FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: nick c on April 28, 2024, 05:03:27 PM
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Hi Guys,
I recently picked up a 1970 F250 with 360/C6 with the intention of a fun street/shop truck build. Top on the list of things to do is address the anemic 360. I haven't decided on full scope of build as yet.
Found a local gentleman who had swapped to a 460 in his highboy extended cab 4x4 build. I purchased two 390's from him, one is a core and the other he pulled from the truck after two lifters collapsed.
My question is cam sizing; he stated it's a custom hydraulic roller and the cam card lists:
gross valve lift intake: .520 exhaust 0.520
Advertised duration in: 272 ex: 280
duration at 0.050 in: 208 ex: 213
lobe seperation 112
Is this a bit on the small side for a street 390? It was used in his ~6500lb truck, my f250 is roughly 4400lbs. Should I consider replacing with a different cam during the rebuild process?
I'll have more questions to pose as I tear the motor down and consider swapping parts.
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I ran a 224* 110lsa .519 HFT in a 76 f250 with 4.10s and 35s. 390 had Edelbrock heads and 9.2:1, it was a pretty good combo, a little lazy way down low with the heavy wheels, mild gearing with 35s, and heavy weight. For real “truck” use the cam you have is very good.
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It certainly strikes me as a truck cam, which makes sense given the previous application. It's a 10:1 compression build with Edelbrock rpm intake, and C8 heads with some work done.
I don't envision hauling heavy loads or towing on a regular basis, just to the lumber/steel yards when material is needed for my projects. The Dana 60 has 4:10 gears and it's sporting regular tires.
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So this is a used cam? I'd be leery of using it in a different engine, especially if the lifters aren't matched to it.
I'm sure Brent will hop in here, but it's my opinion that that is a very small cam, meant for an RV type or heavy towing application. I used a Crane piece in my old '68 Highboy, which weighed about 6600 lbs with the stuff I kept in the bed. The cam had the same lift, but was 224 @ .050, on a 114 separation. I had a stock "S" intake, Holley 750 and headers, so not exactly a performance build. Using 28" tires, I was never more happy with a 'true' truck engine in my life. It idled nice, pulled from a stop perfectly no matter what I had or didn't have attached to the truck...including pulling a trailer with another truck loaded on it. Had plenty of power to pull any load or go through heavy snow drifts without putting the engine under a wide open throttle/high load situation. It was also fun to drive and could get up to speed on an interstate on-ramp without going WOT....which I often did anyway, just for the fun of it. Just my experience with a similar truck/engine combo.
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It’s a used motor with that cam in it. It has several collapsed lifters. Reportedly has approx 40k mikes on it.
The previous owner suggested new lifters, rings, bearings.
Plan is to pull apart, see what I find and adjust to my needs.
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Yeah, that's a small cam indeed. Meant for heavy towing/lugging.
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Compression at 10:1 on that small of a cam is a high cylinder pressure deal. Definitely a low end grunt package that might actually be on the fringe as far as fuel tolerance. Somebody wanted to make diesel like power
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Thanks gentlemen, I'm likely to going to reach out to Brent for a custom grind more in line with my goals.
Already need lifters, a cam change will mean different pushrods and springs, then you may as well consider different heads... These things are damn rabbit holes.. ::)