I have a 86 Silverado i recently got painted and have rebuilt the 305 ci. I bored it .30 over, Edelbrock 600 cfm 4bll, Edelbrock Performer Intake Manifold, and Headers. It has plenty of power and will skin the tires back anytime. But i have a thirst of more power! My friend has a 350ci block that comes with a turned crankshaft and connecting rods and is bored .30 over for $300. If i took all the performance parts off my 305 and put it on the 350 i wonder how much power gain i could feel. Does anyone have a clue to how much HP i could be pumping out if i do this change. Any suggestions would be appreciated!!!!

 

It is not only the horse power 50 ponies give or take but your torque will also increase. You will definently notice a diference. There is always the strocker 350. The 383 put new crank and pistons in it. It will give 450+ horse and about the same in torque now theres a motor. Almost BIG block power that is what I am going to biuld for the old 87 Monte SS When I finally acumulate all the parts I want PM me if you want to talk.

 

Roughly around 30-35 horses in the upper RPM ranges is primarily where the gains will be. The 350 has the same stroke adn more bore....allowing for better breathing at upper RPM's. If you don't have a more aggresive cam than stock, then the power difference may be even less.

 

If you do go for the 350 dont use your 305 heads on it. The 305 has 58cc combustion chambers, Most 350's have 76cc chambers. You would have waaaay too much compression for todays gas and a 5000lb truck.

Around 11:1 and very small valves. Would definatly have torque but you would have to run C-12 in it.

 

Oh i forgot i put a bigger lift cam also, i think it is about a 435 lift. I have got $2500 in this 305, stock rebuilt=$1700 plus the performance parts. I put way to much money in it, could have got a 350 pumping more HP probably for smaller price. I dont know if i should buy the 350 block or not, but if i did i was going to buy a bigger lift cam and prolly rollerrockers. I was planning on putting the Heads off the 305 and putting them on the 350ci for compression cause i cannot afford no $1000 Aluminum Heads. I just dont know if i want to spend all this money!!!! 400+ HP sounds damn good, put i just have spent too much money on motors, im only 17yrs old and i work at a grocery store making $5.15 hr!!! But when taxes come bak i will have about $700 saved. But if i did all this i would have to replace my 700R tranny cuz it would not stand the HP. WHAT SHOULD I DO!!!!!!!

 

$5.15/hour!

Tell your govenor to get on the ball. MW in cali is $6.75!

Anywho 350's are a dime a dozen. I recomend that you pick up 2 books. One is "How to rebuild your small block chevy" the other is " How to hotrod small block Chevy's".

You can get them at most hotrod shops as well as Pep boys. There are several variatons with 350's. Some have 4-bolt mains, Dipstick on the other side, Some have a lot of nickle in them and some are made in Mexico. Stay away from the ones made in Mexico. They are very thin and the steel is soft.

These books will explain all that and then some.

 

Yea the one im thinking about getting is a 4bolt main. Im just scared imma blow head gaskets if i switch the heads.

 

4 bolt main is nice, but not necessary for a mild engine...for 400hp, I would find a 4-bold main block. The 305 heads have the smaller combustion chamber + SMALL PORTS....which are good for low end torque, but kill high end power....stay away from them.
Get both books chris142 recommends...I have had them for years.

 

Just because it's got 4-bolt mains isn't the perfect reason to buy it. You would be better off with a hi-nickle 2 bolt than a "Hecho in Mexico" 4-bolt block.

As for heads: I think that you would hate the hi-compression. You would have to retard the timing so much to prevent detonation that the engine would have less power than your currant 305. Gas milage would suck too.

If you really want to go 350 here's what I would do. I would find a good standard bore block with both 010 and 020 cast into the area behind the timing cover /and or behind the flexplate. Most of these were cast in the early 70's.

Bore it and have the rods and crank checked and ground if necessary.

Put flat top pistons in it and 1969 350 2bbl heads #441. These have open chambers, 1.94 intake valves and 1.5 exhaust valves. They are very thick castings so they shouldn't crack like thin heads will if they get hot. The ports also flow pretty good. Compression ratio would be 9.0-1 with this setup.

Option #2 would be to go with dished pistons and closed chamber heads. Casting #041 or #186. These heads are a little harder to find.They have the acessory bolt holes for your alternator, ac ect. Same size valves as the #441's.They are also thick castings. Look for 69'or 70' Chevy 4bbl station wagons.




This setup would be about 9.5-1 compression. The heads don't quite flow as well as the #441's but the increased compression makes up the difference.


Run a "Blue racer" cam. They grind their lobes with more taper to help spin the lifters. Really cuts down on cam/lifter wear.

You do know what Chevrolet stands for......right?

Cracks
Heads
Eats
Valves
Races
Only
Little
Electric
Trains...............[img]i/expressions/face-icon-small-happy.gif[/img]

 

Eiger,

I agree with some of what Chris is saying. I have been around race cars for 40 years, I currently have a 69 Camaro SS350. I stroked and bored the original block into a 383 before all these kits were out some 12 years ago. My suggestion would be take your mild built 305 and try to sell it, for about $2000, add a $1000 to that total and buy a 400hp crate motor for your car. You said the lift on your 305 cam was .435, that isnt very mush past stock, in my SBC I run .580 lift but I have an all roller setup, which was very expensive, but it sounds nice with the 306 degrees of total duration. The cost of crate motors are pretty cheap nowadays. If that wont work, buy the 350 block, you'll need to make sure it good, a good engine shop with charge you for that, if its standard bore take it .030 over, buy some TRW forged pistons, and steel rods, add a decent medium grind cam. The machine shop can "clean up" your heads, freshen the valves and the springs, retainers, seats, have then change the rocker studs too, I learned this the hard way, they can clean up the ports some too for a couple hundred bucks. You then can use your intake, carb, and headers. Actually the 600cfm carb may be a little small for the 350, it depends on what heads you go with. Edelbrock makes a cam to match your carb and intake, with some mill and port work on the stock heads you should notice a good 75 hp gain over what your 305 had.