Alright guys here is my dilemma. I can't make up my mind for cam selection and really need your advice.

Quick specs:
68 F100 2WD
390 FE (process of being rebuilt) H395P 9.3 to 1 compression
DT2EAA Heads
Perform Intake
600 CFM Holley 4 Barrel
Power Drum Brakes
C6 Trans
3.73 Gear
Stock height tires (will stay like this)

This truck will be a Restomod and looking for more of hotrod.. but also capable of pulling some truck duty when needed. I want to it sound mean and drive great! I've been looking at the 268H and the 270H but it doesn't have to be those cams or from that manufacturer and I really just need some direction and or experience!

My concern about the 268H is with the 3.73 gears I will have limited power-band and with the 270H I don't want to lose a lot on the bottom of the RPM range, but I figured the 3.73 would make up for that?

Thanks in advance! Happy Thanksgiving!

 

The difference between those two cams is minimal. Either will work. If you can swing the cash, I'd go with a mild hydraulic roller though, once you add in the possible cost of wiped cam lobes and bad lifters, there really isn't a cost differential in going roller.

 

I have the 270H in my 390 but either cam would be a good choice for a mild build in the 9.0:1 to 9.5:1 CR range. They don't have a ton of overlap so you can still pull in 18-21 inches of vacuum and have good brakes.

 

well, I ended going with 268H, after talking with the Compcam tech it was on the edge where I may need to go to a higher stall converter if I went with 270H. After I ran the different cam profiles on Engine Analyzer Pro, the 268H was actually made better power till about 4500 rpm.

Now, I am just really freaked out about the break-in. Here's what I think I may try.

Clean Cam with mineral spirits
Heat with heat gun to displace any moisture
Spray cam and lifter tops with graphite and after drying coat with compcams supplied lubricant.

Any suggestions?

 

copy and pasted from Montana hiboy...

1) Be sure the timing and carb are dialed in before starting the cam break-in procedure, you want the motor to fire off right away, now's not the time to be doing a "tune-up".

2) Use a quality break-in oil high in zinc content, tossing in another pint of zinc additive for good measure certainly doesn't hurt.

3) Using a drill prime the motor beforehand and check to see you have good oil pressure.

4) Run the motor fluctuating between 2,000-2,500 rpms for 20-30 minutes (if you have straight pipes your neighbors will love you )

5) Dump the break-in oil and change out the filter, re-fill with a quality oil high in zinc, i.e. diesel oil or racing oil.

 

It's actually more important to closely examine the lifter faces to make sure they're convex (slightly domed) and verify that each rotates freely in it's bore when dropped in place. Over on the FE big block forum on Network54, the genral consensus there is poorly machined lifters are mostly responsible for the cam failures of the past ten years. My two failures were likely due to that too. Although the liberal use of moly lube on the lifters of the first (sides and bottom and cam lobes) failure likely could have caused that one lifter to rotate and fail in the 20 minute breakin run. The second I fired up when the weather was in the low 30's and the oil was thick could have also prevented that failed lifter to spin as well. No matter who you get the lifters from, check em out before dropping them in. If any one lifter fails to rotate at any time, it will fail and wipeout the lifter and lobe in short order. And for this reason, run it wihtout the valvecovers in place on fireup just to verify the pushrods are rotating as it runs. If they do not, then neither is the lifter under it. One of my failed cams was a Comp (280H for a Cleveland) the other was a Crane Energizer (272*) You could have gone with the 270H without changing the converter. Neither of the two I listed here had stall converters and had no problems getting out of the hole with street gears (3.70's in both) I also had a GT390 in a 70 F100 with a 290-something duration cam and it too was fine with a stock converter with 3.50 gears. You really gotta get wild with the cam duration to need a stall converter.

 

this is great feedback, so what is the procedure to verify if the lifter is machined correctly?

 

They should have a convex bottom face. And they all should be uniform as compared to each other. I wish I had been aware of this back when I had those two failures, it never occured to me at the time that poor machining could be a factor. All this started at about the time US production of lifters ceased.

 

should I have the lifter bores grooved by a machine shop?

 

Why would you want to ? You would just lose oil pressure via those grooves.

 

The 268H cam is very close to the same specs as the factory 390GT/428CJ cam. No special stall convertor was used on those cars when ordered with auto trans, and many were also equipped with A/C and power brakes.


I have a true 390GT cam in the 74, paired with the stock C6. Trans has had a shift kit mod done to it, some 25 years back (about the time the engine was built), but still runs a bog standard convertor. A bit touchy taking off without getting some wheel slippage in the dry. Almost impossible to take off without some slippage in the wet or on dirt/gravel. I imagine this would be even worse with a higher stall convertor......


As for cam break-in, all the advise above is spot on. Especially the part about examining everything well before assembly.

Some people will even go to the extreme of using lighter valve springs during the cam break-in. A lot of extra work, that isn't really needed on a "street" cam. Race only engines, this step can become important......