Guys,
I've got a problem choosing a cam for my 390/406 engine I'm building. I need to run on pump gas, preferably 87 or 89. I'm looking at the 268H comp cam. If I run it 4 degrees retarded (110/110) I'll have 8.2 DCR with 10.2 SCR. That'll give me 356 hp at a shift point of 4603 rpm ( according to the calculator ).
The trouble I have is that I want this engine to idle at 600 rpm so it won't tear out my transmission everytime I go from Park to Reverse. Any suggestions would be appreciated. The engine is intended for drivability with a 1800 stall converter and 3.25 rear gear. C6 transmission.
Here are the specs:
1. 390 bored .03 = 395ci Decked .010
2. L2291 Pistons = 1.776 compression height 10cc dish
3. C3AE-C Heads = 68cc 2.02/1.65 valves
4. 427 Rods = 6.47 length ( it's a long story but the whole engine is balanced and I'm not buying new rods and rebalancing the engine).
5. 406 aluminum intake ( single 4barrel 600cfm Holley)
6. 7 qt. Milodon oil pan, splash shield and HV oil pump, oil gallys opened.
7. .020 or .030 steel head gasket ( 8.0 DCR or 8.2 DCR )
8. Maddog full length headers w/ 2 1/2 exhaust and high flow mufflers
Also, is the difference between 8.0 DCR and 8.2 DCR worth having a .054 quench as opposed to having a perfect .045 quench.
Thanks guys, Jim

 

Subscribed. I'd be very interested to hear what everyone else says on this topic.

 

Guys,
Your too late. I ordered a cam yesterday evening from Lunati (custom grind). It'll give me approximately 340 HP at 4717 shift rpm. It'll have 10.2 SCR and 7.8 DCR. I'm running 7.8 DCR and 9.5 SCR with the 390 in my other vehicle ( 87 octane), but, I'm getting 7.8 DCR by using .070 quench. This engine has .045 quench. My cranking pressure should be about 177 psig with this cam at ICL . Jim

 

Jim

Calculations are one thing, and you seem to have several variables in your setup. The real world sometimes can be a little different. Can you post after you install the cam and let us know how things worked out for you? Nothing like "been there done that" so to speak.

 

Riderman,
I've got my cam now and the spec sheet is:
Advertised Dur - 282 / 296
Max lift -------- .500 / .500
Dur @ .050 ---- 214 / 224
LSA / ICL ------ 114 / 110
Overlap -------- 61 degrees
I told Lunati I wanted a low DCR so I could run low octane gas and have an idle and vacuum. The DCR on this cam figures out to be 7.73 with a .044 quench using a .020 head gasket.
I used to have a 66 Fairlane GT with the 428 CJ cam. That cam had an LSA/ICL of 117 / 117 and it idled excellant and gave me good power at 10.5 compression. This engine has 10.2 compression.
I'm optimistic about this engine build although when the machine shop installed the valve guides they cracked three of the guide housings where it tapers down to the valve head. They claimed that happened often with an FE head. The heads have had the runners and bowls cleaned up and has 2.02/1.65 valves with 68cc chambers. I hate they cracked the housings.
I'll have the engine running next week and I'll post the idle quality and vacuum I get with this build. I've got a test stand that I use to run the engines I build for about ten hours before I install them. That way I don't have to worry about timing, leaks etc. Jim

 

Jim, thank you for the follow up! We look forward to your actual result's.

Riderman

 

Riderman,
Finally got my 390/406 running. I had a problem with the machine shop that did my heads. I have 2.02/1.65 valves with 67cc chambers. It's a hard head to come by and cost $400 for the bare heads if you can find them. This machine shop doesn't freeze the guides when they install them and guess what, they knocked the top guide casting out of one head. I had them go back and cut all the top guide castings off and install Viton positive valve seals. I've run the engine about 3 hrs now and this is what I get with the 282/296 advertised, .500/.500 lift, 214/224 Dur @ .50, 114 LSA and I put it at 109 center line. Installing and adusting the 1.76 adjustable rockers was a no brainer.
It idles at 500 rpm, it's smooth but it would take an idiot to not know it's cammed. I set the timing on 6 degrees and I have a steady 17 inches manifold pressure.
When I first fired it I just let it run at 2500 for 20 minutes to break the cam in. I pulled the plugs and they were white. I went to #66 main jets and now the plugs are brown. I also used the biggest accerator pump cam that holley makes for the 4160 (600cfm). I now get the full travel of the accerator pump. It comes off idle when you punch it without any hesitation and sounds good. I'm using a 65 power valve also (13 inches).
I also checked all the cylinder pressures after a couple hours and every cylinder was 185-200 (rings really haven't had time to seat properly yet), that's letting each cylinder bang four times on the compression guage.
Another thing I did was put the vacuum guage on the dipstick and seal the oil fill and road tube. I got 1 1/2 lbs PRESSURE. I think the intake is well sealed.
The oil pressure is @ 60 lbs over 2000 rpm, 45 lbs at @ 1200 rpm and it idles at 20 lbs at 500 rpm when hot.
So far I'm pretty pleased with the outcome. I know I sacrificed HP to be able to burn 87 octane but I still have @ 330 hp shifting at @ 4650 rpm.
Hopefully my 7 degree slant 1" carb spacer will be here this week ( the carb looks funny slanted down hill ). The engine isn't in the vehicle yet so the real evaluation will come later. Jim

 

Jim

Thanks for the info. Let us know when it's installed please. I think I may copy your build this fall/spring, if you dont mind. There aint nothing like "been there done that" with real world figures, for a build that works as expected.

Thanks,
Rich

 

What are you putting this in? If installing into a 2wd F100, you may have clearance issues with that pan.

 

TX,
It's not a truck. It's a 63 Galaxie XL. I use this FE engine forum to get the best information on FE engines. I use the Ford Musle Forum also. Between the two, I get answers. Jim

 

Awesome. Good luck on your build!

 

Cool stuff. I'm envious of your oil pressure. Do you happen to know what bearing clearances you wound up with?

I'm using a high volume pump, with 0.0025" clearances, and I get:

85 psi cold

15 at idle when hot

45 at 2000 rpm when hot

 

Argess, did you run any oil restrictors in the heads?

I'm running the Melling HVOP and see pressures in-line with Jim's.

 

And if not, and even so, are the rockers and shafts in good shape? If not, that's were the oil pressure is going.

Also, critical, is oil weight.

 

Oops...dont' want to get too off-topic. Yes, I run restrictors to the heads, solid lifters so those galleries are blocked off. Run Castrol GTX 20W50 for break-in and am about to switch to 15W50 Mobil 1. Have done 3 different engines, always the same results in oil pressure. I just figure it's the loose bearing clearances I run. That's sort of why I asked the OP about his clearances.