Lq4 with 706
02-10-2012, 08:16 PM
#1
TECH Apprentice
Thread Starter
Lq4 with 706 When I bought my 6.0 I was told it was an lq9. Today I pulled #3 plug, using a snap on camera scope I discovered a dish piston that would be an lq4 not the flat top of an lq9. My delima is:
I have a set of fully cnc ported 706 heads that are milled .007 according to my measurements. I compared them to my untouched 241 that measured
4.756 and the 706 hight was 4.749. I measured from valve cover surface to deck of head.
I got a tsp ms4 for Christmas from a good friend and am wanting to use the 706 heads now to increase compression and gain power. I was going to use a .060 head gasket instead of a .051 factory thick gasket to make up the difference. I'm just not sure how this will work.
I do have a friend that builds cylinder heads for a livinging and he says it will be ok, but I would like to hear from experienced tech members who have experienced this dellima.
Also I'm not aginst using the 241 just that the 706 cnc will make more power then a factory cast head.
Thanks for your help
I have a set of fully cnc ported 706 heads that are milled .007 according to my measurements. I compared them to my untouched 241 that measured
4.756 and the 706 hight was 4.749. I measured from valve cover surface to deck of head.
I got a tsp ms4 for Christmas from a good friend and am wanting to use the 706 heads now to increase compression and gain power. I was going to use a .060 head gasket instead of a .051 factory thick gasket to make up the difference. I'm just not sure how this will work.
I do have a friend that builds cylinder heads for a livinging and he says it will be ok, but I would like to hear from experienced tech members who have experienced this dellima.
Also I'm not aginst using the 241 just that the 706 cnc will make more power then a factory cast head.
Thanks for your help
02-11-2012, 12:13 AM
#3
You need to keep your quench area around .035. With a .060 gasket, it will be way more, causing a loss in power.
Also using the 706 5.3 heads on a 4 inch bore will seriously shroud the valves.
Also, unless it has been done already, you Will need to install ls1 intake valves. In your setup, I would have your 241's milled and run them.
Also using the 706 5.3 heads on a 4 inch bore will seriously shroud the valves.
Also, unless it has been done already, you Will need to install ls1 intake valves. In your setup, I would have your 241's milled and run them.
02-12-2012, 12:32 AM
#4
TECH Apprentice
Thread Starter
If the mill removed .007 from the head and I add .009 to the gasket then .002 is what I'll add to the quench. Correct? The combustion chamber has been worked over as well on the 706 heads but I haven't measured the cc yet.
But the "quench" should be no more then .002 more then if all is factory aside from the larger valvles. Correct? Tsp stage 2.5 5.3 heads flow like 320 cfm according to there web site, so these will be close to that simply looking at them you can tell they are extensively worked over. And when contacting Texas speed by phone I don't get much of an answer. I understand Ill have to measure ptv clearence and maybe have to fly cut the piston. And I know that 243/799 cnc'ed would be better but I don't have them I have 706's. The compression jump should be at least a point which is good. I used the search feature and couldn't find any one running this same set up. Maybe this will be the first documented one?
But the "quench" should be no more then .002 more then if all is factory aside from the larger valvles. Correct? Tsp stage 2.5 5.3 heads flow like 320 cfm according to there web site, so these will be close to that simply looking at them you can tell they are extensively worked over. And when contacting Texas speed by phone I don't get much of an answer. I understand Ill have to measure ptv clearence and maybe have to fly cut the piston. And I know that 243/799 cnc'ed would be better but I don't have them I have 706's. The compression jump should be at least a point which is good. I used the search feature and couldn't find any one running this same set up. Maybe this will be the first documented one?
02-12-2012, 01:18 AM
#6
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If the mill removed .007 from the head and I add .009 to the gasket then .002 is what I'll add to the quench. Correct? The combustion chamber has been worked over as well on the 706 heads but I haven't measured the cc yet.
