When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
That's a good deal for a good block. But what do you mean you can't use oversize pistons? I thought it was common in the Cobalt community to use .002" custom oversize pistons. That's the only way I would do it moving forward because this time I had sleeves installed in an old shitty block and that is cost prohibitive compared to getting a stronger gen 3 block and just going .002" over. Also after I had the damn sleeves installed the shop called me and said even with the brand new sleeves I had too much PTW clearance so I still ended up going oversize but .02" which is generally not advised. Every-time I take if for a rip I am worried I am going to crack a cylinder but I was impatient and wanted my engine done so I could get some driving in this summer. Just be patient and make sure it is done to your liking.
I was going to say it shouldn't have been stone honed but didn't want to ruffle any feathers. You don't stone hone a worn, tapered cylinder. You're good up to .007" clearance for a boosted cylinder. If your installing new rings with those used pistons all you want to do is de-glaze it.
They didn’t use stones. They used the *****. And we are taking it back to get honed.
That's a good deal for a good block. But what do you mean you can't use oversize pistons? I thought it was common in the Cobalt community to use .002" custom oversize pistons. That's the only way I would do it moving forward because this time I had sleeves installed in an old shitty block and that is cost prohibitive compared to getting a stronger gen 3 block and just going .002" over. Also after I had the damn sleeves installed the shop called me and said even with the brand new sleeves I had too much PTW clearance so I still ended up going oversize but .02" which is generally not advised. Every-time I take if for a rip I am worried I am going to crack a cylinder but I was impatient and wanted my engine done so I could get some driving in this summer. Just be patient and make sure it is done to your liking.
For the reason you said lol. I personally have never seen cobalt owners use over sized pistons.
Just stock bore and stock sized pistons.
Also I don’t know if y’all have heard of John Walters but he’s well known in the ecotec community. He’s who I bought the rods and pistons from. He builds these motors and he told me to take it and get it honed with 220 grit even if the pistons are used.
They didn’t use stones. They used the *****. And we are taking it back to get honed.
What you had done is correct if your just putting in a set of new rings on used or new standard pistons into a worn bore. You don't want to hone it with stones as the bore has taper and slight imperfections that the flex hone gets to. A stone hone will not likely hit every spot and if they run it until it does, you could end up with too much clearance. The recommended grit is for the ring break in, not the pistons. Different rings require different grits as I posted earlier.
The Custom Diamonds Jeffrey ordered for me are slightly oversize to allow for the wear and honing of the cylinder to specs. Diamond calls for .004" and another .001-.003 depending on use. Boosted up to 15psi can have another .003" added which is why I said you would be ok if they ended up at .007" New they are 3.4645"
Why are you taking it back to have more metal taken away because what they already did is what should have been done unless the cross hatch is too flat.
That is correct as they are assuming the bore is new with a finished hone and proper cross hatch for ring break in.
In your case and mine we are just de-glazing with the same proper cross hatch and grit for a new set of rings in a used bore.
Are you having your crank balanced? I know if you don’t it can cause vibrations at high rpms. I’m only spinning to 8k. I don’t know if that’s considered high rpms and if I’ll have an issue is we don’t get the crank balanced.
Are you having your crank balanced? I know if you don’t it can cause vibrations at high rpms. I’m only spinning to 8k. I don’t know if that’s considered high rpms and if I’ll have an issue is we don’t get the crank balanced.
I'm not balancing the crank anymore then GM did but I am going to run a fluid damper since my components are no longer what the OEM harmonic damper was chosen for.
My rods are now all equal weight as well as the pistons and the combustion chambers are being CC'd. One chamber was off a lot from the rest with some bad casting.
Hone and deglaze are used interchangeably kind of and are the same thing for the most part. All you are doing is restoring the crosshatches without changing the cylinder bore. Hone to fit they actually remove some material were as deglazing the idea is to not remove any material and restore the crosshatch so your rings can break in properly.
When I first went forged I just ball honed or deglazed my cylinder walls with a dingle ball hone and drill. Though it may have been something I did wrong I burned a lot of oil so I will never dingle ball hone a stock size bore again. Though like I said it will probably work fine for you if done right. This time around I had them hone the cylinder walls to fit each piston exactly and if I recall correctly the machine shop shot for .004" PTW. I don't burn "any" oil now.
What HGT is wondering about is you saying you are sending it back to get deglazed or honed for a second time? What you currently have should be fine if the crosshatch angle is good and they used appropriate grit.
I balanced my rotating assembly which I think is what you are referring to balancing the crank. To properly balance a rotating assembly you must include basically everything that moves with the crank like rods, pistons, flywheel and harmonic balancer. As forged pistons are not perfect and also different mass than your stock pistons you can benefit from balancing your rotating assembly when revving to higher rpms. Typically this would include balancing the weight for both the heavy and light end of the rods with each other and all the pistons balanced with respect to each other prior to balancing the rotating assembly.
Ya i know all about balancing it. And we are bringing everything with the block. I was just curious about balancing it if I’m only raving to 8k but we are just going to get it done anyways. Also, we aren’t taking it back. We are leaving the cylinders as is. Restored the crosshatches.
Only 8k lol. Pretty high compared to a stock redline of 6,500. Anything you can do to reduce crankshaft vibrations will extend the lift of the engine. I think it's worth doing and in your application as well because you will be going to redline often.
Are you still running the single fan shroud? I switched to a dual fan and below is the wiring to hook it up. Our fan currently sends fan one output to a resistor installed in the shroud to drop the speed. That goes directly to fan one in the dual fan shroud.
I would think single fan would be plenty sufficient for drag racing. I have never had an issue with mine. Hell it only raises about 5 degrees during a 1/4 mile pass lol.
12-15-2017, 06:52 AM
