858 head rework

[Joe R.]

Before I started reading this board regularly I had some 3873858 heads (for L-72 427 / 425) done by Stiegemeier Engine Air Flow. I'm now regretting not having done my homework up front. I gave Bob the bare heads, he installed the valve train. I'm trying to figure out the specs for the parts he installed, without much luck. Here's what the receipt says (my comments in parentheses):

030 11/32 liners K-Line (11/32" - .030" Black Beauty boring tool)
8 2240 in (intake valve, qty. 8, who is the mfr.?)
8 1775 ex (exhaust valve, qty. 8, who is the mfr.?)
11/32 locks
mill .002
mult angle valve work
530 viton seals (mfr.?)
spring rate 120 # seat
300 # open at 520 lift
assemble and set up
16 - 1900 studs (qty. = 16, who is the mfr.?)

Does any of this matter or should I just rip everything out and put GM / Sealed Power parts in? I would use the second design valve springs. He mentioned that the valves were 0.1 " long to give an extra 0.1 " of lift, though I have subsequently found that to be false. I told Bob that I planned to use the 3863143 solid lifter cam. But I didn't specify the valve train parts for him. I did give him a set of Comp Cams valve springs to use. I also asked to have the heads ported though I don't know if that was done. I will get the back angle cut on the valve head to help low lift flow. I plan to have the chambers CC'd and matched to within one CC from highest to lowest. I will have air flow testing done.

Ideas?

Thanks,
Joe

[Joe R.]

Valve sizes

I have seen some conflicting information as to whether or not there is any benefit to changing the valve sizes for better flow. What do you guys say?

Joe

[Clem Z.]

Re: 858 head rework

Before I started reading this board regularly I had some 3873858 heads (for L-72 427 / 425) done by Stiegemeier Engine Air Flow. I'm now regretting not having done my homework up front. I gave Bob the bare heads, he installed the valve train. I'm trying to figure out the specs for the parts he installed, without much luck. Here's what the receipt says (my comments in parentheses):

030 11/32 liners K-Line (11/32" - .030" Black Beauty boring tool)
8 2240 in (intake valve, qty. 8, who is the mfr.?)
8 1775 ex (exhaust valve, qty. 8, who is the mfr.?)
11/32 locks
mill .002
mult angle valve work
530 viton seals (mfr.?)
spring rate 120 # seat
300 # open at 520 lift
assemble and set up
16 - 1900 studs (qty. = 16, who is the mfr.?)

Does any of this matter or should I just rip everything out and put GM / Sealed Power parts in? I would use the second design valve springs. He mentioned that the valves were 0.1 " long to give an extra 0.1 " of lift, though I have subsequently found that to be false. I told Bob that I planned to use the 3863143 solid lifter cam. But I didn't specify the valve train parts for him. I did give him a set of Comp Cams valve springs to use. I also asked to have the heads ported though I don't know if that was done. I will get the back angle cut on the valve head to help low lift flow. I plan to have the chambers CC'd and matched to within one CC from highest to lowest. I will have air flow testing done.

Ideas?

Thanks,
Joe

my guess manley valves,i don't have my lit so this is just a guess and the 530 seals is the size,.530, the guides were cut to this outside diameter. he reduced the stem diameter from 3/8" to 11/32' which is SBC size

[Joe R.]

Re: 858 head rework

Clem,

Thanks for the reply. Summit Racing carries Manley valves. But those numbers didn't come up as Manley parts on their web site. The 1775 part number brings up a Sealed Power valve (1.995 " head dia., 4.687 " length, .3427 " stem dia., single groove, 46 Degree Seat Angle), which doesn't seem to be the right one. Here's what I have on the original valves:

intake, chrome plated stem, 2.189 " head dia., 0.372 " stem dia., 5.218 " O.A.L., single groove, GM 3864808 Sealed Power V-1905

exhaust, chrome plated stem, 1.72 " head dia., 0.3718 " stem dia., 5.355 " O.A.L., GM 3860002 Sealed Power V-1911

That's interesting that you mention that he reduced the stem diameter from 3/8 " (BBC) to 11/32 " which is SBC size. He did say something about making the valves lighter. How helpful is that? What is the disadvantage?

Joe

[Duke W.]

