2V Dyno Results - Part 3 & 4

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Part I
Engine: 250ci - Bone Stock - Headers - DUI ignition.
Upgrades: 2V Adpator (various carbs)
Carb - CFM - Max HP (Gain/Avg) - Max TQ (Gain/Avg) - C/O
Stock YF 1V- 180 - 75 @ 3950 (0/62) - 110 @ 2500 (0/100) 7.5% (rich)
Autolite 2V - 240 - 79 @ 3750 (4/67hp) - 118 @ 2550 (8/107lbs) 6.5%
Weber 2V- 300 - 80 @ 4100 (5/65hp) - 116 @ 2650 (6/105lbs) 6%
Holley 2V- 350 - 80 @ 3950 (5/68hp) - 120 @ 2600 (10/109lbs) 6.5%
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Part II
Engine: 200ci - 264-110 Cam - Headers - Log Head
Upgrades: DUI dizzy - 2V Adaptor (various carbs)
Carb - CFM - Dizzy - Max HP (Gain/Avg) - Max TQ (Gain/Avg) - C/O
Autolite 1V - 180 - LOM - 62 @ 3900 (0/49) - 93 @ 2900 (0/81)
Weber 2V - 300 - LOM - 70 @ 4300 (8/51 hp) - 94 @ 3350 (1/83 lbs) 4% (lean)
Weber 2V - 300 - DUI - 85 @ 3900 (23/66 hp) - 105 @ 3300 (12/97 lbs) 4% (lean)
Autolite 2V - 240 - DUI - 83 @ 3950 (21/67 hp) - 105 @ 3400 (12/98 lbs) ?
Autolite 2V - 245 - DUI - 84 @ 3900 (22/68 hp) - 105 @ 3300 (12/99 lbs) ?
Holley 2V - 350 - DUI - 87 @ 3800 (25/69 hp)- 106 @ 3200 (13/100 lbs) 6%
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Part III
Engine: 250ci - Bone Stock - Headers - DUI ignition
Upgrades: Modified Log Head (MLH) - 2V Carb (various) - 1.50 Exh Valves
Carb - CFM - Max HP (Gain/Avg) - Max TQ (Gain/Avg) - C/O
Stock YF 1V - 180 - LOG - 75 @ 3950 (0/62) - 110 @ 2500 (0/100) 7% (rich)
Holley 2V - 350 - MLH - 98 @ 3850 (23/70hp) - 140 @ 2500 (30/112lbs) 6%
Autolite 2V - 240 - MLH - 93 @ 3850 (18/78hp) - 143 @ 2550 (33/125lbs) 6%
Autolite 2V - 287 - MLH - 97 @ 3800 (22/80hp) - 144 @ 2500 (34/128lbs) 4.5% (lean)
Autolite 2V - 356 - MLH - 99 @ 3750 (23/80hp) - 145 @ 2500 (35/129lbs) 3.5% (very lean)
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Part IV
Engine: 250ci - Bone Stock - Headers - DUI ignition - Modified Log 2V
Upgrades: 1.6 High Ratio Rockers
Carb - CFM - Rockers - Max HP (Gain/Avg) - Max TQ (Gain/Avg) - C/O
Holley 2V - 350 - 1.5 ratio - 98 @ 3850 (0/70hp) - 140 @ 2500 (0/112lbs) 6%
Holley 2V - 350 - 1.6 ratio - 100 @ 3900 (2/80hp) - 142 @ 2450 (2/129lbs) 6%
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Summary
Results using the Holley 350 with a 2V adaptor; verses the Holley 350 on a modified head (direct mount 2V) with 1.5 rockers; verse the Holley 350 on the modified head with 1.6 rockers.
Carb - CFM - Rockers - Max HP (Gain/Avg) - Max TQ (Gain/Avg) - C/O
Holley 350 - adaptor - 1.5 - 80 @ 3950 (5/68hp) - 120 @ 2600 (10/109lbs) 6%
Holley 350 - modified - 1.5 - 98 @ 3850 (23/70hp) - 140 @ 2500 (30/112lbs) 6%
Holley 350 - modified - 1.6 - 100 @ 3900 (25/80hp) - 142 @ 2450 (32/129lbs) 6%

