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1983 Chevy Blazer 4x4 - Nuts & Bolts

Rear View
David Kennedy
| Contributor
Posted May 1, 2003

More Power From a 305/350 TBII had the 305 V-8 in my '89 Chevy 11/42- ton rebuilt by a professional shop. Due to limited funds and not having a second vehicle, I was unable to swap it for a 350 since shops wouldn't accept my 305 as a core. I had them put an RV cam and flat-top pistons in the engine since the guy said that it would be like a night-and-day difference in low-end torque over stock. I am not impressed with the performance of the motor at all and actually believe it was more powerful before it was rebuilt. This could be due to the fact that I've only put about 6,000 miles on the new motor.

What are the best bolt-on power accessories to spiff up my 305 to get somewhere near the torque of a 350? I'm not looking to spend much more than $500-$800. Would a performance intake, a performance TBI, or headers make up the torque? What would you recommend?Denver Fletcherby e-mail

In 1989 the throttle-body injected 305 was rated at 175 hp at 4,000 rpm and 270 lb-ft of torque at 2,400 rpm. The throttle-body injected 350 bested that number with 210 hp at 4,000 rpm and 300 lb-ft of torque at 2,800 rpm. Is it realistic to think you can squeeze another 35 horses and 30 lb-ft out of the 305? Maybe, but we doubt it. We think GM would have given it to us from the factory. Edelbrock (800/416-8628, www.edelbrock.com) lists a power package for 305 and 350 TBI engines along the lines we think you are interested in. The combo recommends heads (PN 6085), a cam (PN 3702), an aluminum intake (PN 3704), and headers (PN 6666) to increase the powerband of these motors. This could be a good combo for you to buy into a piece at a time as money allows, but the whole deal costs more than your budget. We'd try the intake and headers first. If anything, you'll gain power and ditch some unwanted weight. Then we'd experiment with running super unleaded fuel to take advantage of the engine's automatic timing advance. We'd top it off by switching to 5W-30 Mobil 1 oil to reduce friction and gain some power there too.

Dana 60 vs. 14-bolt
I have a 6-inch lift on my '83 fullsize Blazer. I want to put at least 38s on it. I have read a lot of your articles on bigger axles and which ones are best for certain applications. I don't have a lot of money to spend and don't want to add a lot of weight or kill my ground clearance too badly. My truck is used only for off-roading, so when I use it, I beat it. I know my best option is to swap in a 14-bolt. I was wondering what the difference in strength is between the eight-lug and the six-lug applications. Also what are the pros and cons of a Dana 60 rear axle? Will I have to swap out my NP208 transfer case for an NP205 for more strength?Eric HansenDickeyville, WI

If money is tight then stay with the NP208. We bet you'll break the front axle or driveshaft long before you hurt the transfer case. Run the eight-lug 14-bolt with full-float axles out back. Don't bother with the six- or eight-lug 911/42-inch ring gear semi-float axle because the cost difference is almost nothing, and the full-floating 1011/42-inch 14-bolt (9,999-pound weight rating and 6,242 lb-ft max torque capacity) is much stronger than the semi-floating 911/42-inch (5,940-pound weight rating and 4,993 lb-ft max torque capacity) according to AAM's specifications for its current axle products. For the same cost reasons we'll recommend you skip the rear Dana 60 because it will not bolt in to your GM application as easily as the 14-bolt. Otherwise it is a fine rear axle. Your front 10-bolt axle will need to be converted to match the rear-axle bolt pattern with eight-lug hubs, rotors, and caliper mounts from a 31/44-ton truck. You can swap these parts onto your six-lug front axle without the need to replace the whole assembly.

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