Which Cam for 1970 LT1

69z28freak · Jun 28, 2012

Which cam should I use in a 1970 LT1 motor.

Here are the other specs
Rear Gear 3:73
Trans M20

Here are some cams I am looking at

Stock GM cam that was in the LT1
3972182 Mech. 242/254 .459"/.485" 11.0:1 116

GM 140 Off Road Racing Cam First Design
3927140 Mech. 257/269 .493"/.512" 12.0:1 112

Ultradyne
531259 278/282 .248/252 & 530/541 108

2 other suggestions

ZLP955 · Jun 28, 2012

Mike, hard to recommend a cam without a bit more build info like proposed compression ratio, heads (I think you were staying with the stock GM iron heads?), etc. Your engine builder should discuss this with you, and the valve springs lifters and so on need to be matched to the chosen cam. You are also staying with the finned aluminum valve covers to resemble a DZ engine, so that will limit your max lift. Might also be worth heading over to the Nastyz28 forum and searching there, plenty of good 2nd gen engine experts there.
A few years ago, I remember a guy who had a Comp Xtreme 278H in his 350 - turns out it's a marine cam and I thought he was crazy, but it sounded fantastic (read "nasty") and he was very happy with the way it made power.... I searched for it and found a sound clip:
http://www.compcams.com/base/multimedia/soundbytes/compcams278.mp3
Enjoy

69z28freak · Jun 28, 2012

ZLP955 said:
Mike, hard to recommend a cam without a bit more build info like proposed compression ratio, heads (I think you were staying with the stock GM iron heads?), etc. Your engine builder should discuss this with you, and the valve springs lifters and so on need to be matched to the chosen cam. You are also staying with the finned aluminum valve covers to resemble a DZ engine, so that will limit your max lift. Might also be worth heading over to the Nastyz28 forum and searching there, plenty of good 2nd gen engine experts there.
A few years ago, I remember a guy who had a Comp Xtreme 278H in his 350 - turns out it's a marine cam and I thought he was crazy, but it sounded fantastic (read "nasty") and he was very happy with the way it made power.... I searched for it and found a sound clip:
http://www.compcams.com/base/multimedia/soundbytes/compcams278.mp3
Enjoy

Thanks Tim I will check it out. I am going to let my engine builder decide which way to go, but I want to educate myself on the various cam options so that I end up with the best possible option. I just posted a thread at NastyZ28. I like that sound byte, that is exactly what I am looking for. That cam sounds similar to the 140 cam.

Here are the details.

Rear Gear 3:73 - 12 Bolt
Trans M20 - Possible upgrade to M22W gear set
11:1 Comp
492 Angel Plug Heads 2.02 valves, same head as 186 with angled plugs
780 Holley 5053 List vac secondaries

alanrw · Jun 28, 2012

Interesting, how do they get to .012" valve lash? What is different about the setup that allows such a tight lash compared to the factory original?

alan

TJS69 · Jun 28, 2012

My advice to anyone using double hump heads is to only use cams that the factory used or something smaller ! These heads do not flow well enough for the new cams.

ZLP955 · Jun 28, 2012

alanrw said:
Interesting, how do they get to .012" valve lash? What is different about the setup that allows such a tight lash compared to the factory original?

alan

Wondered the same thing - never seen such a small lash spec'd for a MFT cam.... am tempted to e-mail their tech support guys to ask!

OAKLYSS · Jun 28, 2012

Use the GM 754 2nd design racing cam. It is the later cam after the 140, and was designed for the 350 LT-1 Z/28.

z28rich · Jun 29, 2012

alanrw said:
Interesting, how do they get to .012" valve lash? What is different about the setup that allows such a tight lash compared to the factory original?

alan

low lash cams have been around for a long time.:yes: if you can spend the extra dollar,go with a roller hyd cam. they can still spin 6500 all day and no valve adjustment.just look at how well the the new LS engines run. Im just about done with my 69 DZ 302 and it has a lunati roller hyd cam..I"ll find out next month what it does on the dyno.:hurray:

69z28freak · Jun 29, 2012

z28rich said:
low lash cams have been around for a long time.:yes: if you can spend the extra dollar,go with a roller hyd cam. they can still spin 6500 all day and no valve adjustment.just look at how well the the new LS engines run. Im just about done with my 69 DZ 302 and it has a lunati roller hyd cam..I"ll find out next month what it does on the dyno.:hurray:

Interesting Rich. I guess I am going to find out soon enough. I am going old school in keeping with the clone theme. I am trying to build a 69 Z 28 clone on a shoe string budget. Since I am not spending much on the motor as the conversion is so expensive, at some point down the road if I am not happy with the motor I can upgrade. I was thinking of building a more modern Motor, hydraulic roller in a newer once piece seal block, but decided to go the nostalgia route instead. I know I would have made more power etc, but I am committed to the project as is. I wanted to have the solid lifter sound and the vibe of a 69 Z 28. I realize by todays standards these old motors are way behind in the performance arena. Just curious how much extra to do the cam upgrade.

Bear in mind that I am looking for a rough idle cam that I can rev high.

69z28freak · Jun 29, 2012

OAKLYSS said:
Use the GM 754 2nd design racing cam. It is the later cam after the 140, and was designed for the 350 LT-1 Z/28.

How is the idle with this cam and high will it rev?

69z28freak · Jun 29, 2012

ZLP955 said:
Wondered the same thing - never seen such a small lash spec'd for a MFT cam.... am tempted to e-mail their tech support guys to ask!

The guy who is building my motor has this cam in his 1970 Yenko Nova with an LT1. He says it runs great. He suggested it to me.

OAKLYSS · Jun 29, 2012

69z28freak said:
How is the idle with this cam and high will it rev?

The idle is very radical, like the 140. Youtube has some 140 idles.

bilodeaulynn · Jun 30, 2012

I am obviously in the minority here, but... why not use the stock 178 cam?

Ran like stink from the factory. Less likely to wipe a lobe. Still pulls strong to 6500, and you are highly unlikely to exceed that on a regular basis if you are driving this on the street.
The 140 barely has sufficient vac at idle for a street car with power brakes. The 754 really does not have sufficient vac. I have personal experience with both, many years ago. Put a 140 cam in a buddy's 68 z in 1970, with the 142 springs. Pulled hard to 8,000 rpm with small diameter long tube headers. I can't imagine running the 754 regularly on a street car. If you are wanting to enjoy the car for many trouble free miles, go with the 178. If you want a little more, go with the 140, but beware, you will spend more time fiddling with it to keep it right. If you want to spend the first hour or so each weekend tuning and figuring out which plug is fouled, adjusting lash and worrying about wiping a lobe, put in the 754.

Just my two cents, and only because you asked.

LT1FUN · Jun 30, 2012

I am running the Comp Cams XE268H in a 70 Z28 with the stock exhaust manifolds and 202 heads, factory aluminum intake and carb with a 4:10 rear end gear and a M21. I find it to be a perfect cam for the street.

z28rich · Jun 30, 2012

69z28freak said:
Interesting Rich. I guess I am going to find out soon enough. I am going old school in keeping with the clone theme. I am trying to build a 69 Z 28 clone on a shoe string budget. Since I am not spending much on the motor as the conversion is so expensive, at some point down the road if I am not happy with the motor I can upgrade. I was thinking of building a more modern Motor, hydraulic roller in a newer once piece seal block, but decided to go the nostalgia route instead. I know I would have made more power etc, but I am committed to the project as is. I wanted to have the solid lifter sound and the vibe of a 69 Z 28. I realize by todays standards these old motors are way behind in the performance arena. Just curious how much extra to do the cam upgrade.

Bear in mind that I am looking for a rough idle cam that I can rev high.

call Shane at Lunati,he'll hook you with a cam:yes:I had a lunati solid in my last Z engine and it really ran sweet:thumbsup:

ace's68 · Jun 30, 2012

I'd go with a more modern design, so I would choose the Ultradyne, they make pretty good cams. Except I'd have that cam on a 110 LSA to pick up some vacuum considering it's got tons of duration already.