Re: 858 head rework

Did you ask the machinist for the valve manufacturer?

These early big block rectangular port heads have a restrictive exhaust. The OE E/I flow ratio is well under 0.75, which means it needs more exhaust than inlet duration on the cam.

I recommend opening up the exhaust seat to accept a 1.88" valve along with the normal pocket porting to eliminate the OE annular ridge where the factory rough cut valve seat forming operation meets the as cast portion of the port. (The exhaust seat area should be sonic tested for sufficient material and most should be okay.)

With similar pocket porting on the inlet side the E/I flow ratio should end up near 0.75, which means that a cam with equal duration on both sides is best, and you can't beat the OE ...143 cam for broad torque bandwidth and excellent top end power bandwidth to 6500+.

I don't know about those valve springs. The second design OE dual spring/umbrella seal assembly is bulletproof, but the K-line spiral valve guides need a "positive" type valve seal. The umbrella seal that is integral with the second design dual valve spring may not provide adequate oil flow contol.

Duke

[Joe R.]

Re: 858 head rework

Did you ask the machinist for the valve manufacturer?

I recommend opening up the exhaust seat to accept a 1.88" valve along with the normal pocket porting to eliminate the OE annular ridge where the factory rough cut valve seat forming operation meets the as cast portion of the port. (The exhaust seat area should be sonic tested for sufficient material and most should be okay.)

I don't know about those valve springs. The second design OE dual spring/umbrella seal assembly is bulletproof, but the K-line spiral valve guides need a "positive" type valve seal. The umbrella seal that is integral with the second design dual valve spring may not provide adequate oil flow contol.

Duke

Duke,

I'll ask Bob to go over the receipt with me.

What is the GM part number for the 1.88 " exhaust valves?

It sounds like I need new valve guides to go with the 3970627 valve springs. What do you recommend?

Joe

[Clem Z.]

Re: 858 head rework

i would not change a thing unless you are looking for max HP. i would remove each valve and relube the the guides and valve stems with cam lube and replace valve stem seals. the springs specs are close enought for a stock cam.

[Joe R.]

Re: 858 head rework

Clem,

I am looking for max hp. What would you do then?

Thanks,
Joe

[Clem Z.]

Re: 858 head rework

Clem,

I am looking for max hp. What would you do then?

Thanks,
Joe

find a good shop with a flow bench and have them go thru the heads. if you are near Michigan i would talk to the people at Katech as they are one of the best with chevy engines.

[Joe R.]

Re: 858 head rework

Clem,

I'm in St. Louis. I took them to Bob Stiegemeier with Stiegemeier Engine Air Flow because a friend from work was high school buddies with Bob. He said that Bob used to (maybe still does) build heads for NASCAR. I figured that was good enough for me. I think I will take out the hot rod parts, install the GM parts and have Bob port the heads. I will have him run it across the air flow bench too. I will use the 1.88 " exhaust valves as well.

Joe

[Clem Z.]

Re: 858 head rework

Clem,

I'm in St. Louis. I took them to Bob Stiegemeier with Stiegemeier Engine Air Flow because a friend from work was high school buddies with Bob. He said that Bob used to (maybe still does) build heads for NASCAR. I figured that was good enough for me. I think I will take out the hot rod parts, install the GM parts and have Bob port the heads. I will have him run it across the air flow bench too. I will use the 1.88 " exhaust valves as well.

Joe

if you plan on running headers and open exhaust make sure they install "venturi" type exhaust valve seats as these make a big difference in exhaust flow.

[Joe R.]

Re: 858 head rework

Clem,

No, I plan to run the stock exhaust manifolds. I'd like it to look stock but run like a striped a** ape.

Joe

[Clem Z.]

Re: 858 head rework

Clem,

No, I plan to run the stock exhaust manifolds. I'd like it to look stock but run like a striped a** ape.

Joe

make sure you get the back angle cut on the valves as that helps low lift flow and that is good for the street.

[Joe R.]

Re: 858 head rework

Clem,

What is the best angle for the back cut on the valves? Is that done on both the intake and the exhaust valves?

Joe

[Clem Z.]

Re: 858 head rework

Clem,

What is the best angle for the back cut on the valves? Is that done on both the intake and the exhaust valves?

Joe

yes you do both and i am not home so do not have my paper work with me