Will the LB9 heads work out okay, or will the compression ratio be way too high? I am not sure what compression ratio the LO5 has, as I am not sure of the numbers off it, and it has been rebuilt, .040 over. I will be getting it tomorrow, and I will then know a little more about it and I will be able to look up the pistons and see what they exactly are.

Basically I'm looking to give my car a little extra power, and retire this ole 305.

For now I am thinking:

LO5 Short block, rebuilt, pistons currently unknown. Stock rods and crank.
LB9 Heads, Pocket Ported, deshrouded and rebuild, 1.94 intake valves.
Ported TPI base
Aftermarket runners
30lb Injectors (FORD Racing, or otherwise)
aFPR
350 Chip, probably custom with hot timing (still learning prom tuning)

What do you guys think... will this be a improvement over my 305, or would I just be wasting the effot of putting it together like this. I would like better heads, but I won't be able to afford them for a long time. I am thinking the LB9 heads will give the compression ratio a good boost, which will make up for the lower flow.

 

The L05 and LB9 share a 58cc chamber from what I've been able to find, therefore compression ratio would remain the same. The early 416 casting LB9 head (used up to '86 on LB9 and L69 H.O. 305s) would offer you the best chambers to work with for your porting and 1.94 valves, so be sure to get those castings.

Search on "porting 416" and you should find the recent flow data provided by a fellow 3rd gen member. Very impressive.

 

Sounds fine. Should make comparable power to a mildly modded L98 setup.

 

Only reason I said to stick with the LB9 heads is cause that's what I have right now. They are 081 castings ( I Believe, stock 305 TPI from 1987 ). I never knew the LO5 had 58cc Combustion Chambers... but that would be cool. I guess I'm gonna just have to wait and see about the pistons so I can figure out compression ratio.

 

I take it the LO5 is a 350.... The only problem I see is the chamber diameter is smaller than the 350 bore. Chamber size isn't the only consideration, diameter of the chamber effects your quench.

Any sharp edges that extend into the bore are potential hot spots. Hot spots create preignition, aka, pinging....

Try trading your heads to someone or checking the newspapers for someone junking out a car. Might even find a good buy on ebay.....

 

Thanks for your help guys, but I think this post should now be killed. Between reading what Captain C said and finding out the compression of these pistons is 9.6:1 with 64cc heads, I have realized there's no practical way to use my LB9 heads. I would just kill the flow, risk hot spots and pinging, and have a really high compression ratio. My search begins, I need some L98 Heads.

 

Check with a local performance machine shop. Usually the guys at a place like that can help you find something cheap and take your heads in trade. Stock 350 Camaro heads aren't that expensive. Seems like I saw them online somewhere for $350 a set. You could possibly sell yours for $100to someone needing stock heads for their passenger car or pickup with a 305....

Also, they might be able to tell you if you can open up the chamber enough to eliminate the hotspot problem. That would also enlarge your chamber slightly and reduce compression. I think you can do that, albeit they would still make better pickup truck heads.....

The machine shop I used last time (and never will again) initially installed a set of 89 stock heads on my engine instead of my World heads. The stock ports looked like they would flow pretty good with a little work on them.

58cc heads will boost your compression up to 10.1:1 IIRC.....