Hey guys. I've been piecing together an engine rebuild for some time for my 1976 F250 with a 390. I'm not looking to put together a race motor, but I'd like it to have a proper amount of power for the size engine. Its obviously a truck, so low end power and "area under the curve" is more important than high end and peak power. I have most everything picked out, and I was hoping some of you have input on a few camshafts I have selected. The combination of pistons and head gaskets I have chosen should bring quench to around 0.040 and compression to around 9.15:1

The camshafts I am tossing around are:

Crane 343971
Advertised Duration: 248/260 degrees
Duration at 0.050": 192/204 degrees
LSA: 114 degrees
Intake Closing Angle: 54 degrees ABDC
Dynamic Compression Ratio: 7.86:1

Crane 343901
Advertised Duration: 260/272 degrees
Duration at 0050": 204/216 degrees
LSA: 112 degrees
Intake Closing Angle: 58 degrees ABDC
Dynamic Compression Ratio: 7.66:1

Crane 343942
Advertised Duration: 272/284 degrees
Duration at 0.050": 216/228 degrees
LSA: 112 degrees
Intake Closing Angle: 64 degrees ABDC
Dynamic Compression Ratio: 7.35:1

From how the dynamic compression ratio values came out, it seems that the first would work best with premium gas, the second with mid grade, and the last with regular. I know there's a lot more to the equation than DCR, such as quench, head material, timing, temperature, etc etc, but I'm hoping that my ballpark estimate isn't too far off. I also don't want the idle to be crazy thumpy, but it doesn't look like any of these cams would be, right?

I guess my question to you all is if these cams match up to what I have planned, and if any of you have any experience with these or similar cams. Thanks!
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Have you considered a roller cam ? it will cost a little more but it's money well spent if you can swing it.

You're going to get 50 opinions and half of them will be useful. here is mine , give Brent Lykins at Lykins Motorsports a call or email him . he will take all your engine specs , desired use and everything right down to your gear ratio and tire size and custom spec you a custom grind cam that will be delivered to your door for only a few dollars more than a generic off the shelf cam. it's a no brainer . I've been 110% satisfied with the ones he's done for me and yes, Ford is his specialty

 

2X on this. Everything 440 sixpack said plus with a roller cam there'll be no worry about cam break-in. And, you'll be able to run a modern oil instead of the high zinc oil. I ran a high zinc oil for several thousand miles (with my roller cam) and then switched to a synthetic blend for several thousand miles. That got me close to 1 more mpg (from mid-12's to mid-13's)… with a stroked FE in a pickup.

Brent can also answer any questions you may have...saving you possible mistakes.

While you're at it, consider custom pistons to dial in your compression ratio and get a modern ring pack for reduced friction and better seal.

 

The pistons I have picked out aren't custom per se, but they do have a different compression height from stock 390 pistons so they won't sit in the hole so deep. Based on compression height and deck height, I calculated the pistons being in the hole 0.010", which will get me 0.040" quench with the right head gasket and would also give me room to mill the deck of the block if it's not flat, then I would use a thicker head gasket. The compression ratio with these aftermarket pistons and head gasket combo is estimated at 9.15:1

 

That would be a good compression ratio if you want to run pump gas. but your cam will effect it, all the more reason to talk to Brent before you go any farther.

 

What heads, intake, etc....Brent will want to know all the details. He will pick and send you a cam that will work for your combo and use. Either him or Blair Patrick bar none. So I second, or third, or fourth what others have said. A roller is not a must, but it is a little insurance. To perform correctly springs will need to match the cam etc. and I am sure you know this already. New pushrods will be needed as well and you will need to measure for them etc. If you go with a roller cam you will need a new dizzy gear and it will need to be set up on the dizzy correctly...do not mess this part up, it is easy to do.
A custom cam for your combo will do far better than any shelf cam, roller or flat tappet. Like I said, either Brent or Blair, will ask a lot of questions, the more info you give the better they can select a cam. You sound like you have realistic goals, so that is plus, they won't have to reel you into to reality HAHA. The cost will be high, about triple likely if you go with a roller and Morel Lifters vs a shelf flat tappet. However, if that is an issue, I believe both do it, but I know Brent has some tricks for flat tappet cam grinds that can help prevent issues. Not bullet proof but helps. If you go the flat tappet route, have the timing around 14-18 initial and close to where your max will be before starting, fuel in the bowl etc. so your truck will start fast, use a quality break in oil....basically be smart about it. Feel free to talk that through with either of them as well as they can and will give you the details.
I used Brent for a lot of my 445 parts and the cam he selected did very well on the dyno, I do not have a report on how the truck feels but hopefully I will in the next few months....engine is going in next week if my schedule holds. I ran the same block in different form with a flat tappet prior to the build..no issues there but at the level of investment I have in it now, I could not justify taking the 1 in 50-100 chance of wiping out a lobe on start up.
If you are doing all of part of the assembly I recommend making a check list on the details so no step is missed, torque, assembly etc. I may be rambling but building a nice motor is pricey and time consuming and I hate to see someone make costly mistakes for lack of info.
Good luck.

