I'm looking for a couple little tricks to get some extra muscle out of my 400. I've done everything that I know to do with increases in performance each time but I have run out of ideas. I have a 400 bored .040 over. Other than that, the block, heads, pistons, rods and crank are stock. I have a Comp cams 260H camshaft, Weiand Action + intake and a Holley 750 double pumper. The carb. has 77 jets in the front and 85 jets in the rear and it is adjusted frequently for optimum performance. A K&N 14X4 air filter sits on top. The fire comes from an MSD mechanical advance dist. set at 22deg. initial advance and a total advance of about 48deg. by 2200 rpms. This is powered by an MSD 6T. I run headers, 2.5" pipes and straight through mufflers with 3" tips in front of the rear wheels. Also, I run 115 octane fuel when I'm racing 200ft. flat out. The truck is a '78 F-150 4X4 longbed with 35" tires and I have reduced the weight as much as possible to still be able to race in street class. Sat. night I am running against a '79 F-150 shortbed with a 460 and 33" tires. The last time we faced each other he beat me by .08seconds. I need to pick up a .1second somewhere. Help?! Lastly, I drive the truck to the track on 38" tires and run pump gas. Any ideas or suggestions would be appreciated.

C&C Racing
Orangeburg, SC

 

You may be wasting your money on 115 octane fuel. The amount of power you get from fuel is based on BTUs, not octane. What compression are you running?
I think you have covered most of the engine improvements.

What axle gears are you using?

 

I know the fuel probably doesn't help much but I run it anyway. I'm not sure about the compression but it should be close to stock. I' running 4.10 gears, spool in the rear and open diff. in the front.

 

The 115 fuel is hurting your performance. You don't need or want 115 with a fairly stock compression ratio. Retune using midgrade fuel.

 

Try to look into the BTU (British Thermal Units) of the 115 octane gas. If it's almost the same or lower than pump gas you could be loosing power.

You could use more compression than stock but the biggest difference you can make is the gears.
A 4.10 ratio with 35" tires is the same as 3.00 with a 26" tire. You are way under geared.

I'd recommend 5.13s. It sounds like a lot until you compare it to other tire sizes.
A 5.13 with 35" tires is the same as 3.81 with 26" tires.

It's also a tolerable ratio with your street tires.
A 5.13 with 38" tires is the same as 3.50 with 26" tires.

Your torque will go up about 25%. Your truck will feel like it has 100 more horsepower.

 

I would like to go to a lower gear but I drive this truck to the track. With 38.5" tires at 60mph, I'm running about 2650rpms and about 2850rpms with 35s. It's all I can do to keep the temp. down on the highway in the summer on 100* days. Trust me, I want the gears but I'm scared I'll never make it to the track. I was thinking more along the lines of 4.88s too.

 

Something's not right. Either your tach or speedometer.
Try your numbers here.
http://www.fordmuscle.com/calculator/rpm.shtml

 

>You may be wasting your money on 115 octane fuel. The amount
>of power you get from fuel is based on BTUs, not octane.
>What compression are you running?
> I think you have covered most of the engine improvements.
>
>What axle gears are you using?

Here's my 2 cents here .. If you not running the compression for the 115 octane fuel then you slowing your self down.Find out want you motor really needs in fuel and run that. High octane fuel burns slower....... Here me here. SLOWER................ that will slow you down in racing. want to pick up a 10th try running the medium grade pump gas.

ShaZam

 

I'm sure the speedo's not right and the tach is a cheap one. I'll definitely try the lower grade gas. I never new high octane could slow you down. I am seriously thinking about going to 4.88 gears and also changing my cam and pistons. All I need to do is rob a bank. I'm looking at one of these two cams and I want to go to a flat top piston. I'll definitely put in an aftermarket timing set as well so I can get to 0deg.

STREET AVENGER
NEW! HYDRAULIC, Smooth idle. Improved low-end torque. No additional modifications necessary. 1500-5000 284°
284° 218°
218° .528"
.528" .304"
.304" 110° Sep
105° Int C/L 04°BTC 34°ABC /
44°BBC -06°ATC
80400LUN HYD
NEW!
71900ML 73815 75702LUN 77006 N/A 84150




TRUCK AVENGER Description
NEW! HYDRAULIC, Smooth idle. Has gobs of mid-range power. Great for towing and highway usage. 1200-5000 260°
260° 210°
210° .508"
.508" .294"
.294" 110° Sep
106° Int C/L 01°ATC 31°ABC /
39°BBC 09°BTC
90400LUN HYD
NEW!
71900ML 73815 75702LUN 77006 N/A 84150

 

have you thought about getting a pair of the Aussie Heads. im working o getting a pr now if you want the info on getting them let me know. some are gonna be shipped in 3 weeks to CA. and some to FL in about a month.

Paul

 

I am interested in the Aussie heads. What advantages will they give me? Will I have to modify anything that bolts to the heads?

 

well to tell you the truth i dont know a whole lot about these heads. im looking in to it myself.do a search on Aussie Heads there are alot of thread's in the archives. and guys who can answer your questions alot better then i can. but if ou do want a pr send me an email and i'll give you the guy;s info on getting them my email address is my user name @webtv.net

 

From what I know, the Aussie heads are just the same as the American 2V Clevelands. In fact, from what I know the 400M heads are just the same as the Cleveland 2V heads, except the exhaust ports are plugged up by water jacket.

I would be interested in a set of Aussies though, how much?

Flatline, that sort of fuel is only useful if you are running 14:1 compression, or 15 lbs of boost. The biggest thing that will improve HP for you is raising the compression, or getting a blower/turbo. Either way, you will need new pistons. Well, you don't NEED new pistons for forced induction, but it's a really good idea if you want your motor to last.

 

115 octane : Any octane over what you need to prevent detonation will slow you down. It burns too slow.

48 degrees total timing : 40 degrees should be the max. Again too much will slow you down.

Put a bag of ice on your intake manifold before the run and get the engine temp also as cool as you can.

Run high pressure in your front tires, the back too if you don't spin a lot.

Maybe remove the air cleaner.

And "nail that tree"!