What's the CR for the stock '89-'92 305 LO3? 8.5? I'd like to mill the heads so CR is in high 9s... I don't think my engine is going to live to see a blower or N2O. While I am at it, I'll probably do some porting to. I'd use 305 HOs as a baseline.. Will the stock bottom end be able to handle it? $$$ for machinework? New rockers and springs are a must in this case, as is probably a different cam while I am at it... How much will milling the heads affect the valvetrain geometry? How hard (expensive) is it to change the pushrod length, if that is the case? I know I have a TBI, but don't worry about that, I am in the process of building a custom computer based on Megasquirt from diy-efi.org...

Anyone? This is a Tech/General engine board, there has to be someone who did engine buildups who is merciful enough to respond...

I think LO3s run 9.3 cr. I wouldn't bother.

Hm...
OK. Before I quit, what's max VE for a 305?

I am thinking it's dynamic CR might be low enough so pump gas can tolerate higher comp.

Besides, I am really interested in machinework pricing, I want to see how viable is it to get some of those things done...

Like, how much $$$ is milling?
boring&honing?
extrude-hone porting of intakes?

And basically I need detailed specs for 305 LO3 (I am going to try & find them online)..
bore, stroke, connecting rod length, piston type (flat, domed,..)..

Is it cheap to get longer connecting rods? Perhaps I should be trying to decrease ILF to tolerate higher RPMs..

I am just looking for cheapest that can be done on a 305 bottom end to gain some power, whether torque or hp , it's not really cruical right now, as long as torque loss in bottom end is not outrageous, because i'd use it mostly for street. I don't know if I can afford a 350 right now, and at this point I am not even sure a Chevy 350 is the best base for a good street motor (yeah, I know, it's better than a 305, but still..)

If it were me, I wouldn't do anything to the 305 bottom end. I've got pretty much the entire top end redone on my 305, but I'm just gonna swap out shortblocks.

The crank in a 305 has a 3.48" stroke.
The bore is ~3.75 odd inches.
Don't know about rod length...
I think that the pistons were slightly dished (it's been a long time since the heads were off, and I can't remember now).

From what I hear the L03 swirl port heads are total junk.

The rod length is 5.7"

The bore is 3.735
Stroke 3.484"

Pistons are dished to 12cc's. They are cast aluminum.

Here......

Gen.I, "Small Journal"
265...Mains-2.30"-Rods-2.00"
283...Mains-2.30"-Rods-2.00"
302...Mains-2.30"-Rods-2.00"
327...Mains-2.30"-Rods-2.00"

Gen.I, "Medium Journal", includes "Vortec" 305 and 350 thru '98
262...Mains-2.45"-Rods-2.10"
267...Mains-2.45"-Rods-2.10"
302...Mains-2.45"-Rods-2.10"
305...Mains-2.45"-Rods-2.10"
307...Mains-2.45"-Rods-2.10"
327...Mains-2.45"-Rods-2.10"
350...Mains-2.45"-Rods-2.10"

Gen.I, "Large Journal"
400...Mains-2.65"-rods-2.10"

CHEVY SMALLBLOCK V-8 BORE AND STROKE LIST
262 = 3.671" x 3.10" (Gen. I, 5.7" rod)
265 = 3.750" x 3.00" ('55-'57 Gen.I, 5.7" rod)
265 = 3.750" x 3.00" ('94-'96 Gen.II, 4.3 liter V-8 "L99", 5.94" rod)
267 = 3.500" x 3.48" (Gen.I, 5.7" rod)
283 = 3.875" x 3.00" (Gen.I, 5.7" rod)
293 = 3.780" x 3.27" ('99-later, Gen.III, "LR4" 4.8 Liter Vortec, 6.278" rod)
302 = 4.000" x 3.00" (Gen.I, 5.7" rod)
305 = 3.740" x 3.48" (Gen.I, 5.7" rod)
307 = 3.875" x 3.25" (Gen.I, 5.7" rod)
325 = 3.780" x 3.62" ('99-later, Gen.III, "LM7" 5.3 Liter Vortec, 6.098" rod)
327 = 4.000" x 3.25" (Gen.I, 5.7" rod)
346 = 3.900" x 3.62" ('97-later, Gen.III, "LS1", 6.098" rod)
350 = 4.000" x 3.48" (Gen.I, 5.7" rod)
350 = 4.000" x 3.48" ('96-'01, Gen. I, Vortec, 5.7" rod)
350 = 3.900" x 3.66" ('89-'95, "LT5", in "ZR1" Corvette 32-valve DOHC, 5.74" rod)
364 = 4.000" x 3.62" ('99-later, Gen.III, "LQ4" 6.0 Liter Vortec, 6.098" rod)
383 = 4.000" x 3.80" ('00, "HT 383", Gen.I truck crate motor) (5.7" rod)
400 = 4.125" x 3.75" (Gen.I, 5.565" rod)

There's plenty more at WWW.MORTEC.COM

AJ

Yes, sir. You are correct, sir.

Thanks for the link, AJ.. Looks very oldschool. I was trying to figure out the approximate VE of my 305 setup. Here's one link I found:

http://www.ac427.com/html/tech_airflow.htm

I'm thinking 80% with a bone-stock intake manifold I have and a ported throttle body...

Are HO "swirl port?" I know my stock heads are junk, but I think decent gains can be reaped from porting the HOs? As a matter of fact, there was one guy doing it over this summer and he posted all the pics on the board.. Sitting Bull, I believe?

Could I fit 6" rods into my otherwise stock 305 bottom end? Why? So my engine tolerates higher RPMs better...

Hand porting will improve the flow of any head. It's always worth it to me to get heads ported, no matter how crappy they start out at.

I had my AFR's milled from 79 cc to 63 cc. You check valvetrain geometry by marking the valve stem tip with a magic marker and looking at the marks left by the rocker arm on the valve.

The problem with using 6" rods in the 305 is trying to find a piston for it. If you can't find any off the shelf pistons, then Ross will make a custom piston for anything you can think of for about $550.