Rebuilding- How do I know what measurements to buy? .020, std, recommendations

[MarkAngelo05]

Hi!

First of all, thanks for taking the time to read this.

I decided on rebuilding my 7 bolt motor rather than swapping the 6 bolt in it. My 7 bolt has about 117k miles on it, and the head (which I just put on) has 8k miles on it.

Problem- Compression checks out at around 125-130 psi on all 4 cylinders. I add some oil, then it bumps up to around 150 psi'ish... I'm also starting to burn some oil.. so this tells me its time for the bottom end to be rebuilt.

I've been boosting 18-19 psi on this block for about the past 10k miles, and (cross my fingers) have not had any signs of crank walk. I also have an upgraded clutch which claimed 18% more holding capacity than the stock clutch. (XTD stage 3, 6 puck sprung disk clutch kit) which has been on there for about 8k miles, still running well and not slipping at all.

I recently changed the oil and my magnetic oil plug seemed to collect very very very very little amounts of metal contamination

I recently dynoed 260 ish whp at 19.5 psi on my current setup. I would like to achieve the 300whp area with a "fresh" stock'ish build.


Now for the questions--

I'm shopping around for new pistons, bearing set, piston rings, and I am most likely getting some stronger rods.

I am a little confused about the measurements and tolerances. On all rebuild kits, and even buying parts individually it asks you if you want ".020, .050, STD, etc etc" How do I know exactly what to get? specially for the thrust bearing/washers, main bearings, and piston/rod bearings...

Do I have to actually take my engine apart, get it hot tanked and cleaned out and have the parts checked and measured before I order my rebuild kit?

I'm set on staying at 8.5:1 compression, so are stock 2G pistons made by topline okay? Does it make any sense to stay with 2G pistons w/ Eagle rods, or other stronger rods since 2nd gens are known to have weaker rods?

I'm doing the balance shaft eliminator kit as well. I'm going to reuse my arp head studs, but I'm trying out the new SCE ICS Self sealing head gasket, (recommended by Maperformance)

Thanks in advance for all your help!

Aloha from hawaii!

Mark

 

[HOTSHOT100]

hi ,

I have buy top line piston .020 oversize for my rebuilt and from now everything is fine . (I have around 300whp). I have another set of topline pistons for sale but with standard size (not oversize)

the best bearing you can get is ACL or clevite . I think ACL Race is not available for 7 bolts .

for the rods if you want to save money keep your 2G rods , for 300whp you dont need stronger Rods .

 

[Dream On]

Wait and find out from the machine shop what you need. If your cylinders are out of round, then you'll need to get it bored. If not, honing may be all you need and you can use standard size pistons. The crank will also be checked and they may need to grind it if it's been scratched. Mitsu cranks are supposed to be non serviceable, but there are bearings for cut cranks.

 

[MarkAngelo05]

So if they say my crank needs to be grinded, then I wouldn't use the STD. bearing size.. I would you the bearing size which compensates for the amount ground off my crankshaft?

Also, if it doesn't need grinding, should I have them polish my crank?

What should I have the machine shop do? I saw that video of the dude putting together a 4g63... I saw him measuring the cylinders and grinding the piston rings... Is that standard procedure?

Should I just have the machine shop bore the cylinder if needed, and HONE, and Micropolish my crank then install the pistons on the Rods.

Then I'll put the motor together myself? Any recommendations??

Should I upgrade my 2G rods? or am I fine with my stock 2G rods and Topline 2G pistons? For 300-350WHP?

Even though my head is pretty new, and my headgasket is not blown or anything, should I still have the head reshaved, or no?

Thanks!

Mark

 

[DarthBulk]

I just took a block to the machine shop, and here is what they told me. Since our engines are turbocharged, you should only bore it larger if you HAVE to, to remove scratches or out of roundness in the cylinders. The rule of thumb is to stay with the smallest amount of boring needed. You don't need that little bit of extra displacement that comes with boring...make up for it with boost. The machine shop recommended I stay with standard bore (if the cylinders are ok) or 0.020 over at most.
They also had harsh words for Taiwanese pistons. They said they wouldn't use anything other than good brands like Ross, JE, Wiseco, etc.
Measuring the pistons and sanding the rings is standard procedure...don't skip it!

 

[danny_l_2005]

Yes, don't order any kit yet until you know what the machine shop tells you what you need.

