Duntov “097” vs 30-30 Camshaft

[motorman]

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.

the 30-30 cam was speced at .025 when it came out but there was not enought vacuum for the FI to run correctly so they changed it to .030

 

[Stan's Customs]

Is the LT-1 cam referred to in this thread the same cam that was in the 370 hp solid lifter Lt-1 350 crate motors around 1970?

~Stan...

 

[Tom Bryant]

Yes. Also in the Z28 and '70-'72 Corvette LT1

 

[Seaside63]

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.

Subfixer, may I ask what pistons and heads you are running to get the 10.5:1 ?

Thanks, SS63

 

[Stan's Customs]

Thanks Mac...I have a few other questions too.. I'll start another thread rather than hijack this one...

~Stan..

 

[Subfixer]

Subfixer, may I ask what pistons and heads you are running to get the 10.5:1 ?

Thanks, SS63

I'm running stock '64 300hp (.060 over) replacement pistons (brand unknown), and stock 461 heads with 1.94/1.50 valves (as came with the 300hp engine. Head gaskets are single standard steel shim gaskets (I didn't measure the thickness).

The CR is assumed as the shortblock was originally built as a replacement 300hp engine (original unbored shortblock in storage). I have not done any of the math necessary to calculate the true CR.

Although I think I'm mistaken with the CR. As stock, the 300 hp version came as 10.25:1 not 10.5:1. With that said, the assumed CR should read 10.25:1.

Lots of assumptions, but it sure runs great. Spins the tires without much effort and plenty fast enough for me.

 

[saopm]

Does anyone know the stock volume of the 461 heads? My guess is between 62-65cc.

 

[Seaside63]

I'm running stock '64 300hp (.060 over) replacement pistons (brand unknown), and stock 461 heads with 1.94/1.50 valves (as came with the 300hp engine. Head gaskets are single standard steel shim gaskets (I didn't measure the thickness).

Thanks Sub,

My engine has the domed pistons but I haven't decided what to put back in there. I was thinking of using a thick composition gasket to drop the CR a bit but maybe flat tops is really what I should be looking at.

I appreciate the response.

I also can't decide between the original 097, a 30-30 or the LT-1. It appears that the LT-1 loses the idle characteristics of the 097 and 30-30.

 

[Seaside63]

Does anyone know the stock volume of the 461 heads? My guess is between 62-65cc.

Saopm, that's the numbers I've always heard.

 

[Subfixer]

I also can't decide between the original 097, a 30-30 or the LT-1. It appears that the LT-1 loses the idle characteristics of the 097 and 30-30.

The rough idle is still there but not as pronounced as the 30-30. More lope than the L-79 (350hp) cam.

 

[allcoupedup]

Does anyone know the stock volume of the 461 heads? My guess is between 62-65cc.

Measure them!

I purchased a "rebuilt" set and set them side by side with my cores and got a funny feeling so I CC'd them. Most chambers came out to about 57 CC due to multiple millings. I could have unshrouded the intake valve to add some CCs but I decided to use another set of heads.

Most 461s are 62cc - 64 if they have been unshrouded. If you use 62 cc in your calcs you might be OK but you leave the door open for trouble. If your heads have ever been cut (milled), the Combusion chambre is likely less than 62. Most first time rebuilds are OK because a head cut is offset in terms of compression ratio by the use of a thicker head gasket.

Since you have non stock pistons and are going with a decking, you really need to measure all variables to be sure you don't end up with a dog motor or one that needs race gas.

Brian

 

[allcoupedup]

Thanks Sub,

My engine has the domed pistons but I haven't decided what to put back in there. I was thinking of using a thick composition gasket to drop the CR a bit but maybe flat tops is really what I should be looking at.

I appreciate the response.

I also can't decide between the original 097, a 30-30 or the LT-1. It appears that the LT-1 loses the idle characteristics of the 097 and 30-30.

If you need to drop the CR and have a choice between flat-tops or domes and a thicker gasket, go with the flat-tops. The reason is this will decrease the quench. With a given CR, an engine with a smaller quench will be less prone to detonation.

If you look at race engines you will often find a zero deck height (or negative) for this reason.


That being said I am using something like .03 -.04 deck height, .03 -
04 head gasket, domend pistons and ~66cc heads. It is not ideal in terms of quench distance but it works and ends up right about 10.0:1. LT1 has a nice nasty idle but I've never listened to a 30-30 and an LT1 side by side.

Brian