420A STD Bore pistons

[OblivioAssebit]

So I finally started working on my turbo build again ( a year later). I took my block in to get decked and cleaned up and was talking to the machine shop and they said that since i have std bore pistons they were for sure going to be loose and I shouldnt even waste my time and should sell the pistons and get bigger pistons. However, I know that the the compression was perfect before I took the motor apart and there is no scoring. The machine shop also only works on drag motors. I just took it to them because i figured they know what they are doing.

Am I screwed or should it be fine? I dont want any blowby.

 

[Slo2gen]

Did you take a depth micrometer to see if the cylinders where true all the way down before you took it to them? They may be a reputable shop, but I have seen it (more recently) where good shops just sell you more work because they need the money. It may also be the fact that they don't feel comfortable putting std bore pistons back in and would rather you over bore it for a better fitting piston, when they overbore it they will be able to fit the pistons to your block. If the stock bore is already too big from wear then there is nothing that they can do for you. When talking about tolerances like this you can't just eyeball it. Just go up to the shop and talk to them, I'm sure you'll get a feel from them if you really need it or they are just wanting money.