Budget 390 opinion

[darren121671]

I'm building a 390 for my 1970f-100. I need help picking a cam. The engine is a 4.080x3.780 with stock rods with ARP rod bolts. Speed pro flat top 4 eyebrow pistons 10-10.5 compression . Heads are 428 CJ with stock valve size. Blue thunder LR intake. And a 735 CJ carb. I have read that I need to keep the duration @.050 under 221 for power brakes. What is limit with enough vacuum and duration? Can I get into 230-240 range?

[ScotiaFE]

I personally think power brakes are over rated.
Along with heated seats.
It is more about how you drive than anything.
Be honest and you will have a great driving vehicle.
240* in a 10 to 1 396 ci is a bit of a pain at slow speed in traffic.
Out on the highway with room to run it's great.

[jayb]

I think you could get away with 228 or 230 and still have enough vacuum; 236 is too much, based on at least one cam that I ran.  Alternatively you can always get one of those add-on electric vacuum pumps if you guess a little too high on duration.

[machoneman]

I personally think power brakes are over rated.
Along with heated seats.
It is more about how you drive than anything.
Be honest and you will have a great driving vehicle.
240* in a 10 to 1 396 ci is a bit of a pain at slow speed in traffic.
Out on the highway with room to run it's great.

Hey, heated seats are great, just like my heated steering wheel, in my new Kia Optima! Can't wait to get my Stangs out once this stupidly cold winter ends but in the meantime, those heaters rock! 

[darren121671]

Thanks guys. Theses are the cams I'm looking at. Lunati 219/227@.050, lift .540/.552 LSA/ICA 112/108, 227/233@.050 Lift .552/.564 LSA/ICL 110/106. Comp cams 218/224@.050 lift .513/.520 LSA/ICA 110/106, Howard's 213/223@.050 lift.525/.525 LSA/ICL 112/108. I know all of these cam are very similar, but which one would you choose for my combination.  My goal for this engine is 375- 400 hp. And still be able to drive it to California on pump gas with power brakes. I know I might be dreaming but tell me what you think.

[CaptCobrajet]

I think I'd stay around the 220 mark, and 112-ish on the lobe separation.  A truck used like a truck is easily over-cammed if you are not careful.  As far as the power brakes go, you can operate brakes at 230 on a 390, as long as you keep the lobes spread to 112, but it will start to be sluggish off-idle and up to around 1500 if you go too far.  I'd go .500 lift, 220 @ .050, and 112.  If you go hydraulic roller, add about 4 degrees to it, since the quicker ramps will restore some of the off-idle response.  Might want to think about a smaller manifold for a 390.........maybe even an iron CJ intake if in a truck, or a PI or Streetmaster. JMO.

[mlcraven]

Less cam than you want, but for comparison purposes a Comp XE 256 (212 @ .050 on the intake / 219 @ .050 on the exhaust, 110 lobe separation, just a hair under .500 lift) on a +30 390 sustains 17-in vacuum at idle and 20-in+ above 1500 rpm.  This engine has a set of cleaned-up iron GT heads w/3-angle valve job, 10:1 compression, aluminum PI intake and a 650 cfm Holley on a 1-in spacer.  Not a screamer but very smooth and steps out with authority above 2000 rpm. 

[darren121671]

So which cam out of the 4 would you guys pick? I haven't contacted all 4 cam manufactors but lunati recommend the the 219/227 lift .540/.552 for this set up. I'm just worried about having enough vacuum for power brakes.

[RLander]

Not a truck but might as well be.
64 galaxie with 3.00 gears.......
the XE262H from comp
Hydraulic Flat Tappet, Advertised Duration 262/270, Lift .513/.520
Has done this ol thing very well. Power brakes work really well and I used to drive this thing 160 miles every weekend to come home from shool. Then it was my daily driver for a few years. Cruised great, pushed that thing pretty darn well.
390, 9.5:1, FPA headers, C8ae-h heads with bigger valves and mild port work, edelbrock RPM intake and 650 carb.

[NIsaacs]

I would say any of the cams listed will work fine. Remember, when you need good brakes you are on deceleration, lots of vacuum. When you are at idle speed (low vacuum) you are going slow enough you don't need power brakes. I will also say, none of those cams will get you 400hp on pump gas. I have found with heavy trucks, the FE is prone to detonation with small cams and performance ignition timing on regular gas. So to get by, I used cold plugs, reduced ignition timing and poor performing truck but it would live. Disclaimer: I am not a cam guru at all

Nick 

[jimeast]

A little off track, but... do the requirements for vacuum change as you go up in cubic inches as it relates to duration and lobe separation?

[rockhouse66]

Also off track, but all the cams on your list are split duration and I wonder what others would say about perhaps a Comp 268H or 270H instead?

[cjshaker]

I think Blair is close.
I've been running a Crane solid cam in my 6000lb '68 F250 4wd for 20 years and it has been perfect. 227@.050, 112LSA, low 5s on lift. C4 heads with an iron S intake and 750 Holley vacuum secondary. It's a fantastic combo, roughly 380-390hp and will pull/haul anything I want to. Enough vacuum for PB, although mine are not power. About 10:1 compression and no detonation with 89 octane and 38* timing. With an MSD Blaster ignition, it starts instantly in any temp or weather.

I can't say enough good things about this cam for an all-around good street cam for a 390 in a car or truck. It pulls strong and smooth from idle to 5500, but most of its power is done by 5000. I've pulled loads over 7500lbs with ease on countless occasions. At those loads, a good hill will make me drop to 3rd, but that's a result of cubic inches. At lesser loads, hills are not an issue.

[mlcraven]

Not a truck but might as well be.
64 galaxie with 3.00 gears.......
the XE262H from comp
Hydraulic Flat Tappet, Advertised Duration 262/270, Lift .513/.520
Has done this ol thing very well. Power brakes work really well and I used to drive this thing 160 miles every weekend to come home from shool. Then it was my daily driver for a few years. Cruised great, pushed that thing pretty darn well.
390, 9.5:1, FPA headers, C8ae-h heads with bigger valves and mild port work, edelbrock RPM intake and 650 carb.

The cam I should have selected (but which the Comp rep, incidentally, advised against  ).

[cjshaker]

Darren, of those choices, I'd go with the Lunati. The Howards is a bit small, IMO, and I'd stay away from the others with 110 LSA's if you actually want to use it as a truck. A wider LSA will give you a much friendlier and useable power band. But I think you can still go a bit more than the Lunati and it won't feel so "stockish" in terms of power. The heads and intake would be overkill with such a mild cam. I'm assuming by your posts that your set on a hydraulic?