9.5 :1 532 cam question

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9.5 :1 532 cam question

Post  TravisRice on April 9th 2017, 3:26 pm

This is a build I did back in 2010. It was assembled and then stored but never used. It's a pump gas 4.3 arm 6.7 rod 532 with a set of Charlie Evans ported D3 iron heads. It has a 870 vac sec carb, performer rpm airgap manifold, headers, zf-5speed in a 67 F250 2wd standard cab and I originally put a comp X4262H camshaft in it to tow with. Now it will not see any towing at all, I've changed directions again and was looking at the X4270H, or the X4278H camshaft for something that sounds good and runs decent. NO STRIP USE.

Question is, how much does the advertised rpm range change when adding 72 cubic inches over a standard 460 spec camshaft? The X4270H is shown as 1600-5800. The  X4278H shows 2000-6000 and whats the thoughts on using one of these grinds in this application?

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Re: 9.5 :1 532 cam question

Post  The Mad Porter on April 9th 2017, 3:51 pm

TravisRice wrote:This is a build I did back in 2010. It was assembled and then stored but never used. It's a pump gas 4.3 arm 6.7 rod 532 with a set of Charlie Evans ported D3 iron heads. It has a 870 vac sec carb, performer rpm airgap manifold, headers, zf-5speed in a 67 F250 2wd standard cab and I originally put a comp X4262H camshaft in it to tow with. Now it will not see any towing at all, I've changed directions again and was looking at the X4270H, or the X4278H camshaft for something that sounds good and runs decent. NO STRIP USE.

Question is, how much does the advertised rpm range change when adding 72 cubic inches over a standard 460 spec camshaft? The X4270H is shown as 1600-5800. The  X4278H shows 2000-6000 and whats the thoughts on using one of these grinds in this application?


Figure about 600 rpm with the same intake and cylinder heads.

For a given rpm a 545 move the same amount of air approximately 800 rpm lower than a 460. A 521 about 500 rpm lower.




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Re: 9.5 :1 532 cam question

Post  TravisRice on April 9th 2017, 3:59 pm

Thanks Scott. I was considering the SFT in the for sale section that I emailed you about. But really don't want to up the compression and figured if I could find something in a hydraulic flat tappet and the valve adjustments would be little to none. I fool with enough stuff that needs the valves adjusted, not that I mind, but one less thing to worry about. Pretty much can get in it and go for the day and drive it with no hassles.




















































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Re: 9.5 :1 532 cam question

Post  The Mad Porter on April 9th 2017, 4:37 pm

TravisRice wrote:Thanks Scott. I was considering the SFT in the for sale section that I emailed you about. But really don't want to up the compression and figured if I could find something in a hydraulic flat tappet and the valve adjustments would be little to none. I fool with enough stuff that needs the valves adjusted, not that I mind, but one less thing to worry about. Pretty much can get in it and go for the day and drive it with no hassles.

Given the IE ratio on the iron heads I add 12 to 14 degrees exhaust timing these days. Performance on the top side is much better. For your situation I would do a 227 / 241 hft




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Re: 9.5 :1 532 cam question

Post  Straubtech on April 10th 2017, 2:36 pm

What are the flow numbers on the heads?

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Re: 9.5 :1 532 cam question

Post  TravisRice on April 10th 2017, 6:35 pm

Standard port sizes, not CJ.

Intake .300/222.3
.400/276.5
.500/305.5
.600/322.8
.700/334.1

Exhaust .300/101.6
.400/155.3
.500/165.3
.600/166.6
.700/167.5

Flowed at 28"
2.200 intake valve
1.75 exhaust valve

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Re: 9.5 :1 532 cam question

Post  4604X4 on April 11th 2017, 8:32 am

The intake flow looks fine, but the those exhaust flow numbers look pretty low. I guess you didn't pay for the max port work.
I would send the heads back to Charlie (or Scotty) and pay for some additional work on the exhaust side.

The TFS 290 Power Port heads (stock out of the box) flow 180 @.400, 204 @ .500, 225 @ .600, and 240 @ .700 on the exhaust.
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Re: 9.5 :1 532 cam question

Post  Straubtech on April 11th 2017, 11:24 am

4604X4 wrote:The intake flow looks fine, but the those exhaust flow numbers look pretty low. I guess you didn't pay for the max port work.
I would send the heads back to Charlie (or Scotty) and pay for some additional work on the exhaust side.

The TFS 290 Power Port heads (stock out of the box) flow 180 @.400, 204 @ .500, 225 @ .600, and 240 @ .700 on the exhaust.

