Duntov “097” vs 30-30 Camshaft

[allcoupedup]

Looks like you have flat tops. Unless your cylinder head chambers are small or your block has been decked your comrpession ratio might be different than stock. LT1 and 30-30 like higher compression motors. You should measure and determine your actual static compression ratio so that you do not have another engine/cam mismatch. Measure your piston/deck height and your cylinder head combustion chamber volume and select a head gasket to get you between 10.0:1 and 10.5:1. If you cant get in this range you can change/modify the pistons/heads. If you get below 9.5:1 you might think about using a different cam.

Regards,
brian

 

[Vette66AirCoupe]

This is making me think back to when I took my '60 back to the dealer who sold it to me for an intake/carb swap we agreed to at the time of purchase. I asked him to adjust the lifters on the "283/230" engine it was purported to have in it. Pretty loud for hydraulics I thought. No wonder, it was a solid lift cam! Oops, the dealer relied on the sellers info which was incorrect. No harm, no foul, I'm happy to have it as it is. Funny how that noise that was bothering the hell out of me is suddenly music to my ears.

I also remember, WAY back around 1969 when I bought an 097 cam and stuck it in my 283 Chevy SS Impala. I was told to adjust the valves at .012 and .018 which I did. That sucker sounded like a typewriter! God awful noise. I took the car to the speed shop where I bought the cam and the guy said, "well, maybe it's really the 098 cam". What? I wrecked the car soon after becasue I had put my money in camshafts instead of brake shoes but I've wondered ever since what that cam was. Anybody ever hear of an 098 cam? :confused

 

[Vette66AirCoupe]

DESCRIPTION:
SOLID: Excellent response, good mid-range, noticeable idle.

Gotta love that description! Great choice!

 

[BarryK]

Terry, I am still somewhat interested in possiblyt changing out the cam in my car for one with better low-end torque but everytime I think about it I remember your comment as you were next to me at a traffic light (you were in the '60) telling me not to swap out cams because my current cam just sounds too good at idle - nice and lopey!
That sound is the main reason my cam is still in the car and I didn't swap it out last month when I had much of the motor apart.

 

[Vette66AirCoupe]

She's a keeper Barry. At your current horsepower level why bother changing unless that torque issue is really eating you up? Besides, as evidenced by my prior post, cam changes don't always bring the desired result.

 

[BarryK]

it only bothers me everytime I have to take off from a stop...............

 

[Kid_Again]

Hi Kid,

Yes, the 340hp engines had the factory 11:1 domed pistons

Take care,
Brian

Thanks...thought so.

 

[Tom Bryant]

it only bothers me everytime I have to take off from a stop...............

I know the feeling. My '59 was hard to get moving with the 270 horse (097) and a 3.36 rear. I had a 3.70 in for awhile and it was much nicer. I had to take it back out because it was noisey. I have another 3.70 that I'm thinking about putting in but you loose the highway rpms.

Every time I think on this a TKO 5 speed conversion makes even more sense. Have the engine you want and the drivability too. With the 5 speed I could even run that 4.56 Twin Pull I've been saving all these years and still be in the 3.00 range

Tom

 

[BarryK]

Tom
I already have 4.11 rear gearing!
The L76 is just notorious for lack of low-end power.
it's one of the reasons I'm hoping to have the budget in another year or two to pull this original motor and tranny to store and preserve it and drop in a nice 383 stroker motor and a 5-speed Keisler

 

[JohnZ]

I also remember, WAY back around 1969 when I bought an 097 cam and stuck it in my 283 Chevy SS Impala. I was told to adjust the valves at .012 and .018 which I did. That sucker sounded like a typewriter! God awful noise. I took the car to the speed shop where I bought the cam and the guy said, "well, maybe it's really the 098 cam". What? I wrecked the car soon after becasue I had put my money in camshafts instead of brake shoes but I've wondered ever since what that cam was. Anybody ever hear of an 098 cam? :confused

No such thing as an "098 cam"; the "097" Duntov cam was part number 3736097, and they were ground on core casting number 3736098 (which was also the part number for the raw core).

 

[Vette66AirCoupe]

No such thing as an "098 cam"; the "097" Duntov cam was part number 3736097, and they were ground on core casting number 3736098 (which was also the part number for the raw core).