What interesting, is the average HP and Torque numbers. The high ratio rockers didn't add much to the peak, but increased the average numbers considerably. The same holds true for the Autolite carbs. Unfortunately, we didn't have a good selection of jets on hand. We first tested the Autolite 356 with 54 jets, which netted 90hp (2.0% C/O). We then jumped up to 58 jets which netted 94 hp (2.5% C/O), then to 62s which resulted in 99 hp (3.5% C/O). Even with the 62 jets we were still very lean (3.5% C/O). If we had the proper jets on hand, we estimate that the 356cfm would have netted around 110-115 hp (6% C/O is ideal).

I should also note that the Holley has a slight stutter, which disappeared with the Autolite carbs. And that even tho the peak numbers are better with the bigger carbs, we have no idea how this effects the drivability and/or mileage. To my ear, the Autolite 287cfm seemed to idle a little better, accelerate smoother, and faster, even tho it was slightly lean and made a little less peak power. With the proper sized jets, I'm assuming the power would be slightly better than the Holley, with improved drivability and gas mileage, due to the smaller venturi sizes.

I wanted to test the Autolite 356 with bigger jets, combined with the high ratio rockers, but it was getting late and everyone wanted to leave. Hence I was somewhat dissappointed. All in all, with the dyno time, parts, and labor, this set me back around $1600 bucks (ouch). However I feel we accomplished a lot, and hope the information gained will be put to good use.

We may decided to test a modified a log head on the 200ci, which was tested in Part II, to see what can be gained. But I need to save up some cash first.

Mike & Gene, great job done. The cost of knowledge does not come cheap.
I am trying to work a deal with my local dynojet owner to test 3 carburetors.
1 a 7448-350, a 4412-500 with large annular boosters & then a 4412-500 with small pro-billet annular boosters.
Part III
Engine: 250ci - Bone Stock - Headers - DUI ignition
Upgrades: Modified Log Head w/ 2V & 1.50 Exh Valves (various carbs)
Carb - CFM - Dizzy - Max HP (Gain/Avg) - Max TQ (Gain/Avg)
Stock YF 1V - 180 - LOM - 75 @ 3950 (0/62) - 110 @ 2500 (0/100) 7% C/O
Holley 2V - 350 - DUI - 98 @ 3850 (23/70hp) - 140 @ 2500 (30/112lbs) 6% C/O
Autolite 2V - 240 - DUI - 93 @ 3850 (18/78hp) - 143 @ 2550 (33/125lbs) 6% C/O
Autolite 2V - 287 - DUI - 97 @ 3800 (22/80hp) - 144 @ 2500 (34/128lbs) 4.5% C/O (lean)
Autolite 2V - 356 - DUI - 99 @ 3750 (23/80hp) - 145 @ 2500 (35/129lbs) 3.5% C/O (very lean)
Seems like all the carburetors are very close on power, the the autolites with the annular boosters definately create more torque.
What seems odd though is when the tests are not done on pony carbs dyno the holley seems to do a lot better???? Bill

I can't tell you why it made such a dramatic difference on Mike's motor, only that it did. If you watch the videos, you can clearly see how much time it took for the Holley to make max rpm, verse the Autolites.

As far as the testing on Gene's motor, the Autolite faired better as well. The Autolite 287cfm made almost the same power as the Holley 350 (1hp less) even tho it was 20% smaller, and running lean. The Holley was right on, as far as the jer size, and max out at 98hp, while the Autolite still had room to go. If we would have had the proper jet sizes, I'm quite certain it would have easily went over 105 max HP, which would also increase the average power. The smaller Autolite also made 10 more average HP, which means it did considerably better at the low and mid range rpm's, to average out that much higher.

Next, the smaller Autolite made 4lbs more torque at peak, and 16lbs more for the average. This means the torque was better, not only at the low and mid range, but at higher rpms as well. All this while being 20% smaller, and lean.

