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Hard seats on exhaust only Pulled a 59 AB apart that was put together by a friend of my dads around 1975 with a 4" crank and 3 5/16 pistons. Has adjustable lifters. The intakes are soft and exhaust are hard. The valve seats are ground at 45 deg but the intake valves are at 30 degrees.
Everything looks great except the intake valves. What think you guys about leaving the soft seats in the intake and just resembling with new intake valves. |
Re: Hard seats on exhaust only So here’s my2cents on this subject. I will probably get a lot of flack from the “expert’s “ That build so many engines. How many small block Chevy are still running around this world with non hardened seats. Or many other 50s-60s-70s engines with non hardened seats. Give it a nice valve job good valves & guides. I prefer stainless valves & bronze liners in guides but that’s my preference. I have many engines in 3 countries with many miles on them & this combo with zero issues. Maybe I’m just a lucky guy.
Good luck with your decision. Cheers Tony Let the fun begin. |
Re: Hard seats on exhaust only Agreed, run it
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Re: Hard seats on exhaust only That was my feeling.
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Re: Hard seats on exhaust only Only thing I would change is the exhausts to 30 degrees. Good for 15% more flow and it only costs some time.
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Re: Hard seats on exhaust only Quote:
Pete, does the 30 degree seat work for the intakes too? Thanks! |
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Re: Hard seats on exhaust only 2 Attachment(s)
To change the seat angles from 45* to 30* would require "sinking" the valves a fair amount, it works much easier when you want to go from a 30* to the 45*, we've done many Pontiac's and Old's using this setup!
Many of the "true" race heads we now use have 50* and 55* seat angles, I don't agree with these steep angles but "it is what it is" so to speak! Thanks, Gary in N.Y. P.S. To answer the OP's question, you really only need the exhaust seats installed, much like the cast-iron aftermarket heads now come? The other issue with these Flatheads in the valve seat area is the fact that most times the original seats (inserts or not) are so badly corroded they require too much grinding to get down to a good "base". We recently started putting in all 16 new seats (photos below) to correct this condition AND to get the valves back to the hgts they're suppose be at from the factory! "Sinking" (grinding) valves too far down in the port is not really good practice! |
Re: Hard seats on exhaust only 100% agree with above statement by Gary. You do not want valves sunk.
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Re: Hard seats on exhaust only Hardened seats are only used on the exhaust... That being said, the only vehicles that NEED hardened seats, are those that are run under heavy load and see a lot of miles. An occasional use flathead has ZERO need for them. The risks of cutting out the old, perfectly good metal FAR outweigh any perceived benefits, unless it is done for repair purposes.
Plus, what a lot of places install as 'hardened' seats isn't much different than the metal they cut out. It's an upcharge that is un-needed in 95% of the heads people have them installed in. |
Re: Hard seats on exhaust only Years ago I did allot of flow bench testing, most of it was a waste of time but I did learn a few things. When testing port flow, you must have the head on. Unfortunately the cylinder head has allot to do with flow. So the answers you get don't mean much. With tat said, the seat angle had little to do with flow, hard to measure. sometimes something looks good, but doesn't preform as well. Just like those 40% headers.. Removing the intake seat in the 59 block allows you to install the chevy 1,72 intake valve, be carful when blending in the bowl, it gets thin there. Again, this doesn't improve flow much better than the 1.6 valve. I'm working on this problem right now. BUt????
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