Hey guys,

Ok here we go, I drive an LB9 and the heads are shot. I dont want to just machine them, i'd like to gain at least a FEW hp out of the ordeal, but this is a SERIOUS budget project. If I took a set of L98 (350tpi) heads and decked them down a few cc's, say somewhere around 61, with it having a lower seat, and larger valve sizes, @ .450 lift, will I hit anything? Also if i ran a high compression head gasket, can i get back to 58cc? Or at least VERY close to my stock compression of 9.5:1. Last question is with heads being decked, that theortecially will pull them farther apart, will i have problems with my TPI base bolting to the heads? Any gaps?

If there are anythings I should know, ask, or be concerned with after doing this please let me know. Thanks!

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Much better choice: go with something made to do what you want to do - World Products S/R Torquer 305's. 58cc chambers, 1.94/1.50" valves, 171cc intake runner volume. They'll take your lift out of the box. The TPI will bolt on without modification.

About $590 shipped unassembled from Competition Products, add $50 for assembled. If you want to improve them a little, do a bowl blend (why I got them unassembled, as well as the budget thing).

You'll be dollars ahead and they will flow as well as L98 heads with very little cleanup. They need 350 style head gaskets, I'm going with a high compression Fel Pro.

Center bolt valve covers require removal of the perimeter bolt bosses from the heads. No big deal (but another good reason to get them unassembled).

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 CC system w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker 2055 headers, 3" Catco cat & 3" catback, restalled TC, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

 

I knew that would come up.......

I can't afford them, absolutly out of the question.

Just please answer on what i have to work with

also any comments about compression can be withheld, that also has all been taken into deep consideration. Thanks!

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TPI,

Unless the heads are cracked, they really can't be "shot" - and even cracks can be repaired.

350 heads on a 305 are not a good idea. You won't recover the lost compression through milling and a gasket, unless you mill so much that you go through the deck casting - you'd have to take at least .060" off the heads to regain the static compression ratio if you are starting with 64cc chambers. Even at that, the valve sizes and positions won't fit in the smaller 305 bore without interference.

Personally, I'd rebuild the heads and do some porting both behind the valves and through the runners. Drill, ream, and press in some naval bronze valve guides if the old ones are worn - don't knurl them. A slightly larger intake valve can be beneficial, and a shorter radius on the exhaust ports will free up some flow on that side. Radiusing the valve margin at the face will provide more flow improvements than a multi-angle valve grind. If you were lucky, you'dbe able to find a pair of used 305 HO or TPI heads that someone removed in favor of S/R/ Torquers or another aftermarket head.

There is a pair for sale on ebay right now:
http://cgi.ebay.com/ebaymotors/aw-cg...item=595104407

14014416 castings, 305HO/TPI, 58cc chambers, 1.84"/1.5" valves - just like what you need.

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Later,
Vader
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Thanks for the effort


but i'll look elsewhere

my question was very specific.

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These guys are giving you pretty good advice really...
To answer your questions:
If I took a set of L98 (350tpi) heads and decked them down a few cc's, say somewhere around 61, with it having a lower seat, and larger valve sizes, @ .450 lift, will I hit anything?

You arent listing the cam duration, but even without that the lift isnt much, so you shouldnt see any problems at all.

Also if i ran a high compression head gasket, can i get back to 58cc? Or at least VERY close to my stock compression of 9.5:1.

As it is, GM used a thin gasket on the 305's. You are going to lose compression no matter what you do if you stick with 350 heads. If you were to get the chamber down to 61, the compression with thin gaskets like what GM used is gonna be around 9.2:1 at best.

Last question is with heads being decked, that theortecially will pull them farther apart, will i have problems with my TPI base bolting to the heads?

Straight milling of the heads doesnt pull them any farther apart. With lots of milling on head on a V engine, you end up with one of 2 problems. If you just cut them, the ports are effectively lower and may not line up with the manifold right. .030" isnt a whole lot but theres gonna be a small step anyway. It should seal fine. Angle milling throws the intake face angle off so that has to be corrected, but the port height is for the most part saved doing it that way.


I really think running 350 heads is kind of a waste, if you are looking to do it as a performance advantage its a wasted effort. There will be a loss of compression, and on some heads the chambers will extend past the fire ring on the gaskets, in which case you will have to use 350 gaskets. Milling heads and having a valve job done to old heads even if I use the place I worked at, which was the cheapest prices around, you are looking at a minimum of 150 bucks in labor. Then too, are the guides in the 350 heads any good? Most arent. Thats another 100 bucks plus parts... now you are up to 315 if you need guides. The only thing I can figure is you have a friend or you are doing this work yourself. I would seriously be on the lookout for some cheap 305 castings before I would throw some 350 heads on it, or just deal with the loss of compression, run a normal gasket (good idea IMO) and when you have more budget do things right. For more power either way, you'd really need to port the heads, and thats something you can do in a day with the right tools and some minor effort on your part.

 

thank you, i appreciate that.

vadar someone was looking for you in the chat room by the way.


So guys, will ZZ4 heads with the 58cc chambers work on my 305? any issues with that? Thanks.

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