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What CFM carb are you running on your 460

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electrowoman

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« Reply #25 on: July 11, 2008, 06:32:45 PM »
The 850 didn't do much the first time out.   I just put on the 50cc pump and bolted it down.
I got about 50 rpm's more from it if that.

Back in the garage I pulled the carb to check the insides,  72's in the front with a 45 power valve and 74's in the back.  I couldn't see a number on the rear power valve.  It had the pink secondary spring, I changed that to the long yellow. (second lightest)

I put  74's in the front and 78's in the back, this is a vacuum secondary dual power valve carb by the way.   I picked up about 100 rpms.  The plugs are still pretty light.

I now have  76's in the front and 80's in the rear with a 5.5 power valve up front.   

We'll see how this works Monday.   I'm impressed with the way the carb responds to the changes so far. 

Do any of you have the vacuum secondary 850?   How is yours set up?   I went with the vacuum secondaries to save some fuel in cruise mode.  I've used them for about 30 years on this boat.











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Jason1978nordic

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« Reply #26 on: July 12, 2008, 09:22:12 AM »
there is no mention of fuel line size, fuel pump ,regulator or any that should be plenty of carb im running dual 450 cfm and its plenty check fuel system first just an opinion for what its worth........Jason

electrowoman

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« Reply #27 on: July 13, 2008, 05:06:46 PM »
3/8 line, Holley high output mechanical pump, no regulator.

We'll be going out tomorrow, I'll let you know how it does.

just squirtin

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« Reply #28 on: July 13, 2008, 09:15:50 PM »
upgraded to 850 speed demon  from 750 what a big difference

460 with alum heads/rollers/stealth man/

Sleeper CP 19

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« Reply #29 on: July 14, 2008, 04:38:41 PM »
upgraded to 850 speed demon  from 750 what a big difference

460 with alum heads/rollers/stealth man/

The engine in question has Water logs for exhaust. That might be holding it back a bit.

But i would think the 850 would help it over 5,000 rpm's, but I might just be getting held back by exhaust and pump.

Sleeper CP
Going fast is only half the fun...What you make go fast is the other.

electrowoman

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« Reply #30 on: August 30, 2008, 04:40:31 PM »
Time for an update.  I put on the long bolt logs, jetted the 850 at 78 primary 80 secondary.
The rpm's top out at 5100 to 5250 depending on load and wind. 
What total advance are you guys running?

That damm chrome balancer makes it so hard to see the timing marks I'm guessing it's pretty close
28 degrees total now.

I was going to play with that but I've just been taking it easy on the engine for the most part to break it in nice and easy.  The GPS showed a best of 61.5 the only day I took it out.  I borrowed it from my brother....

I'm happy with the jetting, I do need a slightly heavier secondary spring it has a bit of a flat spot before it takes off. 

 I'll just finialize the timing advance and be happy with that.   I'll be putting on a place diverter this winter and maybe a new impeller.  That remains to be seen.

What top end are you guys seeing from something similar to a 23 footer with an A impeller, Berkeley 12JE?   

I don't mean with a speedometer,,, I mean with a GPS.   My speedo says 64 to 65 MPH when the GPS said 61.5.  I'd probably be satisfied if I didn't have use of the GPS   ;D

HDriderTH

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« Reply #31 on: August 30, 2008, 04:57:20 PM »
454 chev .030 over...thats a 460, right? Two 1050 Dominators......try bumping your timing up to 37-38

'82 Sanger Bubble deck, Blown 454....V-drive

LakesOnly

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« Reply #32 on: September 03, 2008, 12:27:24 PM »
454 chev .030 over...thats a 460, right? Two 1050 Dominators......try bumping your timing up to 37-38
This ain't no chevy.

Electro, I skimmed this thread and don't see anywhere what octane rating your fuel is....

If you have the 75cc chamber heads, then you are at ~11.5:1 c/r and so 28* is all your engine can handle (detonation-wise) but this ignition timing setting is not optimized for your overall engine combo.  If you have high octane fuel (AvGas 100LL or better), then bump total timing to 32*BTDC@3000 rpm, and then do plug readings and rejet carburetor as required...but remember that 32BTDC@3000 with 11.5:1 c/r on pump gas is a no-no.

If you have the Edelbrock 95cc head will put you at about 9.75:1 and with pump gas 32*BTDC@3000 rpm should do it. With race gas, try 34-35*BTDC@3000 rpm, and then do plug readings and rejet carburetor as requried.

LO




« Last Edit: September 03, 2008, 12:30:16 PM by LakesOnly »

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« Reply #33 on: September 03, 2008, 01:16:45 PM »
I'm using the 95cc heads.  I didn't see the need for more compression than 9.75. 

Right now I've been using regular grade pump gas with no issues.

I want all I can get out of this combo and I'll be happy.  I know this isn't a 70 mph boat but 65 seems very reachable with this package. 

I'll have to paint the scale on the balancer so I can read it.  I'll work up to the 34 a bit at a time to make sure it doesn't detonate.   

The long bolt logs seem to have given it about 100- 150 rpms.  It's hard to really nail that down because of different water and wind conditions.

The  run yesterday on the gps was max 62.5 mph.  The only thing different was the logs.  61.5 max the last time.  I wish I could say the long bolts gave it that but was it wind? water?

We'll play with the timing this week to see what else may be there.

 


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