The 390 engine I have is bone stock, and has probably 4,000 miles on it since it was completely rebuilt. I'd like to pep it up a bit, but not make it into a drag racing machine. I'm looking at using the Holley 600cfm that is on it, but installing the Edelbrock Performer package (manifold and torque cam) plus maybe a good set of headers. Realistically, how much performance would this add? Factory rating is only 180hp. It has a C6 tranny as well.

 

Was the engine a complete stock rebuild? Would have been nice to put a little hotter cam than stock. The stock cam is pretty small. I think it has a .481 lift and around a 195 duration at .050. If it is still stock the upgrades you have mentioned should give you a good wake up. Maybe shy of 250HP. Not to mention the 50 pounds you are going to save by going with the aluminum manifold.

 

I bought the truck from a friend of mine and I had reassembled the engine for him about 6 years ago. Everything is totally stock to my knowledge.

So what would it take to get the engine to 350+ HP on pump fuel without making it an RPM-race engine? I'll mainly use it for hauling trailers.

 

You will definitely need a bigger cam. I would stay away from either of the edel cams. With the head designs on the stock FE heads a dual pattern cam will really help you out. Putting 1.65 exaust valves will really help but that is pretty involved. The 600cfm carb is a little small for 350HP but will probably get you by. Your compression is what is REALLY hurting you. You could bump it up to 10:1 by using the TRW L2291 forged pistons. They are about 32 bucks a pop from summit. Upping the compression will help a bigger cam work better. You could probably stay with the pistons you have and "cam" your way up to almost 300. I'll get on the desktop dyno when I get home and tell you what it says. It is not absolutely accurate but will give you a good idea. Did you do the oiling mods when you rebuilt it? If not I would at least pull the pan and put a HV/HP pump in it. The stock oiling system is not made for turning the revs you are going to need to get that much power. If you are willing to take a little time and spend a little money 350HP will be no problem. Let us know if you are willing to change the pistons out and we can go from there. Also I don't know what gear ratio you have in the back but you can really wake it up if it is a low ratio right now and you switch to a higher one.

 

> Also I don't know what gear ratio you have in the back but you > > creally wake it up if it is a low ratio right now and you switch to > a higher one.

Yea, Rats one to talk about rear gearing

 

You would be correct. I have a serious problem back there. All in good time man.

 

Just busting your chops bro...by the way, congrats on your build up, sounds like you did it right.

 

I know. Thank for the compliment. What gear do you think I should run? I am debating between a 3.89 and a 4.10. I don't do too much interstate driving and at this point gas mileage is obviously a concern. I'm just thinking with posi and road slicks a 4.10 still might be a little too much. Basically looking for best performance.

 

Scratch that about the gas mileage. I meant to say gas mileage is of absolutley no concern.

 

 

I'm running 4.10 gears on my 69 F250 with 390 and C6. I feel like it's too much gear. It's almost like I'd be faster with 3.73 or 3.55 gears. I feel like I'm closing in on the red line without going fast enough. I'm running 255/70r16 tires that could stand to be a bit taller, which might help. But, I really wanted 4 same size tires just for the sake of rotation. Has anybody seen some sort of chart that shows 1/4 mile estimated times versus HP, weight and gear ratio? I have yet to actually run a 1/4 mile drag, but I suspect that I would run out of RPMs before I ran out of track.

Greg

 

How far from stock are you? I would definitely agree that 4.10 is too much for a stock 390. I have 3.25 gears now and I shift into 2nd at about 45 mph (loosing rubber) at 5000 rpm and by the time it hits 3rd I'm going about 85 - 90. I'm looking for a gear to go well with posi and slicks and 295/50R15 tires. E.T. is my main concern. Not going higher than 4.10 though.

 

Who me? Stock, not so much.

Edelbrock RPM intake, Ed Performer 750 Carb, Crower Power Beast cam, All MSD ignition, Dynomax headers 4 into 1.

Currently runs good to over 6000RPM in park, I have seen 5500 RPM in first and second.

Greg

 

It really depends on the size tires you run, Rat. I run 4.10s with 35s and its not even close to too much gear. Also, what rpm do you want at 60 mph?