However, the 287 dropped off slightly after hitting peak, which means it was still to small. While the Holley held a straight line after hitting peak, meaning it was max'd out. Based on the results we got from the 351cfm, I would assume the best sized carb for Gene's 250 would be an Autolite in the 300cfm range. It should make around 105 peak HP with an average around 80-82. With the torque coming in around 146lbs and an average of 130lbs or better. Unfortunetly we didn't have one to test, so I can only make an assumptions base on our results. However, I'm pretty confident of those assumptions.

So in my book, a carb that makes more peak HP & TQ, with more average HP & TQ, while being 15% smaller (300 vs 350cfm), would be a better bet. Not only would it offer more power and torque, the drivability should be better as well, due to the smaller venturi's (higher velocity), which the numbers prove out. And it should do better on gas to boot. As you can tell I'm sold on the Autolite's, but on the other hand, I haven't tested a Holley with annular boosters (yet).

I plan to add the average numbers for part II, however I misplaced the dyno sheets, so I need to find them first.

Mike, and everyone involved, I'd like to thank you all for the time, money, and effort you have put into this endeavor. While my initial plan for my next motor was a fully built, fuel injected CI Aluminum head, the impending adoption of two children has put the squeeze on my available funds, so I am looking at a more cost efficient build with somewhat lower hp/torque aspirations. The research that you have done will be invaluable as I move forward.

I've got an '81 200 motor that I'm tearing down to rebuild. I've been trying to figure what will go into it. I'm thinking zero deck the block, I have an old style shim gasket, mill the head to 52cc (I believe stock is 62cc), use stock valvetrain and dished pistons, but go with the CI/Clay Smith 264S-110 cam (264/264 - 214/214 - .450/.450 - 110* - 1400-5000) and an Autolite 287 2bbl direct mount carb. For now I'm not sure if I'll be using my current C4 or if I'd use the manual tranny that came with it (I believe it is a T4 and I'd rather not incur the additional cost of the conversion/rebuild yet).

EDIT: Forgot to mention that for now I'll be using my '69 exhaust manifold.

Chuck,

That sounds like a great combination. Get some mild port work done on the head if you can. It will really wake it up! I think the 264cam will work great for this combination. If you can afford it, the DUI distributor and a set of 6 into 2 headers would really benefit you. Just my .02 cents.

Gene

Thanks for the feedback Gene. But like I said, with the adoption I need to keep the expenses down so I'll be sticking with my Pertronix II and stock exhaust manifold for now. I'm mostly interested in highway cruising, and with 2.83 gears, 205/60-15 tires and the C4, I figure I'm currently turning 2900-3000rpms at 75mph, so mid-range hp and a flat torque curve is what I'm looking for. Re-reading this thread, I just realized that I'd come up with the same cam that you did.

But back on topic, I know the 200 test was done with a bone stock bottom end, does that include the factory cam? (On a related note, does anyone know what the specs are of a factory cam?) It sounds to me as if the 287 Autolite would be a good selection for a stock-to-mild 200 buildup like I'm planning, with enough tunability left.

The tests on my motor were a 250 with a completely stock bottom end, and that does include the stock camshaft. Lift specs for a stock 250 cam are .368 but I'm not sure what the duration is at .050

The other test here in Phoenix was done on a 200 but it had the 264 cam in it. Stock lift for a 200 camshaft is around .372

Mike, one of the reasons the 350 holley was close in power to the autolites, because this carb uses straight leg covered boosters. They have a much better signal than the 4412-500 downleg nozzles especially with a small engine.
With a big V8 engine the downleg boosters might perform better than another venturi design.
It seems with these small engines the booster signal which results in superior fuel atomization is the large annular nozzle. Second is the covered straight leg booster of the holley.
Further tests will tell.

Gene, your maverick must be a pleasure to drive with the new head & extra carburetion.
Just think if you had some more camshaft in the engine??
You should try Michael Raley's 4412-500 carb just to see if it helps.
Since you are not at 4000 feet elevation such as pony carbs is it might suprise you. Bill