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Old 08-21-2010, 03:54 PM
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350 Chevy engine combo help !

I'we got somewhat decent street SBC that i was wondering if it would be possible to make anywhere near 375-400 HP out of with some old school equipment !!!

What I got
350 Chevy freshly rebuilt.
Mallory distributor with MSD 6Al ignition box.
Stock Cast crank and Gm rods.
Forged dome pistons.
3947041 GM heads, with 1.94"/1.5" valves, mildly modified.
10.75 to 1 compression ratio.
Stiffer valve springs and Comp cams Magnum roller rocker arms 1.52 Ratio
Old Edelbrock TM-1 Single plane intake.
Holley 650 Cfm double pumper carb.
1.5/8" Long tube headers.

I was hoping for someone that could point me to a decent camshaft, that would direct me to my Hp goals, and be streetable if possible !
I would like to use Hydraulic Flat tappet cam that can not be to lumpy, need vacuum for power-brakes and such !

Would like the RPM range to be from 2000-6200/500 If possible.
Do you think it would be possible for me to make these kind of HP numbers with my old school equippment ? with begin street friendly.

Best regards, and hope for help -_-

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Old 08-21-2010, 06:42 PM
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sure those parts will work you can do anything if u have bottomless pockets
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Old 08-21-2010, 07:46 PM
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Use a Isky 280H Mega cam isky #201281
www.iskycams.com
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Old 08-22-2010, 09:06 AM
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Is my intake manifold holding my back in making any decent Hp numbers ?
Thanks for the recommendation F-Bird
Best regards.

Ps. This engine is going into an Old Jeep CJ6 that's on 35" tires and is going to be used mainly as a toy, Sand/mud/snow.
The Jeep Weighs 3100 Lbs race ready W/o Driver. And has lockers in front/rear with 4.56:1 gears.
TH-350 Transmission, What type of converter do you recommend for my ? I only have 2000 Rpm Stall at the moment !
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Old 08-22-2010, 11:13 AM
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The TM-1 will give up a good bit of torque to a modern Performer RPM dual plane
The 280H mega cam wants a 2800-3000 stall. If you want to stick to a 2000 stall use the next smaller 270H mega cam. Isky #201271
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Old 08-22-2010, 11:18 AM
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4.56 gears with 35 inch tall tires is like a 3.65 gear with 28's. so, you shouldn't run too big of a cam. But since the jeep is light, you have some leeway.

but the compression is high (10.75:1) for a smaller cam. So, you have a mismatch here. (gear doesn't match the compression ratio)

to get a smoother idle and be able to use that much compression, you need to use a wide lobe separation angle (LSA). a wide lope separation reduces overlap which smoothes out the idle and closes the intake valve later which bleeds off cylinder pressure. However, wide lsa's reduces peak hp and peak torque but extends the rpm range and gets better mpg with a better idle.

I thinking a cam with 280 degrees advertised with 230 degrees at 0.050" ground on 114 LSA should do the trick. Then use a 2600-2800 stall. Set timing to 20 degrees at idle, 36 total, then use the an adjustable vacuum advance on manifold vacuum with 10 degrees more timing. so timing should be 30 at idle (with the vacuum advance) and 46 revving in neutral (with the vacuum advance).

furthermore, those heads will need screw in studs and guide plates. stronger valve springs will pull out the pressed in studs.

I would use a regular RPM intake (non-air gap).

the heads are the bottle neck in making power.

get some aluminum heads to compensate for the extra high compression. edelbrock performer heads would work ok.
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Old 08-22-2010, 11:18 AM
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i like the compcam 280H, that could get you 375-400hp, the 350 could use a 750dp, with the 2800-3000 stall
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Old 08-22-2010, 02:42 PM
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I am thinking about going with 3000 stall converter, because this is only a sand toy. But another thing, Would it be Impossible to run a cam like this on pump gas with my compression ? 93 Oct would be OK. since this is not daily driven.

