I was curious about how much horse power i added to my 71 5.0 by changing the intake to an edelbrock air gap and put an edelbrock 600 cfm 4bbl carb on my truck i also added an electronic ignition setup i can tell that i have a lot more power but im just wondering what i added, if you have a guess that would be great, the original was 210 hp i believe, and I also wanted to know about the 347 stroker kits and if it would be a good idea to do a rebuild with and if there are any problems with them, such as heat and so on.. When I take the engine rebuilding class and the trany class at my college im thinking of doing the 347 stroker upgrade or should I just rebuild a 351? any comments would be great

thanks

 

im not the wisest when it comes to automechanics by anymeans. but heres my 2 cents. i would rebuild a 351. you will be able to get some mean performance from a 351 and since your rebuilding you can simply use performance parts. ive seen alot of rebuilt 351w ho efi with about 375-400 hp on all the ones ive viewed. of course you probably won't be going to the extreme like most of those sites, but you can get some awesome performance from the 351. but then again since you already have the 347 anything done to it would be cheaper. just depends on how much you can afford and how much performance you want.

 

I agree with modru2004 see if you can sell or trade the 302 for a 351. Actually it is a good thing to start fresh, my suggestion purchase the best quality head you can afford new/used and then get a 351 shortblock and put that thing together you should be happy and cheaper in the long run. IN reality it depends on what you want. You can build a nice 302 that will roast the tires and make you happy for a little bit of money would it make the same power as a comparable 351 no but who cares as long as your happy right. Good luck with whatever you decide

 

I don't know if you'll be able to get much for a '71 302 block, but whatever you do don't throw money away on a 347. The parts alone will cost you over $1,000 before you even have your block machined for the extra clearance that the long stroke crank needs. Point is, why do all the required work to make a 347 when you can have a 351 that will be nearly identical externally and already has a 3.5" stroke. If you still want to spend money, get a 351 block and buy Summit Racing's 3.85" stroke crank, which will give you 393 ci with a .030" overbore. A 393 will be cheaper to build, have a much better stroke/rod ratio, and it won't guzzle oil and blow up like 347's do. JWT brought up a good point about strokers though, you need to make sure that your heads can match the additional airflow requirements of the motor. AFR 185 heads would be ideal for a 393 stroker, but Canfield and Brodix also make heads that could maintain good intake velocity and still be able to feed a big-displacement Windsor out of the box. TK

 

I have some good HP right now but for some reason it still seems like i have just a 302 what could i add to make it so I'm not intimidated when i pull up next to that 350 elcamino if i wanted to stick with my 302. what are some good heads that aren't too costly that i could buy used or new and can give me some good extra HP. are there any good rebuild kits for my engine? i just would hate to rebuild this engine since it has about 15,000 miles on it and seams like a waist to do even though i would be adding performance to it. I'm just a student in college taking a few auto classes for fun and knowledge so i don't know to much about what kind of pistons i should get and so on, plus i have about as much money as a college student has so any suggestions would help out alot

Thanks

 

if you really want to blow some people away that have more motor than you, you better hook up some juice. Edelbrock makes an awesome nitrous kit that runs about $360 that can give you a very safe 50, 75, or 100 HP whenever you need it. The great thing about Edelbrock's nitrous kits is that they are designed with safety in mind, and not damaging the engine in any way. They've designed the Performer kits for stock engines, so you don't need forged rods or slugs to handle the added power. The good thing is that the nitrous will not effect your drivability whatsoever so long as you can keep your finger off the switch. You can also put a steep gear in your rear end, like a 4.10. That will suck if you're driving on the highway, but you'll be able to cruise comfortably up to 65 MPH, and have the ability to accelerate quickly whenever you want. Of course, that AND a shot of nitrous will put you in the low 14's, which will scare many Camaro owners. TK

 

I agree with torqueking but something over looked is what cam do you have now? A comp cam or crane cam along with some headers would really improve things for you, let the cam company choose the cam for you, you'll be happier that way and a little more confident with the decision. YOu might consider a tranny shift kit as well they are cheap and easy to install just get one you can live with you don't have to get one that snaps your neck everytime it shifts gears look into transgo and you determine which performance level you want rv/towing might be a good one. With the cam and headers along with your intake and carb you may very well see 50+ hp naturally aspirated, maybe. Look into some gt-40 heads off a 5.0 explorer/mountaineer pre 97 or mustang gt's they will bolt down and if you add the cam/ headers/ heads you should see a very noticable improvement. YOU could go for the gt-40p 97 1/2-2001 explorer/mountaineer heads they are better than the plain gt-40 but when it is time to get headers you will need some gt-40p specific headers, the truck shorties for the p heads may very well fit your application and they run $220. I will put it this way it will run you roughly $400 +/- to port your existing heads and you can find gt-40/gt-40p used but ready to bolt down cheaper than that and they would flow better than your current heads ported. Good luck, if your only looking for a street terror then feed the 302 some performance parts you should be happy. check e-bay and www.corral.net classifieds you should be able to find some decent priced heads/ headers for your application. I saw a set of gt-40 on e-bay completely checked over used but ready to bolt down for $170 and $60 shipping that isn't bad at all, there were other fairly priced heads given all info is correct as well. Later and good luck

