I found a pair of used LB9 (081 casting) cylinder heads for $40.
I am looking for the best bang for the buck. So what mods if any should i do to them before installing them. Remember I'm looking for the most HP/Dollar.

I'm considering:

1. Larger Valves (What are the largest valves I can use and do the valve seats need to be enlarged?)

2. Milling the heads for greater compression (How much can I safely mill these heads to fit a stock LO3 block and increase compression while avoiding any problems?)

3. New Valve Springs (My LT1 cam has about .450 lift and the most I want to rev it to is 5500 maybee 6000)

4. Three angle valve job (worth the money?)

5. Port & Polish (would do it my self but there is the cost of the materials)

6. Vavle seals (These are pretty cheap but how hard are they to install?)

Any comments or other suggestions? Thanks.

Lance

 

1. 1.94" on the intakes, leave the exhausts as they are. Obviously you'll need new valves; for the most bang for the $$$, get the Manley "Street Flow" ones, with the undercut head.

2. Don't bother. Just get them surfaced so you can be sure they're flat.

3. Absolutely.... I'd suggest some one of the major cam mfrs' entry-level spring, such as a Comp 981 or the equivalent from Crane, Lunati, Ultradyne, etc.; avoid GM or "budget" ones like K-Motion; get the retainers & keepers that go with them, throw away the sheet-metal splash shields and exhaust rotators,and stack .105" of shims under the exhausts.

4. Yes. At least go back witha stock one, which is 3 angles.

5. This is the cheapest HP money can buy. Additionally, #1 is pointless without this.

6. If you get the Fel-Pro ones, you just stick them on the valve guides. Even I can manage it. Use the "positive" ones, not the umbrellas, and don't bother with the O-rings.

Power lives in the heads. All else is a waste if they have restrictions, or if the springs don't control the valve motion. If there is any one place to spend money where it will pay off, it is the heads. People who un-bolt and re-bolt big shiny chrome things that sit right up on top of the motor, and then wonder why their car is slow, are living proof.

 

Get a die grinder (not a Dremel tool). You'll never look back.

 

So first of all, I found the valves you mentioned in the summit catalog for about $70. Not bad. Now will I need to have the valves machined for the three angle or will they come like that. Also, will I need to have the valve seat enlarged to use the 1.94" valves? Please bear with me. Valve train stuff is sorta new to me.

Also, is it not a good idea to gain some compression by shaving those heads?

Vader, I owe you thanks for hooking me up with the LB9 heads. I'm picking them up tonight. You mentioned a die grinder. Is that a pneumatic tool? I don't have an air compressor. What do you suggest in that case?

Thanks for your advice.

Lance

 

Black,

Glad you found your heads, and at a pretty decent price.

First, the valves will have ONE seat angle - 45°. The valve SEAT is what is normally cut three times when performing a mulitangle valve job. The 46° cut is what seals agains teh valve, and can be a very narrow surface in a three-angle grind. Personally, I wouldn't even bother for a street engine. The minimal gain you'll get (if any) will be compensated by a loss in service life. Three-angle valve grinds usually don't last for very many miles. Even the short-trackers around here (and in Oregon) have given up in multiangle grinds and have recovered by cutting a radius on the face side of the valve margin to help with edge flow. It's less expensive, more durable, and flows as well if not better than the 3-angle seat work.

Of course, there is more than one angle in the valve seats, but I never really counted the bowl cut as part of a multiangle job. It's just normal, good valve installation procedure.

The undercut, swirl polished valves are another advantage for flow, but don't create any sacrifice in durability. They're worth the minimal cost difference.

Yes, you'll have to get the valve seats cut open to accomodate the 1.94" intakes. In order to take full advantage of that, you should also cut the valve bowls open (pocket porting) and trim the valve guide boss where it intrudes into the valve bowl. Don't raise the guide, but contour the excess casting around the guide that only takes space and impedes flow.

Those heads already have 57-58cc chambers. Cutting them any more than is necessary to clean them to a flat surface may raise the compression beyond what your engine can handle on pump fuels.

Die grinders are available in both pneumatic and electric versions. The electric ones are obviously more expensive, but when ofset by the cost of a compressor that you don't already own, can be a good bargain. Make sure whatever you get has at least a ¼" collet.

But before you do anything, call a few shops in your area and ask about machining costs, lead-times, and ask their advice for whether a multiangle seat is a good idea for the street. Their natural tendency would be to sell you more services ($$$), but you may be able to weed out some by what they will try to sell you. If you already have a favorite shop, at least have your heads tanked (cleaned) and checked for cracks before you do any other work to them. Don't bother with a pressure test. Iron heads usually reveal cracks easily with a standard MagnaFlux test.

 

Incidentally, I tried a heavy-duty RotoZip for some port work the last time I did it, mainly just to see how well it would work. The spindle is too short and large to effectively reach into the ports for much more than gasket matching, and the cooling air flow out the end is more of a niusance than a help. I'd suggest a regular electric die grinder.

