Head Porting

[4 l-bodies]

hey todd, question about the 942's. do you leave the damper spring in or do you just run the main spring.

It looks a little tight in there with the damper spring.

Brian

I always run the damper spring. Supposed to help with harmonics. I did test pressures with and without damper though at some point. IIRC w/o looking, it wasn't much different w or w/o damper. What I always check carefully is valvelock or retainer (whatever is hanging lower) and valve seal clearance. Pretty tight with .500+" camshafts. It helps considerably if you can order valves with groove lock cut around .315 to .330 instead of factory .360-.370". That also helps to easily get spring heights around 1.700+" and helps out with lower closed pressure. Haven't yet found +.050 LS retainers or +.050 stamped 5/16" valve locks. I literally have 1700 -.060 stamped hardened keepers. Easy to identify by their green color. Enough for 200+ heads! Enough for a few lifetimes... Anyone need any? Hehe.
Todd

[Aries_Turbo]

I always run the damper spring. Supposed to help with harmonics. I did test pressures with and without damper though at some point. IIRC w/o looking, it wasn't much different w or w/o damper. What I always check carefully is valvelock or retainer (whatever is hanging lower) and valve seal clearance. Pretty tight with .500+" camshafts. It helps considerably if you can order valves with groove lock cut around .315 to .330 instead of factory .360-.370". That also helps to easily get spring heights around 1.700+" and helps out with lower closed pressure. Haven't yet found +.050 LS retainers or +.050 stamped 5/16" valve locks. I literally have 1700 -.060 stamped hardened keepers. Easy to identify by their green color. Enough for 200+ heads! Enough for a few lifetimes... Anyone need any? Hehe.
Todd

Thanks! I have them installed on my head but i havent ran the combo yet.... soon though. I still have a stock cam so it should clear with ease

Brian

[thedon809]

Started trying to port my head.
Stock

Cleaned up short turns and throat.

Little deshrouding.

[cordes]

Good for you. I'm waiting on some new cartridge roll mandrels to finish off mine. I'll post up some pics when I'm done to see whether or not I should bother with buying valves, etc. So far, I think it's goind well.

In regard to your head, how did you measure how far you laid back the portion of the chamber on the spark plug side? Were you basing that off of any head pics you've seen at all?

[thedon809]

Good for you. I'm waiting on some new cartridge roll mandrels to finish off mine. I'll post up some pics when I'm done to see whether or not I should bother with buying valves, etc. So far, I think it's goind well.

In regard to your head, how did you measure how far you laid back the portion of the chamber on the spark plug side? Were you basing that off of any head pics you've seen at all?

Stock, it's kind of a straight line. I more or less grinded just enough to get a radius. This picture I posted on the first page of the thread is what I'm basing it off of. Ken aka 5digits posted this. I trust his knowledge. Obviously I ain't welding and filling the other area though.

[cordes]

Thanks. I'm going to deshroud opposite the spark plug side, as I've read quite a bit of description of the measurements involved. I've seen a ton of heads which leave the spark plug area fairly stock, so I'll probably go that route as I don't know that I'll have the skill with my current knowledge to do something repeatable to each chamber.

[thedon809]

Up to this point I have done everything with a corded Dremel. Not ideal to say the least, but it works. Problem is you can't really use long bits. Then I remembered I already have a die grinder so I ordered some burrs and mandrels.

[cordes]

That's great. I can't imagine doing all of this with a dremel. I am hoping my mandrels come in sooner than later.

[thedon809]

Here's a look at a CNC ported ls3 chamber for reference. Obviously not 100% applicable to our heads but it has some similarities with a 782 chamber. Would not look much different if the hump next to our spark plug was ground almost all the way off.

[cordes]

Thanks for the pic. I can seem some similarities for sure.

[4 l-bodies]

This is typical of what my big valve swirl chambers look like.
Todd

[cordes]

Thanks Todd. Do you make a template for the deshrouding and transfer it to the head, or do you measure and scribe lines with a compass or some such?

[chromguy]

This is typical of what my big valve swirl chambers look like.
Todd

She sure is pretty.....

[4 l-bodies]

Thanks Todd. Do you make a template for the deshrouding and transfer it to the head, or do you measure and scribe lines with a compass or some such?

Yes I do have templates for BV, +1mm valve, std. valve, and of course G-head. I do also use dye and scribe lines too. Ultimately measure chambers and ports with burette. Here is a +1mm G-head that I did recently. Notice the soft edges to avoid hot spots in chamber? Probably can also see the faint lines of combustion chamber fire ring. This one flows like a very good BV head. I was going to put this one on my bone stock 50K survivor GLHT, but what a waste of a cylinder head being choked off by that crappy log manifold (lol)!
Added picture of stock NOS G-head. What's cool about this one is crossdrilled g-head (huh)?
Todd

[cordes]

Thanks again Todd. This has been an incredibly informative thread.

[4 l-bodies]

Thanks again Todd. This has been an incredibly informative thread.

Sure glad to offer input. Porting is fun but can be very tedious. I've been porting some Corvette 90-95 ZR-1 heads lately. 32 valves, matching injector housings, intake manifold runners, all that port matching. Yikes!!! REALLY time consuming... pretty big gains to be had even in naturally aspirated mode.
Todd

[thedon809]

My ghetto way of getting them close to the same.

[cordes]

That seems like it would be a good way to go. On my practice head, I used a compass.

[thedon809]

What diameter and grit cross buff do y'all use for the exhaust ports?

[4 l-bodies]

What diameter and grit cross buff do y'all use for the exhaust ports?

If your asking me, I don't use cross buffs.
Todd