Holley Carb tuning 396 - Chevelle Tech
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post #1 of 10 (permalink) Old Jul 17th, 17, 3:49 AM Thread Starter
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Aleksander
 
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Holley Carb tuning 396

Hi guys. After last years bummer dyno session and a few upgrades and fixes i though id start doing some carb adjustments, the reason i want to start adjusting it is while i was on the dyno they jettet the carb down to 72 in front and put a 134-21 metering plate in the rear. they told me it was alitle rich to begin with i do not know what jets that was there before. but before they did this change i felt a kick in the seat when ever i floored it and now there is no real omph. the dyno with the new jetting showes an avrage of 13,72 afr and is consistant but its to me lean. I opened the carb last night to verify this jetting i also noticed one of the primery jets where black stamped 72h while the other was bras stamped 72 i guess its the same but i thought id mention it. i hooked up CO machine and one side is richer then the other while trottleing to 1500rpm that is why i wanted to share this. I think i sorted the timing out its now 18 initial + 20 mech all in by 2600rpm + 12 degrees vacuum conected to manifold vac. I forgot to mention the PV is stamped 65 and there is a yellow spring for the secondaries.

some info about the car/engine:

396 +0.30
Speedpro pistons l2240nf30
Edelbrock c396 intake
Holley 3310-6 carb
3904390 heads large oval port not ported with new valve job
Full length headers onto 3 inch collector onto 2,5 mandrel bend pipes
Lunati vodoo cam 60202 "10110702"
Info on the cam
Intake. Exhaust
[email protected] [email protected]
Adv 262. 268
Lift at valve
0.530 0.542
Lsa 112

Th 400 trans
full weight 69 chevelle
27,2" diameter rear tires

I changed out the rear end gear sience last year from 3.08 to 3.73 it woke it up some in 1st but i feel the car would be slower in 1/4 mile thinking of installing a gear vendor next year.
I also changed out the "stock" converter that stalled at around 1200 with a TCI breakaway 2400 stall speed. i am thinking of going back to my old converter cause i feel this converter is all noise and no go to be honest, i am going to try and do a 60ft time and a 0-60mph to se if it is actually as slow as i feel but it stalls much higher then advertised. around 3000. its no problem driving with but when you floor it nothing really happens.
I have now written a small novelle so i guess i leave it for now and se what respons i do get.

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Last edited by Aleksander 69 chevelle; Jul 17th, 17 at 3:59 AM. Reason: to litle info
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post #2 of 10 (permalink) Old Jul 17th, 17, 6:30 AM
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Tom Terrific II
 
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Re: Holley Carb tuning 396

72 is what it should have had to begin with. 65PV is OK although I prefer the quick opening 85 and 105.

the dyno should show 12.6 to 13:1 acceleration and 14-15:1 steady state cruise.

You should have a pretty good running deal there.

Don't worry about the kick in the pants feel, a well tuned 750VS won't have that as they are smooth. the kick in the pants feel is either the beginning or end of a bog or lean spot.

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post #3 of 10 (permalink) Old Jul 17th, 17, 9:04 AM
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jeff
 
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Re: Holley Carb tuning 396

This is why I like to tune at the track or tune then go to the track. or time it another way.

Dyno AFR is for Dyno AFR you tune the jet, timing etc to get max acceleration.

In short give the car what it wants.
You may end up at 11.9 AFR wide open or 12.5 for best ET.

It would be nice if you had your old metering plate.. you could install it and retest.

I know what you are saying about the converter.
It is like you are driving through it.

B&M 3000 behind my buddies 396 feels that way.
Same goes for a summit high stall behind a 350 I built for another friend .

But the feel changes once you take advantage of it.
Sticky tires that hook solid and then flash that converter on a launch you will see what I mean .

pussy footing around they feel like they are slipping all the time.
At the track hookin' up it feels solid.


I got a coan 4500 stall and it does not feel like the summit or B&M when just driving around.. It feels closer to the stock low stall converter. Just saying.

