Sr20det rebuild questions for people who really know the answer?

[frankies1390]

Hey im rebuilding my red top due to a spun rod bearing from the previous owner. the bottom end is all going to be replaced... new cp pistons, crank bearings, machined, balanced, polish the crank. But can't decide on 86.5 or 87. mm pistons? any suggestions? Also my crank bearings are at .025 right now which tells me its been machined/rebuilt before. How do i check the clearance for the correct main bearings? Any suggestions on those as well? Then onto my head... I live in Eugene, Oregon and no one i mean no one can give me a staright answer on how to check shim clearance and tighten the valve train up? Anything will help and will be greatly appreciated!

[RPS13 DRIFTER]

well i know with any thing bigger than a .20 over you gunna need sleeves because it makes the cylinder walls to thin so i would go with 86.5 pistons. in my opinion.

[Hijacker]

You can go up to a .040" (87mm piston) overbore without resleeving. However, I always feel a little uncomfortable doing that as the bore walls do get a bit thin in my opinion. However, people more qualified than I have said the motor would be ok at that bore out.

As far as checking for bearing clearances, if you're having a shop machine them, you're probably going to have to rely on the shop to help you out on the checking. I believe the SR crank will handle .040" machining on the journals.

As far as shim checking, we have a ton of information on this site about doing it. I have a section about it in my rebuild tutorial linked in my sig. But basically, you need to buy/make a dial gauge stand that fits in the hole for the HLA and you measure the top of the rocker guide (slotted shim) to the top of the adjacent valve stem (no shim on it). The difference in height is your shim thickness.

[frankies1390]

Hey thanks for the input its nice to see a reply.... I have also read about the bore being too big and thinning the walls so i will stick with 86.5. For the crank i will speak with a machine shop to see what they have to say? The shim deal is where i get lost, is there a thread that has step by step process? Or something you can forward to my e-mail. [email protected]. Anything will help at this point cause even in my FSM it shows nothing about how to tighten the valve train up unless i'm missing a page? Oh also whats your opinion on rocker stoppers? Thanks again! Frankie

[Hijacker]

Rocker arm stoppers are always a good investment. They are by no means an insurance policy against head damage from over revving, but they can help keep things from getting really bad.

I mentioned the rebuild link in my signature. Click it. I explain the process in that tutorial. There is no way to "tighten" up the valve train. The point of the shims is to ensure that the rocker arm sits level across its pair of valves. If it doesn't, then the valves open with a bit of a lope as one is actuated more than the other, and your rocker arm can prematurely wear and break due to extra stress.

[frankies1390]

Awesome thread by the way! Very explanatory! Hey i noticed in your picture that your using the Mahle pistons... Whats the story on these? i can get the Mahle piston kit for $399.00, I can get the CP piston kit for $450.00 what do you suggest on that route? Thanks again...