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Discussion Starter #1
I called a place to ask about putting my engine on their dyno and they gave me the name and phone number of the guy who runs the dyno. I called that guy and he told me that my carb is too small for my engine and it will lean the engine out at upper RPM's. I am not looking for a recomended carb size.

I'm looking for a confirmation or two that the scenerio of a lean out condition due to a too small of a carb is/is not possible? Thanks!
 

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Cantard
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you really don't want to put your motor on a dyno with a dumb F'ck like that on the controls:)sphss Carbs meter fuel based on the amount of fuel passing thru them. Any jackass worth a shit can make a 572 run dead rich with 600 cfm carb if so inclined. Find another dyno
HEY GN7!! I am suposed to be the crusty one around here!! LMAO
And your right.
 

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Just Me
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Are you running the engine NA (normally asperaited)? If there is no boosted air flow then the a properly functioning carb should be able to maintain the A/F ratio. It may run out of power due to lack of air and fuel but not go lean or rich as a result. I would agree with GN7. If that is the type of knowlege they are imparting before you pay them to dyno your engine, I would steer way clear of them. Perhaps he meant your carb doesn't flow enough air for the rpm/displacement you were talking about. But, if he can't articulate what he means, how can you trust his recomendations on tuning your engine.
 

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Hey hot Rod, I personally would NOT dyno a motor with that small a carb on that big a motor. Yes it can work but tuning will be a bitch. I would be happy to let you go to the dyno with my 750 vac sec, It's on the boat as I type but can have it off before you get here. The numbers you will show will depress you and that is not worth the money you will spend. Beg borrow or whatever a 850 or 930 then go to the dyno. Both will bolt to your'e manifold and feed the motor even if the jetting is off a pinch. Alot has to to with feul, but alot also has to do with air mass flowing to the motor. If you get both on the right page the power will show. IMO M
 

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Cantard
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Hey hot Rod, I personally would NOT dyno a motor with that small a carb on that big a motor. Yes it can work but tuning will be a bitch. I would be happy to let you go to the dyno with my 750 vac sec, It's on the boat as I type but can have it off before you get here. The numbers you will show will depress you and that is not worth the money you will spend. Beg borrow or whatever a 850 or 930 then go to the dyno. Both will bolt to your'e manifold and feed the motor even if the jetting is off a pinch. Alot has to to with feul, but alot also has to do with air mass flowing to the motor. If you get both on the right page the power will show. IMO M
I do hear what your sayin, Whats the point of dynoing what you are not gona use.
 

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northern member
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base set-up

dude , a 850 will fuel your 468 fine . i thought your cam might be a little to rad even with your compression . you do need a single plane for the r's your lookin for as many others have already said . i thought you had one with your orignal pile of parts you listed way back ??? any single plane would be better :)st :)grn :)sphss get some good gas from Busby jet it fat timing locked @ 36 and go from there :(:( :)hand
 

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dude , a 850 will fuel your 468 fine . i thought your cam might be a little to rad even with your compression . you do need a single plane for the r's your lookin for as many others have already said . i thought you had one with your orignal pile of parts you listed way back ??? any single plane would be better :)st :)grn :)sphss get some good gas from Busby jet it fat timing locked @ 36 and go from there :(:( :)hand
After doing dyno time I will tell you that to prduce the numbers you hope to see the dyno guys WILL lean on the motor hard, run a very thin oil for fast and low friction flow. they Will kick the timing in the balls to achieve a good number. I have raced cars and boats in the 40 plus range but kick them right back down for the simpithy of the motor after the finals are over.IMO M
 

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Discussion Starter #11
Hey ol guy, my carb is a 850 Holley DP w/mech secondaries. I don't need to borrow a carb, but thanks a lot for the offer!

I'm thinking (hard to believe isn't it :D ) that I should have some more patience and just ditch the idea of using a carb to get on the water faster, keep making and saving my pennies to get my MFI flowed, run it on a dyno with the MFI, and call it done. That seems to make the most sense.

I had a single plane intake but I sold it. :)st
 

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I called a place to ask about putting my engine on their dyno and they gave me the name and phone number of the guy who runs the dyno. I called that guy and he told me that my carb is too small for my engine and it will lean the engine out at upper RPM's. I am not looking for a recomended carb size.

