ok. I have a 1987 camaro with a lg4 (low output 305) engine. car craft did a build up of this car using L31 vortech heads (i'll have them next month), a mild cam, 750cfm holley carb, and a single plane edelbrock super vicor intake. the problem i have is this. the peak power with this set up is made at 5800 rpm. it cant be the cylinder heads because they are off a 350cid chevy truck. it's a mild cam too so that isnt it also. so my only guess is that it is on the intake manifold. i will be getting the parts together as soon as i decide on the intake manifold. my car with an automatic transmission shifts at about 5500 rpm and i would like to make hp and torque sooner if i could. i dont want to have to wind the car all the way just to make power. as far as transmission work goes i am still looking into it and as soon as i find a wrecked iroc i plan on ripping the whole axle out of it for the posi/gears/disk brakes if anyone wants to know. any input would be nice. thanks.

 

If you want more reasonable street performance I'd stick with a dual plane manifold...high-rise dual planes are great for street motors. A buddy of mine had an Edelbrock Performer air-gap on his old mostly stock L69 and was happy with it.

 

might think about a weiand stealth dual plane they are cheaper than the edelbrocks and from everyone i've found who uses them was quite happy with the results!

It's what i plan to use on my mild 305.

 

i knew the best bet was probably a dual plane intake manifold but will a hight rise manifold fit under a stock camaro hood? also the intake manifold will have to be for vortech heads so are either of those an option for what i am doing? i havnt done too much shopping around yet so i really do appreciate any help on this.

also. would you recommend building the bottom of the engine since it will be out of the car anyway. just to put some better quality pistons/rods/crank? thinking maybe higher compression pistons since i never plan on putting a turbo or blower on it. really i am just looking for a little more reliable power out of the little 305. thanks again.

 

Welcome Aboard!

Most of the "programming" of an engine is accomplished by the valve events. A shorter- or longer-runner intake will compliment or detract from what the camshaft and valve timing are doing, but the cam is critical.

A "mild cam" installed in a 350 or 400 SBC may not be so "mild" when installed in a 305.

And it's only my opinion, but 750 CFM is a lot of carburetor for the smaller, longer stroke/bore ratio engine. It can be made to run well, but don't expect peak performance right out of the box. It's likely benn jetted, has secondaries adjusted, and is power valved for a 350 as it arrives at your door. You'll have a little work to do to make it run properly on a 305.

Additionally, the L31 Vortec castings are good flowing, but have 64cc chanbers. The loss of compression may cost you some power. For a later version 305, the 14101081 castings are a good alternative, will maintain compression, and flow fairly well as cast. With a little port and valve work, they can actually flow quite well. There are also 305 aftermarket heads that work well if you're intent on other than stock castings. The World S/R Torquer 305 heads can do well, but will do better with some port work.

You may want to review the head selection before they are delivered.

 

That isn't necessarily the case. Vortec heads can be altered to accept earlier intakes. There are even commercially available templates w/drill bushings available to redrill and tap the Vortec heads to accept older style intake patterns. A little alteration of intake port locations and the sky is the limit:

http://www.goodson.com/store/templat...886c41a87e3378

Frankly, if you're going to perform a full rebuild, it may be better to find a different block, build it up as time permits, then have it ready for a weekend swap. The more obvious choice would be a 4" bore block, since the availability of performance heads, pistons, and complete rotating assemblies is much better. The 4" bore opens up a lot more possibilities for cylinder heads.

 

http://www.popularhotrodding.com/eng...cks/index.html

I just posted this link on another thread. This buildup of the LG4 with it's "small" 3.746-inch bore netted 372 hp. Granted, it was at high rpm (6,200) but how about 300 hp at only 4,500 rpm climbing nicely all the way up? Sounds good to me. They used the edelbrock airgap manifold, a relatively short duration cam (224/230-degrees duration @ 0.050-inch, and 0.477/0.480-inch lift, on a 110 degree lobe separation. Idle quality was good, with 13 in-hg of manifold vacuum at 850 rpm), and EngineQuest (EQ) replacement Vortec cast heads. These heads are machined for 1.94/1.50-inch valves. So bottom line...get the AirGap manifold, follow this buildup and make serious power! Good luck. By the way...I agree 750 cfm is too much for this engine. Stick with the stock q-jet or get yourself a sweet demon 650 cfm carb.