What are the differences besides the CC size? I have found 2 sets of heads..a set of lb9s and a set of l98s i can get for 75$. I know the l98s need new valves and everything but the lb9s are good.

Supposedly my motor has 9.6:1 compression so Im worried about getting lb9s...I also have no idea what CC the lo5 heads on my motor are tho.

Which should I get...arent the valves the same sizes?

edit::: found out heads are 64cc. Would lb9s raise the compression to much?

 

L98 in. valves are 1.94, LB9 in. valves are 1.84...both use 1.5 exhaust.

if you have 64cc chamber heads now, then adding the 55cc chamber heads will bring you to around 10.5 to 1

 

Your best most cost-effective/power solution would be to get the good LB9 heads and have the intake valves opening to 1.94. They will then be virtually identical to the L98 heads. Then port and polish them yourself by following the intructions linked at the end of my sig. Good for at least 30 more hp

And YES you can do it yourself for DIRT CHEAP!

If compression gets a little high just use a thicker head gasket. Easy solution.

 

L98's are aluminum.

 

Better do some more research, L98s are not aluminum unless they are off a Corvette.

 

FYI


If you DO go with the smaller chamber 305 heads, and you decide to use a thicker head gasket, MAKE SURE and check the quench with the new gasket / heads....too much gap will cause worse spark knock that too much compression....

BTDT...

 

What heads do you have on the motor now?

 

right now it has a set of lo5 swirl port heads on it. With a TERRIBLE cam. .360 intake and .385 exhaust.

I figure a lt1 cam with a set of lb98 or l98 heads will make a huge difference. Paceparts claims you get up to 300hp with just a ly4 cam swap on the motor. I wish I still had the lt1 cam I bought awhile back...to bad i sold it. I could have stuck it in there.

 

I'd say it's close to a toss-up. If you already have marginally high compression then a swap to the L-98 heads would drop it down some vs. what you have now, and they already have the larger valves a 350 will appreciate. If your compression is where you want it already then you might want to go with the other 305 heads with some work done to them to get the flow rate up some.

Any idea on what pistons you have in the 350 now? Flattops? Dished?

 

Im not sure what my pistons are. I do however have 9.6:1 with 64cc heads. Arent the l98s also 64cc?

Im leaning towards the lb9s...is 10.5:1 to much to run off 93 octane?

 

Yes, the L98s are 64cc.

10.5 is trouble with iron heads on 93 octane. Use a thicker head gasket and you'll be A-OK

 

Then 'splain it to me. I understood it to be that the RPO was the engine assembly. Thus L98 was a 350 w/ aluminum heads and TPI, blah, blah. The LB9 was the same except it had iron heads instead, so naturally it has to have a different RPO. L98's weren't offered in Z28 and IROC, only the LB9 was, correct? So obviously, the aluminum heads were in the Corvette (Cadillac too?). Please don't think I am being an ***, I'm not. I just want to understand this correctly.
Thanks

 

3rdgenstm
This link will give you details of models and availability.
https://www.thirdgen.org/newdesign/tech/techdb.shtml
But a short explanation,
LB9 was a 305 available from 85-92
L98 was the 350 available from 87-92, but unlike the Corvettes they had iron heads.

 

Well I think Im getting a set of l98 heads. I have found a set for 95$ shipped that are in working order. So Im not worried about the compression now.

Now all I need is money for a cam

 

lol

only the vetterzzzzzz.

welcome to the boards

 

if you want to get technical, L98's is the Corvette motor and B2L is the Camaro/Firebird motor. So, the L98's are alum, where the B2L are Iron. The B2L is more commonly refered to as the L98. I would go with the L98 Alum Vette heads since your running such a high compression if you can find them. The LB9's are gunna flow like crap. With porting, it could be better, but ported L98 vette heads would be better IMO.

 

Thanks for the input and help. I am not real familiar with the TPI engines. I thought the LB9 was the 350 (wasn't the B2L an early 350 option-- before the L98???)

 

Big Al posted while I was writing my reply. Thanks big al. I didn't think I was that ignorant on 3rd gens. Thanks for the help everyone!!

 

LB9 is a 305. B2L is a 350 w/ iron heads. L98 is a 350 with alum heads. The B2L is the RPO code for 350's in fbodies. refer to previous statment about the engines. Just helpin ya out. the LB9 was the only engine in Z's and Irocs in 85-86. In 87, the B2L came in as the top engine.

 

The RPO code for the 350 in my 89 GTA was L98. I still have a picture of the tag somewhere.

 

Thanks for the help everyone !! I didn't mean to start anything.

 

How are 083 heads ?

 

Decent but not as good as Vortecs, not close. Flow 185ish int, 125ish exh. A bit of porting especiaslly on the exh side helps a lot. Mine have a bit of porting and seem to do pretty good.

 

The 083 and 217 heads are modest in stock form.
They can get very good with generous porting.
Bigger valves too. Generous porting does not mean a lil pocket port.. Get in there deep and get serious.
They get very good with serious effort.
The chamber is nominal 64 cc.. You can play with that with mods to good effect too. Especially with bigger valves + porting.

The Aluminum 113 L98 heads same same. Modest in stock form great potential with generous porting effort.
The 081 305 version same same. but 58cc? +/- chamber.. Lots of room to deshroud and improve with a die grinder..

If you just bolt them on stock or put minimul effort into them keep your expectations modest.
All these can get a good result with generous good work input.

 

On any of these heads on a 350 or a 305 finish them to get the real measured compression ratio up to 10:1 or as close as possible with finished chamber volume + gasket choice.
Avoid exceeding 10.50:1 cr or more.
Don't bother with the lil factory cams LT-1 LT-4 take outs etc... Great HR cam for this stuff with ported heads is the Melling #22280. You can play with its installed position a bit to tweek the low/mid torque to good result.. 107/113 try 104/116 for a hot torque curve. Ported heads like valve lift.. Needs springs, likes headers and RPM hi rise manifold.
Likes gears too. Hang on tight 🤣!

 

I have a l98 1988 firebird GTA it's 083 cast iron only Corvette got the aluminum head.other heads have obstructions in the ports to make a swirl not very good.theL98 heads don't have it just like early heads used on old lt1350/350.mild port n polish on floor and short side radius's.add flat tops close to 11to1.tjats why they came with dish pistons and low power numbers .but difference is the block eas designed for roller cam.easy to get 450hp 450 ftlbs.streetable.induction is the bottle neck increase throttle body and runner size.or slap a qjet and good distributor and forget the computer.