porting & changing valve size on 853 castings?
Thread Starter
Joined: Apr 2004
Posts: 1,378
Likes: 14
From: Atlanta, GA Ft. Walton Beach, FL
porting & changing valve size on 853 castings? Thinking of having my 853 heads ported, polished and changing valve sizes w/ stainless steel valves intake 2.02 exhaust 1.57 can this valve upgrade be done w/ hand porting?
also thinking about milling these heads for a 11.0:1 compression ratio (I only use pump gas).
I also would like thoughts on port matching the LS6 intake manifold is this just done on the bottom? & is it recommended?
all this for a 346CI stock LS1 w/ tame cam, tame TC & Lts. just looking for a fast fun reliable daily driver.
I'm new and just asking for advice car is rarely drag raced.
Thanks
also thinking about milling these heads for a 11.0:1 compression ratio (I only use pump gas).
I also would like thoughts on port matching the LS6 intake manifold is this just done on the bottom? & is it recommended?
all this for a 346CI stock LS1 w/ tame cam, tame TC & Lts. just looking for a fast fun reliable daily driver.
I'm new and just asking for advice car is rarely drag raced.
Thanks
Last edited by badmfkr; Mar 17, 2007 at 06:13 PM.
It really isnt a bad way to go if you dont have the money for aftermarket heads. A local guy in VA Beach, VA has a ported set on his T/A and a cheater cam. He dyno'd 423/378. Its a six-speed car but the point is they are capable of good power when done right.
Not sure if you meant me or not. I also have a set of stage II ported 853s (stage II = bigger valves, usually 2.02 / 1.57), and a 230/224 cam. My heads are unmilled and I'm using stock head gaskets. I put down 423hp / 371tq. Be careful with milling the heads and running larger valves as your ptv clearance is quite a bit closer to begin with.
FFHP - Force Fed High Performance. Now bankrupt. The heads were on sale and were less than $1k and came assembled with 2.02/1.57 valves, PP Gold dual springs, new stock head bolts and gaskets. Many of the sponsors on the right can offer similar deals on better heads than I've got. If I were to do it over again, I wouldn't go with bigger valves at all. I'd instead go with a set of ls6 style ported heads and mill them to boost cr. By the way, the current ls6 style port jobs flow just as much as my heads, but have way better compression and mid lift flow!
Well, after measuring my heads, and a stock set of 853's, I found out that my heads were milled roughly 0.036" which bumps up my compression to about 10.9:1 using the stock 0.053 graphite gaskets. I wanted to run a 0.040 gasket to cut down my quench, but that's not going to happen at this point in time. I'm going to play it safe and order as set of 0.051" cometics and call it a day.
Be careful milling too much because of PtoV clearance issues.
Be careful milling too much because of PtoV clearance issues.
Thread Starter
Joined: Apr 2004
Posts: 1,378
Likes: 14
From: Atlanta, GA Ft. Walton Beach, FL
853
Originally Posted by bshell
FFHP - Force Fed High Performance. Now bankrupt. The heads were on sale and were less than $1k and came assembled with 2.02/1.57 valves, PP Gold dual springs, new stock head bolts and gaskets. Many of the sponsors on the right can offer similar deals on better heads than I've got. If I were to do it over again, I wouldn't go with bigger valves at all. I'd instead go with a set of ls6 style ported heads and mill them to boost cr. By the way, the current ls6 style port jobs flow just as much as my heads, but have way better compression and mid lift flow!
or can they be handported for the valve upgrade?
PTV I'm assumming it means piston to valve clearance?
my cam only has a 551. lift. is lift what makes it close if so will this be an issuse w/ my 551. lift.
I also planned to use stock GM head gaskets.
on the LS6 heads how much milling would you have do to acheive what compression?
Thanks for advice
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I'd be a little weary of hand ported heads. Unless the porter has a lot of experience with lsx heads and has a flowbench to test the work on. Its real easy to overport and kill flow. With cnc'd heads you'll have a tested, proven setup. Take a look at the sponsor list, there are a number of stock casting cnc'd heads available for $1k or less.
Cam lift is not an indicator of piston to valve clearance issues. Max lift occurs near bottom dead center. You need to look at int/exh duration and lsa. If you are keeping the cam in your sig and running stock gaskets, you should be fine.
Cam lift is not an indicator of piston to valve clearance issues. Max lift occurs near bottom dead center. You need to look at int/exh duration and lsa. If you are keeping the cam in your sig and running stock gaskets, you should be fine.
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Originally Posted by badmfkr
must the stock 853 heads be CNC ported to use the bigger valves?
or can they be handported for the valve upgrade?
PTV I'm assumming it means piston to valve clearance?
my cam only has a 551. lift. is lift what makes it close if so will this be an issuse w/ my 551. lift.
I also planned to use stock GM head gaskets.
on the LS6 heads how much milling would you have do to acheive what compression?
Thanks for advice
or can they be handported for the valve upgrade?
PTV I'm assumming it means piston to valve clearance?
my cam only has a 551. lift. is lift what makes it close if so will this be an issuse w/ my 551. lift.
I also planned to use stock GM head gaskets.
on the LS6 heads how much milling would you have do to acheive what compression?
Thanks for advice
Ben T.
Originally Posted by bshell
I'd be a little weary of hand ported heads. Unless the porter has a lot of experience with lsx heads and has a flowbench to test the work on. Its real easy to overport and kill flow. With cnc'd heads you'll have a tested, proven setup. Take a look at the sponsor list, there are a number of stock casting cnc'd heads available for $1k or less.
.
.
Have you personally seen any of those $1K CNC LS6 heads? I've been doing some head porting for a while I'm not convinced those are the best option, with their nearly 240cc intake runners. I'd rather take a nice hand ported LSx casting with a 220cc runner over a CNC LS6 head with a 237cc runner, especially if both flow the same... atleast for my builds.
Ben T.
Thanks Studytime, I was impressed as well. I know my heads were overported (cnc'd 853s by the way) in that they have 247cc intake ports and 68cc chambers. I also have a bit of a parts mismatch with the cam in that I have a much better flowing intake cycle vs exhaust right now.
I'd say that 90/90 still isn't idea for an LS1. A good single plane intake would be a way better, so having a reverse split still doesn't sound like a bad idea.
Even Thunder's new cam the TRak cam is a reverse split at around .150" and above if I'm not mistaken. Compare duration of the LSk intake and the TR exhaust lobe and it's evident. There are people putting up plenty of power with it and a 90/90, so I really don't think your TR230 is a horrible choice with the 90/90.
Ben T.
Even Thunder's new cam the TRak cam is a reverse split at around .150" and above if I'm not mistaken. Compare duration of the LSk intake and the TR exhaust lobe and it's evident. There are people putting up plenty of power with it and a 90/90, so I really don't think your TR230 is a horrible choice with the 90/90.
Ben T.
I have a set of #853 5.3 heads, with Farra stainless steel 2.02" int and 1.57 int. valves and a three angle valve job ,shaved .030" and hand ported & polished and the chambers are polished also, and has Patriot gold springs and titanium retainers, I had these on my 347cid. and perfect for it. they have been freshened up ready to go. if you know any body needing this heads ill take 700.00 + shipping
Originally Posted by Randy WS6
I have a set of #853 5.3 heads, with Farra stainless steel 2.02" int and 1.57 int. valves and a three angle valve job ,shaved .030" and hand ported & polished and the chambers are polished also, and has Patriot gold springs and titanium retainers, I had these on my 347cid. and perfect for it. they have been freshened up ready to go. if you know any body needing this heads ill take 700.00 + shipping
