Hey guys, I found a Lunati catelog they seem to have alot more options for big block cams oposed to the comp cams I was looking at. Other than lift what should I be looking at? Is the lift the main thing that sets that rough choppy idle? I know converters and gears are all taken into condieration, headers, etc.... I will probably gear this thing down the road sometime next year and change the tranny, etc.

Phil, Check out the BSE build sheet. I am sure you have seen it floating around this site. Street friendly and it ROCKS. Mine loves 90 octane pump gas, tire frying rocket. It goes rumpty bump bumpty rump too! I am gonnna go 11's with it this spring. Mr.4 Speed this site is running a little less cam, his cam would serve you nicely as well. No doubt you would like either one! With stock 049 heads, around 9.5/1 compression and a holley avenger carb your looking 490 horse 525 torque all on a very nice curve. It's enough to put a big grin on ya every time I start the car!!!! :cool:

Duration to a point makes the choppy idle. Probably more so the rate of lift and the area under the curve.

Personally, I'd ask what relatively mild cam will make the most power. So what if the idle isn't as bad ass as the competition.......showing them your tail lights is what counts!

As I said before, I ran high 11's with a Comp 280H in my 70SS. Choppy but crisp idle....like they say. And GREAT power.

As an old buddy once said...."so what if it smokes a bit....who's eating it?"

Hey Craig you like that Airgap manifold? I had one on the small block and im putting the same on the BBC. BSE Build sheet?

The 280H is probably in my top 2 choices out of comp cams. Im looking through the lunati now, just cruisin' the options. Lunati PN# 07201LK .540"
.540" Lift HYDRAULIC, Fair idle. Good performance street camshaft with a lot of low end and mid-range power. 2800-6000 Range. Im not sure what there def. of a fair idle is though. But the numbers seem pretty good. Something right under 550 lift would probably be good. From what Ive read about my oval closed heads.

See this is where im thrown off a bit. The 02003LSK Lunati Cam has only .519 lift, and it has a lopey idle. I think the duration is a little more.

Another example.......
When I sold off my 70 Chevelle SS, I kept the engine.
I sold the heads (Closed Chamber 1970 heads) to a buddy with a 70 Nova.
He put them on a flat top 468, with a Comp 292H Cam......a bit big in my book. I also sold him my Perf RPM manifold and my 3310 Holley....and I'll be damned if he didn't run 11.7 @ 114 in his Nova...shifting at 5500.....with 3.08 gears!
To be honest, I didn't think the 292H was a good choice, but he had enough converter to make it work with the 3.08's.......
So I think the 292H might be another consideration....but you better have a loose conv.
Ron

Phil, The BSE build sheet refers to a proven combo that was put together by Ed Bigsley / Racer1320. He use to post here often, but not anymore. Some liked him, some did not. None of that matters. Run a search on this site, or I am sure someone will dig it up. The list covers the complete build, even the converter that works with the combo. I know several folks that have come fairly close to matching the engine build, and I have not heard anyone complaining about the performance that they ended up with. I was looking to put together a combo a few years back, wanted to replace a weak 350 with a BBC. (Sound Familar?)I didnt know squat, found someone that did (Ed), and put it together. Ended up very happy first shot out of the box. Bad ass pump gas RAT. If your gonna build it one time, you will be hard pressed to do better for dollars spent going the BSE build. That's my story and I'm stickin to it!!!!!! graemlins/thumbsup.gif

