Hopping up the 500 Cadillac
(1898) |
m (Reverted edits by 190.1.61.134 (Talk); changed back to last version by Jon) |
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| − | + | Many things were learned about what to use, what works and what doesn’t after MANY DYNO pulls. | |
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| − | + | 1. 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 | |
| − | + | Cubic inches. This does not affect longevity but does increase Torque. Horsepower does NOT really increase. | |
| − | + | 2. 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. | |
| − | + | 3. 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 | ||
| + | With big valves and bowl work are worth 25 hp over large chamber heads with big valves & bowl work. | ||
| + | 4.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. | ||
| + | 4. The Edlebrock intake works good on a 500 inch or smaller motor if you don’t exceed 4500 rpm. | ||
| + | 5. 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. | ||
| + | 6. The MTS is worth 50 ft lbs torque and 50 horsepower at 5000 rpm over the Edlebrock. | ||
| + | 7. 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. | ||
| + | 8. 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 | ||
| + | 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. | ||
| + | 9. 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. | ||
| + | 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. | ||
| + | 10. 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. | ||
| + | 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 | ||
| + | exceed 5000 RPM. | ||
| + | 11. 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. | ||
| + | MTS and others have some excellent ones that will take high spring loads. The heavy rocker arms require a minimum | ||
| + | Of 130 lbs of seat pressure. Beehive conical springs work best to counter the harmonics that cause premature valve float. | ||
| + | With a normal non-beehive 130 lb spring we were on the verge of valve float at 5100 rpm. Higher spring pressure can wipe out | ||
| + | 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. | ||
| + | 12. With aftermarket rocker arms you cannot use stock valve covers. You have to use tall ones for clearance. | ||
| + | 13. 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 10:1 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. | ||
| + | This will give the motor low speed pep. Plug the vacuum advance. They Over-advance and cause pinging. This distributor tip works well | ||
| + | In DEAD STOCK APPLICATIONS. | ||
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| + | With the wimpy large chamber heads and Pontiac valves the best pulls | ||
| + | were: | ||
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| + | As observed and UNCORRECTED: | ||
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| + | 555 ft lbs torque @ 3400rpm yet still @ 525 ft lbs @ 4400rpm | ||
| + | 442 hp @ 4500rpm still showing 438 @ 5100. | ||
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| + | {{youcanedit}} | ||
| + | [[Category:Engine]] | ||
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