Taking power out of motor?

[mitchadamyk]

Hello everybody! I am new to this forum and have nwver ppsted before but i have a question. I have a 1984 Chevrolet Scottsdale C20 with a 305 in it. My dads friend is giving me a good deal on a 1985 parts truck with a 355 in it. My plan is to take the 355 put to replace the 305. My question is what is the best way to take some power out of the engine because i plan on using the truck occasionally to haul or tow things and i dont want to have 400hp. I was thinking maybe putting stock heads on it because it has 9.5:1 compression. Let me know what you guys think.

 

[RangRayy]

What are the specs on the 355? This is a very odd question. Not many people want to take the power out/away from an engine. You could have a great power source with a lot of lower end torque great for towing/hauling. Also just because you have a high horse motor doesn't mean you always have to romp on it, just nice to have the power available when you need it. Just my opinion though.

 

[74 Shortbed]

Odd for sure never heard that one before, lol, you don't take HP out of a motor, unless it's non streetable in it's current condition, can always use power..

 

[mistaake]

Don't press the gas pedal so hard??

 

[Burban]

Smaller carb might be a way. Take whatever is on the 305 and swap it.

Problem being I think they may have put the same 750cfm Q-Jet on everything?

Maybe find an old 2bbl carb. https://www.summitracing.com/parts/urm-3-3337/

Also makes it easier to swap back, if you decide you want the power again.

 

[mitchadamyk]

What are the specs on the 355? This is a very odd question. Not many people want to take the power out/away from an engine. You could have a great power source with a lot of lower end torque great for towing/hauling. Also just because you have a high horse motor doesn't mean you always have to romp on it, just nice to have the power available when you need it. Just my opinion though.

Yeah im not sure if 100% want to take power out yet. I dont currently have the engine yet but its a 355 (as previously stated) it has a low end torque / towing cam, a 650 Edelbrock carb with an edelbrock intake (not sure which one) and im assuming aftermarket heads because of the high compression. Also the reason i wanted to take a little power out is because im 17 and i need to use the truck for a bit more than just sunday drives and gas is not to cheap here in canada, but ill try it out first i guess.

 

[mitchadamyk]

Odd for sure never heard that one before, lol, you don't take HP out of a motor, unless it's non streetable in it's current condition, can always use power..

Its more that im not sure if i can afford the gas as i am only 17, but its not my daily so it should be fine. I was just wondering the best way was if i wanted.

 

[mitchadamyk]

Smaller carb might be a way. Take whatever is on the 305 and swap it.

Problem being I think they may have put the same 750cfm Q-Jet on everything?

Maybe find an old 2bbl carb. https://www.summitracing.com/parts/urm-3-3337/

Also makes it easier to swap back, if you decide you want the power again.

Carb on the 305 is a broken 750 Q-Jet lol, the one on this motor is a 650 Edelbrock i believe. I might just leave it anyways though.

 

[RangRayy]

Yeah im not sure if 100% want to take power out yet. I dont currently have the engine yet but its a 355 (as previously stated) it has a low end torque / towing cam, a 650 Edelbrock carb with an edelbrock intake (not sure which one) and im assuming aftermarket heads because of the high compression. Also the reason i wanted to take a little power out is because im 17 and i need to use the truck for a bit more than just sunday drives and gas is not to cheap here in canada, but ill try it out first i guess.

9:5.1 isn't that high of compression, more or less stock. My 355 for my other project has 11:1 compression and a 7-4 can swap,was said to be 350+ hp but never put it on a dyno.

What's wrong with the 305? If you're worried about the 355 having too much power why not leave the 305 in? If you're gas conscious hate to say it but you're driving a big heavy truck. Find a set of 193 swirl ports or vortec heads for it.

Gas isn't cheap here in the Midwest either. Gear the rear end right and invest in an overdrive transmission if you do not already have one.

 

[mitchadamyk]

9:5.1 isn't that high of compression, more or less stock. My 355 for my other project has 11:1 compression and a 7-4 can swap,was said to be 350+ hp but never put it on a dyno.

What's wrong with the 305? If you're worried about the 355 having too much power why not leave the 305 in? If you're gas conscious hate to say it but you're driving a big heavy truck. Find a set of 193 swirl ports or vortec heads for it.

Gas isn't cheap here in the Midwest either. Gear the rear end right and invest in an overdrive transmission if you do not already have one.

305 has a buggered lifter and the carb is broken, also its just old. Im getting this 355 for $250 so i might as well just put it in aha. Was told it had about 400hp.. Not sure if thats correct or not.

 

[RangRayy]

305 has a buggered lifter and the carb is broken, also its just old. Im getting this 355 for $250 so i might as well just put it in aha. Was told it had about 400hp.. Not sure if thats correct or not.

That's not a bad price. But how long has it been since it was rebuilt? How many miles has he put on it since? Hell why not throw that bad boy in and you'll have a nice hauler/ rubber burner at your disposal. Plus side it's not your DD so why not enjoy it? I can't afford much with my two projects but I do it anyways because they're fun and I enjoy tinkering with them.

 

[Burban]

Yeah, if you want to save gas, carb is the way to go. My buddy thru a 2 bbl on his 350 because he wanted better gas mileage. I'm hoping to throw a Holley 4360 Economaster on mine, not so much because of mileage, but because the Q-Jet is trashed and it's the only spare carb I have, and it fits.

Course the engine has to run first

Lifters are cheap tho' and it's not meant to be too hard a fix, the 305 is always gonna drink less than the 355, maybe save your money, overhaul the 305 and get a smaller carb?

 

[highdesertrange]

a 2bbl carb is not going to get you better mileage. keeping your right foot under control will get you the best results. highdesertranger

 

[bucket]

a 2bbl carb is not going to get you better mileage. keeping your right foot under control will get you the best results. highdesertranger

Yep, and the engine needs to be properly tuned. A 400 hp 350 that is built for lower end and midrange can get just as good mpg as a stock motor. Possibly even better if you keep your foot out of it.

 

[Green79Scottsdale]

A lot of good advice in here. As stated already, it sounds like that 355 was built for a vehicle like a truck. Good low/mid torque numbers will be good for hauling/towing, and you don't have to be hard on the gas pedal to get going. And the MPG difference will be negligible between the two. More power is always good when towing. If it wasn't, then no one would be using the high tech diesels these days for towing.

Personally, I would look at fixing the Quadrajet that is currently on your 305, and put it on the 355. Depending on the intake, there is a good chance it will bolt right on. If you doing a little tuning on it your MPG shouldn't be horrible. The Quad is a good carb, there is just more involved with tuning it. It will be a good learning experience for you. And if for some reason the Quad does not work, you have the Edelbrock you can throw back on. My very first experience with dealing with and rebuilding a carb of any kind was last year when I rebuilt the Quadrajet on my '79. I had found a good video and bought a book on it, so I jumped right in. I had some learning moments, but it runs great now!