BSE Combo is as follows:
"454+.060 = 467
-TRW # 2399 pistons with Speed Pro file fit rings
-10.0 - 10.7 CR depending on deck height, final combustion chamber volume and head gasket used.
-Clevite bearings - mains, rod and cam
-Fel-Pro gaskets
-GM 3/8" rods with ARP bolts and GM crank(cast is fine at this level) with ARP main studs and GM windage tray
-Moroso 6-Quart kicked-out pan # 20401 with pickup # 24440
-Melling oil pump
-Manley or DynaGear double roller timing chain
-#215 closed chamber oval port heads '67 - '68 with 2.19 / 1.88 valves, gasket matched and bowls blended
-Performer RPM Q-Jet Manifold with GM lifter valley splash shield
-Q-Jet carb with 75 main jet, 45B primary rod, AX secondary rods and B hanger
-1/2" phenolic 4-hole spacer
-GM carb heat shield
-Ultradyne 288 / 296 hydraulic cam with matching springs - double w/damper. cam specs are 231I / 239E duration @ .050 with .550 / .575 lift ground on a 110LSA. Install on a 108 intake centerline
-Rockers - either crane steel long slots or a roller. Isky are the best aluminum, Crower the best Stainless steel. Neither are needed at the power level.
-3/8" one piece pushrods Crane or Comp
-MSD ignition- 6AL box, coil and distributer(optional-allows easy curve adjustment)
-Headers - 1 3/4" PRIMARY TUBE WITH 3" collectors. Remove collector(cut off) and install(weld) Flowmaster Scavenger Collectors # C-134214300
-3" headpipes with 3" crossover and 2 1/2" tailpipes. All bends to be mandrel. Use Flowmaster Big Block mufflers 3" in and out, offset - offset (quietest performance muffler) or DynoMax Oval RaceMagnum.
-Mallory Comp 140 fuel pump, regulator and filter plumbed to stock 3/8" fuel line.
-Mobil 1 10W-30 oil, Ford type F trans fluid and Mobil 1 gear lube
-indexed spark plugs
With a turbo 400, ATI 10" converter, 3.73 gears and either slicks or DOT slicks this combo will run 11.60's to 11.90's depending on weather, tuning and driver. My best was 11.49 @ 115 in mine shaft air weighing 4000+ lbs. on pump gas.

This combo is fully streetable and was regularly driven to the track some 140 miles away and 2+ hours(one way) on a weekly basis. It was driven anywhere, never over heated and got 12-13 MPG on the highway with a lite foot.


Set the total timing to 36 degrees and shift at 5800 for best ET.

For my current combo just substitute a Comp cams street roller 238I / 244E duration @ .050, Performer RPM Air-Gap(not worth any ET), Holley 950 or 1000HP, 4.10 gear, lose the tailpipes and raise the shift point 200 RPM to 6000 and you'll run high 10's. Just don't forget things like a roll bar, SFI balancer, SFI bell housing shield, non-clip axles, and a real good suspension / tire package."


I found it.........check it out. Craig

What tire size would you run with the BSE combo with 3.73?

I'd run a 275/60/15

i think first of all you should ask yourself how much vaccum do yo need ? do you have power brakes a/c and if you sacrafice the vaccum in favor of an idle are you willing to drop the 250-300 bucks you,ll need for a electric vaccum pump. if your gonna run at street lvl with some strip use id go towards a cam that makes extreme torque . the bigger the duration the less vaccum you have and the more gear and converter you need .

Ive got 295/50/15's it was fun making those fit ;) I have front disc, and rear drum, gutted the AC. Well that makes sence about duration, more converter and vaccum, Ill keep that in mind. Ive been cam shopping for about a week now smile.gif Ive found lots of nice prospects!

I wish someone here would run the Comp 280S. It looks like a great grind with mint midrange peak.

Lift has nothing to do with the sound. Lobe separation and duration make that choppy sound. The choppy sound is created when the intake and exh. valve are open at the same time to create a vaccum filled chamber effect. Lift however is determined by how well your heads flow. If max cfm is found at say .600 lift... then you would want a cam with say .630 lift. because .022-.030 will be taken away when you adjust the valves, plus rocker arm deflection would put you right back at .600. Duration basically in a nut shell sets the RPM range because its how long the valves are open relative to crankshaft degrees. Check out 3 or more cams 10 degrees is eqaul to "about" 200 rpms + or -. ;)

So with lift, the closer the intake and exh numbers are together gives more vaccum/ choppy sound?

Please consider onna the Isky 280 Mega grinds, either on 108 or 110.....

High lift to help torque to say the least..

pdq67

Have a link for that Isky? smile.gif

Think the lift may be too high for my springs? It looks pretty good though.