Do an all or nothing launch and see if you like the converter.. Tires needs to hook up though. If it is spinning it will feel no better.
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post #4 of 10 (permalink) Old Jul 17th, 17, 10:01 AM Thread Starter
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Aleksander
 
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Re: Holley Carb tuning 396

I might be missing something here but it was dynoed on a loaded dynojet that was conected to the hubs so to me the afr 13,7x is under "almost" real load. I have never really had a problem with the car not sticking its been more of a problem of mine . i want it to smoke some tyres. i guess that is the problem with a big and rather meaty tyre. 305/30-20.
I would hope that someone is running my cam in a simular engine to tell me where to go but we will see what happens.
Ive been mostly driving with my kid and wife so i havent gotten to really test the converter yet we will see when i really try it out

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post #5 of 10 (permalink) Old Jul 17th, 17, 9:52 PM
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jeff
 
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Re: Holley Carb tuning 396

Did you finally get it to rev past 4500 RPM
I remember you changed valve springs as seat load was way low.

Is it making more than the 245HP at the hubs now?

The things i do not like or should I say not care for on the 396 of yours is the 9.5 compression pistons.. that is assuming about 100cc chambers.
If the valve job sunk the valves you could be much lower.
This kills some power. Cylinder pressure makes TQ.

You have a smallish cam but where the intake valve closes makes a huge impact on Tq .
Most cams ground wider close the intake valve a bit later bleeding off some cylinder pressure.

I have found with weak flowing heads (say stock non ported) that tight Lobe centers help them out.
Earlier closing intake valve and more overlap to pull that extra air in.

Maybe I am in left field thinking circle track engines. Non ported head rules etc.

I would port the heads run a lot more compression and larger cam an a tighter LSA.
But that may not be your goal.. a gas sucking 396.

Take it out and hold throttle to 1500rpm with brakes on then nail it to flash that converter and see if it spins the hides.
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post #6 of 10 (permalink) Old Jul 18th, 17, 3:35 AM Thread Starter
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Aleksander
 
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Re: Holley Carb tuning 396

Thank you Jeff. Yes it now spins above 4000. by how much i do not know my shift light is flashing at 4500 *blush* and i rev past that. like i said i have only been driving around with wife and kid this year so how it really preforms i do not know .
I should have cc`d the heads that way i could tell how much the valves had sunk in but i shaved the heads so i thought id pick up some there but who really knows now. Its my first engine build sience high school and it was on a budget. i would not be suprised if i start a bigger build later on with a 5xxcu block. Maybe i take it back to the dyno later this year and se how far it spins. going to do a get back to you with the all inn launch later and we will se how it goes.

oh one more thing can i do a compression test and find out if i am really low with the cr? if so how and what should i be seeing for numbers? i know this is not accurate but it might give me an idea if its really bad

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post #7 of 10 (permalink) Old Jul 18th, 17, 8:10 AM
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jeff
 
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Re: Holley Carb tuning 396

You can check cranking pressure but there are a dozen factors to consider.
When you do it take all spark plugs out and have the battery fully charged and open the throttle.

I have checked throttle closed and throttle open and seen 15 psi difference.

Hey for your first build since high school and doing it on a budget it's a really good build.
That thing should give you 100,000+ miles of good times.

And sounds like it is more of a drive the wife and kids around vehicle.
I have never been out of the USA and I have no idea on how the laws and streets or race tracks are in Norway.

Around here sometimes you have to full throttle blast it just to merge onto the highway or get ran over.
The track is 50 miles from me and $15 on test and tune night gets you as many passes as you dare to make.
Or as many passes as you can after getting back in line and waiting.
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post #8 of 10 (permalink) Old Jul 18th, 17, 8:48 AM Thread Starter
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Aleksander
 
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Re: Holley Carb tuning 396

well th 400 3.73 rear gear 27 inch tyre i am glad its not ment for the freeway. planning eigther a gear vendor or a 4l80e next season so i can actually use it as a holliday car and go somewhere other then into town and scare the pedestrians. Parts here are pricy though so keeping the build in budged was not easy. i had to to all my self other then the +0.30 and milling of head. i think "hope" i ended @ 3,5k $ in the engine and i dont think that is to bad. We do have a small open drag comming up close soon but i need 3 point harness and well i dont have it so i guess i will not attend

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post #9 of 10 (permalink) Old Jul 18th, 17, 1:23 PM
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Tom Terrific II
 
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Re: Holley Carb tuning 396

is your car a 69? should have the roof mount for the shoulder belt. feel along the headliner above the trim, see if you can find it.
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post #10 of 10 (permalink) Old Jul 19th, 17, 3:52 AM Thread Starter
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Aleksander
 
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Re: Holley Carb tuning 396

I found this picture of the car before it came to norway so apparently there is hope to fit 3 point harness. but i am not racing it ..."yet" and i have no headrest so i really se no big point in it yet
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