Cam question
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Cross-Country
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From: australia
Cam question
I have a 1990 f150 351w which I bought 6 months ago. The PO rebuilt the engine and kept it pretty stock. It was bored 20 thou and he put KB flat top pistons in which I believe have 12cc valve reliefs. My question is his choice of Cam and I know not much about cam choices.
The cams specs I believe to be-- 194-204 @50 270 - 280. .424. to .448. lobe sep 109 119.
The engine pulls well to 4500 rpm then its no point pushing any harder. I would like it to pull hard all the way to 5500 if thats possible?
The cams specs I believe to be-- 194-204 @50 270 - 280. .424. to .448. lobe sep 109 119.
The engine pulls well to 4500 rpm then its no point pushing any harder. I would like it to pull hard all the way to 5500 if thats possible?
Cargo Master
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That cam has very short duration and it works great in a low compression, low rpm 302. In the 351 it's too small to go to a 5000rpm power peak. I'd do something like 205-205 on a 108 that would get you there and still idle very smoothly.
Cargo Master
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FTE Legend
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No 0.050" duration simply determines emissions and vacuum/idle quality, with 270/280 deg total duration this cam is not restrictive but on this displacement the stock heads and intake are a proven bottleneck. I've put bigger cams in stock 5.8's and got the same results... peak HP occurs at 4500rpm, you can rev it more if you like but it doesn't make more power.. just noise.
Cargo Master
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No 0.050" duration simply determines emissions and vacuum/idle quality, with 270/280 deg total duration this cam is not restrictive but on this displacement the stock heads and intake are a proven bottleneck. I've put bigger cams in stock 5.8's and got the same results... peak HP occurs at 4500rpm, you can rev it more if you like but it doesn't make more power.. just noise.
If this engine had a cam with more duration the engine would peak at a higher RPM than 4500. The heads are not that restrictive at this displacement.
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Cross-Country
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From: australia
Thanks fellas, now im more confused 
I am curious to why the PO picked this cam for the rebuild. I asked about it when I bought the truck and he said it was for low down torque.
I am curious to why the PO picked this cam for the rebuild. I asked about it when I bought the truck and he said it was for low down torque.
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FTE Legend
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It was probably chosen to be compatible with the factory EFI system as much as anything, it is similar to the OEM grinds used in these motors so it was a safe bet.
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Cargo Master
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A couple of years ago I did a 393 Windsor for a customer with a street rod. It was a simple build using a stock rebuilder 302 piston, stock heads etc. With headers, an Edelbrock intake and a 600cfm carburetor it was good for 354 horsepower at 5100rpm and 436 lbs/ft torque at 3400. It runs good in a '49 Ford. In that engine I used 218 @ .050 ground on a 106 lobe sep.
The 393 was making more than 345 horsepower from 4400 to 5500rpm so it didn't "brick wall" or fall off very much in the band that I was testing.
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That is a nice combo but exactly what head was used, the E7TE head used from '87 on only flows 155cfm on the intake, barely over 100cfm on the exhaust. That is what the OP has to work with.
The early C9/D0 351 heads and the late model GT40 heads have bigger valves and flow close to 200cfm untouched, that starts to get into the range needed to make around 350 hp.
The early C9/D0 351 heads and the late model GT40 heads have bigger valves and flow close to 200cfm untouched, that starts to get into the range needed to make around 350 hp.
Cargo Master
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That is a nice combo but exactly what head was used, the E7TE head used from '87 on only flows 155cfm on the intake, barely over 100cfm on the exhaust. That is what the OP has to work with.
The early C9/D0 351 heads and the late model GT40 heads have bigger valves and flow close to 200cfm untouched, that starts to get into the range needed to make around 350 hp.
The early C9/D0 351 heads and the late model GT40 heads have bigger valves and flow close to 200cfm untouched, that starts to get into the range needed to make around 350 hp.
That example being a 393 with 40+ cubes should have an RPM range that's close to 800rpm lower than a 351 with the same stuff. I checked my notes and you're right on with your flow numbers. I've tested a GT40 head and it flowed 198 @ .500 lift. In my computer I don't have an E7 but I do have an E6 with the closed in high swirl chamber and it flowed 152 at .600 lift.
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Cargo Master
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Really? The stock non HO 302 cam has a 108 lobe sep.