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What is a better lsa for a 396. 107 or 110. I have a .030 396 with 9.75 to 1 compression rpm intake with 800 thunder series and msd ignition. It is daily driven with a 4 speed and 3.73 gears. I want something that is 2200 to 2500 to 6000 rpm range. I alrafy have a comp cams magnum 550 lift i and e with 292 at 50. And 110 lsa. The second i like is the big mutha thumper. It is 522 intake and 507 exh with 295 intake and 243 intake and 257 at 50 and 107 lsa. Any thoughts would be great
Which one will make the most power? That's the one for me.
But if you're after that sound.. but it runs like a sickly pig... choose the latter. my 3 cents.
There is no better or worse lobe separation angle. It depends on what you want from the motor and what you're willing to tolerate in terms of manifold vacuum. Higher LSA will have a smoother idle with more manifold vacuum for things like power brakes. Lower LSA will have a rougher idle and may not support power brakes, but will make the most power overall. You will find that the majority of aftermarket cams are ground on 110 LSA because it seems to be the best compromise. If I were tasked with camming your motor and didn't have to deal with power brakes, using an off-the-shelf grind, it would be 110. Here is some help in understanding phasing and LSA from CompCams.....Quote:
Originally Posted by 70chevybb
http://www.compcams.com/Technical/FAQ/LSAproperties.asp
You need more static compression ratio to support that much cam, 10.0:1 to 10.5:1 minimum.Quote:
Originally Posted by 70chevybb
Here's the best match I can find for your motor. I know you won't use it, but for the benefit of others on this board, I will outline what I would see as the right cam for the rest of your combination.....
First off, it would have to be a roller cam, with hydraulic roller offering the most trouble-free and maintenance-free. Big block Chevies have a propensity for eating flat tappet camshafts. A builder should also take into consideration that the cam that makes the most max power may not be the fastest cam, if it gives up low and mid-range power to get the top end power. Going fast means producing the most power you can "under curve", not just at the top end.
Howards Retrofit Hydraulic Roller, part no. CL120245-10 cam and lifter package.
1800-5400 rpm operating range, noticeable idle, good street performance, needs at least 9.5:1 SCR....
Advertised duration 278/284 split duration for production iron heads.
0.050" duration 225/231
53 Hydraulic Intensity (low limit for quiet operation and reasonable power production in a street motor)
Valve lift 0.567"/0.578"
Intake centerline 106
Exhaust centerline 116
Lobe separation angle 110
I don't mean to belittle you or demean you in any way, but it has been my experience that these "rump-rump" cams are designed primarily to extract money from the jeans of young fellows who don't know any better. They are what is known to the rest of us old rodders as a "poser cam" and are designed to impress the troops down at the Sonic Drive-In rather than produce good power.Quote:
Originally Posted by 70chevybb
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Im not offended. Im 50 years old and my last daughter is gettjng married in sept. The budget is tight right now but not after September. I bought the 396 for 1500 buck already rebuilt. They installed the rigs wrong as you probly seen in another post. It put a pretty good mark in one cylinder but i ball honed it for the new rings which are cast for now. I just want the car running for the rest of the summer. I choose to install new pistons as the scr was only 8.3 to 1. I am sure it will run a whoke lot better for now. The new engine will be a roller with aluminum heads after the wedding. Thanks for the info