Yet another 351M-to-400 build

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#46

03-16-2011, 10:50 PM

Carny

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Hope I'm not being to nosy, but do you mind sharing how much this build is costing?

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#47

03-16-2011, 11:55 PM

PDX_F250_78

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Quote:

Originally Posted by Carny

Hope I'm not being to nosy, but do you mind sharing how much this build is costing?

+1, would you mind sharing the cost?

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#48

03-17-2011, 03:11 PM

jlj6t

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About $7500.

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#49

03-17-2011, 08:25 PM

jlj6t

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******** width="480" height="390">

<embed src="http://www.youtube.com/v/8t78bR_XW_g?fs=1&hl=en_US&rel=0" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="390">*********>

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#50

03-17-2011, 08:27 PM

jlj6t

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#51

03-21-2011, 08:02 AM

jlj6t

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More pics, post dyno

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#52

03-21-2011, 08:53 AM

jlj6t

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Final Dyno Curve

Since we switched to the Weiand intake and were pleasantly surprised by the results, Tim wanted to see what switching the carb from the Edelbrock Thunder 650 to a Holley 850 would do. Here are the results...

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Edelbrock 650

Peak CorrHP 359
Average CorrHP 324
Peak CorrTorq 471
Average CorrTorq 431

Holley 850

Peak CorrHP 374
Average CorrHP 333
Peak CorrTorq 476
Average CorrTorq 443

Interesting to know! For now, we're sticking with the Edel 650. As I'm not planning on racing/dragging/etc., my butt-in-the-seat meter won't really notice the extra performance. The 650 carb should be a little more "streetable" as well. But down the road...

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#53

03-21-2011, 10:37 AM

PDX_F250_78

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Quote:

Originally Posted by jlj6t

About $7500.

What is the warranty?

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#54

03-21-2011, 03:42 PM

crsmiffy

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those figures are interesting! I can understand the horsepower for the bigger carb being higher, but to see the torque higher as well goes against usual philosophy. How do they compare in the rev range, i.e. does the 650 peak earlier as you say the 650 is still better on the street?

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#55

03-21-2011, 04:06 PM

wyoming4x4

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650 to small!

engine is requiring air and the 650 is a restriction in this applicaiton. so lets say a 750 would be nice for this applicaiton. 650 is only 325cfm on front and a 850 is 425cfm on front barrels. so the engine is wanting air. So I would be looking at a nice carb to really make this thing make torque where you need it. Nice engine build with a mild setup. NICE Build tim!!

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#56

03-21-2011, 05:40 PM

jlj6t

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Yes, the 650 seems to restrict some flow at high RPMs. Can't argue with that! But...

The torque and power curves generally lie right on top of another up to ~ 3500 RPMs. It's not until you start revving up pretty high that the higher flowing carb makes much of a difference. The peak torque is the same (within a few pounds) at roughly the same RPM (~3100). If I wanted this engine to make it's living at 5000 RPM, it'd make sense to go with a higher flowing carb like the 850. There is a decent amount to be gained on the high rev end by doing so. But I'm more interested in how she performs on the low-end (the sought-after low-end torque). That's why we went with small-port 2V heads, "small" OE valves, etc., to promote a higher velocity (and therefore better mixing) of air/fuel into the combustion chamber at low RPMs. As the curves show, there is virtually no difference between the 650 and 850 carbs on the low end. I would expect a crisper throttle response at part throttle in the smaller 650 carb as a result of the smaller bores (as above, smaller = faster until it becomes restrictive). Lastly, the mileage should be marginally better with the smaller 650 carb. Not that that's much of a concern

In summary, the high-end gains (where she would seldom see) IMHO do not outweigh the low-end losses (where she would make her hay).

I'm very new to this game, so if I'm all jacked up on something, please correct me!

JJ

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#57

03-21-2011, 05:46 PM

TMI

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With the 650 carb, it pulled about 1.3 lbs of vacuum
Me myself, I try to build engines for %90 of the way a customer drives
their vehicle.
I would stay with the 650 because of the throttle response, idle characteristics,
& low rpm drive ability.

Warranty... what warranty??

No seriously, I seldom get asked this question. Our typical machine shop warranty is 30 days. For the most part, if there is something wrong that your shop did, usually you know about it very quickly.
Here is the way I look at it, anybody can give you a warranty to say what ever you want. Try and collect on it if you have issues.
My conscious is our warranty. Weather it is 1 month or 5 years down the road, if it is black & white that we did something incorrect, I will take care of the customer.
It is not worth the few thousand $$ I would save by not taking care of a situation, in comparison to having our name smeared all over the internet and the business we would loss because of that. Yes, we have had issues, we are human. If it comes off the dyno, very seldom can the customer break it after that (seldom, not impossible)

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#58

03-21-2011, 06:31 PM

crsmiffy

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J' that is where I was coming from. I am a believer in air velocity for torque. I do realise what wyoming is saying re:restrictions, but again considering Holley's carby calculator (and a few others) that a 600-650 is adequate for a 400ci engine up to 5500rpm then the approx flow rate of 325cfm (if the engine is loaded for torque then the other barrels may be opening anyway) would be enough for lower rpm operation. This was why I asked the question as it seemed a bit against the grain for the bigger carb to have better HP AND Torque. Good luck and it looks like you will have a bit of fun with it.

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#59

03-21-2011, 06:33 PM

smokeyb97

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Justin, I know you've got to be excited about this engine that Tim has built for you and I agree with using the 650 carb. There's no question you'll be much better off using this carb on a daily driver. When my engine was dyno'd we used a Holley 750 to run the break-in then made a few pulls, then put the Edelbrock 600 on and made a few more pulls because it was the carb I would be using all the time. The Holley made about 7hp more, but at high rpm. Keep us up to date when you get it installed and on the road.

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#60

03-22-2011, 07:01 AM

jlj6t

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Quote:

Originally Posted by smokeyb97

Justin, I know you've got to be excited about this engine that Tim has built for you

Excited ain't the word!

Sam, out of curiosity, what kind of air cleaner you got on top of your beast in your sig pic there? I've still got the old Edelbrock chrome air cleaner, but I'm thinking of making a change.

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