Best regards. and Thanks !
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Old 08-28-2010, 08:33 PM
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Well i'we have reached a final decision on how I want to have my Jeep.

I am going to finish it this fall and would like to bring it up to you guys before i start making some progress !

My plans have changed a bit, Since this is only a dune toy and sand drag racer, I'we got my hands over a 8" 4500 stall Coan Converter that i'm going to use in the Jeep !

I'm going to raise the compression to 11:1
I Want to run solid lifter camshaft, with about .500"-.550" lift, but then it comes to the question, What LSA would be the right one ?
One day I might add a small NOS system - 150 Hp / 200 Hp Max.

Hydraulic VS Solid camshaft for my application ? Talking flat tappet here.

Also I plan on running this type of rocker arms - http://www.summitracing.com/parts/CCA-1411-16/
Are they capable with mechanical cam, with this type of Locks ?

Would the TM-1 Intake be Ok or would Victor JR be a better choice performance vise. What about Performer RPM ???
I think i wont spin this engine much over 7000 RPM !

Would my 650 Double Pumper be Ok or should i go to something bigger ?

Since i'we decided to only race in this Jeep then I'm going to run it on 100 OCT LL Aviation gas

Spell the beans !
Monzter.
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Old 08-28-2010, 09:55 PM
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Solid lifter cam all the way, will make more power than a similar hydraulic. Howards cam #110812 249/252 @ .050", .534/.542" lift, 106 lobe seperation would work good 2500-6500 rpm powerband. # 110822 252/260 .543/.563" lift 106 seperation would also work 2600-6800 rpm powerband. These are both tight lash (.016-.020") cams, easy on valvetrain. Get the direct lube lifters.

Howards Cams available at www.competitionproducts.com . They are a great place for engine and valvetrain parts. Don't forget springs to match if you are not sure what your current spring specs are.

Any modern intake will beat the TM-1 badly. Vic Jr, Holley Strip Dominator, Pro Products Hurricane, Weiand Team G. A Performer RPM or Air-Gap if you want a dual plane, but the dual plane would prefer a bigger carb due to the divided plenum(each cylinder only "sees" half of carb). An HP main body upgrade for your 650 DP turns it into a 750-780 DP, these are a great upgrade. The 650 would be great on a single plane like those listed, you could always increase its size later with the main body..

Adding a 2.02" intake valve with the related bowl blending/chamber relieving will really help also, so would a 1.6" exhaust but not as critical, could stay with 1.5"

Your rockers will work, might need better nuts(polylocks).

If you are making a commitment to 100LL, why stop at 11-1, go right to 12.0-12.5/1. Only stay down at 11-1 with the 100LL if you are serious about using the nitrous, 12-1 and nitrous will require 110 race fuel.

Should be a rocket off the line with that converter, expect a 3800-4000 stall from it behind your 355.
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Old 08-28-2010, 10:58 PM
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With a 4500 stall use isky cam #201CC1, needs a stiff rear gear too.
The TM-1 will work fine. 10.75:1 cr is plenty.
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Old 08-29-2010, 09:24 AM
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The thing i was wondering about the rocker-arms locks was if I could use them with mechanical camshaft or would i have to go to Poly locks ? Since this a'int going to be anything other than a racer, then i don't mind checking valve lash once in a while !

And yes about the gasoline, I wan't to keep it on the Aviation gas With or with-out NOS because of the cost of the Race gas ! Also if I could get away with using 93 Oct just on Motor then that would just be bonus !

I need to check my valve springs to see if they fit the bill for what i'm going to do ! And also need to tear down the engine to see what camshaft is inside now... I'we seen that with spring that many guy's are using are the Comp's 981, but with my calculation's they can only handle about .500" lift, is that true ?
Would it be needed to make the seats deeper so that I can handle all the lift I'm aiming for ?

