Hello,

I'm building my 79 Trailduster into a viable tow rig. Currently have 3/4 suspension and brakes (Dana 60s front/rear, 3/4 springs). I'm going to build up a 440 for towing. I have:
-stock block, crank, rods.
-452 and 906 heads on the shelf
-big block truck oil pan and engine mounts
-big block truck exhaust manifods and headers

I'm not incredibly concerned about fuel economy even though this is my daily driver, but I want to run 'junk' pump gas (87 octane). I'm more interested in resistance to detonation under a load and running cool under a load (I know; they are related). Oh, and lots of low end torque and low/mid range power.

That said, can anyone provide real world experience with regards to:
-heads (stock or aluminum?)
-pistons/compression
-cam

Thanks!
Danan

Use the "452" heads , they have the hard seats stock for unleaded fuel. I would not build any motor with more than 9.25 to 1 for todays pump fuel with iron heads, the motor home, vans and 3/4 and 1 ton pickup motor pistons have thicker tops than the passenger car pistons did in the same years 8.5 to 1 comp. ratio would be safer yet Cam timing needs to be small like a Comp Cams Magnum 260 or a R.V. grind by a good company No Mopar Purple shaft cams

Go to the trucks forum and look up "building the super towing 440", it'll educate you.
R.

I hear you on the compression. My understanding is that the 452 heads are induction hardened, which is not as hard (especially after years of hard use and a valve job or two) as a hardened seat insert. I was thinking about maybe going with aluminum heads and six pack pistons so I could maybe get close to 10:1 compression with the benefit of aluminum heads to fight detonation.

I'm also with you on the cam comments. Definitely don't need a spiky power curve that is high in the powerband for this truck.

I'm very wary of building a low compression smogger motor; I hate how they run. I'm currently running a 360 with 9:1 compression, a 340 cam, performer rpm intake and holley vac secondary.

My advice to you is to look in the truck section of Moparts. Keith @Dunnick Racing has already done a 440 tow build with all the specs and dyno work done. Everything you should need is in his thread, any questions and I'm sure Keith will fill you in. Dave

One member used Ed heads on a heavy motor home 500" RB. Hopefully he will see this. It apparantly worked fine. The Ed heads also make it more practical to build in quench... which can help prevent detonation. I'd go with Cab's 8.5 "safe" number for CR on iron heads, especially with the objective to run regular, small cam and extended hard running while towing. If you can build in quench or use the aluminum heads, you can push the compression. If you are willing to run premium while towing and/or in hot weather, you can push CR a little also.

I did a very similar exercise with my truck, but not to the extremes you asked for and I built quench into both combos.

First was an 11:1, iron head 440 with the small summit hydraulic cam. Pulling power was phenomonal and mileage was great. I was able to pass cars going up I70 to the Eisenhower tunnel, with a trailer and a '48 chevy loaded on it. On a trip to Phoenix I averaged 18 mpg. However, after the drop in elevation down in to Phoenix, detonation was bad enough to hurt a couple of pistons.

I yanked that motor and dropped in another iron headed 440, this one around 9.8:1 but with the same small summit hydraulic cam. You can definetly feel the drop in power driving around at my altitude. Mileage has also dropped some too and the best average I've managed was around 15 mpg, but I haven't taken any extended road trips with it like I did with the previous version.

The example your talking about would likely be even more extreme because the spread is much greater. IMO, you need to be very cognizant of the dynamic compression ratio you are putting into the mill and tailer it for where and how you drive.

Another interesting antecedent to this all; I took the lower compression motor to a dyno fun day with some local car club members. While I took some razzing for bringing my truck out with the muscle car guys, it all stopped when I tromped them in torque under 3500 rpm and matched the highest output 440 6bbl in horsepower, albeit mine was all done 4500 rpm, but the numbers were there. Unfortuantly, I never did a dyno pull with the higher compression engine.

All very interesting; this is the discussion I was looking for. I read Dunnuck's thread with interest (the first one, before he deleted all of his posts). His second thread is very good as well.

I'd really like to hear about the e-head motorhome engine mentioned above; I think this is a good direction to go in.

How about flat top pistons and either edelbrock or stealth heads to build an actual 10:1 to 10:5 static compression? I'm thinking that this could be done with cheapo TRW 2235 pistons (heavy but strong). In any case, I'm not a fan of cast or hyper-u-cracked-em pistons.

As Dunnuck's thread suggested, I'll use a performer rpm manifold, headers, and a holley vac secondary.

With an aluminum-headed 10:1(-ish) engine, what dynamic compression would you guys recommend for a tow rig using pump-junk fuel that didn't detonate? When I get home (currently deployed) I'll call comp cam and hear what they have to say.

Thanks for everyone's input; it's helping me zero in on a good engine build plan.

Semper Fidelis,
Danan

Here is a calculator I use regularly. It's nice because you can factor in boost and altitude, if they apply to the situation.

http://www.rbracing-rsr.com/comprAdvHD.htm

If you are going to do Edelbrock heads, RPM intake, and flat top pistons, your engine will be very close to the one done by car craft in November 2001, and updated with a Comp HE275HL cam in 2002?
Power was 535-545HP range, and 557-583 ft/lbs depending on the cam and intake used as they ran the same basic 440 engine in several comparison articles.

Thanks for the tip. I'll see if I can find that article on the web. I'm thinking that the aluminum heads and somewhere just under 10:1 compression should work fairly well. The good thing is that I typically don't have to worry about high ambient temperatures in the Pacific Northwest!
That should help prevent detonation as well.