2000, this combination produces a peak torque of 576 lb/ft at 3500 RPM and peak horse power of 522 at 5500 RPM. As a point of interest, the RPM/torque numbers look like this: 2000/552, 2500/565, 3000/572, 3500/576, 4000/575, 4500/562.

Third, the discussion...
Dart, don't worry about stating your opinion, that's what these forums are all about. Putting an 850 in the simulation produces slightly higher numbers (3500/578 lb/ft, 5500/528 hp). I'm just wondering if the slight loss in numbers would be made up with a gain in throttle response.

I understand that 4.10s and slicks with a specific stall converter would be a contender. However, that doesn't take into consideration my statement about "comparably equipped cars". Remember that a car accelerates its hardest at its peak torque. Since hp is a measurement of the ability to do work over time, it's better to have your peak torque at a higher RPM. So, again with comparably equipped cars with different cams, this cam will pull harder from the start and through about 4000~4500 RPM. Now not too long after that I have to shift. The car with the larger cam gets to continue to about 6000~6500 RPM before shifting, thus getting to accelerate harder and keeping the torque multiplication advantage of first gear. Same thing for the other gears. At the end of the 1/4 run, the larger cam is going to win every time. At the start, however, this configuration will jump ahead, it just wont keep the lead.

Anyway, the 'Cuda isn't set up for drag racing. With the .98 torsion bars in front and 245/45 R17s in back, it wouldn't launch too well anyway. That coupled with my sloth-like reflexes doesn't lend well towards drag racing success.
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  #22  
Old 07-13-2002, 02:25 PM
Doug Wilson Doug Wilson is offline
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Mr. Cuda - I read your post 3 times and could find no fault with it. ... Damn!
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  #23  
Old 07-15-2002, 11:27 AM
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Ok, I understand where you are coming from but the number on the dyno seem a bit high to me. I would like to know how the combo runs when you get it completed. Would you make sure to post the results of your build when you are finished?

If you are looking for throttle response I think a double pumper would be the carb of chioce. You are building a low end motor that will turn on around 2000 RPM and it will need the extra fuel from the DP. I would almost guarantee that a 750 Vac sec wouldn't get the job done especailly where you would want most of the fuel coming in. With your combo the heads are going to flow some seriuos numbers and that would make me lean toward the 800-850 even more. I think (as I stated earlier) the I think the 830 would be a good choice ($381).

Information From Summit:

Model 4150, mechanical secondaries, classic finish, no choke, dual feed, 830 cfm, four-barrel, carburetor

This four barrel carburetor flows 830 cfm and features externally adjustable center-hung floats, dual 30cc pumps and feeds, dual metering blocks with replaceable jets, four corner idle system and mechanical secondaries. It combines maximum tunability for the street or strip and a classic finish for one great performing package.

This carb doesn't have a choke, so you will have to decide if you want to run it or not. I think this carb will offer everything you need and more. It is more of a "race" style carb, but you are building a fairly big motor and the price is right.

Tell me what you are thinking with the carb...
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  #24  
Old 07-15-2002, 04:16 PM
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Mr Cuda

Have you thought about an elastimatic cam and carb main body?

Cam gets bigger with rpms and sucks the throats open larger.



Sounds to me like you already know what your doing. Only information I could provide is something I learned when deciding on carb size myself. I talked with a guy who does nothing but setup and build Holleys for racing. He found out drag racing setups don't work well on circle and road tracks when coming out of the corners. Not enough booster signal. So he went smaller, the dyno numbers dropped but the car had better times and was more responsive because the booster signal was greater.

Dyno's don't measure acceleration. He has since applied that knowledge back to his drag racing setups and still insists his setups will produce lower dyno numbers but better time slips.
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Old 07-15-2002, 08:54 PM
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Actually the 830 should have the annular booster which will give you better throttle response especailly at lower RPM and startup.
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Old 07-15-2002, 09:55 PM
Mr. Cuda Mr. Cuda is offline
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OK, now I'm leaning towards an 850, or the 830 from Summit. I'm lucky in that here in Sparks we have a Summit store so I can go down and take a peek.

I'm planning on putting the engine on a Dyno before I put it in the car then again after. This is providing that I can find an engine dyno here in Reno/Sparks. I don't expect to see those numbers because of the elevation here. I also want to see exactly how much power I lose from the flywheel to the rear tires.

I'm not familiar with the 'elastomatic' cam. I'll have to look up some info on it.

Thanks for the input, everyone...
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