Some questions on the engine build for my 1975 dodge power wagon 318. I plan on running kb flat top pistons, the compression ratio will be about 10:1. Edelbrock 6000 rpm intake, Holly 600 cfm carb, hedman headers, HEI. Was hoping for 300-400+hp still getting mpg above 8mpg. I have 302 casting heads off an 87 318. Any help on how to build this would be great!

What size values should I run?
How much should I port?
Any suggestions on a cam?

Please help
thanks,
Ryan

 

Welcome.

Any valve size, porting or cam recommendations will depend on desired power band.

Tire size, gear ratio and useage will need to be known.

 

I think it's better to build a stroker....
Step up to Eddy heads
VooDoo or a Wipplash cam, Soild or roller
Airgap
850 holley
MSD 6 AL and dist.
0 Deck the block

460-500HP.....

 

Thanks for the responses,

I am running 3:52 gears 35 inch tires 727.
Would like an rpm range of 500-5500 with just a hydraulic flat tappet cam.
A stroker would b nice but I don't think I have the budget for that.

 

It will be going into a truck, looking for street use with the occasional trail and tow. I would like to keep the original engine which is why I'm sticking with the 318. It now has a few bolt on mods intake, 4 barrel, headers, HEI. Which did not give to much power. Will be pulling the engine soon, trying to find the best way to go in the build.

A few cams I've been looking at.

http://www.summitracing.com/parts/cc...iew/make/dodge

http://www.summitracing.com/parts/cc...iew/make/dodge

 

If you figure the cost of a stroker IT is not that much more than a rebuild

 

How much does a complete kit go for new or used? I only planned on new pistons and rings, I was going to use the factory crank and rods

 

Ok...Now that we got an idea where you would like to be....
to answer the question...
1. Use what you have with a good valve job.
2. Porting should be Just a light clean up and light blend and also gasket and port match.
3. I would say the VooDoo Would fit the bill.
http://www.lunatipower.com/Product.aspx?id=2966&gid=258

Don't look for a lot of H.P. Gain... But this cam will give you a nice Torque curve, with an idle you can live with....

Just my 2 cents
Keep us posted

 

Our '92 D250 with '87 LA 318, 302 head, 1.75"+1.5" valves, pocket port+match,3.55 gear, 904, 32" tire, Ed Performer manifold and headers uses a Comp XE 256 H cam with 901 springs and posi-loc seals. The truck has home built flatbed and is my Son's daily.

Very happy with this cam, with the small valves it has great breakaway torque and surprising top end pull. I compared your two cams and mine on Comps program with 10:1 compression and they are 303,319 and 327 HP all 388-391 Torque, the XE performing the best. With the small ports and valves making a lot of port velocity you'll get the 300ish HP and lots of torque.

I got to be honest and if your going to a 10:1 piston I'd be tempted to go bigger valves in the 302's or Magnum heads then go a much bigger camshaft. It's just too tempting for a guy like me to want that 350-400 HP engine. You would lose some low end driveability but this could be made up with a Torque Converter change.

318's small stroke and that compression are very snappy.

 

With what you are doing ? Just your gas mileage will decrease with oversize valves

 

What size values should I run? 1.92 1.60? Will the voodoo do as well at low rpm as the comp I had in mind (larger one) or the xe that was mentioned? Also will all get about the same mpg?

Thanks

 

I looked at this a lot when making my decision and the XE 256 H, or one similar, made the most torque, any bigger and horse power goes up while torque takes a bigger loss.

More horse power will lose fuel economy, so bigger valves lowers port velocity at low rpm's which sacrifices efficiency. I think the Voodoo's description answers your low rpm question.

 

I realize the budget is tight, but building a torquey motor to band-aid tall gears with large tires seems counterproductive. A stock 318 with 4.11:1 gears for those tires is a better combo than anything mentioned above. My two cents I guess.

 

Just looked up the XE 256/268 that looks perfect for what I will be using it for and great knowing it worked well for you I think I'll go with that. After porting to the standard 318 gasket size. What size values should I run? And I may switch to slightly lower gears somewhere down the road after an axle swap.