Cam advice
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Senior User
Joined: Aug 2008
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From: Fayetteville Arkansas
Cam advice
i just bought a 1979 F100 swb with a 300i6 and 3.03 3spd trans that I’m wanting to turn into a weekend driver/cruiser/Hotrod, I’m collecting parts for my 357w swap and I’m undecided between 2 cams and was looking for advice from those that have used these cams in the past and which one would be better for my application. My specs are
F4TE 351w factory roller block
Scat 3.5 stroke crank
Scat 5.95 connecting rods
AFR 185 heads 58cc
Edelbrock RPM Airgap intake
Holley SA 670 carb
Pistons- I don’t have yet looking for around 10:1
I will be using a 1968 Toploader 4spd out of a Mustang and a 3.50 rear gear
The 2 cams I’m looking at are the Comp XE 270hr and XE 274hr and I cant decide between the 2, I’m not building a race truck just a nice driver and I’m wanting enough vacuum to run brakes etc so if you were building this motor which one would you use and why?
thanks
F4TE 351w factory roller block
Scat 3.5 stroke crank
Scat 5.95 connecting rods
AFR 185 heads 58cc
Edelbrock RPM Airgap intake
Holley SA 670 carb
Pistons- I don’t have yet looking for around 10:1
I will be using a 1968 Toploader 4spd out of a Mustang and a 3.50 rear gear
The 2 cams I’m looking at are the Comp XE 270hr and XE 274hr and I cant decide between the 2, I’m not building a race truck just a nice driver and I’m wanting enough vacuum to run brakes etc so if you were building this motor which one would you use and why?
thanks
FTE Legend
Joined: Jun 2006
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From: Ottawa, Ontario
What is with the Scat crank and rods? You plan to spin it hard or add nitro or were the stock parts damaged?
What are your HP goals?
Do you have a copy of DesktopDyno? I don't see an XE274 for a Ford, what is more important to you a bad *** sound(lumpy idle) or a broad powerband.
What are your HP goals?
Do you have a copy of DesktopDyno? I don't see an XE274 for a Ford, what is more important to you a bad *** sound(lumpy idle) or a broad powerband.
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Senior User
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From: Fayetteville Arkansas
Conanski I bought a F4TE shortblock and traded some parts I had laying around for a Scat crank and rods still new in the box so I’m gonna use them instead of my stock crank and rods, I really don’t have a horsepower goal my plans for this truck are for it be a cruiser I can take out on nice days to tear up the backroads here in the Ozarks, I want it reliable enough to drive anywhere but I also haven’t spent all this cash to build a stock type motor. Comp does make a XE274hr for a 302 roller application and these 2 cams I’m looking at are for a 302 motor I’m hoping if I did go with the 274 my cubic inches of 357 will tame said cam a bit
Hotshot
Joined: May 2003
Posts: 11,141
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From: south louisiana
Either will be fine with power brakes. They're nowhere near too big for that. Especially with a dual plane intake. You'd have to get a lot bigger on the @.050 numbers and a narrower LSA combined with a single plane intake to get issues with power brakes.
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The xe cam lobes from comp are very aggressive. I assume you have the standard afr8017 spring on those heads? You will notice valvetrain noise with those lobes. It will not be whisper quiet if your used to or expecting that.
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Senior User
Joined: Aug 2008
Posts: 291
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From: Fayetteville Arkansas
Woody you’d be correct I am using the AFR8017 springs and I have read that about the XE line being noisy, I’m not dead set on these 2 cams and I’m not really looking for a radical idle, Thanks for the info
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Hotshot
Joined: May 2003
Posts: 11,141
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From: south louisiana
I'm running a Ford Z303 in my 331 and from reading the description you'd think it was extremely radical but it's kinda tame if you ask me, This is .587 lift with 1.7 rockers, 228* @ .050 with a 112 LSA. It idles more like an RV grind most time, only lopey when cold. I ran this same motor in an 89 Ranger for a couple years with power brakes, never had issues with it. Ran a B303 and 1.7's in a 5.0 with a Vic Jr and never had issues there either in the Ranger. The B cam had a lopier idle than the Z. Both cams are noisy with full roller rockers. You could go up to a cam with probably 10-15* more duration with a 112 LSA and not have problems. Or use any EFI grind (which most Hyd rollers are) and still not have vacuum issues at idle. The wider LSA's negate this problem as they have less overlap, which is the cause of low vacuum. The big carb cams with their narrow LSA and wider overlaps are where you'll have issues here. The EFI grinds are more street friendly, and work great with a carburetor, the higher vacuum makes the carb circuits respond faster.
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From: Fayetteville Arkansas
Thanks Baddad I think I’m gonna go with the Comp XE270hr-12 I was also looking at the XE270-14 , the Toploader 4spd I have is a 2.32 first gear close ratio that I will be converting to a 2.78 wide ratio but even still with that 2.78 first gear and 3.50 rear I’m worried that my truck will take off like an old lady on a Hoveround at Walmart so I steered away from the XE274hr, I’m hoping the 270 will give me the torque I need low enough to make the college kid next to me in a new V-6 Camaro sweat coming off the stoplight while still being able to catch second gear at 5600rpms
Hotshot
Joined: May 2003
Posts: 11,141
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From: south louisiana
Thanks Baddad I think I’m gonna go with the Comp XE270hr-12 I was also looking at the XE270-14 , the Toploader 4spd I have is a 2.32 first gear close ratio that I will be converting to a 2.78 wide ratio but even still with that 2.78 first gear and 3.50 rear I’m worried that my truck will take off like an old lady on a Hoveround at Walmart so I steered away from the XE274hr, I’m hoping the 270 will give me the torque I need low enough to make the college kid next to me in a new V-6 Camaro sweat coming off the stoplight while still being able to catch second gear at 5600rpms
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From: Fayetteville Arkansas
Baddad thanks again you gave me a lot to think about and I’ve been doing good amounts of research on this as well. The truck I bought is extremely clean but the previous owner put 32’s on this 2wd shortbed, don’t know why? It looks like a 4wd as it sits but I will be changing wheels and tires, I think I’m gonna run the close ratio to see how I like it and maybe go to a 3.70 rear If needed, as far as cams I’m looking at the XE274HR and XE276HR they are close in duration but the xe276 has less lift, they are both 112 cams so my thinking is I can have the duration of the XE274HR cam with the lift of the XE270HR. What are your thoughts on the Comp XE276HR in a 351 build
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Baddad thanks again you gave me a lot to think about and I’ve been doing good amounts of research on this as well. The truck I bought is extremely clean but the previous owner put 32’s on this 2wd shortbed, don’t know why? It looks like a 4wd as it sits but I will be changing wheels and tires, I think I’m gonna run the close ratio to see how I like it and maybe go to a 3.70 rear If needed, as far as cams I’m looking at the XE274HR and XE276HR they are close in duration but the xe276 has less lift, they are both 112 cams so my thinking is I can have the duration of the XE274HR cam with the lift of the XE270HR. What are your thoughts on the Comp XE276HR in a 351 build
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