Solid is the way to go you say, and that's grate to hear that if i'm running single plane intake then I can get away with running smaller carb than with dual plane intake...

Comparing solid to hydraulic HP vise ? what are we talking about here ?

http://www.summitracing.com/parts/HRS-112081/ - how do you like this cam ? is it ground on a to narrow LSA ?

http://www.summitracing.com/parts/LUN-40113/ - Here's one from Lunati, This one has not as much duration @.50" lift.

http://www.summitracing.com/parts/ISK-201027/ - shhh, I'm hooked
How would you think this would perform in my engine ? Would I need as stiff gears with this one compared to the one you recommended Mr. F-Bird ?

Would i be close to 400 Hp with these part's ?

Monzter.

Last edited by monzter; 08-29-2010 at 09:52 AM.
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Old 08-29-2010, 03:08 PM
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The Howards cam you linked is a little big duration-wise for your intended use, will want a 74-7500 rpm shift point. (You want your shift point about 400 rpm above peak power point). It would need more gear. The other two cams would work fine.

At 11-1 you would have to really stay on top of tuning to run straight 93. Mix 93 octane 3 to 1 with the 100LL would work out fine. 100LL straight when spraying over 100 hp. Make sure to retard the total timing when spraying nitrous, 2-3 per 50 hp sprayed. Must have 5 psi fuel pressure insured at all times.

Reason I suggested polylocks is you may or may not have problems with the providd nylock nuts that come with those rockers when used with solid lifters. Polylocks are just foolproof.

The 981 spring might handle the lift, put it doesn't have enough pressure for the solid lifter cams faster rate of lift. Both Competition Products and Isky sell a stock diameter "drop-on" spring for solid cams. Howards #98213, Isky 235-D. I'm sure Lunati has one as well.

Solid cam will be 20 hp/30ft.lbs better than a hydraulic. you should make 400 hp easily, could make 450+ with larger valves and more bowl and chamber work.
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Old 08-29-2010, 03:54 PM
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I suggest you pony up for some real rockers and forget those fosdick Magnum units.

I read a lot of what engineers and tech people from the manufacturers write as well as talking to the racers at my home track, Firebird International Raceway, where I tech inspect.

Several years ago, the famed cam grinder Racer Brown did some tests with roller rockers and determined that the roller tip was snake oil. The diameter of the roller is too small to make a mechanical coupling with the valve stem tip and therefore, the roller just skids across the valve tip instead of rolling. The real value in a rocker is in the trunnion bearing where a roller will lower oil temperature and reduce friction to free up a little hp. It makes little sense to pay good money for a roller tip rocker if it has only a ball and socket trunnion like the Magnum rocker. I'd just as soon walk out to the street and throw my money into the gutter.

If you want to do yourself some good, use rockers that have a roller trunnion. Scorpion is a good quality product at a reasonable price. My personal favorite is Harland Sharp.
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Old 08-30-2010, 10:47 AM
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Well guys. I'we got some good news and some bad !!!

The good news first - They are that these heads DO have 2.02"/1.6" valves and are going to be pocket ported !

Then the bad news - The engine someone sold me as 350 is 327 !!! Which might be good or bad ?

I have calculated the compression using this 327 with the Dome pistons, Their NR are L2166N and are supposed to be -5.3cc Dome which puts me right at 11.1:1 Comp

Eric These valve springs you recommended for use with solid cam are a little to stiff, The Isky springs do have spring rate of 350 Psi which is the MAX for the magnums Chromoly Steel, At least that's what they say at Comp Cams.

So Possibly I have to aim for new camshaft because of these news ?
I'm still going to run this 8" 4500 stall Converter in the Jeep and I need it to spin somewhere near 7000 RPM !

Should i Keep the TM-1 On because of this small engine or go straight to Victor JR ?

Anyone made good sucess with 327 ?
Could I make as good engine with it as I would with 350 ?

Monzter

Last edited by monzter; 08-30-2010 at 10:54 AM.
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