how bad of a combination is this??? even with ramshorn vette manifolds in a 327.. I absolutely love the sound of the 140 cam, but will it run decent with the ramshorn manifolds, or be a complete dog?

car has the m-20 and 3.73 gears with chambered exhaust.

I'm considering this cam compared to the 30-30.

compression is 11 to 1.

thanks

Imho, the -140 cam REALLY NEEDS at least 12 to 1 CR. to run it's best!

I would stay with either the 30-30 OR use say, the old Isky Z-30 at 11 to 1!

SY1 know's more about this than I do so maybe he will chime in....

And I would run open 2.5" dumps right under the ramshorn outlets when I wanted to play to uncork her! Point them straight down inline with the ramshorns outlets...

My long gone Crippled Buddy had the Z-30 in his '58 'Vette rag-top that was hand controlled and I saw 7200 rpm one night in 4th gear AND she was still pulling.

'64, 375hp/327 FI motor and 4-speed, the Z-30 solid cam, same manifolds and dumps and 3.08's!

Talk about a quick 8 miles! 160 to 170 mph was the speed!!

pdq67

I wouldn't do this. It might be something you could live with, but I don't know anyone who has done it. The -140 needs headers and GM says 12:1 pistons as a minimum. Everyone I know that has run this cam, including myself has always been 12:1 or higher motor and with headers. I know it was common when the first gen cars were plentiful and new that guys would swap out the -140 into a stock 302 short block with headers and run them. I met a fellow once who talked about doing this with the old Edelbrock Trantula intake and a -140 cam on an 11:1 302 and he loved it. But I don't know of anyone who's done it with stock manifolds, or the rams horns, which I believe come in a couple different diameters. Maybe the large diameter rams horn would work okay?

The 3.73 would be okay with the M20's lower first gear, but again more rear gear is usually desirable. It is a great sounding cam, but more importantly is it pulls hard, even in a 331. If you really want to do this I'd go with a set of good headers and make sure you are running the correct valve springs for this cam also, they'll be different than the 30-30 springs.

You know, I don't know what springs the 30-30 cam used but the what I call, "Z-" springs, or -142 springs were made to run with the -140 cam if not mistaken.

I will get into my old Chevy Power books and get the spec's of the springs and post them tonight. I just always figured the Z- springs were ran on both cams but now that SY1 mentions it,don't think so.

And the newer LT1 springs are different yet??

But I will say that the Z- springs are onna the best bangs for the buck there is in the way of CHEAP hy-po valve springs, imho!! ($25 to $30/set CHEAP!!!)....

pdq67

PS., Z-28, 30-30 cam springs;
Offroad -140 First Design cam springs; and
Later 350 engine LT1 cam springs...

Back again AND I got Competition Products cat. with the aluminum head and engine crank kit on it's front, HPBooks, "How to Hotrod Small-Block Chevy's" and the 6th Edition of Chevy Power around me.

Competiton Products list the LT-1/Z-28, 1.25" OD dia., springs at":

1.70" = 120#, 1.25" = 300#. Coil bind at 1.16"

They also list the newer LT-1/ZZ3/350HO, 1.273" OD dia spring's spec's at:

1.70" = 110# and 1.25" = 310#. Coil bind at 1.16".

HPBooks list's the -142 spring spec's at:

1.70" = 110# and 1.25" = 260#.

Chevy Power say's 1.241" OD dia., spring PN 3911068 was used on all 302 and 350 high performance engines BEFORE the -142 spring came out!! it's spec's are:

1.70" = 80# and coil binds at 1.16". I love the lack of spec's!!!

(Fwiw, Comp. Prod. lists a stock 1.25" OD dia. spring at: 1.70" = 90# and 1.25" = 220# and coil bind at 1.125".)

Chevy Power also lists the 1.273" OD dia., -142 spring's spec's at:

1.70" = 110# and coil binds at 1.16" with a rate of 358 #/".

I guess all this is telling me that all cams including the old -097 Duntov and 30-30 cams used the stock low performance spring b/c the -142 spring didn't come out until the -140 solid cam came out!!

Therefore I guess we have to say that there isn't such a thing as a hy-po Z-28 spring??? I donno??

BUT I do know that the what they are selling as Z-/-142 springs work darn good!!