I wouldn't choose anything under .500" of lift, and I agree, if you're sticking with camel humps with no work, old school cams are the way to go... Seen a few posts about the DZ302's not running well on anything but the 30/30 and off road cams. I however, just really don't like old, outdated cams, not saying they don't work, I just think there are newer better designs to suit most builds, even ones that are using old school parts/methods.

Also, make sure you get springs furnished with the cam, even if the heads have new springs, you likely won't make it past 6,500rpm if the springs do not match the cam well enough, see it very, very often, especially on guys that use springs furnished with the heads, even with a mild cam!!!

69z28freak · Jun 30, 2012

ace's68 said:
I'd go with a more modern design, so I would choose the Ultradyne, they make pretty good cams. Except I'd have that cam on a 110 LSA to pick up some vacuum considering it's got tons of duration already.

I wouldn't choose anything under .500" of lift, and I agree, if you're sticking with camel humps with no work, old school cams are the way to go... Seen a few posts about the DZ302's not running well on anything but the 30/30 and off road cams. I however, just really don't like old, outdated cams, not saying they don't work, I just think there are newer better designs to suit most builds, even ones that are using old school parts/methods.

Also, make sure you get springs furnished with the cam, even if the heads have new springs, you likely won't make it past 6,500rpm if the springs do not match the cam well enough, see it very, very often, especially on guys that use springs furnished with the heads, even with a mild cam!!!

Thanks AJ that is good advice

TJS69 · Jun 30, 2012

New Cam technology + old head technology = disappointing result.

Old Cam technology + new head technology = satisfactory result.

New Cam technology + new head technology = Awesome result.

Old Cam technology + old head technology = good result.

Unless someone has experienced what you are asking... DON'T believe them.

I have a newer Ultradyne hydraulic cam, and it was terrible with my old double hump heads.

I installed NEW Edelbrock heads and NOW it works GREAT !

69z28freak · Jul 12, 2012

TJS69 said:
New Cam technology + old head technology = disappointing result.

Old Cam technology + new head technology = satisfactory result.

New Cam technology + new head technology = Awesome result.

Old Cam technology + old head technology = good result.

Unless someone has experienced what you are asking... DON'T believe them.

I have a newer Ultradyne hydraulic cam, and it was terrible with my old double hump heads.

I installed NEW Edelbrock heads and NOW it works GREAT !

thanks tom i am going with the stock LT1 cam. that was helpful information.

69z28freak · Jul 24, 2012

bilodeaulynn said:
I am obviously in the minority here, but... why not use the stock 178 cam?

Ran like stink from the factory. Less likely to wipe a lobe. Still pulls strong to 6500, and you are highly unlikely to exceed that on a regular basis if you are driving this on the street.
The 140 barely has sufficient vac at idle for a street car with power brakes. The 754 really does not have sufficient vac. I have personal experience with both, many years ago. Put a 140 cam in a buddy's 68 z in 1970, with the 142 springs. Pulled hard to 8,000 rpm with small diameter long tube headers. I can't imagine running the 754 regularly on a street car. If you are wanting to enjoy the car for many trouble free miles, go with the 178. If you want a little more, go with the 140, but beware, you will spend more time fiddling with it to keep it right. If you want to spend the first hour or so each weekend tuning and figuring out which plug is fouled, adjusting lash and worrying about wiping a lobe, put in the 754.

Just my two cents, and only because you asked.

Thanks Lyn that is great information.

Which Cam for 1970 LT1

69z28freak

ZLP955

69z28freak

alanrw

TJS69

ZLP955

OAKLYSS

z28rich

69z28freak

69z28freak

69z28freak

OAKLYSS

bilodeaulynn

LT1FUN

z28rich

ace's68

69z28freak

TJS69

69z28freak

69z28freak

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