primer84z

I had begun to become disheartend by the fact that many people flame the lg4 for being only 145hp stock. Hey the tpi has 200+ stock, i can see where the criticism came from. But finally i found total enlightenment and inspiration from the website listed below. Car craft made 325 hp on a lg4. Thats right 325. Nothing was done internally except for a cam swap. The rest is heads (the ones they used only cost around 500 for a complete pair), headers and exhaust, edelbrock performer rpm intake, and a holley carb. Check out the website and see for yourself. Our day of reckoning has arrived.

http://www.goingfaster.com/spo/carcraft325hp305.html

Mark A Shields

Yeah, the stock LG4 is horrible, but when the weak parts are replaced it's the same as any other 305. Mainly, the cam, heads,and exhaust.

zippy

you shouldn't have been disharted in the first place. it's an engine just like any other and can always be improved. it's good you did some research, but that issue was 3 years ago and it wasn't anything new then. it's just a shame it took 3 years for you to find it.

primer84z

well ive only had the car for 9 months and didnt start modding it till about 4 weeks ago. i just thought that a 305 would never compete with a ls1.

rezinn

LS1s may be rated at 325hp, but they actually make a good deal more. Don't expect to beat an LS1 with that buildup because you will be very dissapointed.

1991tealRSt-topGuy

if those results are true and accurate i might keep the car a 305 and get me some vortec heads

Ward

iTrader: (1)

Add GM L31 Vortec Heads- 324.7bhp @ 5800rpm / 316.5 lbs-ft torque @ 4800rpm

Adding the L31 GM Vortec heads to the Victor / Holley combo above netted this figure. The heads had to be extensively worked in order to get them to install correctly with this engine. The Vortec heads have a unique intake manifold bolt pattern requiring a special and costly GM or aftermarket intake. Indeed, the Edelbrock Performer Vortec aluminum manifold is almost 40% more expensive than the regular Performer manifold! The valve cover bolt holes are the centerbolt design, meaning that early blocks and installations will have to switch over to the post-'87 center bolt valve cover design and late-model guided rocker arms. The heads have a volume of 64cc which will require milling in order to avoid compression loss on a 305, and the larger-diameter chamber outline requires that you use 350 head gaskets, a solution which could also cause a loss of compression. Car Craft milled the heads 0.045 inches and used a thin 0.015 inch head gasket to bypass these possible problems. With this work done, CC managed to maintain a CR of 10.0:1 on the small block with no detonation problems, even using 89 octane gas, once the L31 Vortec heads were installed. 1.6 ratio rocker arms added a few hp and lbs-ft of torque but not enough to warrant the expense.


Yep thats about the biggest PITA i have ever heard of to install heads. And I thought I had it bad since I gotta drill steam holes!

primer84z

i think with that setup and a 3.73 posi rear i should be able to hang with most ls1, if not, theres always the bottle.
Bottle fed babies are stronger.

and to the guy saying its a PITA to get heads milled, machine shop will do that for 50-100 bucks, and the vortec intake manifold from edelbrock goes for 130-150. ill pay that then use say world s/r heads and lose almost 30 hp, according to those dyno numbers anyway.

Mark A Shields

Don't forget though the dyno sheet on an LS1, there's no power curve, it's more like a plateau, it's more than just about HP. Although 325HP will be a big help.

1991tealRSt-topGuy

since i have an 87, i have centerbolts and the newer style rockers.......i want to change my rockers anyway

i assume the valves on the vortec heads will clear the 305's small bore without modification

ummmm the edelbrock intake aint that expensive

sounds like a plan for me!!!!!

what would be a safe level for me to bump the compression up to and still be able to use street gas (93 octane around here)??

cuz my compression is already 9.3:1 stock

ummmmm what else.....

what kinda rocker arms would be the BEST (regardless of price) upgrade......

i just got my taxes back, so either i can get my paint job done and put my tranny in OR put my tranny in and work my motor even more.........

what would you do?

DM91RS

No milling on the heads and it runs great

DM91RS

Hmm....sig does not show up today?

Anyway LO3 with Vortec heads....Edel performer Vortec intake...LT4 cam...Crane gold 1.6 Centerbolt full roller rockers...Tes headers...3" exh...

Seems like a guy on here named Checkeye is running them on a LG4