Hopping up the 500 Cadillac
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Many things were learned about what to use, what works and what doesn’t after MANY DYNO pulls. | Many things were learned about what to use, what works and what doesn’t after MANY DYNO pulls. | ||
| − | + | + The crankshaft can be offset ground .300 smaller to the same size as a big block chevy | |
Which yields a 35 cubic inch increase. Coupled with a slight overbore you now have 540 | Which yields a 35 cubic inch increase. Coupled with a slight overbore you now have 540 | ||
| − | Cubic inches. This does not affect longevity but does increase Torque. Horsepower does NOT really increase. | + | Cubic inches. This does not affect longevity but does increase Torque. Horsepower does NOT really increase.=== |
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| + | # When this is done you can use 6.800 H-beam chevy rods which are MUCH stronger and very affordably priced. | ||
Cadillac rods will fail above 5000 rpm. | Cadillac rods will fail above 5000 rpm. | ||
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| + | # While 1974-76 large chamber heads can be used, there is a substantial power increase to be had with | ||
1968-1972 small chamber heads if they are fitted with 2.19-1.84 chevy valves. Small chamber heads | 1968-1972 small chamber heads if they are fitted with 2.19-1.84 chevy valves. Small chamber heads | ||
| − | With big valves and bowl work are worth 25 hp over large chamber heads with big valves & bowl work. | + | With big valves and bowl work are worth 25 hp over large chamber heads with big valves & bowl work. |
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| + | The BEST heads to use are the NEW Aluminum ones from MTS. When these are Fully Ported by an | ||
` experienced head porter (like BPE) they are worth about 100 horsepower over a stock head of any type. | ` experienced head porter (like BPE) they are worth about 100 horsepower over a stock head of any type. | ||
| − | + | # The Edlebrock intake works good on a 500 inch or smaller motor if you don’t exceed 4500 rpm. | |
| − | + | ||
| + | # Larger motors or those with good heads need the new single plane from MTS. Power will NOT drop off | ||
Like the Edlebrock which are airflow limited. The Edlebrock will make more 30-40 ft lbs more torque under 3500 rpm. | Like the Edlebrock which are airflow limited. The Edlebrock will make more 30-40 ft lbs more torque under 3500 rpm. | ||
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| − | + | # The MTS is worth 50 ft lbs torque and 50 horsepower at 5000 rpm over the Edlebrock. | |
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| + | # The factory type Q-jet works good on the Edlebrock. It does NOT seem to work very well on the | ||
Single plane even with rejetting. Reversion from the huge secondary’s on the single plane may be the problem. | Single plane even with rejetting. Reversion from the huge secondary’s on the single plane may be the problem. | ||
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| + | # Multiple sizes and types of carburetors were tried. Best torque and horsepower with the large chamber heads | ||
Was with an out-of-the box 750 Holley. Best by 20 horsepower. The large chamber heads flowed only 710 cfm MAX | Was with an out-of-the box 750 Holley. Best by 20 horsepower. The large chamber heads flowed only 710 cfm MAX | ||
Measured through the CARB At 5200 rpm under load on the Dyno. Larger carbs up to 1000 cfm were tried and | Measured through the CARB At 5200 rpm under load on the Dyno. Larger carbs up to 1000 cfm were tried and | ||
ALL LOST horsepower & torque. | ALL LOST horsepower & torque. | ||
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| + | # The long stroke Cadillac whether 4.300 stock or 4.600 stroker need plenty of cam. Several cams have been tried. | ||
For any type of performance use a minimum of 234-244 @.050 tappet rise with as much lift as you can get works well. | For any type of performance use a minimum of 234-244 @.050 tappet rise with as much lift as you can get works well. | ||
This cam will peak at 5100 rpm but still have good torque at 3000 rpm. With really good heads, add 10 degrees or 244-254 duration. | This cam will peak at 5100 rpm but still have good torque at 3000 rpm. With really good heads, add 10 degrees or 244-254 duration. | ||
Stock heads & stock valves only need about 220-230 duration. Anything bigger will not flow any more air because of head flow limits. | Stock heads & stock valves only need about 220-230 duration. Anything bigger will not flow any more air because of head flow limits. | ||
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| + | # Engine SIZE DOES NOT AFFECT HORSEPOWER. Engine size DOES affect TORQUE. SHOCKING as this sounds, | ||
A 350 cubic inch engine with good flowing heads will out horsepower a 550 cubic inch engine with poor flowing heads. | A 350 cubic inch engine with good flowing heads will out horsepower a 550 cubic inch engine with poor flowing heads. | ||
The 550 will out torque the 350 at low to mid RPM. TORQUE is what makes the car go. The Cadillac has POOR FLOWING HEADS | The 550 will out torque the 350 at low to mid RPM. TORQUE is what makes the car go. The Cadillac has POOR FLOWING HEADS | ||
so you have to Maximize Torque and help the horsepower under 5000 rpm. This is why the Cadillac is GENERALLY limited to not | so you have to Maximize Torque and help the horsepower under 5000 rpm. This is why the Cadillac is GENERALLY limited to not | ||
exceed 5000 RPM. | exceed 5000 RPM. | ||
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| + | # Stock rocker arm stands are fragile over 100 lbs of valve spring pressure. This light spring pressure limits RPM to about 4600. | ||
More radical cams or more rpm require more valve spring pressure. This requires after-market rocker arm assemblies. | More radical cams or more rpm require more valve spring pressure. This requires after-market rocker arm assemblies. | ||
MTS and others have some excellent ones that will take high spring loads. The heavy rocker arms require a minimum | MTS and others have some excellent ones that will take high spring loads. The heavy rocker arms require a minimum | ||
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the cam lobe of the Cadillac Blank because of its small size. Beehive springs can extend this to perhaps 5500-5700 with the same pressure. | the cam lobe of the Cadillac Blank because of its small size. Beehive springs can extend this to perhaps 5500-5700 with the same pressure. | ||
You better have really good heads to flow enough Air at that rpm and still make horsepower at that rpm. | You better have really good heads to flow enough Air at that rpm and still make horsepower at that rpm. | ||
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| − | + | # With aftermarket rocker arms you cannot use stock valve covers. You have to use tall ones for clearance. | |
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| + | # The factory HEI distributor works fine if it is modified slightly. The stock advance curve is about as screwed up as any I have ever seen | ||
For performance applications. The curve that seems to work well is 25 degrees mechanical advance at 3000 rpm for 19:1 HIGH COMPRESSION | For performance applications. The curve that seems to work well is 25 degrees mechanical advance at 3000 rpm for 19:1 HIGH COMPRESSION | ||
Motors with 8 degrees initial. For LOW COMPRESSION under 9.0 CR use 20-22 degrees mechanical advance all in at 2500 with 12-14 initial advance. | Motors with 8 degrees initial. For LOW COMPRESSION under 9.0 CR use 20-22 degrees mechanical advance all in at 2500 with 12-14 initial advance. | ||
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