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Calling all FE gurus.....

Calling all FE gurus.....

Joined: January 9th, 2004, 4:07 am

February 5th, 2004, 9:49 pm #1

Ok ..new project beginning asap. I am building a 390. I need to get as much torque as possible . What machine work or mods can I do or parts can I add to achieve maximum torque from this engine? It will go in a half ton truck that is used for hauling wood,construction equipment, and recreational vehicles as well as trail driving. I believe the r/p gear ratio is 3.50 and it has a manual np435 transmission. The heads are stock D2's Thanks all.
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Joined: December 16th, 2000, 4:59 am

February 7th, 2004, 5:54 pm #2

First the cam. A roller cam would be best for max torque, hyraulic or solid. That's the best way to get a lot of lift and a lot of area under the curve without a lot of total duration. A roller maybe cost prohibitive at around $900 for cam/lifters/springs. Second best choice would be a nice solid flat tappet cam without too much total duration. A Compcams 270S or 282S solid cam would work good in a truck. You'll get more area under the curve and more lift than a comparable hydraulic flat tappet cam which will give you more torque. If you just really want a hydraulic flat tappet get a modern grind like an Extreme Engery grind from Compcams. Keep the total duration in the 260-270 degree range.

Next, I'd run as much compression as you can. More compression = more torque. The downside is you are usually more limited on compression in a truck application as they are more likely to be lugged or carry heavy loads making them more likely to ping or detonate. Just get as much compression as you can with the gas your gonna run.

Pocket porting of the heads will help flow at all valve lifts giving you more torque and power without losing anything. It's a win-win situation.

I think small tube (1-3/4" primaries) headers are better for torque than exhaust manifolds even at low rpm. Combine the headers with a 2-1/4" or 2-1/2" dual system including a crossover pipe and you'd be set.

A small runner dual plane like an Edelbrock Performer combined with a small 4 bbl carb (600 cfm or so) would help, too.

Just my opinion,

Paul
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Joined: February 4th, 2004, 8:49 pm

February 10th, 2004, 4:54 pm #3

This may be an elementary question, but why can a solid flat tappet cam have more "area" open then a hydolic?

Is it because the solid cam can lift the valve much faster then a hydrolic lifter is capable of?

I have also heard that solids set the valve down more softly (assuming that the pushrod is not flexing and the valve is not floating). It this also true?

Makes me want to take the old GTA cam out of my 390 and switch to solid with a bit higher stall converter.

Pippin
User Name: TorinoBP88
1868 Torino GT Fstbk
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Joined: December 16th, 2000, 4:59 am

February 13th, 2004, 12:48 am #4

worrying about the problem of compressing the plunger in a hydraulic lifter. It's just metal on metal in a solid lifter. The steepness of the cam lobe is limited by the properties of the metals and the oil.

With a hydraulic lifter, acclerating the lifter too fast will collapse the lifter plunger (I believe). This affects hydraulic rollers, too. They cannot accelerate the lifter and valve as fast as a solid roller and sometimes not as fast as a solid flat tappet.

Solids rule.

Paul
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Joined: February 17th, 2004, 8:46 am

February 17th, 2004, 11:55 pm #5

Ok ..new project beginning asap. I am building a 390. I need to get as much torque as possible . What machine work or mods can I do or parts can I add to achieve maximum torque from this engine? It will go in a half ton truck that is used for hauling wood,construction equipment, and recreational vehicles as well as trail driving. I believe the r/p gear ratio is 3.50 and it has a manual np435 transmission. The heads are stock D2's Thanks all.
I'm pretty sure most 390 blocks are capable of excepting 428 cranks. This will surely give you a little more torque and a little more power. This will probably be more expensive than most bolt on's, because there's machine work involved( I think you have to bore .060 over in a 390?) Plus you'll have to find yourself a set of 428 rods too. I also agree that headers, particularly tri-y's will help you scavenge low end torque which is what your lookin' for.

There's no replacement for displacement,
Erik
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Joined: February 4th, 2004, 8:49 pm

February 18th, 2004, 1:28 am #6

I have seen two different threads on the list where people have commented on the try-y Headers... and torque.

Does any one have a picture or a link to a site about them. I have been working on a 68 Torino Fstbk 390 GTA and want to build the maximun midrange (and some upper power increase) so the car (a bit on the heavy side) will launch fast in the 1/4 and drive well in the out of corners on twisty roads! My max intended RPM is 5500 to 6000, rareley going over 4800-5000, though.

Pippin
User Name: TorinoBP88
1868 Torino GT Fstbk
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Joined: December 16th, 2000, 4:59 am

February 18th, 2004, 2:46 am #7

"GT" pattern, which is what you have if I remember right.

Paul
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