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  Some Holley tuning help, please...

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Author Topic:   Some Holley tuning help, please...
a351must2
Gearhead

Posts: 320
From: Snohomish, WA, USA
Registered: Jun 99

posted 05-05-2001 04:13 AM     Click Here to See the Profile for a351must2   Click Here to Email a351must2     Edit/Delete Message   Reply w/Quote
Since there's always the possibility of better tech advice here than on Stangnet, I'll post here too.

Any thoughts on carb tuning going by these dyno results from my 351w? The A/F ratio just doesn't seem good to me, but I'm no expert

The carb is a Holley 4160 750cfm vacuum secondary with a 4150 conversion kit installed. It had the lightest spring available on the diaphragm for the vac. secondaries while it was on the dyno.

The cam is 224 intake, 228 exhaust @ 0.050" and 296 intake, 299 exhaust advertised. The lift is 0.484" intake and 0.488" exhaust. Measured compression is 11:1, static is 174psi. Headers are 42", 1 5/8" tubes with 3" collectors and about 3' of 3" pipe behind them, 3" non-chambered mufflers, 2.5" tailpipes. Intake is a port matched Edelbrock RPM and heads are aluminum Edelbrock RPM with 1.90I, 1.60E.

That should be everything to be known about the motor, short of the gear drive, roller rockers, lightened 5.0L flywheel, and underdrive pulleys.

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capri man
Gearhead

Posts: 6417
From: doerun, ga.
Registered: Nov 2000

posted 05-05-2001 08:44 AM     Click Here to See the Profile for capri man   Click Here to Email capri man     Edit/Delete Message   Reply w/Quote
hi, i am not much of a speed pro, but looks like the car is falling on its face before you get to 4500 rpm. are you sure you got enough cam to run the amount of fuel through that your engine needs? i would change cams before i started messing with the carb. thats just my opinion, i could be wrong!!!
good luck------mike r-----capri man

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steve'66
Gearhead

Posts: 8826
From: Sonoma,CA,USA
Registered: Mar 2000

posted 05-05-2001 02:35 PM     Click Here to See the Profile for steve'66   Click Here to Email steve'66     Edit/Delete Message   Reply w/Quote
Your engine combo is very similar to ours. We have a little more cam, and 2.02 intakes. We've never been to a dyno, but I can tell you it's good for 110 mph @ 3100#s. It's interesting how it's lean at 2000 then fattens up at 3200, then leans out at top end. Why did they stop at 5700? How was your cam degreed? We used a 110* cam advanced 4* FWIW. How's your 750 jetted? We're running 70s in the front and 78s in the back right now. I'm sure someone will be along with dyno experience (like Alex) after the weekend races.

SteveW

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a351must2
Gearhead

Posts: 320
From: Snohomish, WA, USA
Registered: Jun 99

posted 05-05-2001 03:25 PM     Click Here to See the Profile for a351must2   Click Here to Email a351must2     Edit/Delete Message   Reply w/Quote
The cam was ground at 114 degrees to keep the idle smooth (I used to run a stock stall C4 auto) and I installed it straight up. The engine has all stock fasteners in the bottom end and cast pistons so I didn't want them taking it over 6000rpm on the factory tach. I guess that ends up being 5800rpm. Plus the HP curve started fluctuating above 5500rpm so something is wrong up there and that is where they should've, and did, shut it down.

At 2940lb race weight, I expect to run a little more than 110mph. What gets me, is that this engine used to be in my '74 with a C4 auto, and I ran a [email protected], then got promptly kicked off the track. Back then, I ran a 670cfm ProJection and 1.75" dual exhaust. I'm starting to wonder if their MPH measuring at the end of the track measured wrong that time.

As for jetting, I've never touched the jetting up front and never looked at what's in there. The secondaries have whatever jets came with the 4150 conversion kit. The tuner said he stayed with the same jets after running on the dyno.

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steve'66
Gearhead

Posts: 8826
From: Sonoma,CA,USA
Registered: Mar 2000

posted 05-05-2001 11:57 PM     Click Here to See the Profile for steve'66   Click Here to Email steve'66     Edit/Delete Message   Reply w/Quote
Why did they kick you off the track?

Your mph should have been an easy 11 second pass, do you remember the 60' time or the 330' times? That's interesting, were you running street tires?

The dyno numbers are at the rear wheels right?

SteveW

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a351must2
Gearhead

Posts: 320
From: Snohomish, WA, USA
Registered: Jun 99

posted 05-06-2001 12:05 PM     Click Here to See the Profile for a351must2   Click Here to Email a351must2     Edit/Delete Message   Reply w/Quote
yes, the dyno is at the rear wheels.

My 60' was 2.6sec. And the 330' was 6.48sec I was on street tires (225/50-15).

I was kicked off because I could pass the tech inspection for a 14.0+ time , but definately nothing less.

Noth my '74 and this car have more like road race suspension. Little or no weight transfer.

I do believe my '74 was a bit lighter than this car, that's the biggest difference I know.

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a351must2
Gearhead

Posts: 320
From: Snohomish, WA, USA
Registered: Jun 99

posted 05-07-2001 10:53 AM     Click Here to See the Profile for a351must2   Click Here to Email a351must2     Edit/Delete Message   Reply w/Quote
Is more advice available today?

The plugs read perfect yesterday and the tailpipes are nice and black inside. I'm also told I shoot flame out the exhaust during high rpm shifts.

The car is running great and the only pinging I hear is if I slowly tip into the throttle between 2000 and 2500rpm.

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steve'66
Gearhead

Posts: 8826
From: Sonoma,CA,USA
Registered: Mar 2000

posted 05-07-2001 05:31 PM     Click Here to See the Profile for steve'66   Click Here to Email steve'66     Edit/Delete Message   Reply w/Quote
This ones for you Alex.

SteveW

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