I have been studying the old car craft article on the 305 hop up, along with the differences between the LG4 and L69, and was wondering what you guys thought. Would the XE262 xtreme energy cam be the best choice still or is there something better? Assuming stock heads for now but a head change would be in the near future. Also, would it still be worth changing the L69 manifold to one like the RPM Q-jet? Last, would headers be a significant improvement over the L69 manifolds....I'm sure they're better buried it real significant?

 

the only difference between the LG4 and L69, engine wise, is cam and compression.

Headers, by themselves, combined with a 3" catback, will free up 10-20hp over the stock manifolds.

Compare the XE262 to something like a lunati 60102. Similar, same kind of range. Little more lift with the Lunati, little more duration with the comp. Little different lobe separation but otherwise very comparable.

the Performer RPM with Qjet doesn't fit without a drop base air cleaner. The Performer intake will. By itself, it's not worth getting if you don't upgrade your heads and exhaust.

 

I don't like being a 305 build nay sayer but, the best and only mod I'd recommend to do to a L69 is exhaust. Front to back exhaust. That's the biggest choke. The intake isn't a choke factor at low power levels, a cam will yield some power but the factory cam isn't all that bad for a street car (compared with the LG4 cam), and a head change is a waste on a 305 when the heads on a 350 will yield so much more power for less money. If it's a good running, good compression engine, leave it alone. Good gears and exhaust will make a world of difference. Or pull it, store it, and put in a more fruitful power plant. Otherwise a L69 is a great street power plant as it sits.

 

I have to agree with the above statement. The exhaust on third gens is notoriously poor. Work here will give you a decent bang for your buck. The heads on an L-69 aren't half bad especially for a 305. The intake isn't half bad especially at that power level. The cam isnt terrible (especially considering your somewhat stuck with a flat tappet cam) though I think it would be a decent bang for buck to add 1.6 rockers. Changing any of the aforementioned parts will show gains, but for the cost and effort required, I'm not sure it would be worth it.

Also, keep in mind, this may be a carbed engine but it is still electronically controlled with electronically controlled timing. Significant modifications will force you to re-work or eliminate the ECM.

 

Just for general info, compare the difference in size between the LG4 and L69 Y-pipe (post #7). Also note manifold sizes in post #4:

https://www.thirdgen.org/forums/exha...-question.html

The L69 intermediate pipe is 2.75" (often rounded up to 3"). The OE L69 intermediate pipe was larger than the after market piece I bought for my old LG4, lol.

JamesC

 

And to add to this,

If you do anything that requires pulling the motor, such as cam swaps or the like, you might as well find a 350 to put in because dollar for dollar, you get more from a 350.

You can even find a running one from a wrecked truck or car to put in. The motor won't care and your ECM won't care. All you need to do is re-tune your Qjet a bit and put a 350 knock sensor on it.

That said. Modifying 305 heads with 1.94 intake valves will do wonders to wake up the motor, combined with a new cam and 3" exhaust with headers will make for a nice little street motor pushing 250+hp.

 

I took an Lg4 and put an edelbrock performer intake, 650 Holley DP, Headers,3in exhaust, and a Summit cam I think 218 218 with somewhere around 458 lift if I can remember right and it ran 14.80s in a 1987 Firebird Formula. A full second better through the 1/4 than it ran with stock Lg4 but I thought it would make more power than that. My stock 91 Z28 LB9 auto ran a tic faster pretty much bone stock. I had heard the L69 and Lg4 shared the same heads so I figured id make a lot more power but I didn't... Wish I woulda done a 350 and saved my time

 

Thanks so much for the responses. I was thinking if I did similar mods and pulled 320+ HP that it would really change the car. The motor needs pulled due to needing to drop the oil pan to clean it and replace timing cover. MY endgame for this is 350/383 build but I don't have the money for that right now....got about $500 to put into it right now and get it back on the road. That's why I was thinking headers, cam, manifold and milled vortec heads would be some stuff I could shop around and aquier. And also thinking if any of the related L69 parts would notreally be worth changing due to minimal gain.

 

If you only have $500 now, just fix what needs fixing. Take all money you have left and put it in a savings account for a 350/383/anything better than a 305. You're not keeping the 305 there's no point in wasting money on it. 500 isn't going to get you quality parts that you'll reuse anyway.

 

Cam/springs alone is going to run north of $300. Intake is $150 (and not worth it without headers/full exhaust/head work). Wise advice from aliceempire.