I am rebuilding my new-to-me Sami and opted for the flat top pistons in .5mm oversize.

Everything was fine until when I installed the pistons after getting everything back from the machine shop realized that they are .038" higher (measured from the wrist pins) than the stock pistons.

This puts them 38 thousands above the block deck at TDC (the stock pistons were flush at TDC).

That worries me about possible interference when the engine is hot, or at high RPM.

The head gasket is .074" thick before torquing it down, and I am guessing it compresses somewhere between 0.010"-0.015" when torqued. This would only leave about 0.022" between the pistons and the combustion chambers at TDC.

Anyone use these pistons and have interference problems?

I found a place that sells copper shims to be used w/ a head gasket ($115) to give more clearance, but this will drop the CR somewhat, which defeats the HC of the flat tops. Someone else said he runs two stacked OEM head gaskets w/o problems.

??

I just want a reliable motor that makes a few more HP than the stock edition.

Bob

Suzuki has two different but very similar engines that can be used in a Sami - one is known as the G13A and is an 8v 1324 cc engine - the other may be called G13B or G13BA and is an 8v 1298cc engine - which do you have?  You can find this information on the end of the block closest the flywheel - should be a raised casting saying either G13A or G13B

Both engines use the same pistons and many other parts interchange - the difference in capacity comes from a longer stroke crank in the G13A engines, I'm not certain but I believe the block is taller and the rods may also be different.

More to the point - I just did pretty much what you're doing now - a 0.5mm overbore and flat topped pistons - on a G13B and had no issues with the pistons standing proud of the block - my engine is in a Suzuki Swift, but I have a friend who did pretty much the same thing except he went 1.0 mm over and his engine is in a Sami.

We both have over 2000 miles since the rebuilds with no problems.

Where did you get your pistons from?

My engine is the carbed 13A.

Maybe my pistons in a 13B would not stick up out of the block.

I got my rebuild kit and new pistons from Mizumo Motors

Overhaul Kit
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=220445214210&ssPageName=ADME:X:AAQ:MOTORS:1123

Flat top Pistons:
http://cgi.ebay.com/ebaymotors/86-95-1-3-Liter-Suzuki-Samurai-Flat-Top-Pistons-Rings-_W0QQcmdZViewItemQQhashZitem3ca3ab126cQQitemZ260443935340QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories#ht_3621wt_834

I started the engine today, and the valves seem noisy (I was warned to expect this), and I was hearing the pistons hitting the head or valves themselves, the (experienced) folks who listened said they were valve noises.

Thing idles and  runs smoothly, and has more zip than before, which is to say it's not as dangerous as stock (like on freeway entrance ramps).

Bob

Whoever warned you to expect noisy valves is probably not familiar with these engines - they do not use hydraulic lifters and require the valve clearances to be manually adjusted - once those adjustments were properly done prior to startup, there is no reason to expect any unusual noise from the valve train.

Suzuki does have engines with self adjusting hydraulic lifters than can be quite noisy on the first start after a rebuild, until the lifters "pump up" and self adjust, but not the 1.3 8V engines.

Are you sure the pistons sent are the right part #? and also did the machine shop
give you back the right crank and rods? I think there could be a mix up there

Wild

RE: Mechanical lifters-
Yep, I know they are mechanical solid lifters, and we set the intakes to 0.013" and the exhaust to 0.016" prior to replacing the valve cover.
They can be heard more when the engine is warm than when started cold, but they are not silent when warm by any stretch of the imagination w/ the hood open. I would not call them "loud," but they are noticible.
As far as the pistons, they had the right part # on the boxes compared to the ad I linked to above, and the diameter was correct.
We never had the crank out of our hands, and I do believe the shop didn't do a switcheroo on the rods.
We determined that the new pistons WERE 38 thousandths taller by pushing the wrist pins as far out of the new pistons as possible, and into the holes in the old pistons. When we did this, we could see that the new ones stuck past the old ones by enough to account for the 38 thousandths all by themselves.
I've rebuilt around 10 engines myself (this time around I had two experts with probably 100 engines under their belts), and we were all perplexed by the pistons being above the block.
The machine shop that did the work builds extreme performance engines as well as plain vanilla ones, and said they routinely set up engines with protruding pistons, but never with less than 0.025" of clearance between the piston top and the bottom of the head (0.035" if the rev limit is between 6000 and 8000rpm), and thought we should be fine, but it still makes me nervous.

Bob

The stock pistons in a 1.6 set down about 10 thou below the block
deck height, I used some forged SRP pistons in the turbo engine and
they had a higher deck height than the stock ones, so I had them milled
down to flush, I should of payed more attention to the specs on the new
pistons, they were for a Honda engine, but I didn't pay close enough attention
to the dish and more to the CR which is about stock instead of 8.5:1

Wild

RE: Mechanical lifters-
Yep, I know they are mechanical solid lifters, and we set the intakes to 0.013" and the exhaust to 0.016" prior to replacing the valve cover.
They can be heard more when the engine is warm than when started cold, but they are not silent when warm by any stretch of the imagination w/ the hood open. I would not call them "loud," but they are noticible.

That's way too loose. Factory settings are 0.006 and 0.007 cold. I've set like you've done before and it rattled like a diesel!

-Eric

Quote from: bobinyelm on July 13, 2010, 11:08:04 PM

RE: Mechanical lifters-
Yep, I know they are mechanical solid lifters, and we set the intakes to 0.013" and the exhaust to 0.016" prior to replacing the valve cover.
They can be heard more when the engine is warm than when started cold, but they are not silent when warm by any stretch of the imagination w/ the hood open. I would not call them "loud," but they are noticible.

That's way too loose. Factory settings are 0.006 and 0.007 cold. I've set like you've done before and it rattled like a diesel!

-Eric

I agree.  Set the valve clearances correctly and it will quiet down the valves greatly.

Ah HA!!!

I looked again at the specs in the workshop manual, and the 13-16 settings were actually 0.13 and 0.16 (not 0.013 and 0.016) alright, but in mm, and NOT in inches.

The decal posted is not present on my car.

The 0.006 and 0.007 in settings will no doubt quiet the engine (hot) down considerably!

Thanks for catching our mistake.

Bob

Happy New Year!

FINALLLY!! I found a reference to the same problem i am having.
I also bought the Muzumoauto with the $50 flat top upgrade.

So my 88 sam G13a has the flatops running approx 0.050" over the deck height!!!. The deck was shaved 0.007" cause a sleeve was sinking but i just can't see this working out too well without further action. It sounds like from your string that you ran with the 0.038" piston - over - deck height, is this correct? How is she running now? 

I am not sure what to do. I can't afford to machine the pistons and don't feel I should have too
1. Is there a known correct flat top available?
2. Would I be better off getting the stock dish?
3. If i fly cut the pistons flush will I have too much compression and have to run JET FUEL?? ;p}

Sorry for the lengthy post, I'm freaked out and need to get this assembled by Monday (It could happen). I sure feel better finding this though, i never heard of this issue and thought i was crazy :/ 

L:JW
-lowmass -

I'm pretty sure that the flat top pistons are taller, the ACL catalogue gives different dimensions for the flat top and dished pistons. I would need to look upthe exact details on my PC, I'm on the laptop now.

My pistons came from Low Range Off Road, and going from memory, I'd say the only difference (other than the diameter of course) is that they didn't have the dished top - I don't think they were any taller.

That engine's been back together maybe 8~9 months, used every day, and the only problem we've had since the rebuild was a leaking seal inside the distributor.