Advice for BBC motor for towing

[phat rat]

I'm looking at either rebuilding the present 454 or buying one done. The truck is an older crew cab dually, 4.56 gear, 4spd and Gear Vendor OD. Truck weighs almost 7000 lbs ready to go. My car trailer weighs 3700# empty and I also pull a 30 ft travel trailer. This is not just flatland towing as I frequently head west through the Rockies.So here are some of what I'm considering.

1--- This motor is together, but I'm wondering if it would have good bottom end. I'm told the compression is about 9.2 to 1
Isky 270/280 mega Cam and lifters Lift is .542 Int. .565 Exh. Dur @ .050 221 int 232 exh.
Keith Black 201+.040 Pistons
Crane Valve Springs 99839-16
Edelbrock Performer Intake
Eagle Cast 4.000 stroke Crank
Reconditioned Stock Rods with new arp bolts
Heads are 781 castings and have bronze wall liners in the guides and some short side work done. Along with a performance 3 angle valve job. surfaced and chambers measure 115cc

2---A rebuilt 454 HO
Block Cast iron with 4-bolt main caps
Crankshaft (P/N 14096983): Forged steel
Connecting rods (P/N 10198922): Forged steel
Pistons (P/N 10215228): Forged aluminum
Camshaft type (P/N 24502611): Hydraulic
Camshaft lift (in): .510 intake / .540 exhaust
Camshaft duration (@.050 in): 211'c1 intake / 230'c1 exhaust
Cylinder heads Iron ; 118 cc chambers
Valve size (in): 2.19 intake / 1.88 exhaust
Compression ratio: 9.75:1
Rocker arms (P/N 12523976): Stamped steel
Rocker arm ratio: 1.7:1


3--- rebuild the 2 bolt main I have as a mild 489" stroker with about 9.1 to 1 compression, a cam similar to the Crower Cams Torque Beast, with 478/503 lift and duration 204/214, 781 heads

[enjenjo]

I would lean to number 3. My only concern would be keeping the intake velocity up enough to stop fuel seperation.

[UGLY OLDS]

I too would think about #3...    Do some home work & verify that you will still be in the "range" of that cam's torque curve when you are in 4th /Overdrive ...You don't need horsepower as much as you need torque that comes in early & stays through maybe 4500 RPM ...You don't want to be climbing hills at 6K+ RPM to make the engine work.....  Just my thoughts....(The nice thing is that you have 8 forward speeds available ..... Gears are your friend ...... )


Bob.........

[phat rat]

I was just using that cam as an example. Here's what their site says about it

TORQUE BEAST / Performance Level 2 - Strong bottom end power.
Excellent for trucks and heavy cars. Economical price.
RPM Power Range: 1200 to 3800 / Redline: 5200 plus.

At 70mph this truck is running 3000 rpm in 4th OD. Really it's only a 6 spd as creeper and 1st don't get to high enough mph to get into OD

Isky site says this about the cam in number one. I think it's too much cam coming into it's power too late. But the guy who built it swears he's built a bunch of motors similar to this and they were great for towing.

Good all around performance. Good idle & vacuum. 3.70-4.11 axle ratio. 9.5-10.:1 compr. Computer compatible with stage 1 or 2 chips. Stock converter. RPM-Range (2200-6500) Valve Lift (.542 .565) Valve Lash hot (.000 .000) ADV Duration (270 280) .050 Duration (221 232) LC 114

[UGLY OLDS]

TORQUE BEAST / Performance Level 2 - Strong bottom end power.
Excellent for trucks and heavy cars. Economical price.
RPM Power Range: 1200 to 3800 / Redline: 5200 plus.

At 70mph this truck is running 3000 rpm in 4th OD. Really it's only a 6 spd as creeper and 1st don't get to high enough mph to get into OD

Isky site says this about the cam in number one. I think it's too much cam coming into it's power too late. But the guy who built it swears he's built a bunch of motors similar to this and they were great for towing.

Good all around performance. Good idle & vacuum. 3.70-4.11 axle ratio. 9.5-10.:1 compr. Computer compatible with stage 1 or 2 chips. Stock converter. RPM-Range (2200-6500) Valve Lift (.542 .565) Valve Lash hot (.000 .000) ADV Duration (270 280) .050 Duration (221 232) LC 114

[/quote]

I feel cam # 1 seems more "Real World" .. By "RPM Power Range" are they meaning torque??  If so I think thats about the range you want to stay with ... Cam # 2 seems to make HP all the way to 6500 RPM ....I think that's WAY too high in the powerband for what you are planning ...If it was going in a car...no issues..But I think a 454 truck engine is pretty well done "breathing" at 5500RPM at best ...( Probably less than that ... :?: ) I'm prolly wrong but I am looking for power in a "usable" RPM area.. ....Maybe others can chime in with more idea's

Bob....