I disagree. Exhaust is under pressure. All it wants to do is get from the high pressure side to the low pressure side as soon as that valve opens. Critical lift on the exhaust side is from as soon as the valve is cracked to around .250" of valve lift. Duration is what is key on the exhaust.

It just just needs a camshaft to give the exhaust port time to get out.

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Re: 9.5 :1 532 cam question

Post  gt350hr on April 11th 2017, 4:41 pm

Straubtech wrote:
4604X4 wrote:The intake flow looks fine, but the those exhaust flow numbers look pretty low. I guess you didn't pay for the max port work.
I would send the heads back to Charlie (or Scotty) and pay for some additional work on the exhaust side.

The TFS 290 Power Port heads (stock out of the box) flow 180 @.400, 204 @ .500, 225 @ .600, and 240 @ .700 on the exhaust.

I disagree.  Exhaust is under pressure.  All it wants to do is get from the high pressure side to the low pressure side as soon as that valve opens.   Critical lift on the exhaust side is from as soon as the valve is cracked to around .250" of valve lift. Duration is what is key on the exhaust.

It just just needs a camshaft to give the exhaust port time to get out.


+1 , began running longer duration , shorter lift cams on my Boss 302s 40+ years ago. Not every cylinder head is the same though. Some work with a single pattern and some with a shorter duration exhaust. "Hot Rod" magazine doesn't tell you that LOL

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Re: 9.5 :1 532 cam question

Post  Straubtech on April 11th 2017, 4:55 pm

75% I/E ratio the rule of thumb is the duration at 50 will be the same. Go below that you favor the exhaust. Go above that you favor the intake.

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Re: 9.5 :1 532 cam question

Post  68galaxie on April 11th 2017, 6:11 pm

Is the 75% rule of thumb changed by valve area?

Example BBC with 1.88 exh valve vs. BBF with 1.76" exh valve, both flowing the same 250 cfm?

Intake flow on a bench is more useful than exhaust - as real exhaust conditions are nowhere near what the flow bench tests.

Like to know your opinion on this - Cheers!
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Re: 9.5 :1 532 cam question

Post  Scott Foxwell on April 12th 2017, 8:48 am

68galaxie wrote:Is the 75% rule of thumb changed by valve area?

Example BBC with 1.88 exh valve vs. BBF with 1.76" exh valve, both flowing the same 250 cfm?

Intake flow on a bench is more useful than exhaust - as real exhaust conditions are nowhere near what the flow bench tests.

Like to know your opinion on this - Cheers!
Exhaust numbers on the flow bench are about meaningless except for cam design. They don't represent anything even near what the engine is actually seeing, but we can learn trends and develop relationships based on those numbers. The thing I look for most on an ex port is quiet. They can even be a little unstable, but the more quiet the ex port is, the more power they seem to make regardless of flow.

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Re: 9.5 :1 532 cam question

Post  Straubtech on April 12th 2017, 10:08 am

68galaxie wrote:Is the 75% rule of thumb changed by valve area?

Example BBC with 1.88 exh valve vs. BBF with 1.76" exh valve, both flowing the same 250 cfm?

Intake flow on a bench is more useful than exhaust - as real exhaust conditions are nowhere near what the flow bench tests.

Like to know your opinion on this - Cheers!

It's a starting point. Things like piston speed, fuel type will vary it, but for 80% of the engine builds out there it is a good starting point. When you see a engine with a 60% IE ratio and it has a single pattern camshaft, I can assure you there is more potential in the engine. My best example is a BBC that had an IE ratio of 58%. A cam change from 8 degree split to a 26 degree split netted a gain of 146HP with camshaft change. There is a trend.

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Re: 9.5 :1 532 cam question

Post  gt350hr on April 12th 2017, 12:03 pm

You don't get information like that out of the average tech guy at a cam company either! Most barely know the catalog information. My experience mirrors Chris's.

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Re: 9.5 :1 532 cam question

Post  Straubtech on April 12th 2017, 2:16 pm

gt350hr wrote:   You don't get information like that out of the average tech guy at a cam company either! Most barely know the catalog information. My experience mirrors Chris's.

I'm thankful everyday for the big cam grinding companies. Job security.

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Re: 9.5 :1 532 cam question

Post  IDT-572 on April 12th 2017, 2:39 pm

And us Ford guys, see Dooe-r heads all the time with 400 cfm intakes and maybe 200 cfm exhaust.

But still see 900 hp this blows the chevy guys theory of you have to have a 70% port like the chevy port to make power.

