[79Blazer]

i have a 1979 k5 blazer with a 73 chevy 307 that i have converted to hei,aluminum weiand street warrior intake,long tube headers,and everything else about the engine is bone stock .my question is i was wanting to use the holley 600 carb that i already own on this engine but will it be too much ?should i use a spacer plate under the carb ? any insight would be greatly appreciated, thank you

[FmrStrtracer]

Vacuum Secondary? If so, the 600 should work fine, you may have to adjust jetting and the secondary spring to get the correct opening rate.

[techinspector1]

Originally Posted by 79Blazer

should i use a spacer plate under the carb ?

You never can tell ahead of time how any one particular motor will respond to a spacer plate(s). Experiment with them after you have exhausted all other routes to power.

[cobalt327]

Originally Posted by 79Blazer

i have a 1979 k5 blazer with a 73 chevy 307 that i have converted to hei,aluminum weiand street warrior intake,long tube headers,and everything else about the engine is bone stock .my question is i was wanting to use the holley 600 carb that i already own on this engine but will it be too much ?should i use a spacer plate under the carb ? any insight would be greatly appreciated, thank you

I would suggest you put the carb back to its factory baseline before using it- that will be close to where it needs to be for the way your engine is now configured.

Using the list number stamped into the choke tower of your carb, look up the stock settings HERE. A spacer may or may not help, experimentation is the way to tell. Usually a 4-hole insulator-type gasket can help keep the carb a little cooler.

[cooley8]

Originally Posted by 79Blazer

i have a 1979 k5 blazer with a 73 chevy 307 that i have converted to hei,aluminum weiand street warrior intake,long tube headers,and everything else about the engine is bone stock .my question is i was wanting to use the holley 600 carb that i already own on this engine but will it be too much ?should i use a spacer plate under the carb ? any insight would be greatly appreciated, thank you

Be carefull adding a spacer it will change rev range and may put power band out of usable rev range of that stock engine, also, remember if that is a dual plane manifold that you will need a divided spacer NOT a open one. Hope that helps.

[DoubleVision]

Trying to get more power out of a stock 307 is chasing ones tail. The limiting factor is the heads. The heads have large 74cc chambers so the compression ratio is 8:1. The valves are the smallest of the small block V8 line which is 1.71 inch on the intake side. These small valves are for high torque at low RPM. When they hit 3500 RPM theyre out of breath. You can experiment with spacers, but a open spacers are for high rpm help and since the small cam and small valves are done at 3500 rpm there's no point in trying to help the upper RPM. If it were mine and I wanted more power on the cheap, I would get a set of 416 casting heads off a 305. These have small 58cc chambers that will kick your compression ratio up to 9.5:1, They also have 1.84 intake valves, perfect for the smaller bore of the 307. The ports in these heads are the same size as a 350 at around 160cc. While I was in there I would replace the cam with a Summit racing model as seen here:
http://www.summitracing.com/parts/SUM-1787/
Add a double roller timing set and springs to match the cam and a Rochester Quadrajet carb. If you shopped carefully you could pull this off for less than $500 and you'd pick up 30 to 40 horses and 50 to 60 ft lbs of torque plus get better fuel economy. If you can't afford to go that route then I would at least replace the timing chain. If its never been replaced you can bet its shot. Why I would use a Quadrajet is because of its small primaries create high velocity so it developes low end torque quickly and thats what a small cube 307 needs to help get it up and moving out of the hole. THe small primaries of the Q-jet also conserve fuel better.