INCEASE LOW END TORQUE

General engine tech -- Drag Racing to Circle Track

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magicrat56
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INCEASE LOW END TORQUE

Post by magicrat56 » Sat Jul 29, 2017 5:23 pm

BEEN THINKING OF A CAM SWAP THIS WINTER WITH THE GOAL OF BETTER LOW END/MIDRANGE TORQUE IN MY FULL-WEIGHT CHEVELLE. 3900LB,STREET CAR.I'LL LIST THE SPECS TO THE ENGINE DRIVE TRAIN TO HELP IN YOUR IDEAS. LOOKING TO KEEP A HFT IN THE ENGINE ALSO.THE POWER RANGE OF THE PRESENT CAM IS 3000-6500 PER LUNATI.HOPING TO SHIFT IT TO 1500-5000. ENGINE IS 71 LS-6 SHORT BLOCK;.095 13.9CC DOMES,781 OVALS WITH 2.19/1.88 MANLEY PRO FLO VALVES,BOWLS BLENDED PORT MATCHED.WHAT I BELIEVE IS A PROPLEM IS THE COMP RATIO IS APPROX 8:9.1/9:1AT BEST,WITH TOO MUCH OVERLAP-73*FOR WHERE I WANT TO BE. CAM IS OLDER LUNATI HFT SPECS ARE 296/306,540/540 LIFT. CAM TIMING IS 9/49 INT.62/6 EX.DON'T GET ME WRONG THE CAR RUNS GREAT WITH THE 3:73'S IN IT,IS NUTS WITH THE 4:56'S BUT I REALLY NOW WANT TO RUN EITHER 3:08'S OR 3:31'S. TRANS IS M-20. MY FIRST THOUGHT WAS TO JUST SLIDE IN A LS-5 CAM AND BE DONE WITH IT BUT IN LOOKING AROUNG I KINDA LIKE COMPS 268AH MARINE HFT,268/276,525/525 CAM TIMING OF 28/60INT,72/24EX,52*OF OVERLAP.THE LUNATI IS CUT WITH 114*LSA,110ICL.THE COMP IS 110*LSA,106*ICL.THE OTHER CHOICE RIGHT NOW IS A CRANE 272/284.515/510LIFT CAM TIMING OF28*/64*INT,78*/26*EX,54*OVERLAP. CUT AT 112*LSA,108*ICL. AM I LOOKING IN THE RIGHT DIRECTION WITH THESE GRINGS FOR BETTER LOW SPEED TORQUE AND MANNERS? WOULD LOVE TO SEE MORE THEN 12INS. OF VACUUM AND UTILIZING THE HI-WAY GEARS AROUND TOWN.AS IS WITH THE 3.08 GEARS IN IT IT BASICALLY TURNS IT INTO A 3-SPEED AROUND TOWN. SORRY FOR THE LENGH OF THE POST AND WILL SAY THANKS NOW FOR THE INPUT.

j-c-c
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Re: INCEASE LOW END TORQUE

Post by j-c-c » Sat Jul 29, 2017 6:08 pm

I will say it nicely, others will not, turn off the caps, its hard to read if nothing else.

In-Tech
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Re: INCEASE LOW END TORQUE

Post by In-Tech » Sat Jul 29, 2017 6:18 pm

Since you're gonna get 1.2 million different answers/recommendations I'll throw out, Erson high flowAH. :) idle to 5000+
Heat is energy, energy is horsepower...but you gotta control the heat.
-Carl

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Re: INCEASE LOW END TORQUE

Post by Carnut1 » Sat Jul 29, 2017 6:20 pm

Springsteen fan no doubt. Contact camking with full specs. He knows what grind will do exactly what you want. Thanks, Charlie

magicrat56
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Re: INCEASE LOW END TORQUE

Post by magicrat56 » Sat Jul 29, 2017 6:26 pm

thank you

Monza355
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Re: INCEASE LOW END TORQUE

Post by Monza355 » Sat Jul 29, 2017 7:39 pm

I like the crane cam you listed. I did run that grind in a 350 and it did really good with almost 20"/hg's at idle. It's a decent all around torque cam!

digger
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Re: INCEASE LOW END TORQUE

Post by digger » Sun Jul 30, 2017 1:20 am

I would use a tighter LSA than 112 or 114.

mag2555
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Re: INCEASE LOW END TORQUE

