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Small cams on 106-108 LSA’s

General engine tech -- Drag Racing to Circle Track

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travis
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Small cams on 106-108 LSA’s

Post by travis »

I’m curious...

Why is there little to no off the shelf selection available of under 220@.050 cams, hydraulic roller or flat tappet, on less than a 110 lsa, especially if you get outside the sbc?

The few I’ve used in low compression budget heavy vehicle applications work so well in my opinion. What am I missing?
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Re: Small cams on 106-108 LSA’s

Post by GARY C »

travis wrote: Wed Nov 18, 2020 6:42 pm I’m curious...

Why is there little to no off the shelf selection available of under 220@.050 cams, hydraulic roller or flat tappet, on less than a 110 lsa, especially if you get outside the sbc?

The few I’ve used in low compression budget heavy vehicle applications work so well in my opinion. What am I missing?
Because dirt track cams make the car pull to the left... :)
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Re: Small cams on 106-108 LSA’s

Post by BOOT »

travis wrote: Wed Nov 18, 2020 6:42 pm What am I missing?
Bigger sells period!

They know if they don't sell the big stuff then someone else will.
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Re: Small cams on 106-108 LSA’s

Post by Walter R. Malik »

travis wrote: Wed Nov 18, 2020 6:42 pm I’m curious...

Why is there little to no off the shelf selection available of under 220@.050 cams, hydraulic roller or flat tappet, on less than a 110 lsa, especially if you get outside the sbc?

The few I’ve used in low compression budget heavy vehicle applications work so well in my opinion. What am I missing?
Before he died and the assets of his company got sold, Bill Metzger at LAZER CAMS offered new catalogue cams like this.
He called them "Street Rod" cams; mainly because they would idle rough but, smooth out above 1,200 RPM on a cruise.
Power was not the "main" objective.
http://www.rmcompetition.com
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Re: Small cams on 106-108 LSA’s

Post by 68maliblue »

Comp cams cs260AH-8 at 212 int 218 exh @.050” on a 108 lsa is a great Street cam in a 8.5-9:1 sbc. Isky mega 264 at 214 @ .050” on 108 lsa is another one.
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Re: Small cams on 106-108 LSA’s

Post by travis »

It’s not even that I’m looking for a rough idle...it’s just that these type cams feel really strong from idle-4500 or so, which is perfect for a lot of stuff I build.

The comp 252ah-8 and 260ah-8 I’ve used 4-5 times now. They don’t idle rough at all, but are very responsive right off idle. Much more so than the generic 204/214 “performer” type cams on 112 lsa’s
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Re: Small cams on 106-108 LSA’s

Post by Geoff2 »

D. Vizard in one of his books says that if you want more low end/better idle, you do NOT widen the LSA, you reduce duration.

So Travis it sounds like you are on the right track..
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Re: Small cams on 106-108 LSA’s

Post by Sparksalot »

I haven't built a race engine since 1969 but I love a loud raucous idle quickly clearing to torque in NA applications. You are on the right track for that if that's what you desire. My stuff uses more duration and custom lobes because big power for the street is fun too. This sort of cam can cruise at relatively low RPM with high gearing.

Boosted engines are different.
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Re: Small cams on 106-108 LSA’s

Post by MELWAY »

Definitely a reason why all the Isky mega cams are cut on a 108 LSA.
Wake those ol skool low comp motors up
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Re: Small cams on 106-108 LSA’s

Post by RevTheory »

I had a Howard's hyd/flat cam ground a while back that was 259/259 at .006, 212/212 at .050 and .519/.519 lift on a 108 +4 for a 9.75:1 AMC 360 and you could tell it had a little something in there but the damn thing pulled 19 inches of vacuum and the guy said it pulled like a train just off idle up to 5,000 when he upshifts. He said he couldn't be happier.

You'd think there'd be a market for that sort of thing but I have a feeling that the majority of guys get scared at anything below a 110 LSA. They see 108 and default to "race cam!" I've seen that quite a bit.
Last edited by RevTheory on Thu Nov 19, 2020 10:41 am, edited 1 time in total.
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Re: Small cams on 106-108 LSA’s

Post by novadude »

I am running a Howards 270/278, 217/225, .495/.500 108 LSA cam in a 9.6:1 355 with Vortec heads. My first experience with a "tight" LSA cam.

I couldn't be happier. ~16" vacuum at idle, just a slight lope at 800 rpm idle, and pulls hard in the midrange. With a manual trans, it will also pull down to 1200 rpm at light throttle with no bucking or bad manners. Good gas mileage at freeway speeds. I'll never use 112-114 LSA in a 'street' small block again.

IMO, Vizard was onto something when he made this statement on this forum with regards to LSA in low-CR street engines... "If it ain't tight, it ain't right!"
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Re: Small cams on 106-108 LSA’s

Post by CamKing »

travis wrote: Wed Nov 18, 2020 6:42 pm What am I missing?
You're missing the economics of it.
Most of all the short duration cams you see, are mass produced to keep the costs down. The vast majority of the applications that will be running those short duration cams require the wider LSA, so that's why they're mass-produced with the wider LSA. For the 20% of applications that could benefit from the tighter LSA, there's always the option of having a custom cam made. If a cam company is going to pay to have 100 pieces of 1 part# made, that part# is going to be what works in 80% of the applications, not 20%. A low compression, short stroke engine, can benefit from the tighter LSA, but the vast majority of today's aftermarket performance engines run as much compression as the fuel will allow, and increased stroke. Heck, a 502" BBC is small nowadays.
You're not going to want to run a 208/216 on a 106, in a SBC 383" with 10.5:1.
On a 573" BBC, is most applications, you wouldn't want to be below 114 LSA.
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Re: Small cams on 106-108 LSA’s

Post by F-BIRD'88 »

MELWAY wrote: Thu Nov 19, 2020 6:36 am Definitely a reason why all the Isky mega cams are cut on a 108 LSA.
Wake those ol skool low comp motors up
Some of the Oval track version are on 106 also .
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Re: Small cams on 106-108 LSA’s

Post by skinny z »

LSA notwithstanding but isn't it the overlap that is a defining characteristic? Obviously intrinsically tied into the LSA along with duration but the separation angle in and of itself isn't the whole picture.
That said, it's been put forward here, with great debate, that certain engine profiles (and maybe I'm talking about a 10.5:1 355 SBC here) have a specific LSA that will reliably produce the best lbs-ft per HP.
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Re: Small cams on 106-108 LSA’s

Post by F-BIRD'88 »

What does comp charge to custom grind a sbc hyd or solid flat tappet cam these days?
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