Is a better exhaust port good, heck yea it is, but it's not the end of the world like we were lead to believe 20 years ago.......Rolling Eyes
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Re: 9.5 :1 532 cam question

Post  Straubtech on April 12th 2017, 3:00 pm

IDT-572 wrote:And us Ford guys, see Dooe-r heads all the time with 400 cfm intakes and maybe 200 cfm exhaust.

But still see 900 hp this blows the chevy guys theory of you have to have a 70% port like the chevy port to make power.  

Is a better exhaust port good, heck yea it is, but it's not the end of the world like we were lead to believe 20 years ago.......Rolling Eyes  


The exhaust port is what it is. You just have to cam accordingly.

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Re: 9.5 :1 532 cam question

Post  IDT-572 on April 12th 2017, 3:02 pm

YEP..........
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Re: 9.5 :1 532 cam question

Post  Straubtech on April 12th 2017, 3:05 pm

IDT-572 wrote:YEP..........

Flow a set of LS7 GM heads, I/E ratio is around 60%. Look at the camshaft, 208/230 at .050". Flow a 1.8L Acura head, I/E ratio is 88% intake cam is 188, exhaust cam is 176 at .050".

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Re: 9.5 :1 532 cam question

Post  IDT-572 on April 12th 2017, 3:11 pm

I don't do many LS engines but I do sell a bunch of shelf cams for them, they all seem to have wide LSA's though 113 -114. If they didn't the overlap would be big.
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Re: 9.5 :1 532 cam question

Post  The Mad Porter on April 12th 2017, 3:13 pm

IDT-572 wrote:And us Ford guys, see Dooe-r heads all the time with 400 cfm intakes and maybe 200 cfm exhaust.

But still see 900 hp this blows the chevy guys theory of you have to have a 70% port like the chevy port to make power.  

Is a better exhaust port good, heck yea it is, but it's not the end of the world like we were lead to believe 20 years ago.......Rolling Eyes  



You said it Brother. lol... Cool

...and as was noted in a prior post, how much air is actually moved in dynamic operation, as in intake and headers bolted on, is radically different than what a bench shows. A header primary that turns directly down or away from the exhaust flange is going to hurt exhaust flow vs a primary that has a couple of inches before turn down.

The amount of additional exhaust timing I use is rpm dependent (among other criteria). What works at a 5k rpm peak is not enough for a 7k rpm peak.


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Re: 9.5 :1 532 cam question

Post  Straubtech on April 12th 2017, 3:20 pm

IDT-572 wrote:I don't do many LS engines but I do sell a bunch of shelf cams for them, they all seem to have wide LSA's though 113 -114. If they didn't the overlap would be big.

Then you go on the boards "down under" the LS cams are on 107 to 109. My stuff is on tight LSA's for these engines.

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Re: 9.5 :1 532 cam question

Post  IDT-572 on April 12th 2017, 3:28 pm

All the iron headed ford big block stuff I have built always ran better on 106-108 sep, depending on the I/E ratio.

I did some 4V Cleveland stuff on 98 to 102 seps back in the day with wide splits for 1/4 mile dirt and ran them in drag race stuff to.

Made killer power.

Replacing shelf stuff that had 8 degrees of spilt max and 110 to 112 sep.

Gutless no torque, and about a 500 rpm power band. nothing on top nor bottom.

Most tracks around here wouldn't let 4V Cleveland stuff run, Chevy guys said it wasn't fair, they were big blocks.......... Rolling Eyes

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Re: 9.5 :1 532 cam question

Post  Straubtech on April 13th 2017, 10:07 am

Travis contacted me and about the cam for this project.  We went over his goals and we both agreed a hydraulic roller for his goals of longevity and a "driver build" was the best fit for the project.  I asked him if he minded if I post some info in this thread about the project and how I go about it.  He was fine.

I asked him for the flow numbers and he sent them to me.  Well I have tried to attach it.

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Re: 9.5 :1 532 cam question

Post  Straubtech on April 13th 2017, 11:07 am

This is a low rpm street build. It does have some arm in it but he is not turning it up in the rpm range. The truck is a driver so we are after power in the low to mid rpm range. I think this wear many get lost with peak HP numbers. Travis was clear on what he wants, a driver with good average power. Many want that peak HP number, when in reality the vehicle will never see it or if it does, once or twice a year. Reality sets in when the mill is transplanted and drove and you see you spend most of your time between 2500 and 4500 rpm. I have always felt a phone call is a better "forum" to realize what the customer really wants and I have learned over the year average power under the curve rules the street.

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