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Bracket Talk Bracket Talk Forum Tech Talk - by Abruzzi Engine size change - Convertor questionGo | New | Find | Notify | Tools | Reply | |
| Engine size change - Convertor question | Login/Join |
DRR Pro |
I moved from a 509" BBC to a 555" one. Same engine just opened up the bore and changed the stroke. I left everything else the same save for adding a vacuum pump. Same heads, camshaft, intake, carb and ignition. I run a 8" convertor with a flash of 6100-6200 & its spragless. How big an effect would the additional cubes have on the convertor? Combination at the moment just seems "off" from what it was before the size change. | ||
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| DRR Top Comp |
Depends on the increase or decrease in power. 100hp is 400 rpm's of observed stall, as example. | |||
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DRR S/Pro |
you are probably blowing through the convertor with the added TQ, heads and cam information as well as car information would also be of value. Keeping the Socialists and NEO-LIBERALS at bay with FACTS one post at a time !!! Freedom isn't free !!! Thank a veteran, they will actually appreciate it. | |||
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| DRR Pro |
The heads are BB-2X with some pro level porting. Cam Spec: @.050 282/294 .427/.420 Gross lift .720/.714 Lobe Sep: 110 Installed at 108 ICLThis message has been edited. Last edited by: chasracer, | |||
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DRR Pro |
You've run out of cam and cylinder head for those inches, been here, seen this. NOT to say that a converter change wouldn't help you achieve something. You need 355cc+ intake runners and .800"-.820" lift to do the 555 justice. "Despite the high cost of living, it remains popular." Dave Cook N375 | |||
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| DRR S/Pro |
I agree with Bozman, you'll probably blow through that 8 inch given the flash numbers you posted using the 509. I would try that original 8 inch and see how it acts. That cam looks a little short on the lift side for a 555. It may be time to look at a spragless 9inch. Bob | |||
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DRR S/Pro |
The 555 will not work well with the same parts. Heads to small, cam way to small. More low end torque but it’ll run out of steam as rpm rises. Just last year I upped my engine from a 565 to a 584 Same heads and cam The 584 is weaker than the engine as a 565. Has more torque down low but that’s it... Same converter is a little bit looser. I ran a 509 with an 8” converter and went to a 9” when I built the 565 I can recall feeling like I never should have sold the 8” and just tried it behind that 565 I think it would have been just fine | |||
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DRR Sportsman |
I would try it. That's JMO, and I'm sure the resident expert will tell me I'm wrong. | |||
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| DRR Top Comp |
Listen to the converter, it'll tell you. Less stall is less power More stall is more power RPM and Torque are measurable quantities of engine output If you think you can go faster and more consistent with a diesel operating at lower rpm, have at it, but it's the opposite of what the tire / chassis wants in the burnout, or on the starting line. | |||
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| DRR Pro |
Not sure what "try it" means in this context. But here are the facts, even though I know that the parts are not optimal, I'm not changing cylinder heads, intake, ignition, etc. The 509 ran 4.93-4.94 pretty consistently. If I hadn't messed up the crankshaft, I would still be running it. The 509 launched well and pulled like a beast - I was happy with it so at this point I have basically screwed myself. To be honest, I'm disappointed in the 555 at this point. I'm not in a position to throw a lot at it which is where dial boards and shoe polish come in. I would consider upgrading the roller cam and then going after another convertor. I do have a larger carb that I can put on this deal. Anyone moved up from a 540-555 and have a good condition roller cam they want to part with? | |||
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| DRR Trophy |
I ran an 8" behind my 485, 532 and my current set up which is a 555. I ran the same convertor behind both the 532 and 555 with the same exact internals besides crankshaft and gained about 200 in stall. | |||
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| DRR Pro |
sent PM | |||
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| DRR Pro |
If you can find one used, it's hard to beat the Reher-Morrison 555 Bracket cam, it's a little over .800" lift and easy on parts, or Bullet can do a very similar grind. "Despite the high cost of living, it remains popular." Dave Cook N375 | |||
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| DRR S/Pro |
Goob's suggestion is a good one. R-M 420-116 is an Erson cam, makes good power, does not require huge spring pressure and does not break parts I've used that cam and have one on the shelf | |||
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| DRR Pro |
Thanks for the cam suggestions. I appreciate your help! | |||
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| DRR Sportsman |
[QUOTE]Originally posted by chasracer: Not sure what "try it" means in this context. Try it means put it in and try it. At least you'll know what you need to do, if any adjustments need made. | |||
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| DRR Pro |
I think we're having a comm problem here. I do not know what you are suggesting I put in the engine and try. | |||
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| DRR Trophy |
Your cam is not that bad, I basically used the same pieces in the early 2000's and they always made between 850-900 horsepower. You need to look at others things. Duane Allen | |||
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| DRR Top Comp |
After looking at it, I agree. Put a 1.8 ratio rocker on the intake. Opel core 8" converter will be fine 410-430 gear. @.050 282/294 .427/.420 Gross lift .720 - .768/.714 Lobe Sep: 110 Installed at 108 ICL | |||
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| DRR Pro |
I think changing the cam might be cheaper. Not exactly sure how much 8 Jesel 1.8 rockers cost today. Already run a 4.10 gear. The heads are the BB-2X CNC which are 341 port volume and supposedly 365+ area at .700 lift. They have the 2.30 intake valves. Does anyone know a cam part number close to the R-M cam? | |||
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Bracket Talk Bracket Talk Forum Tech Talk - by Abruzzi Engine size change - Convertor question
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