[phat rat]

That's what I was thinking. I can't see that I would ever be going above 3500-4000 at most in the lower gears certainly not 6500. Don't think of this as a "truck" motor, the 781 heads are a very good flowing oval port on par with the 049 heads. They are not truck heads ie: peanut port.  As you said earlier, gears are your friend and with the GV OD I should be able to keep the motor in it's powerband

Frank, I need to plead ignorance on what you mean by.  "My only concern would be keeping the intake velocity up enough to stop fuel seperation."

[wayne petty]

just want to chip in...

do not use an RV grind.. or anything near it..  they run out of power way to early for towing..  you have to run additional throttle to get the speed you need and the power you need...  this puts you into the power valve and the secondaries..  fuel mileage drops...

years ago when i built a lot more motors.. i put an H230 grind in a 396.. it idled with enough engine vacuum that it would open the diverter valve..

i started using that grind in all kinds of motors..  350 chevys.. 351W..

another customer wanted an RV grind in his econoline 351W... he got 11 MPG...  and could barely drive it at open freeway speeds..  he cracked the heads when it froze on night... i swapped on a duplicate set. and swapped the cam..   H230...  it then got 17 MPG.. and was totally drivable.. he did 200 to 400 miles day..

i tried it in a 460 ford van..  the owner could not believe it was the same van..  all i did was a cam swap...

i have forgotten the specs on the cam.. i guess i can call them if you want.. i got them from american custom cams..  but the H230 grind has been around for a long time..

i am not saying to use that exact cam.. but to use care in selection... as you need enough air flow.. to drive it in up hill in second gear....
and enough manifold vacuum to keep you on the primaries longer...

a cheep air fuel ratio gauge is really required for proper carb tuning..  for optimal fuel economy..

[enjenjo]

Frank, I need to plead ignorance on what you mean by. "My only concern would be keeping the intake velocity up enough to stop fuel seperation."

One of the reasons BBC are hard to get good fuel mileage with, is the ports are big enough that the fuel drops out of the air stream at lower RPMs That was actually the reason for the peanut port heads, to increase air velocity. If your cruising RPM will be in the 3000 range, you should be OK, but under 2500 RPM the peanut heads might be better.

[phat rat]

Just got off the phone from talking with a tech at Comp Cams. This is the one he recommended.

Operating Range: 1000-5000 RPM
Duration Advertised: 262° Intake / 268° Exhaust
Duration @ .050'' Lift: 218° Intake / 224° Exhaust
Valve Lift w/1.7 Rockers: .505'' Intake / .515'' Exhaust
Lobe Separation Angle: 112°

[UGLY OLDS]

What did you finally decide       The suspense is drivin' us nuts    :!:




Bob...........

[phat rat]

Sorry, The Comp cam is the one I decided on, it's now sitting on the shelf awaiting building time. I got a deal on a 4 bolt block a couple of weeks ago.  I picked up the rotating asembly today, Eagle crank and rods, KB pistons. Motor will be a stroker bored .030 for 489 ci.

[UGLY OLDS]

Sorry, The Comp cam is the one I decided on, it's now sitting on the shelf awaiting building time. I got a deal on a 4 bolt block a couple of weeks ago.  I picked up the rotating asembly today, Eagle crank and rods, KB pistons. Motor will be a stroker bored .030 for 489 ci.

I think you made a wise decision.....  I think you will be happier with that cam than something that has to be spun to high RPM to make it work......


Bob .....

[kb426]

I agree. I think the Comp cam will be good. I had a crewcab for a towrig in the early 80's. It had a 260H and an early cast iron intake that was like a high rise compared to the original intake. It made enough power to do the job but never made over 6.5 mpg pulling the trailer. I know this isn't an option at this time but I get to look at 496 engines that are being converted for irrigation use alot. That is the engine I would want if possible. There are some pretty nice heads out there in comparison to the older stuff. Back when every racer had a 1 ton dually, the thought was with the gearing low enough to pull a good sized 5th wheel, you put the engine high enough in the rpm range that a quadrajet couldn't decide if it should open the other 2 barrels or not, creating a lean situation that hurt the engine. Your overdrive is really the answer to alot of this.

[phat rat]

The 496 is a good motor. That's what's in my 02 HD. But I wanted to get away from all the computor controlled stuff. I'm going to run the 4.56 gear first and see what the mileage is with that. if I'm not satisfied with it I have a complete rear with 3.73 gear but think that would be to high so would probably look for a 4.10 gear.

[Crosley.In.AZ]

Interestig cam suggestion on the engine.  Seems valid

The common oval ports should have plenty of volume and speed at 2k RPM and higher I would think.

I would think working the engine on a grade at 3k to 3800 RPM would work well