Post by mag2555 » Sun Jul 30, 2017 6:31 am

And what are you running for. Intake Manifold? I ask this because I refuse to read thru your post with the caps on!

magicrat56
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Re: INCEASE LOW END TORQUE

Post by magicrat56 » Sun Jul 30, 2017 7:26 am

going back to my Edelbrock rpm q-jet and 800 Quadrajet.Should I repost my question;didn't know the "cap" thing was going to upset people. at the moment the car has offy low-rise dual quad with 2 780 Holleys that are set-up on progressive linkage and runs fine; just did it that way for the "look" and turned out well.originaly its started life with a eddy rpm intake with a Brad Urban 3310.in all honesty the Q-jet/performer ran the best with the 3:08/3:31 gear sets.with the offy it needs the 3:73;s as a minimum to pull nice at lower speeds,which being a single -plane makes sense. getting back to the cam question all advice is appreciated.

Newold1
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Re: INCEASE LOW END TORQUE

Post by Newold1 » Sun Jul 30, 2017 7:56 am

Try and read and study the previous posts on "the effects of different camshaft LSA" Lots of good info and learning there.

magicrat56
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Re: INCEASE LOW END TORQUE

Post by magicrat56 » Sun Jul 30, 2017 9:02 am

thank you

Boz-Race Engines
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Re: INCEASE LOW END TORQUE

Post by Boz-Race Engines » Sun Jul 30, 2017 10:40 am

your original cam has way too much valve timing and duration for your compression,which will make it lazy down low something along the lines of 274-278 advertised, 226-230 @050 with 109 - 110 lobe sep with a int c/l of 105-106, would be a great choice, a increase in comp by half a point would be a good thing also, you should be able to make more low to mid power with good power all the way to around 5800 rpm still. dont be too shy on overlap its a easy way to give away power and torque where you need it, it will pull a taller gearing with ease
Its hard to move forward if you have a closed mind,
http://www.davidvizardperformanceseminars.com/

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Re: INCEASE LOW END TORQUE

Post by F-BIRD'88 » Sun Jul 30, 2017 1:34 pm

If you want to try something before going to a different camshaft, try this:

Move the current cam to a more advanced position to increase low and mid torque and cylinder pressure with the modest compression ratio.
Move the 238-248 114 LSA cam to a more advanced 106in/122ex phasing.
New .050" timing 13 - 45 in /// 66 - 2ex

Recurve the distributor mech advance for 24-26deg initial base timing at idle and 36-38deg at max advance.
Do this by limiting the mech advance travel stop to 10-12 degrees.

In the dual quad low rise intake install a plenum divider that fully divides separates
the right/left sides of the plenum under the carbs.

If pistons are below the deck at TDC change the head gaskets for .022" steel shim (Detroit, MR. Gasket, GM NOS 1970 Chevelle 454 LS6) style thinner .022" gaskets to increase the cr.

Try this... compare to the dual plane Performer and QJET.

This will make a big difference in low end torque and throttle response
and overall driving impression. Don't overlook adding the full plenum divider. It is critical.
Same cam, different driving personality.

A alternative to changing the cam which listed choices look fine.

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Re: INCEASE LOW END TORQUE

Post by F-BIRD'88 » Sun Jul 30, 2017 2:09 pm

If not to your liking try Isky Cam #396271.
Be sure to verify installed cam timing phasing 108 LSA 104in/112ex.

Same with the Erson Hi flow1H cam mentioned. The installed phasing matters.
Needs to be a bit advanced.

you'd be much happier using Carter/Edelbrock AFB Carbs on that dual quad intake.

Another way is to use 2 Qjets on spreadbore carb adapters on that dual quad intake.

The New Holley/BarryGrant "Street Demon" 2x4 carbs are another great way to go on that intake.

You should have used the Edelbrock BBC Dual Quad Dual Plane 2x4 intake.

Advancing your current cam a good bit will have a profound effect. The more you advance it the better you will like it and the gain in low rpm torque with the low cr in that motor.
Don't be shy. Get the intake C/L in the 104 to 106 deg C/L zone for effect.
try it for effect. Enjoy...

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Re: INCEASE LOW END TORQUE

Post by Geoff2 » Mon Jul 31, 2017 4:39 am

Yes, use the Carter/Edel AFB carbs. Use the Holleys for door stops.

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