 

[MarkAngelo05]

Around 8k miles ago when I swapped my head, the cylinders still had the cross hatch marks that looked exactly like it was just honed... was I tripping out or what? It was identical on all 4 cylinders.. the top of my pistons had carbon buildup but I managed to break it all loose and clean it up a bit... I also felt the cylinder walls and felt very smooth..

Is this regular to see on a 100k plus engine?? how long does the cross hatch pattern from honing usually last??I would think it would dissappear....

Thanks!

Mark

 

[DarthBulk]

It is typical to still see that pattern on the cylinder walls. But the cylinders are glazed over, that is why they feel so smooth. The purpose of the crosshatching is to wear your rings during the break-in period, so they seat perfectly against the cylinder wall. If you read the Motoman break-in method, I think he says that the crosshatching wears off in the first 20 miles or so. After that you might still see the pattern, but the walls are too smooth to do any more breaking-n.

 

[MarkAngelo05]

Okay, I can't wait to have the machine shop measure everything first then. I don't think the engine has been rebuilt, but carfax does not tell you everything. It the engine has been rebuilt before, then I deffinately might have to bore the cylinders if it has been messed with before.

So, did you guys have the machine shop assemble your engines too? or Just have them machine everything to spec, then install the pistons and all back in? Also, should I have them grind the rings down to spec, or I have to do that myself... I'm already buying an engine stand, hoist, engine leveler, etc... this is going to cost a lot of cash, but I want a healthy engine that doesn't burn oil...

THANKS SO MUCH FOR ALL YOUR HELP!!!

 

[DarthBulk]

Personally, I usually have the machine shop shortblock the engine for me. That's just me. Then the ring gapping and bearings are covered by them. It is not that difficult to do it yourself, it just takes time and you have to know what you are doing. Putting the rest of the engine back together is not all that difficult, and is actually quite fun. Good luck with your build

 

[MarkAngelo05]

Hey! I just got off the phone with the most reputable machine shop here in hawaii. The name is Snyder's Machine...

The owner pretty much told me to bring the parts in, BLOCK, CRANK Pistons And rods, and he'll measure everything and let me know what size bearings to get. As far as Bore size, he said that 99% of the time, he recommends boring atleast .020 over just because most engines wear out. He said that he only cuts the cranks if it NEEDS to be cut, but they Micro polish no matter what.

He quoted me for around 550-800 $$ he'll do these things, BORE, HONE cylinders, Hot tank/clean parts, Cut crank(if needed)/Micropolish, remove and install pistons on 2G rods, Measure and cut piston rings for me, then I can put the engine back together. Or he said it'll be around 800-1,000.00 for him to just do a full stock rebuild (Just machine work). But I provide all the parts like pistons, bearings, etc.

ALSO, HE TOLD ME THAT I do not have to get it balanced and blue printed since it's a stock build. What is that exactly? Don't you need to balance parts of the motor regardless?? DO YOU HAVE TO BALANCE AND BLUE PRINT? AND WHY?

Okay, now armed with this information, All I need to know is if the TOPLINE OIL PUMP ASSEMBLY/FRONT CASE IS trustworthy.??!! How are topline .020 over pistons/rings and my stock 2G rods? I'm set on ACL RACE main and rod bearings, unless anyone has any other suggestions...

I'll be tuning with a wideband a/f meter that is permanently installed on my car, with DSMCHIPS stage 3 eprom ecu, and AFC. Will those topline parts withstand 300-350 whp?? around 20-22 psi of boost?

Thanks for the kind words and information towards my rebuild... Honestly I cannot wait to finally take a motor apart.. I hope nothin is seized up.....

Mark

 

[CPHunter]

honestly i would have never rebuilt that 7 bolt. i got the best machine shop in my area to do my 7 bolt rebuilt and it's shot the bearings twice already. something about new bearing on a 7 bolt that the crank don't like. then again i ran a 6 puck, and it shot them in under 500 miles. doing the 6 bolt now,$1000 down the drain. suxs but learn from are mistakes

 

[MarkAngelo05]

honestly i would have never rebuilt that 7 bolt. i got the best machine shop in my area to do my 7 bolt rebuilt and it's shot the bearings twice already. something about new bearing on a 7 bolt that the crank don't like. then again i ran a 6 puck, and it shot them in under 500 miles. doing the 6 bolt now,$1000 down the drain. suxs but learn from are mistakes

How many miles did you block have when you got it rebuilt.. also, did they cut your crank at all?? did they micropolish your crank?? let me know please.. thanks so much!

Mark