Ridiculous 1000HP 7M Street MK3 Build
- Thread starter NegativeGeForce
- Start date
Got the head back from engine lab. Looks pretty good. Valve lash is right around the .008 to .009 clearance on all valves. It's a shame i will be taking it all apart to do the combustion chambers and shimless buckets.
Last edited:
pete05;1974345 said:
Yep. You can read all about this mod here.
http://www.supraforums.com/forum/showthread.php?683040-finally-an-answer-to-the-7m-head-gasket-issue
Gordon (six pack) gave me instructions to give the machine shop. Using a 9/16 reamer enlarge the holes to a depth of .210 inches. This creates an interference fit for the inserts.
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I finished my measurements to order shimless buckets. Took some better pics while the head was apart. Can't get over the sexiness of the head 
Albert;1974388 said:
Yep, I am going to make them as tight as I can when ordering the shimless buckets. .006 on the intake and .008 on the exhaust.
They actually weren't all .008-.009 when I took the time to really measure them. Here is what engine lab was able to do with just 100 shims I gave them...
intake exhaust
1 0.007 0.008
2 0.01 0.009
3 0.007 0.012
4 0.01 0.012
5 0.005 0.011
6 0.006 0.011
7 0.01 0.011
8 0.009 0.008
9 0.01 0.011
10 0.008 0.01
11 0.008 0.009
12 0.01 0.01
It's all within spec but it is a bit all over the place so I made an excel sheet that calculated the ideal bucket sizes to get close to the low end of the spec. I told the machine shop to just get close enough because I won't be using the stock buckets anyways.
You do realise clearances close down as the engine wears don't you?NegativeGeForce;1974410 said:
Most aftermarket Cams run closer to 13 thou, I set my shimless buckets up high end of spec +2 thou and as far as I know it's still running fine today in Crisp's car after many many thousands of KM's.
IJ.;1974476 said:
I didn't really think about that to be honest. I mean I know they do close up but after how many miles? I suppose I should really take that into consideration especially with higher lift cams and dual valve springs. I didn't order the buckets yet so I will bump it up to the high end of the spec instead. Thanks for the tip (both Albert and IJ).
You pretty much get one go to get it right with Shimless before it get's very expensive and time consuming...NegativeGeForce;1974483 said:
I made the mistake of having the buckets Cryo treated after being assured that the dimensions don't change... they did with the open end of the buckets flaring out 2 thou...
Cryo Guy had to centerless grind them back to spec, as I posted I shot for High end + 2 thou and after initial breakin they were within spec.
IJ.;1974484 said:
Thats good info. What would I do without you guys? Probably on the side of the road somewhere in 6 months wondering why my timing belt broke.
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Been thinking about what Albert and IJ have said and I think the best idea for a newly machined head might be to just run stock buckets for a few hundred miles then swap in shim less.
well this is what I am going to do i going to run a large clearance by about 2 thou since most seating is roughly 2 thou max now what y can do is just place a shim under the bucket like I am going to do for my finale adjustment
in most case's a valve will seat down about 1 to 2 thou pending on how soft seat and valve are so it's best to ask your machine shop they will know
in most case's a valve will seat down about 1 to 2 thou pending on how soft seat and valve are so it's best to ask your machine shop they will know
NashMan;1974651 said:
Well im sure the machine shop will say exactly what you said...valve will seat in 1-2 thousands. Best thing is to let it break in first before dumping 300 on shimless buckets.
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