Thanks John, that explains the confusion but not the fact that I couldn't get the valves adjusted properly. I'm guessing I got taken advantage as this was a resale camshaft (allegedly only used for one 1/4 mile run at Cecil County Dragway) and I was 17 at the time and didn't know squat from Shinola. Who knows what that camshaft might have been!

 

[speedmaster4]

back in the early 60's when you went to the parts counter at the chevy dealer and ordered a service repacement cam for an 097, the part number in the book and on the cardboard tube that it came in....098....i bought a bunch of em.

 

[saopm]

Is there a general rule on compression? What is the highest I can go on 93 Octane? There must be some point of diminishing returns.

 

[speedmaster4]

general rule for streetable comp ratio---octane of gas divided by 10 for iron heads,add 1/2 point for soft heads...so 93 octane = 9.3 comp ratio with iron heads, 9.8 with alum heads....many, many other factors can push up or down somewhat, but this simple, stupid method works

 

[saopm]

According to the 1963 Corvette Shop Manual the compression specification for the ’63 340HP motor is 11.25:1. What kind of octane fuel was readily available back then? 110 octane? Or did most people just retard the timing?

 

[Vette66AirCoupe]

back in the early 60's when you went to the parts counter at the chevy dealer and ordered a service repacement cam for an 097, the part number in the book and on the cardboard tube that it came in....098....i bought a bunch of em.

Interesting. So either way the valve lash was the same I would presume. Does .012 and .018 sound familiar (intake/exhaust)?

 

[allcoupedup]

I run 10.0:1 (actually measured and calculated) and it runs fine on 93 with 10 degrees initial timing. I think I could run 91 if I had to.

11.25:1 was an inflated figure although the 340HP engines came with two steel shim head gaskets to stop some detonation problems. Most people find that they can run up to 10.5:1 on 93 octane with an SHP cam and stock heads. If you're right at 10.5:1, you might have to back off the timing a few degrees.

I recommend shooting for 10.25:1 with the 097, 30-30, or LT1 camshaft. You shouldn't have any problems.



Regards,
Brian

 

[speedmaster4]

saopm:

sunoco 260 was what "everybody" who owned a 'performance' car used... reputed to be 104 octane minimum...after getting a new car,standard procedure was to get a "curve kit" for the distributor--throw away the 'slower' advance springs and just stick on the 'teenie' ones...without headers,gears(rear end), carb rejet, and 'curved' ign--you'd get eaten up on the way to work, not to mention at the strip...pinging or bucking (whole car shakes) meant shift down dummy--retard the timing and loose hp-no way

vette66aircoupe:
actually .014/.018 as i recall...but everybody had their 'speed secrets'

 

[Subfixer]

I'm running a .060 over 327 with 10.5:1 compression and an LT-1 solid lifter cam @ 12*BTDC initial timing with no detonation problems on 93 octane.

While not an original L76 car, the trans is a WR M20 pushing a 3.36 rear. The lower 1st gear of the WR trans works well in this combo. The torque is "almost" as good at low RPMs as the original 300hp engine was. Big difference in the upper RPM's.

 

[Tom Bryant]

Factory recommended clearance for the 097 was .012 and .018. Most of us set the intake to .008 to get a little more intake duration. You will hear a lot of old timers say 8 and 18. Of course the 30-30 cam was .030 and .030. Hence it's name.

In this area of the midwest regular leaded gas back then was 90 or 91 octane at most stations. Low octane (89 and 88) started showing up in the 60s. Sunoco was one of the first with their custom blending pump which started with 190 (89 octane advertised as an economy fuel that we called p*** water) and originally had every graduation by 10s up to 260 (104). The idea was you could blend your gas at the pump to get just what your car needed.

Other stations just had regular and premium. Middle grade is a product of the unleaded period. Leaded premium usually was 97 or 98 except for Union76 which was 104. On the Sunoco pump scale 240 (98) was premium and was priced with other brands premium. 250 (100) and 260 (104) were high performance fuels.

If you had a Union 76 station close by it was the real bargain. Since their 104 premium was their only premium it was priced the same as competitor's premium so you saved a couple cents over Sunoco. The bottom line is that in the '60s you had no problem buying the right fuel at local stations for your 11:1 muscle car with all the timing cranked in it could take.