Is the taper to much for std pistons??!!

[1995gstproblems]

im measuring .004 taper on the top of the cylinders but the out of round is all within spec I think, I'm new to this and this is what I measured on the 1st cylinder.

bottom
straight across
3.348 3.349


3.348 3.349


3.351 3.351
top near head
the std size is 3.345 with .002 max taper,
im using new pistons with new rods and a rec. crank.
The new pistons fit very snug in there though with just the oil rings in. with just a littttllleeeee bit of play which is normal

I'm planning on running 14b eventually 20g ebay turbo for kicks
550cc rc injectors, and stock cams.

This is a low budget stock build and im shooting for 20psi at 320hp or more
depending on my tune. Please help me out and let me know if its necessary to do so.

and another thing about my piston ring gap. I ground then to .030 gap like the forums recommended to run higher boost and on the spec sheet I got from snap-on says its way to big and should be around .350-.400mm with wear limit max of .30 I know those are two different types of measurments but it's what it says on the sheet and I don't know how to convert it. thank you

 

[Cdc1221]

If what you typed is correct, that's only .002" taper. Did you mic the center of the cylinder? Also, yes I believe that's too much ring gap. I gapped mine at .022 top ring and .020 bottom ring I THINK. Its been a few months since I built it.

 

[BogusSVO]

85mm x .03937 = 3.346 STD bore of the block

3.346 - .003 = 3.343 This is what the piston should mic =/- .0005

Giving appox .0035 PTW clearance

Now at the top of the block you have 3.351 - 3.343 = .008 PTW
bottom you measured 3.349 - 3.343 = .006 PTW

Yes you are loose, good chance of a bit of rattle on cold starts with that much PTW

Yes your ring gap is a bit out of whack too, .030 is too much for a cast piston set up (This is coming from a builder of loose engines) Most common I have seen on the fourms is .024 and .020 2nd ring

If you look at most ring manufactures of rings for forged pistons, the tech sheet gives a factor of
.0055 x 3.346 = .0184 for the top

.0035 x 3.346 = .0117 (.012)


So just from the math, I would suggest you bore the block to .020/.50mm

Get new rings and pistons

Weight match the rods, and the pistons.

Why are you going to spend $250-$300 on ebay 20g that has shown to fail time and time again, when there is a Supporting Vendor that will sell you a MHI 20g for $539 (IIRC)?

 

[Cdc1221]

Good eye dale. I forgot about the std piston size

 

[BogusSVO]

I have run the math for this set up once or twice....

But i would like to know what the mid stroke measurement is too. A barrel shape bore would not be out the question.

 

[1995gstproblems]

Why would it rattle, the block was perfectly fine until I crankwalked so im just wondering how it would do it when it hadn't happened before? and would it be safe to run it without a bore and expect to get some good miles out of the engine? Moneys tight and I'm only 17. I don't have much wiggle room on anything. Would I get bad blow by with the .30 gap on the top rings, only cyl 1 is .30 the rest are .27. I havnt touched the bottom or middle rings yet.

 

[BogusSVO]

The math is laid out for you.

I said you may have rattle, you may have had it before and just did not know.

Also pick a measuring system, either imperial or metric.

.30 ring gap, yes you will have horrid blow by.

.030 ring gap, that is still way loose, and yes you will have blow by, but not as bad as .30

It will run as well as you build it.

It will last as well as it built.

No, the block was not perfectly fine, if it was you would not have the taper you have now. That's from wear.

Have you even honed the block?

Or are you just putting rings in?

 

[1995gstproblems]

I've honed it from a 3 blade one at autozone, nothing fancy but it got the job done. I saved my old top rings that are all within .02 of spec so ill use those. Would it be bad if I used the old top rings and new 2nd n 3nrd rings?
Also how long would you expect the engine to last, miles wise with just a hone?
Could it be catastrophic or minor?
I'll be starting a build thread soon so you can have a better look with over 1000 photos just an intimidating job to do with so much info
I've been real deep into dsm's and know that these engines are very sensitive and one little wrong thing can throw them off. Tuners are so difficult to deal with when you 17 and it's your first engine rebuild I'm sorry for all the questions but I have a lot seeing as it's my first thread

 

[BogusSVO]

oh geez... an used autozone loner hone.