 

I've done every bolt-on in the book, and the only way to actually make a motor act and feel like it's more than it is is by:

1) nitrous
2) lower gears
3) high-stalling Torque converter

A good cam and head combo will give a noticable improvement, no doubt, but you can add 100 HP and not go much faster unless you have the right drivetrain setup. Throwing 100 HP on a heavy truck is like pissing in the Mississippi. Add a 4.10 rear end gear in place of your 2.75 stock ratio feels like you just stuffed a big block under your hood. I still like bolt-ons, but nothing compares to the dramatic difference that you'll get if you change your rear end ratio or add a stall converter, and they're both much cheaper than heads and a cam. Do those later when you've graduated college and have lots of money to blow on stuff like that.

 

I agree the gears should be added but if your running a stock motor then it will take off like a champ and fall on its face shortly thereafter. If you want to figure best bang for the buck a cam swap and gears along with a shift kit would be a good suggestion. 71ranchero500 does that thing have a 9 inch in it?

 

This is the reason I stay away from 347's.
Look at the oil 'control' ring groove. The pin bore is so far up on the piston it actually protrudes into the groove. (Hence the oil burner stigma)

 

You know what's cool about being a modern gearhead? You can actually test your own philosophies with our high-powered software.

You mention bang for the buck. Bang meaning improved acceleration, most accurately measured by a 1/4 drag race, correct? Obviously buck is the cost to do the mods we suggested.

Now I challenge you:

on Desktop Dragstrip, the companion program to Dyno2000, perform the suggested mods to the motor he has. Sketch up a price to perform these mods, and then run his Ranchero before and after the mods, and see how much his time dropped.

I'll drop his rear end ratio to 4.10, and run the same engine with nothing but a gear swap.

I think you'll see that even though the stock motor does not breath well at all at high speeds, the additional gear dramatically improves the performance, I would postulate at least 3 times the improvements that a cam and head swap would. I've done everything you can to a SB Ford motor, and it's nothing like the awesome difference that a gear change makes. Besides, if you set it up yourself, you can install Richmond street gears for just under $300. If you go with a full spool it will be even better, and that's another $200 for a full spool (strongest) or $40 for a min-spool (read: differential grenade for street application).

The beautiful thing would be to do both improvements at the same time, since they compliment each other, but a gear change makes all the difference in acceleration. You won't even get to use that power that you just paid for in parts, hours of your time, and blood unless you get a rear end and a Torque converter that puts the engine in the range that your cam works best. Conversely, you can have a lot of fun with the motor you have now if you put a stall converter (2400 max) and a 4.10 or 3.90 gear in it. Later on, when you do a cam and/or head swap, you will be able to really put the additional power to work.

 

In fact, now that I viewed your gallery, I'm almost positive that you have a 2.75 ratio rear like me. What is your cruising RPM at 70 MPH, and what size tires do you have? Your engine looks very nice, and i know it runs well with the work you just did on it, so leave good enough alone for now and have fun with a 3.90 instead of those party-foul 2.75's. I just don't want you to make the same mistake that I did, and build a Torque-Monster 302 that blows up a dynomometer, but doesn't make your truck much faster. A cam and head swap is not a weekend task if you've never done it before, and it will end up costing you no less than $1,500 if you're extremely economical, and probably closer to $2,000 by the time you add up all your gaskets, fluids, and other parts that you break or lose. Take a few more of your classes, and get some experience working on other cars before so can take a great deal of knowledge and a good deal of experience into working on the engine that matters most-yours. TK

 

Moneypit,

thanks for posting that pic, it pretty much shows why that stroker should never be built if you plan on putting some serious miles on it. Pictures say 1,000 words sometimes.

 

Yep, their great for drag cars that get torn down but not for a street car expecting to get a lot of miles on them. One would be better off with a 3.25" stroke (327 or 331), this completely avoids this problem.

 

How does the desktop dyno work? Can it provide estimated 1/8 and 1/4 miles times? If so do a stock 302 with a 2400 stall and 4.10 gears say a 4000 lbs vehicle. Then do one with a cam with a lift of .477 int/ .484 exh advertised duration 256/268 and duration @ .050 212/218 lobe seperation 110 with a 2400 stall and 4.10 gears 4000 lbs vehicle and put on both a low to mid range intake dual plane with a 600 cfm carb . later