Here is a gift to all my fellow Third Gen enthusiasts, thanks to Car Craft (March, 1999) and a great site out there (Goingfaster.com)


305 BUILD-UP PART 1.

Car Craft started out with an 80,000 mile (130,000km) 305 LG4 engine from a 1982 Camaro. They removed the engine from the Camaro and put it straight on the dyno with headers, 3" dual pipes to Flowmaster mufflers, and a HEI distributor with 22 deg total advance. This gave a baseline dyno result of:

197 HP @ 4,000 rpm. 261 ft/lb torque @ 3,100 rpm.

305 BUILD-UP PART 2.

Added an Edelbrock Performer EGR intake manifold, but with the EGR blocked off.

217 HP @ 4,200 rpm. 285 ft/lb torque @ 3,300 rpm.

This is an increase of 20 HP and 24 ft/lbs over stock.

305 BUILD-UP PART 3.

Replaced Edelbrock Performer EGR intake with an Edelbrock Victor Jr single plane intake manifold. Replaced Q-Jet carb with a 750 Holley double pumper.

217 HP @ 4,200 rpm. 285 ft/lb torque @ 3,300 rpm.

This resulted in no change from the previous mods, maintaining the increase of 20 HP and 24 ft/lbs over stock.

305 BUILD-UP PART 4.

Added Comp Cams XE262H-10 "Xtreme Energy" hydraulic flat tappet cam. 218/224 dur @ 0.050, .462/.469 lift, 110 deg LS. Set initial timing to 16 deg BTDC.

270 HP @ 5,100 rpm. 291 ft/lb torque @ 3,800 rpm.

The cam change resulted in a huge increase of 53 HP. Torque was up by 6 ft/lbs.

305 BUILD-UP PART 5.

Replaced stock cylinder heads with World Products 305 S/R Torquer heads.

298 HP @ 5,500 rpm. 308 ft/lb torque @ 3,900 rpm.

A 28 HP increase over the stock heads, and the 305 engine now has close to 300 HP.

305 BUILD-UP PART 6.

Replaced World Products 305 S/R Torquer heads with '96 - '97 Chevy truck L31 Vortec cast iron heads, GM P/N 12558060. These are available from GM dealers in the USA for US $408 a pair, fully assembled. The Vortec heads require a different intake manifold, and Car Craft chose an Edelbrock Super Victor. They kept the same Holley 750 DP. Car Craft says that these heads are a bolt on for conventional small block Chevy engines. If your engine is earlier than '87, you will also need a set of self aligning rocker arms, and a pair of "center-bolt" valve covers.

325 HP @ 5,800 rpm. 317 ft/lb torque @ 4,800 rpm.

TECH COMMENTS

With peak torque at 4,800 rpm, the 325 HP 305 would definitely need some stiff rear end gears (I'd suggest a minimum of 3.73 ratio) plus a high stall converter if the car had auto trans. In my opinion the WP Torquer heads are the better choice for a street engine. I think that a 300HP 305 with 308 ft/lbs at 3,900 rpm, would be a nice street / strip combination.

 

in the full article it says the final intake they chose may not fit under the hood... i would like to know if anyone knows if it does or not. i have an 84 z28 and would like to know before i decide to do the mods stated

 

dont waste your time posting ANYTHING about 305s here .the 350 crowd are closed minded about those engines,even when you point out that a set of cast flat top pistons and a good comp cams cam and a mild port job on these engines wakes them up considerably

 

I didn't see anything posted here other than the sticky, your comment, two comments from one post users...and now mine. Fact is fact, the 305 is a smog engine producing V6 power with the sound of a V8. 350's from that same era weren't much better off. In fact, look at big blocks from say 76-88. 454's putting out 260HP...it was a sign of the times not discrimination on the number 305.

 

do you understand valve shrouding?

do you understand the limitations of a combustion chamber which has a small bore size?

Sure, you get a long stroke for torque but the bore size kills your top end number (HP)


MODS- please perform housekeeping and delete my as well as a few of the other posts

thx

 

I think the discussion to this point has added to the threads. I can see where someone that liked the 305 would get frustrated by people telling them they are not worth building. I can also see your point but to say small bore limits HP? One of the highest HP motors GM built in the 60’s was the 302. It would pass almost all the Big blocks on the Dyno except the 427. With all the original parts and a lot of tweaking they have hit 490 HP at the flywheel in their stock form they could hit 400 HP at the flywheel. I know, but Fly wheel HP is how we rated stuff back in the day.

From a money point of view the above makes no sense. For what they put into that motor you could have bought a 290HP crate motor that could hit 350 HP with almost no risk to the motor and it would run that for 100K miles.

I did the 305 thing back in the early 80s and like everyone I know I ended up with a big paper weight. Once GM started to add more power to them in the late 80’s GM ran into a wall. I was doing a Crank kit a month with the 305 on stock engines under warranty. I cannot remember doing a 350 (truck or car). 305’s have weak bottom ends. I cannot imagine they have gotten stronger with age.

 

Gorn

it was a 4 inch bore......you know, like with the 350.

it had a shorter stroke

I still stand by my request to the mods to delete my posts as well as the other off-topic posts.

 

... Guys all i asked was if it fit under the hood. i have the original block in my car. and i dont want to change it. i was just asking for a little more hp to my 305. I DONT WANT TO DO AN ENGINE SWAP. people have there reasons that mine. make sense? the block only has 49000 miles on it. I have decided on a different intake that should fit. I did not. i repeat did not ask if i should do this. i asked if it would fit.
Good day.

 

BTW. my car is just a daily driver. a little more horsepower is all i want. another 100hp is all i really want. buying a new crate is not what i want to do until i know the car will stay with me for longer than a couple years. which with the original block if the price is right she will be on her way.

 

I can see how this thread got derailed very quickly. It started with the suggestion to put a 400 crank and rods in your 305. Frankly, I'd like to see that trick!!!
mrblock, they used more than one intake manifold in the test, which one was referenced to being a close call? There are some members here who have aftermarket intakes in their 3rd gen, so that info can help. You might also want to post the specific question about intake to hood clearance in the 3rd gen tech section, you'll probably get more hits.
Once the dust settles, I'll clean house here. I'm pretty sure nj's intent was for this thread to be informational, not confrontational.