Stop, just stop.

First thing is those 3 stone hones have the wrong grit stone on them for your build.

They come with what they call a medium grit, I would guess around a 220-280 grit

That is fine if you are building a domestic NA engine with steel rings.

For the thin moly rings that a 4g63 runs, you need to run a fine to extra fine grit, 400 or so

This way you will not chew the moly facing of the ring.

Next, you want to mix and match old used rings with your new rings.

Not the best idea but it has been done before, sometime it works, other times it doesn't.

A new set of rings for stock pistons are about $40-60

As far as how long the engine last, there is no answer for that.

It could run 100k miles just fine, or it could fail on start up.

It could make good compression or it could have horrid blow by

The closer you build it to right, the better your chances are of it being right.

I have seen 100k + junk yard engines run a full race season and win races, I have also seen $50k new engines blow up on the dyno stand.

Personally, I will tell you to put down the tools, and do much more reading so you have a better understanding of what you are trying to do.

Click the link in my sig line, read all of them you will have a better understanding of machine work and engine components.

Then search the fourms and build threads.

 

[1995gstproblems]

I have read over 30 build threads front to back in just this month I've been doing as much research as i can with parts coming in now, It's actually becoming a reality . For some reason it showed I had taper, worse on the top. Today I checked piston to wall clearance and im at .003 which spec max is .004 so my shop guy said it might be fine, also he honed it out with his very nice fine grit one and the cylinder walls look a lot better, I was wondering why it looked so jagged when I did it with the autzone one :bump head: real dumb of me to do so, it was while the engine was still in the car and I was just getting into the build, ive done a lot of research and am going to get new top rings, I have new bottom and 2nd rings so those should be fine. The out of roundness is all within .001 which is spec friendly I thought I had a way bigger problem and was losing sleep over it lastnight. This way I at least no it's within spec even though it has some taper. I'm going to change the plans and have it 250-300hp max until I get enough cash to do a forged build.
I just got my crankshaft today and my rods with arp's are coming in anyday now. hopefully today, this thing should be up and running by winter which falls right on my dead line.
My balance shaft elim kit is coming on the 24th as well
A lot of engine work is hands on stuff so my apologize for sounding stupid
I have a shop to use free of charge anytime so if theres any other little mods I should do before I put it together please let me know.
Oh yeah I also checked the deck surface today and it has zero warpage.
I'm hoping the engine will last me 3-4 years (20k miles) until I can gather enough money for parts.
The hard part will be keeping the engine under 300hp.. So much potential in these monsters

 

[BogusSVO]

I have my doubts on what you are saying about deck warp on the block deck. I have milled a fair number of them and all have been whacked in some way.

I have posted a few pics in other threads on what I have found on block deck surfaces.

Hope you pulled the balls out of the crank too, that way it will be clean.

How did you drop from .008 to .003 on PTW?

Hope the rods were risized ones the ARP rod bolts were installed.

What BSE kit did you order?

Also let me know where you can buy single rings, every time I have needed to do that, the cost was more than a set of rings. Unless you found a set that was opened to steal a ring from.

 

[My1GLaser]

I would listen to Bogus!

Here is my .02...

As long as its not your DD and you don't throw a lot of money into it the first time, then the worst that can happen is some experience. Life lessons cost money more times than not! Just keep the investment to a minimum so it doesn't hurt your wallet so much.

I am not saying that you will fail and your motor won't last! However, building a motor is an art. There is so much that goes into doing one right. I have 20k miles on the first motor I built myself. I took my time and there were delays just like you are having. Mine was tapered .004" I think. (It was 5 years ago) I was just going to rering it until I measured and found the taper. I ended up boring .020" over and building a forged motor. I can't even remember all the delays I had, but it probably added up to at least a month or two of setbacks. I was patient and didn't rush through it.

