ChrisWhewell

Hey ya'all !! Well, as some of you know, a while back I did my own valve job with 1.94's and the Neway cutters. Still running good.
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I have a bare set of LT1 heads, and some 12565311 2.00" intake valves and 12565312 exhaust valves.
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What I'm wondering is, should I just take the heads in to a competent mechanic, or, is it feasible for me to get a two-inch valve on a seat that was originally machined for 1.94 using my Neway cutters ?
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Thanks alot

84Z51J

While they might seal temporarily, IMHO it'll be a countdown to burnt valves. Not worth the risk--your heads won't flow any better anyway, 'til you have the seats recut to size.

rklessdriver

2.00 and 1.560 are the biggest valves the stock seat inserts will fit.

You should have no problem cutting the seats with the Neway. Take your time on the bottom 60* because it's going to take a lot of removal.
Will

ChrisWhewell

Thank you. That's how I should have phrased the question, "what's the biggest valve the stock seat will take ?"

Thanks for answering buddy, have a great day

ChrisWhewell

I did some vortec iron heads with the Neway back in 2012. It took me a long time but I went real slow and was using a jeweler's eyepiece, lots of blue dye. In the end I was able to get every seat width on the valve exactly where I wanted it, and at the exact width I wanted. I can't imagine a machine shop doing that.

The only thing is, I have the K-Line bronze inserts and I'm concerned that if I have my dude install them into the guide bores, that when I put the pilot rod from the Neway into the bronze insert to cut the seats, that the pilot rod might loosen the K-line insert

rklessdriver

It shouldn't loosen the K Liner... if it does something is wrong with the liner of the pilot mandrel.
Will

89onlyZ51

You can go to 2.00/1.56 on the seats, but aren't those ls6 valves with a different stem dia and length? It seems you'd need new guides, too, and would still end up with geometry that's off.

ChrisWhewell

K-line Industries of Holland, MI part number 1851 bronze inserts for the 8mm stems. The LS6 valves are only about .020 longer than the LT1 stock valves, so geometry is not an issue - handle it via pushrod length. Its worth the weight savings

stock valves are
87.5g int.
101g exh.

LS6 valve weights
64.5g int.
74.5b ext.

Maybe I'll just sell the heads, liners and valves and put my time elsewhere !

rklessdriver

Your doing something very much worthwhile. Espc in a limited modification engine where your fighting for every little edge you can get.

We do it to all of our limited class engines **where it's legal**. It's a small help with keeping the valve train stable and it also helps a little with airflow.

Infact this winter I have 2 engines in the shop that I am being forced to convert back to 11/32 valves... only took the Tech man 4 yrs (with us being protested about every race) to figure out that I was using 8mm valves.... Suddenly this year the rule book specifically says 11/32 stem.
Will

ChrisWhewell

Heh-heh, good work !! I had a strong hunch it should be do-able. Just curious, do you have a rough estimate of how much more revvs one can get with those lighter valves before they float ? Can one rev to 7000 ?

I used the LS beehve springs ($40 for 16) on my vortec heads before it became popular I would have put the LS valves in the LT1 heads, except I still have a spare set of LT1 heads I did, sitting in the closet. I ported those myself to the exact specs that David Vizard taught. They have GM 1.94's that were undercut stems and swirl polished from the factory. Just waiting for the day ..... !!

rklessdriver

I can't even begin to estimate that.... too many other things control valve train stability in addition to valve weight.

I can tell you that even factory stock SBC valve trains have some amount of deflection and instability - So swapping to 8mm valves would help even an otherwise stock SBC/LTX engine.

7,000 rpm is totally doable with a hyd roller. Of course it's totally dependant on the cam lob profiles and other associated parts.

There was an engine I spec'd out for a member here that was dyno'd a few months ago.... It pulled to 6800RPM before the valve train gave up.

That engine had a VERY aggressive lobe design, common 5/16 pushrods, simple stud mount rocker arms and the base AFR valve spring package.... Just the upgrade 8019 spring package would have let it turn over 7,000 no problem but there was really no need as I had spec'd the cam to peak power at 6300 and they only spun it to 7K to see how far the power carried past peak. You can see the dyno here:

https://www.corvetteforum.com/forums...95-dyno-s.html

If I were designing something to spend any real time running in the 7K range I would do the valve train a lot different (a lot more $$$$ too).
Will

ChrisWhewell

Thanks alot for sharing the insights, I appreciate every word. Those are some nice torque numbers on that dyno sheet.

ChrisWhewell

A big area I saw for improvement on every LT1 and iron vortec head I've seen, is the perimeter of the combustion chamber adjacent to the top cut on the valve seat - there's always been a little "wall" circumscribing the seat, which varies in "height" from about .005 to sometimes .020, and not consistently between cylinders.

The way I handled it was to (painstakingly) do the 3-angle thing on the seats with my Neway toys, getting the seats to be at the exact desired width and exact desired location on the valve face. Then, I inserted an an old unwanted valve into the guide and seated it on the seat. Next, slowly and meticulously, took a tiny spherical carbide die grinder and chucked it into a drill and went all around the exterior perimeter of the valve and removed the "wall", and then next with the valve still on its seat (to protect the 3 cuts), I used sandpaper to radius or blend the transition area btw. the seat and comb. chamber, then followed it up with some wet 600 grit emery. The transition btw the 30 degree cut and combustion chamber on my heads is as smooth as a baby's a** !!. The whole idea was to permit for better flow at low-lift, to build or enable air-mass intertia early on in the intake cycle. I can't quantify it b/c I didn't dyno before and after, but I sleep at night knowing I did the best job humanly possible. I wore jeweler's glasses and inspected every micron of those chambers , went through a lot of prussian blue and the Neway cutters and I, we became One together, haha. A set of them is on the truck, I installed a Comp XE-250H and a late 70's good Q-jet I rebuilt, and MSD 8365 Dist. because of its awesome adjustability. Probably over 400 ft. lbs at the crank based on Comp's dyno sheet. I know its not C4 stuff but I just thought I'd share anyway.