can someone explain the difference between the pre 85 or 86 305s and the 87 and afters?
i'm trying to buy a motor and I do not know the differences.
any info would be a big help!

thanks,
joey

 

As far as if you are simply trying to identify them by looking at them, 87 and up the valve covers will bolt on through the center of them, pre 87 the valve covers bolt on at the edge.

 

So if I rebuild a 1988 305 and use World Products S/R 58cc heads, there is no difference between an 1985 and a 1988?

Will I be able to use my 1985 emissions stuff?

 

The 85 is a 2 piece RMS flat tappet block, and the 88 is a 1 piece RMS factory roller block (although it may still have a flat tappet cam).

The external supporting components (like emissions stuff) don't care about any of that.

 

Sorry if I am asking dumb questions, I'm new to the car world. What is the difference between roller and hydraulic cams. I'm just trying to learn as much as possible!

For the motors, I could drop in a later engine and it would be fine?

Thanks so much for the help,
Joey

 

A cam is designed to be used with a certain type of lifter. The part of the lifter that contacts the cam can be "flat" (actually it's very slightly rounded), or it can use a roller. Roller cams can be made with more aggressive profiles than flat tappet cams.

In addition, the lifter can also be "solid", or it can be "hydraulic". A solid lifter transmits motion directly to the pushrod, the hydraulic lifter has a pluger and a spring inside, with a valve to trap oil inside when the lifter starts to move. The plunger inside a hydraulic lifter can compensate for normal wear of valvetrain components, but a solid lifter can't, so it needs routine lash adjustments. The self-adjustment of the hydraulic lifter comes at the price of increased weight and reduced a restriction on high-RPM performance.

 

Aperion, you are the best! I understand the basics of lifters!
For the 305 motor, will the 1988 motor that I am looking to buy be a bolt in fit for my 1985 camaro after I [ hopefully, successfully] rebuild it? Or should I look for the older two piece rear main block?

Thanks again man,

Joey

 

Either block will work. The later block will allow you to use a roller cam more cheaply.

 

http://store.summitracing.com/partde...38%2D2&FROM=MG

Is this cam a good choice? Should I use different parts, or stick with the lifters springs pushrods and timing chain that comes with that kit?

Also, I was thinking about using World Products S/R 58cc Heads. Are those heads a good choice?

Thanks,
Joey

 

That's a decent cam. You will need to use push rods for flat tappet lifters (what your '85 has), as the roller lifters, if the '88 has them, use shorter push rods.

The World S/R Torquer 305 heads are decent. Your stock '85 heads could be made just about as good if you are willing to have 1.94" intake valves installed, new valve springs (which you should do if using any factory head), screw-in rocker studs installed, and some basic port clean-up done. I wouldn't install the World heads without having the port bowls (the area right under the valves, going to the ports) cleaned up - they leave them pretty rough as-cast and machined. The cost difference between '85 heads done right and World heads done right isn't much, though.