You are 17 and that is hard to do! If you don't build a motor properly, then you are going to pay for it. It is gonna cost you time or money. (sometimes both!) You don't sound like you have the money to throw at it, so take your time.

Get a FSM!!!!!!! Read on this forum til your brain hurts. Measure everything at least 3 times! Keep the motor so clean that you could eat off of it! Good luck!

 

[LandSpeed-DSM]

Hope you pulled the balls out of the crank too, that way it will be clean.

You must be logged in to view this image or video.

Directions unclear, machinist is in fetal position.

 

[Colt4G63 also]

What BSE kit did you order?

Fixed!

If you don't get the Mitsubishi stub shaft your engine will be trashed in a week anyway.

 

[BogusSVO]

You must be logged in to view this image or video.

Directions unclear, machinist is in fetal position.

Page 2 post 39
http://www.dsmtuners.com/forums/newbie-forum/453196-question-bogussvo-2.html

The pics should help!

Landspeed... Better now?

Fixed!

If you don't get the Mitsubishi stub shaft your engine will be trashed in a week anyway.

http://www.dsmtuners.com/forums/newbie-forum/468879-bse-look-stubby-shafts.html

Colt, this should help....

 

[chaclark83]

Hey bogus Im not saying you are wrong I'm just curious. I've always believed and was taught not to run a larger end gap on the top ring than the 2nd ring because it causes the gasses/pressure to get trapped between rings and can cause ring landing failure.

 

[BogusSVO]

One way is old school, the other is new school.

The tighter top ring started about 15 years ago. It works great for a NA build.

With a turbo/ forced inducted build a looser top ring is better.

More heat is focused in the crown of the piston, therefore transferred to the top ring, and that expands more.

If you look at the ring gap factors from Manley, Wiseco and Total seal rings. The top ring has the larger factor than the 2nd ring

Bore x .0055 for the top
Bore x .0035 for the 2nd

Now Total seal does offer ring sets with a gapless top or a gapless 2nd

 

[1995gstproblems]

the micr. were not calibrated.. It's fixed now and it turns out I have barely any taper, the out of roundness is within .001! The ptw clearance is .004 after a third check and i couldn't be happier! My dsm graveyard 7 bolt arp rods just came in today and the crank came in yesterday with bearings. My other friend who did a couple rebuilds handed down his left over unused rings and i gapped them all to .21 the second rings at .18 so we're all good! The head has some warpage but is perfectly within spec as well. i got new lifters and oil seals and the head is all put together the only thing im waiting on is my oil pump castle plug and my bsdk i got off ebay with the stubby shaft! Then i can start putting it back together, This is a low low budget build but i have all the tools to measure at least twice so im being very precise with everything. I just posted an into to the build with some info about it and am trying to get the pictures all sorted out so you guys can have a better look at it.
My plans have gone back to 300hp+ i just hope the 550cc's are enough with a good tune.
And i'm looking into the turbo you mentioned for 400, I will also be getting some 3 inch piping all the way through straight piped with stainless steel

Oh, and the crank is a reman from the dealership so it came completely cleaned and is ready to drop in.

 

[BogusSVO]

New rods or not, go have the big ends checked for round.

Did you read the BSE link I posted?

 

[Diamond Star Werks]

People still buy from the graveyard? SMH.

 

[1995gstproblems]

I havnt had time to when I get off of work I will though and thay is a mistake I will never do again. One of the worst customer service places ever. They took over a month amd a half to arrive and thay was with me calling amd pestering them everyday for about 2 weeks. So damn unprofessional and ill go get them check as I can't trust there work from what I've seen from them

Fits 4g63 4G63T 4g64 G64B G63B G62B G4JS G4CP G4CS Balance Shaft Elimination Kit | eBay
This is the bse kit I ordered, should be here on the 24th.
With this I can finally put the whole longblock together, now I'll have room in my garage without engine pieces everywhere. hopefully ill reach starting the car in a couple weeks, my deadline is winter tho if anything goes wrong, knock on would.. DSM FOR LIFE