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What's the compression height? What's your deck clearance? I was gonna rebuild my 400 and buy T Meyer pistons, but I started a 460 instead. But I'll still follow your build thread.
I should have that info tonight, I asked my shop to deck the block to give me no more than .005 in the hole. When i picked it up they did not know the number so i am guessing they just squared the block and did not machine it to my request.
I am a little miffed,,, the top of the piston, near the intake is .011 out of the block. The top of the piston near the exhaust is .063 in the hole.
I can deal with the .011 out but not happy about it but the .063 in sucks. The "flat top" piston is .074 different in surface plane,, not very flat. I run a lot of compression on pump gas and the secret is not having a space for the fuel to pre-ignite. My amc is zero deck at 11.7-1 and a voodoo cam running 9+ dynamic ratio and I have no problems on pump gas.
If this 400 pings it is going to be the small area near the plug. The piston is .060 in the hole plus a .040 gasket = .100 down. No different than the stock garbage i took out,,,,, Maybe if i had 75CC heads the area near the spark plug would be machine out some and not cause a squish issue and the flame front would travel in that space.
maybe i am not thinking it correctly but If i was to do it again i would have custom pistons made.
I did not know he made two different pistons, no mention of it on his website. I will email him again. Where would i find the aussie/stock piston info?
Tagging this thread! This is the exact path I plan on taking with my 78 Bronco. It originally had the 351M, but had it rebuilt years ago as a 400. I have been looking at Tim's pistons since I can't seem to find any others for the 400. Only issue is I can't find my paperwork for the rebuild so I don't know if they bored the cylinders out, I may just find another block to use and rebuild that while mine is still running and in the bronco. I have also been going back and forth about using stock heads, or Trick flow or edelbrock. Very interested in your progress, will answer a lot of my questions!
One quick question Chris989, do you think the issue is with the machining on the block or the style of the pistons, or both?
Tagging this thread! This is the exact path I plan on taking with my 78 Bronco. It originally had the 351M, but had it rebuilt years ago as a 400. I have been looking at Tim's pistons since I can't seem to find any others for the 400. Only issue is I can't find my paperwork for the rebuild so I don't know if they bored the cylinders out, I may just find another block to use and rebuild that while mine is still running and in the bronco. I have also been going back and forth about using stock heads, or Trick flow or edelbrock. Very interested in your progress, will answer a lot of my questions!
One quick question Chris989, do you think the issue is with the machining on the block or the style of the pistons, or both?
My block was decked .015 to clean/square it. The piston is out .016. I can use a .050 gasket but i really do not like the design of the piston. It would be better suited for an Iron open chamber head.
Tmeyer quote just sent to me"TB piston were designed to give a higher compression to 400 engines with OE heads. Have the higher part of the piston be our "Theoretical" zero deck height, also worked great with the aftermarket heads."
Since i am using a set of TFs 62 cc i will most likely sell these pistons and have a custom set made.
Something like these are better suited for a CC head.
Agreed, those dished pistons are far better suited.
TMeyer sells Autotec pistons, so maybe he will accept the flat top pistons returned to him in exchange ?
To avoid any further waste of time and money, may I suggest this :
Measure the deck clearance on every installed piston you have now, measured at the flat side of the piston tops, and record those numbers.
When you remove the pistons, measure every compression height on them. (Yes, they should all be equal.)
Once you have those numbers, you can order pistons with the required compression height to give you a zero deck clearance.
If you can't get zero, pistons may exceed the deck safely by no more than 0.006'', assuming the valve to head clearance is ok.
By 'safely' I mean that your squish can go as low as 0.035'' which you'd get with your 0.041'' gaskets.
If you have to have the decks machined again, consider intake manifold fitment !
I'm not a fan of using gasket thickness to manipulate squish height either.
With 62cc CC heads, the 'new' 20cc pistons, and the 'new' deck clearance heights, recalculate the specs with the cam to ensure you don't create a pinging bomb.