I'm looking for a confirmation or two that the scenerio of a lean out condition due to a too small of a carb is/is not possible? Thanks!
Is it possible you heard/understood differently ?

A restrictive carb to airflow will tend to richen up on the top end. And the opposite can be true also - too large a carb going lean.

Each and every carb made is made specifically for a certain air volume going thru it. The more you go over or under of this value, the more issues you'll have in getting it tuned correctly through the whole rpm band.
 

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Resident Ford Nut
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An 850 on your 468 at 6,500 will be just fine. With that intake you are going to run I'm not sure it will make it to 6,500 and make power.

The 565 was still making power at 7,000 with a 1,050 from the math it could use a 1,250 or larger.

The operator is full of crap and I think I may know who he is.....check your p.m's

But the dyno is still a good idea.... get on the water with it.. worry about your injection later. I was at Martinez this weekend, both days were great.

Sleeper CP :D
 

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Discussion Starter #14
An 850 on your 468 at 6,500 will be just fine. With that intake you are going to run I'm not sure it will make it to 6,500 and make power.

The 565 was still making power at 7,000 with a 1,050 from the math it could use a 1,250 or larger.

The operator is full of crap and I think I may know who he is.....check your p.m's

But the dyno is still a good idea.... get on the water with it.. worry about your injection later. I was at Martinez this weekend, both days were great.

Sleeper CP :D
Yea I don't know Jack Sh!t and that's why I start and read through these threads. :D But it didn't make any sense to me when I was told the 850 would lean the engine out in the upper RPM's.

You do know who he is, I replied to your PM. :D

Just keep rubbing it in (you were at Martinez - and I wasn't). :|err J/K, It's my own fault it's taking me so long to get it on the water. I'll get there eventually and as long as it was worth the wait... then it was worth the wait. Biggest, most HP engine I've ever owned, by a long shot.
 

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Hey hot rod, Somewhere I got the idea you were going to dyno with a 600 CFM, My dumb-ass. 850 cfm should do fine and create good numbers up to 6200-6800 RPM. Again sorry, (man I hate it when I have brain farts) M
 

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Nobody
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Hey hot rod, Somewhere I got the idea you were going to dyno with a 600 CFM, My dumb-ass. 850 cfm should do fine and create good numbers up to 6200-6800 RPM. Again sorry, (man I hate it when I have brain farts) M
I think you just read GN7's statement about being able to run a big ass motor dead fat with a 600 carb which is true, that may have thrown ya there!..:D
 

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I think you just read GN7's statement about being able to run a big ass motor dead fat with a 600 carb which is true, that may have thrown ya there!..:D
Hey go fast. You are probably right on that! Maybe my keyboard needs a sobriety checkpoint. I already know a few that do. M
 

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Think about all the "rednecks" running NASCAR restrictor plate racing, those things still run 200MPH, small carb, same deal...BTW I love NASCAR so no offense:)devil X2 on the to large a' hole, they will lean out easier with too much blade and not enough fuel...
 

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Resident Ford Nut
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Just asking:

468 BBC Mark IV, stock stroke, .060 over, 13.25:1 compression, Pro Comp aluminum 320cc intake runner heads (2.3 intake, 1.88 exhaust), full roller, .714/.714 lift, 272/278 duration at .050, 110 centerline, dry Borla upswept style headers, Mallory mag II, and for now a dual plane intake with a spacer and a 850 Holley.

For this combo, what do you smart Chevy guy's ( if there is such a thing ;) ) think would be a good baseline to start with:

34* timing, 86 square jetting, with C-12 VP or VP-110 ?

Just trying to give HotRod an idea. :)bulb

I'm assuming the heads have Rec. ports ?

Sleeper CP
Big Inch Ford Lover :D
 

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I'm still in the tuning range with a 468 ,Brodix BB2 10.1 comp 675 lift 265 dur. Still trying to find the sweet spot with my 850. Hear is where im at 31 center squrits front and rear 84 all four corners and 3.5 PV front and rear still playing might need a little larger jets! Hope this helps for starters! WT:)devil
 
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