But the "quench" should be no more then .002 more then if all is factory aside from the larger valvles. Correct? Tsp stage 2.5 5.3 heads flow like 320 cfm according to there web site, so these will be close to that simply looking at them you can tell they are extensively worked over. And when contacting Texas speed by phone I don't get much of an answer. I understand Ill have to measure ptv clearence and maybe have to fly cut the piston. And I know that 243/799 cnc'ed would be better but I don't have them I have 706's. The compression jump should be at least a point which is good. I used the search feature and couldn't find any one running this same set up. Maybe this will be the first documented one?
But the "quench" should be no more then .002 more then if all is factory aside from the larger valvles. Correct? Tsp stage 2.5 5.3 heads flow like 320 cfm according to there web site, so these will be close to that simply looking at them you can tell they are extensively worked over. And when contacting Texas speed by phone I don't get much of an answer. I understand Ill have to measure ptv clearence and maybe have to fly cut the piston. And I know that 243/799 cnc'ed would be better but I don't have them I have 706's. The compression jump should be at least a point which is good. I used the search feature and couldn't find any one running this same set up. Maybe this will be the first documented one?
While milling the head does reduce PTV clearance it does nothing to the quench. Decking the block, changing piston height (different pistons or rods), or changing the head gasket thickness are the only things that effect quench distance.
.035-.040 is a fairly standard "target" with a bore size around 4" but this is dependent on the build. Having a forged piston (expands more with temp) that is in a looser bore (most forged pistons require this) might call for a larger quench distance as what you don't want is the piston to actually contact the head.
All you did with the new gaskets is to add .009 to your quench. You will need to measure the deck height of your installed pistons and then choose a head gasket thickness that produces the most optimal quench for your set up.
Now, if what you're trying to do is to restore normal PTV then your calcs are accurate. Your original post said you were using the thicker gaskets to "make up the difference" and is spot on. However, if I had a that cam created PTV so tight that a .009 gasket thickness difference was important I'd fly cut the pistons to be on the safe side.
Just re-read the first post. You have dished pistons anyway. the only place that will have any effect on the quench is the small flat ring around the tops of the pistons. Your friend is right, it should work fine. Sadly the dishes are large enough to wipe out most of the quench action but not large enough to avoid the valves regarding PTV. They do help a bit but not as much as would be optimal. It's still a good idea to measure PTV with a large duration cam and flycut as required.
The MS4 at 239/242 is more cam than I would use in this application. Use the thinner head gaskets as you need to maximize compression with that cam.
Check out my new signature... My 19 year old son told me that today and you especially should find it humorous.
Last edited by technicalninja; 02-12-2012 at 01:47 AM. Reason: additions
02-12-2012, 06:53 AM
#7
If the mill removed .007 from the head and I add .009 to the gasket then .002 is what I'll add to the quench. Correct? The combustion chamber has been worked over as well on the 706 heads but I haven't measured the cc yet.
But the "quench" should be no more then .002 more then if all is factory aside from the larger valvles. Correct? Tsp stage 2.5 5.3 heads flow like 320 cfm according to there web site, so these will be close to that simply looking at them you can tell they are extensively worked over. And when contacting Texas speed by phone I don't get much of an answer. I understand Ill have to measure ptv clearence and maybe have to fly cut the piston. And I know that 243/799 cnc'ed would be better but I don't have them I have 706's. The compression jump should be at least a point which is good. I used the search feature and couldn't find any one running this same set up. Maybe this will be the first documented one?
But the "quench" should be no more then .002 more then if all is factory aside from the larger valvles. Correct? Tsp stage 2.5 5.3 heads flow like 320 cfm according to there web site, so these will be close to that simply looking at them you can tell they are extensively worked over. And when contacting Texas speed by phone I don't get much of an answer. I understand Ill have to measure ptv clearence and maybe have to fly cut the piston. And I know that 243/799 cnc'ed would be better but I don't have them I have 706's. The compression jump should be at least a point which is good. I used the search feature and couldn't find any one running this same set up. Maybe this will be the first documented one?
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02-13-2012, 04:34 PM
#8
TECH Apprentice
Thread Starter
Thanks for the help/clarification. I not sure exactly what the hell I'm going to do. I want the car to go as fast as possible. And I do plan to drive it every day. I suppose I should sell the ms4. It was a present