 

When you have experts who'll spec you a custom cam at the price you can get it for it basically makes off the shelf cams a thing of the past in my opinion. Brent accomplished exactly what I wanted in a cam for my 428CJ and I never would have accomplished it any other way with the compression ratio I was dealing with..

 

And to answer your question about a roller cam, I did look at it, but the cost of good roller lifters is out of my budget. It's not going to be a daily driver, just kind of a weekend cruiser, and I am aware of the drawbacks of a flat tappet cam.

 

Very good advice, thank you. The more I hear about Brent, I may drop him a line when I get closer to build time.

 

As I recall the cost of the roller cam and lifters was about $500 more than the flat tappet set up. but remember the roller gives you profiles not possible with a flat tappet so eliminating the risk of eating a cam is worth a lot but it's not the only advantage. if you win the lottery or something try to go with a roller cam, forget the rockers.

 

I have been dealing with Brent - he supplied my cam (and lifters and gasket kit and timing set) and I am getting very close to firing it up. He is great to deal with, quick to reply: brent@lykinsmotorsports.com

Bruce

 

Rookie,

Who ever you get your cam from, if it is a custom cam, even if not....make certain to check the cam bolt threads and depth on the bench with timing gear installed. Not certain about custom flat tappet cams but I know for a fact that on custom roller cams some blanks(cam cores) "can" use a different than stock thread pitch. This is common knowledge to builders that gets missed by one time guys.....the end result can be catastrophic failure and very expensive. Again, another one of those things that needs to be checked and this one falls into the category of you won't know until it's to late. The difference in not enough on pitch that it is far from obvious when bolting things up. I only mention this so you, and others are aware.....cam walk and dropping a lifter is bad news....add it to the check list

 

Would that be taken care of with a cam button when using a roller cam? Not the threads, but the different depth?

 

Unless you are doing some type of conversion from OEM style cam retention, then no....assuming a later era FE block etc....on a typical FE the cam is retained by a thrust plate and two "bolts", the cam is pulled to toward the thrust plate via the Timing Gear and Cam Bolt. This is the only thing that keeps the cam from moving fore or aft in the block. I want to say the stock OEM thread pitch is 7/16-20 and some of the aftermarkets cores can be 7/16-24 ...I may have that backward, and do not quote me on it....I am not by my notes etc, and it has been some time since I have done mine. Point being that it will feel snug, but not cross threaded if it does not match your factory bolt..not enough to alarm you and you think it's ok....it can back off and the cam can walk away toward the back and trust me, that is bad for business. Do some searching and you should find what I am talking about. A good source of info is Ford FE Power forum. In short, make sure it is the correct bolt, pitch, length, and use RED Loctite and torque properly. I am not the first one to do it, but I made the mistake....I got lucky in the sense that I caught it prior to blowing the engine up on the dyno. Costly mistake to learn.....one of those things you don't know until you know unfortunately but as stated earlier, I don't like to see guys new to the game ruin a build over something that is assumed to be common knowledge.....again I think this is only on custom roller cores, but it is wise to verify....for some reason they do not spec that OEM specs be followed on this part of the cam only...I gather custom means custom and it is on the buyer to verify. An FE has building quirks that a lot of others do not....not hard, but knowledge is your friend.....if you want some more info feel free to PM me. I am not a pro builder but I did stay at a Holiday Inn Express.

 

Alright, so I'm most likely going to contact Brent for a custom cam when it comes time to build, but on the off chance I pick an off the shelf cam, or at the very least as a reference for a future engine build, how do the ones I picked out stack up? I'm sort of new to this, so I just wanted some input or helpful criticism on my cam choices.