A place to check for machining is ARA on east Wash, a few blocks past the Crystal Corner. They're a bit pricey, but do decent work. You can probably find someone to do the same work for less is you shop around a bit. Just my opinion, but stay away from Performance Plus. They've had "problems" - if they're even still in business.

 

Vader,

Thanks for all the great info. I'm going to have them checked for cracks and flatness. If they check out I can get the valve seats enlarged for $62 and a set of Ferrara undercut intake valves for an additional $72. The machinist I spoke with says he sells spring that are good for .510 lift up to about 7500 RPM. He buys them in bulk and sells them for $3 each for a total of $48. He will also install the valves at no additional charge.

If I stay with the same size exhaust valves is it ok to reuse the stock valves or should they be replaced?

Also, the shop that I'm in contact with is Performance Head Service on Greenway Cross in Madison. They were reccomended to me by the guys at Checkers. Is this the place you suggested I stay away from?

Lance

 

I dropped the heads at the machine shop yesterday and spoke with the owner.

I asked him about installing 1.94" intake valves and he said that he would advise against it on these 305 heads because of valve shrouding. He said that with the larger valve it gets so close to the side of the combustion chamber that it causes poor flow around that portion of the valve. He said that in his experience that has caused a loss of torque at low engine speeds.

He does reccomend a backcut valve for improved airflow. I think I will spring for some new intake valves if they will really increase flow.

When I told him that the heads are a 58cc design and that my LO3 assembly is designed to produce 10.3 : 1 compression with 58cc heads he said that we could shave the heads down by up to .020 which would reduce the chamber size to approx. 56cc and bump the comp. ratio up to about 9.5 : 1

I think I may have this done unless you guys convince me not to.

What do you guys think about staying with the orig. size intake valves and perhaps shaving the heads a little.

Thanks for your feedback.

Lance

 

Don't do it.

Tell him to do as you asked or take it to another shop. There is nothing wrong with 1.94" valves on a 305 with 305 heads. Period.

 

Black,

The machinist is absolutely correct on the valve shrouding, and should have suggested unshrouding the chambers. They can do it with a shell mill or flycutter, or you can do it with a grinder.

You need to unshroud the valves when installing 1.94" intakes. It doesn't hurt the compression a bit. Sitting Bull has done this, and knows that of which he speaks. I've done it. Nearly everyone improving 305 heads has done it (including World Products on their S/R 305 Torquers!).

Do a search for "porting" and "305" and see what you come up with.

Incidentally, stock 1.50" exhaust valves would be fine, but back cut/undercut stem/swirl polished valves help flow even more. Personally, I'd go with the Manley Race-Flos for the same cost (about $9 each). And a radius cut on the front face/marging area of the valves also helps with edge flow and shrouding issues.

I'd also be asking about the spring source/supplier and specifications/material. It sounds like you are being "upsold" on things you didn't ask for, and maybe don't want.

If you want to drive south for 65 minutes, you can find places that won't circumferentially fornicate you on your requests. I had 1.94s cut last week for $30 - no other B.S.

I'll bet you won't even have to go that far, and can find other local shops that will perform the work you ask.

 

this is totaly off topic, but i was reading this thread... andy they make electric die grinders? so i dont need a big bulky air compressor, just a plug!? To bring this back, i wanted to get a die grinder so i could port my own heads, intake... what have you.... someone PM me if they can with info on the die grinders.. thank you

 

Electric die grinders have been available for years. Here are some common models, not in any particular order of preference:

• Milwaukee 5192,
• Bosch 1209,
• Makita 906H (a little lightweight for serious porting),
• DuMore 35-171 (very heavy duty but small),
• Foredom SCH system (really nice, but pricey).

Forget about anything from Dremel. They're just too lightweight and weak for any serious porting work.

 

Thanks again for the input. I really don't think that the owner owner of this machine shop is trying to rip me off. After all he suggested not not enlagre the valves due to shrouding. It's not like he's trying to sell me all kinds of services I don't need or want.

I'll ask him about unshrouding the valves to accomodate the .194s. Either way I'm getting new backcut and swirl polished intake valves. I think that everyone will agree that they are worth the money regardless of the size.

As for the springs, I'll ask him to provide some specifics before I go with the ones he stocks. I may eventually want to go with 1.6 to 1 roller rockers and I want a spring that can handle all that lift along with the LT1 cam I already have.

Does anyone have any other comments on whether or not I should shave the heads by .020 to bring the comp. ratio up to about 9.5 to 1? Is is safe to take this much off a 58cc head? If so how much torque would .2 of a point be worth?

Really, thanks for the feedback.

Lance

 

Lance,

Twenty thousandths is going to change the static compression by about 0.4 points with that smallish chamber. Even if you unshroud the valves and open teh cahmber volume to 60cc, you'll gain 0.4 points (from about 9.1:1 to 9.5:1) If the heads test flat and true, I wouldn't bother. If they need to be trued, then cut up to 0.060" if you want before even worrying about casting thickness. Just watch the final compression. The gain may not be worth the cost if it isn't necessary.

Just make sure the ports are opened up. You're already gaining flow from eliminating the swirl "humps" and installing larger valves.

Did I mention that this would be an excellent time to install screweed rocker studs?