Camming a 10.3 to 1 350

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Re: Camming a 10.3 to 1 350

Post by RevTheory »

I'm in the 224/224 (maybe a few degrees of exhaust split but not much) @ .050 on a 108 camp. Bullet has quite a few profiles that vary in .006 and lobe lift numbers so you can find something that isn't too hard on the springs.

Depending on what lobe you find, you can decide on a rocker ratio.
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Re: Camming a 10.3 to 1 350

Post by blykins »

I think you'll need more than that to peak that engine at 6200. In addition, you have to watch about tighter lobe centers. I like them too, but with some of the hydraulic roller lobes that are quiet, you can easily get into more overlap than what's necessary to run vacuum accessories.
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Re: Camming a 10.3 to 1 350

Post by groberts101 »

blykins wrote: Thu May 24, 2018 9:52 am I think you'll need more than that to peak that engine at 6200. In addition, you have to watch about tighter lobe centers. I like them too, but with some of the hydraulic roller lobes that are quiet, you can easily get into more overlap than what's necessary to run vacuum accessories.
I'm with you there. That's why a big dual plane would be the best option for a heavy'ish street car, IMO. I bet Mike or Chris would not be choosing a 111° LSA for this app and the lobes won't be too soft either.
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Re: Camming a 10.3 to 1 350

Post by RevTheory »

blykins wrote: Thu May 24, 2018 9:52 am I think you'll need more than that to peak that engine at 6200. In addition, you have to watch about tighter lobe centers. I like them too, but with some of the hydraulic roller lobes that are quiet, you can easily get into more overlap than what's necessary to run vacuum accessories.
I hear what you're saying Brent. From what I've seen though, the slower ramps don't seem to lift the valve off the seat quickly enough to let much air flow in either direction.

As with anything I post, I could certainly be wrong!
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Re: Camming a 10.3 to 1 350

Post by blykins »

Well, we all do things differently.

I'd rather have a little softer lobe that doesn't sound like a sewing machine and doesn't require 425 lbs of open pressure.
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Re: Camming a 10.3 to 1 350

Post by blykins »

RevTheory wrote: Thu May 24, 2018 10:02 am
blykins wrote: Thu May 24, 2018 9:52 am I think you'll need more than that to peak that engine at 6200. In addition, you have to watch about tighter lobe centers. I like them too, but with some of the hydraulic roller lobes that are quiet, you can easily get into more overlap than what's necessary to run vacuum accessories.
I hear what you're saying Brent. From what I've seen though, the slower ramps don't seem to lift the valve off the seat quickly enough to let much air flow in either direction.

As with anything I post, I could certainly be wrong!
Doesn't matter as much with smaller-valved small block stuff, but try a Ford FE with an aggressive ramp and watch how much horsepower you lose.
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Re: Camming a 10.3 to 1 350

Post by RevTheory »

I couldn't pick a Ford FE out of a lineup! :lol:
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Re: Camming a 10.3 to 1 350

Post by Scotthatch »

blykins wrote: Thu May 24, 2018 10:03 am Well, we all do things differently.

I'd rather have a little softer lobe that doesn't sound like a sewing machine and doesn't require 425 lbs of open pressure.
I agree with that ... I tend to run slower ramps on cars that will see a lot of years and miles before the next build ...
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Re: Camming a 10.3 to 1 350

Post by Orr89rocz »

blykins wrote: Thu May 24, 2018 9:22 am Here's where I would be for a 6200 rpm peak:

289/293 @ .006", 235/239 @ .050", 111 LSA, 105 ICL, .563"/.569" with a 1.5 rocker.

This one will have 69° of overlap and will have enough vacuum to run your power brakes, but it won't be noisy or eat valve springs.
Seems bigger than what i would expect for that rpm range

I ran a 230/245 hyd roller in my 383 with afr 195 that peaked 6250 but was flat to 6600. In a 350 with slightly smaller head i would have gone alittle less duration than that. But being a 4 spd and 4.10 gear you could get away with it and it would be a beast up top end
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Re: Camming a 10.3 to 1 350

Post by blykins »

That Brodix head isn't really on par with that AFR head.

You have a point that a smaller engine needs less camshaft to get to the same peak, but you also have to look at how the heads perform.
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Re: Camming a 10.3 to 1 350

Post by blykins »

Scotthatch wrote: Thu May 24, 2018 10:15 am
blykins wrote: Thu May 24, 2018 10:03 am Well, we all do things differently.

I'd rather have a little softer lobe that doesn't sound like a sewing machine and doesn't require 425 lbs of open pressure.
I agree with that ... I tend to run slower ramps on cars that will see a lot of years and miles before the next build ...
If it were not a street car, I would have different thoughts on it. However, I've sent some aggressive lobe cams to street guys, and some of them did not like the sound. I tend to err on the side of conservatism unless the customer tells me up front that he doesn't mind.
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Re: Camming a 10.3 to 1 350

Post by CamKing »

Here's the specs on my 355 SBC in my boat. It peaks at 5,600, and pulls past 6,000rpm

355 SBC
10:1 compression
ported 492 heads
Performer RPM
Holley 600cfm "top-loader"
LS firing order hydr roller cam: 216/220 @.050" .340"/.340" Lobe Lift, 112 LSA, 108 ICL
1.6 rockers
Morel #4602 lifters
PAC 1218X springs

RPM---TQ--BHP
3200--439--267
3400--443--287
3600--445--305
3800--444--321
4000--443--337
4200--440--352
4400--440--368
4600--441--386
4800--441--403
5000--432--411
5200--422--418
5400--412--423
5600--400--426
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Re: Camming a 10.3 to 1 350

Post by Scotthatch »

blykins wrote: Thu May 24, 2018 9:52 am I think you'll need more than that to peak that engine at 6200. In addition, you have to watch about tighter lobe centers. I like them too, but with some of the hydraulic roller lobes that are quiet, you can easily get into more overlap than what's necessary to run vacuum accessories.
The cam I posted on a 350 cid the math shows a peak of 6310 rpm ..... I agree the vacuum may be a issue but I hate giving up power for vacuum .....
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Re: Camming a 10.3 to 1 350

Post by Orr89rocz »

Camkings results are on par with what i have seen in a few milder 350 sbc and lt1 type cars
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Re: Camming a 10.3 to 1 350

Post by RevTheory »

tcb,

Here's an idea of an engine you could look into. David Vizard felt the dyno was ~15 hp on the happy side so take that into account. I'd be inclined to use a softer lobe but that's just me.

http://www.hotrod.com/articles/0611em-v ... all-block/
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