Grind No./Type
280-MEGA HYDRAULIC High performance use/bracket racing. Lopey idle. 2500 Stall. 9.5-10.5
1 compr. 3.90-4.11 axle ratio. Up to 780 CFM Carb. RPM-Range
2500-6800 Valve Lift - INT
.565 EXT
.565 Valve Lash Hot - INT
.000 EXT
.000 ADV Duration - INT
280° EXT
280° .050 Duration - INT
232° EXT
232° Lobe Center
108°

What would you guys choose between the 280H and the XE274H? If I can pull of the 274 Id go with that, the duration and lift is a little higher it requires a 2500 stall which I wont have and the lift might be a hair high for my springs, but if I could get away with it, then id go with that. If not 280H!

With 9.5/1 CR., you don't need an XE cam. Also, you will most likely have retainer/guide clearance issues at .550 lift, unless the guides have been cut down. THe 280H will have plenty of the lopey sound you want and power to spare. Also, the XE line tends to be a little harder on parts. Just so you understand, amy cam in the 280 range ground on a 110LSA will have that lopey sound you want.

Something to remember, Isky cam lift specs are using a 1.75 ratio rocker arm instead of the standard 1.7.

Actually it's overlap that causes a choppy idle. Overlap is when the int and exh valves are open at the same time, right before the intake cyle. Leftover combustion gases contaminate the intake charge, causing a weak explosion or misfire. A good rule of thumb:
Overlap (@0.050") of 0 degrees or more is where a noticeable lope starts.
Overlap (@0.050") of less than 20 deg in a BB is needed for vacuum brakes.

try the Isky Z-45...
it runs good... i promise!

slpin- what is the rest of the equation with the Z-45?

An Isky solid cam, PN Z-45 = 278/244, 108/108, .530" gross lift, .018" lash. This sucker should have an awesome midrange, imho!!!

http://www.iskycams.com/

Sorry, I thought we were after onna the biggest 280 hy-cam grinds out there is all.. Forgot about the shorter valve springs thing...

pdq67

I'm gonna chime in here. If your wanting a decent cam one that sounds as good as it runs I have had good luck with a couple. The first is Lunati # 40208 specs are:

2500-6500 rpm
310°/320°
247°/255°@.050
.558" Intake .566" Exhaust .022/.022 lash
Lobe c/l was 107.5

This cam ran 12.0's @ 114 reliably and 11.0's-10.90's @ 124-5 on a 150 shot. Motor was a 049 headed 468 with 9.3:1 compression in a 3650 car w/3:73's and 2500 convertor. Sold the motor to a buddy with the same combo/looser conv(3000) but with a 250 shot smacked to it made it run 10.20's @ 135

Second Cam is UD 288/296F10 do a search on it. It's one of Harolds before he went to Lunati. I love this cam:) It doesn't idle like the one above it chops and pops like a roller. It specs out at:

255°/263° @ .050
.612" Intake .630" Exhaust I run it @ .022 lash for aluminum heads
Sep is 110°

Performance wise I do not have any data yet but in feels much stronger in the mid-range than the 40208 Lunati did in a 400lb heavier car with 3:23's :D Chris_69_SS has one as well as a wav file somewhere, his car runs 11.30's in the 120 range with this cam. Chris's Car & Combo (http://www.geocities.com/me2gap/Chris_69_SS.html)

Gene,

Yes, bet you are right that a CC 280S at 280/242/285/250, 110/106, .575"/.604" gross lift would be a winner here!!

Did anybody ever ask what his rearend gears are??

May be should know before the dreaded, "more power, Scottie", bug bites too hard???

pdq67

Originally posted by pdq67:
An Isky solid cam, PN Z-45 = 278/244, 108/108, .530" gross lift, .018" lash. This sucker should have an awesome midrange, imho!!!

http://www.iskycams.com/

Sorry, I thought we were after onna the biggest 280 hy-cam grinds out there is all.. Forgot about the shorter valve springs thing...

pdq67 ya... around mid-high 9:1 396, 2 ton+ car, 3.31 rear, stock 049 heads... it ran 12.8@108, untuned...