JPhillis

I was courious if anyone has tried these series of Comp cams? I am unhappy with my .030 350 and and will be starting a 383 in the next month running .040 pistons with a +125 dome and 64cc aluminum heads. Cam specs:Thumpr Hydraulic Flat Tappet Cam and Lifter Kit Adv/Dur: 295/313RPM Range: 2500 to 6500 Intake/Exhaust Lift: .500/.486
. The lower end will be a Scat crank with 6.0 rods. Single plane high rise intake with a 750 dp.

AlkyIROC

A 383 with .040 pistons isn't a 383 any more.

five7kid

iTrader: (14)

I don't understand the purpose of that line of cams at all. High duration, medium lift, means poor idle characteristics with limited high-RPM power.

AlkyIROC

Some of the old muscle car factory cams were like that. Advertised duration over 300* and lift under .450"

JPhillis

Steven, I am well aware that changes the cid, I just did not know the exact cid with .040 piston. I would think 388. Five7kid, This is kind of why I asked, I like the sound at an idle but need the power band at 2800-6500
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This car will rarely see the street except for a possible cruise once in a while in town. Where I live they have them every Saturday night and the local dragstrip is only seven miles from my house.

AlkyIROC

385.594 CID so you could call it a 386.

A 383 +.010 doesn't sound right but that's what it would be. A 383 +.040" isn't correct since that would mean the 350 block would be bored .070" along with a stroker crank.

five7kid

iTrader: (14)

That cam or the old "muscle car" cams will produce tweaky power, not good either for the strip or street. You'd be much better off with an XE cam like the XE284. 2300-6500 RPM, 284/296 adv duration, .507/.510" lift with 110 lobe separation.

.125 dome is going to produce pretty high compression with 64cc chambers. What will you be using for fuel? What heads?

JPhillis

The Block is a 10243880 that is .030 over stock now. The engine has about 500 miles on it. I thought oh having it popped another .010 over verses just honeing the block. The heads I have purchased are are the patriot performances 2054 with a 215 runner/64cc. The pistons I picked should give me a ratio of 11-1 with the heads I purchased. The fuel I will be running is Sunoco 260GT which is available at the pump here.

SLOWMARO355

.030 is 383.....with the right crank and line boring. .040 is not a 383!

doc221978

I tried one of the thumper rollers in an engine and didn't really care for it. I would say for a flat tappet either LUN-60105LK or CRN-114051. That is the part numbers from summit. I have used that lunati, and was amazed at the sound and power for it's specs. I never got imes with that car. It had problems with vacuum for the brakes, and needs a stall and gears.

As for the cubes..... it really doesn't matter. I know a guy in georgia that has a 350 chevy luv that has 722 hp to the wheels at 8,800 rpm's. 2 4's, and all throttle.... no bottle. It all depends on how it's built. The 305 I used to have would smoke a stock LT1. If everyone wants to believe 2 or 3 inches makes that big of a difference, that is their choice. I will stay with a 430 horse 355, that gets 15 inches of vacuum at idle (800 rpm's)

Sonix

iTrader: (1)

11:1 ? Are you sure? .125 dome (how many cc's is that?) only 64cc heads, and a 3.75" stroke is going to have massive CR.

You will need a lot of cam to bleed that off.

The thumpers are best for sound. They do have a tight LSA, which leads to a narrow strong powerband however. They would be "ok", for a tall geared, tight ratio tranny (T-10 or the like), carb, high RPM, etc. Not good on the street, not that great on the track either.

I thought an 880 block was a vortec block, ie a roller? am I wrong on that?
A solid flat tappet, or solid roller would be my best pick. I like my iskyz-25, but you'd benefit from even bigger, z-27 would work great for you.

AlkyIROC

The cam in my 540 has a 114 LSA. It idles very smooth at 1000 rpm with no rump, rump sound. The HP curve is almost flat from where my converter stalls at 6000 to where I shift at 7400.

JPhillis

Here is the link to the pistons I want to use. I am mistaken the comp ratio will be 11.6-1 with a 120 dome. There will be NO bottle on this car so I believe these should be fine.http://cgi.ebay.com/ebaymotors/New-S...Q5fAccessories

Atilla the Fun

If you have a factory roller block, and are going hydraulic, then I'd say start with the 230/236-110 510/520 cam, and expect to change it after a couple of months to a custom cam.

JPhillis

I have been running a hydraulic flat tappet in there for 500 miles. Thats all the miles that is on that engine now and I hate it.

Atilla the Fun

you hate what? Also I should clarify that when I specify a cam to anyone (I am an automotive machinist by trade) I expect them to realize from the lift that it's a roller, as you cant get that lift with that duration in a non-roller without changing rockers.

JPhillis

I have 500 miles on this engine. It does not have the power I had really hoped for. My plan is to pull the engine back out and go back to the drawing board and redo the whole engine again.

Sonix

iTrader: (1)

Hey Atilla, i've noticed you're really proud of mentioning that you're an automotive machinist by trade, you've mentioned that on many threads here. Just a note, we've got many mechanics, engineers, machinists, and subway sandwich artists on here, and the job a person does has little to do with how much knowledge they possess. I'm not knocking you here, I/we appreciate your input, but you might want to skip the blowing your own horn here, because it may just irritate some. The knowledge you give, will lay down your own red carpet for you.
Just a heads up.

JPhillis

I am a mechanic also and now moved into a factory tech position. I work on big iron and am a JD,Cummins,Cat,and Yanmar tech. This is my first performance small block I have ever built, and am trying to gain knowledge by trial and error since I just moved to NC and dont know anybody here. I am not affraid to ask questions and sure wont say I know it all or even try to come off like I do. I am trying to get helpful info from people who are a versed in building power packed small blocks.

Mike Massey

iTrader: (8)

j i wish i could spec it for ya but im not that good. If i were staying with a hyd tappet cam i would look to the lunati voodoo series or contact comp or iskendarian for a custom cam youll have to give them your cars specs and your goals but i think you will get much better performance than the ***** thumpr

Badass355ciz28

iTrader: (17)

a 350 bored .040 over with a 3.750 stroke would be a 385 ci engine