Anybody else have more consistent info on these three springs??

pdq67

Ram's horn ehxuast manifolds won't fit into a first gen Camaro. The pipes will hit the sub frame cross bar as soon as they come out of the manifold. Theres not enough space to bend the pipes to clear the frame either.

this isn't going into a camaro, its gong into corvette

thanks

Aaron

All SB's used the same grocery-getter springs (85# closed, 190# open, or thereabouts), which is quite a tribute to Chevy cam designers; the factory "30-30" Z springs were the same rate, but had a better heat-treat for durability. The springs for the -140 cam were higher-rate than the production springs, but were strictly over-the-counter pieces. :thumbsup:

John,

As always you contribute so much to our topics!

Thanks for verifying what I found out b/c I kinda thought it was hard to believe myself......

AND guys, the reason I am digging deep into this is b/c we have spring problem's, plus, I don't want to run larger diameter springs b/c of machining costs and such so I was looking for what worked for hi-po stock cam use.

I think that unless we get into the real hardcore race cams as well as hy- and solid roller jobbers, that Elgins two springs and both the older -142 and newer LT-1/ZZ3/350HO springs will do fine UNLESS I am missing something??

AND note that I am just talking about hy-po street cams!!!


The Elgins springs Midwest Motorsports sells spec's are;

.500" lift stock OD type = PN RV943X, 110# = 1.75" and 325# = 1.20", 1.15" coil bind.

.600" lift stock OD type = PN RV1943X, 125# = 1.80" and 360# = 1.20", 1.15" coil bind.

Both rated at 391 #/".

pdq67

John's right on again on this. Everything I have shows the 30/30 not requiring a special spring. Once you move up the first level to the -140 cam GM recomends at least the 3927142 single spring with damper or the 330585 dual spring. I've run the Crane 1943 single spring with damper on the -140 cam and used a 1.6 rocker arm. That spring is good up to .580 lift and fits the stock spring pocket.

SY1,

You notice crane's PN for that high lift spring?

Crane 1943, then check Elgin's PN from Midwest Motorsports, RV1943X.

I bet they are the same spring...

pdq67

thats good info about the srpings... but what about the original question?>? LOL

even with manifolds, will the 140 pull harder than the 30-30 once its in the powerband? or will it be choked off by the backpressure?

thanks

Aaron

Imho, it would certainly run best with headers, but if the ramshorns are the big, 2.5" outlet jobbers along with 2.5" pipe nipple dumps right under the outlets straight down, it will be pretty darn free breathing, imho!!

BUT you talk about noisy!!

pdq67

yeah... the dumps won't happen.

but i do have the 2.5 jobbers with a 2.5 chambered exhaust on the car.

i think i'll go back to the LT-1 cam for fun street driving, unless anyone knows of a cam that is as or more streetable than the LT-1 and still has the LOPE to boot.

I want it to still sound similiar to the old 30-30 but have a ton more whoop ass.

Thanks

aaron

Imho, I would sure consider either an Isky Z-25 or Z-27 solid cam for whoop-ass!

Z-25 = 278/244, 108/108, .462" net lift.

Z-27 = 282/247, 108/108, .489" net lift.

And them being on 108 centers, they will "cackle" GOOD.

As far as the old -178 solid cam goes, per WBR, it is a 316/242/336/254, 116/110, .435"/.455" net lift solid cam so is a mild grocery-getter type cam to me. I figure these spec's are almost identical to GM's too.

I figure the old -178 cam is actually a modern 294/314 cam to boot so you will gain quite a bit more mid range with either Isky cam due to them being smaller advertised and on 108 centers!!!

How far off am I guys???

pdq67

welll i've read that tight lobe centers and exhaust manifolds are a "no-no" something about the "exhaust harmonics" ??? I can't recall, but it made sense, and i have a roller cam in the car now on a 108 and it runs worse than it did with the LT-1 and all i can suspect is the lobe center becasue it is smaller all around than the old LT-1 but has more lift.

who knows.

i think i'll stay with about 112 on the lobes just to be safe.

Only last week I posed the same question to Jerry MacNeish. He replied that the 140 cam would be fine provided the stock ignition was blueprinted, the spark plug heat range correct, and the carb was jetted accordingly. He didn't say which plugs or jets should be utilized. My Z28 has 4.10 gears and factory cast manifolds.

Jerry runs an M20 and 5.13 gears - 1st is good for about eight feet :D