Engine Options?

[vwbill]

Hey Guys, I picked up a new set of 1.7L 021-101-371Q stock heads and a set of Kolbenschmit dished 1.7L pistons and cylinders and my question is:Can I use the new cylinders with the old domed pistons since if I use the dished pistons I go from 8.2 to 7.3 compression ratio and lose around 8HP or a passager in the car all the time! Is it a good idea if I use the old pistons to break down the motor again and send the parts to(I think he does this)Jake's to have the parts balanced prior to trying a rebuild?
Is it a good idea to do the short block rebuild yourself or is it better to have the short block done by a machine shop and assemble the top end myself with either all new or new jugs and old pistons. Also, if the heads are new and the cylinders are new do you need to lap the cylinders to the heads?? Thanks Bill

[raygreenwood]

You should do it all yourself. Just measure everything carefully.....have whatever machine work done that you need. Lightly hone the lifter bores but check them for excessive wear.

If the pistons still have life in them...go for it. Clean the ring grooves carefully, check for cracks. Measure the skirts for signs of collapse. It would be nice to know how many miles they had on them. I would say that 70+ K miles may be the limit...as they will eventually wear out from heat cycling. Check the piston to bore clearance. Ray

[DeathBus]

do the work yourself, if the case is screwed, you will be able to tell immediatly. Type 4 cases usually need no work done to them by a machine shop. Rebuild it yourself.

for referance buy

the book- HOW TO REBUILD VOLKSWAGEN AIRCOOLED ENGINES

the video - BUG ME VIDEO TYPE 4 ENGINE REBUILD

with those 2 you cant go wrong!

[vwbill]

Thanks for the vote of confidence guys! I'll get Jake's video first! Just to have a better basis for how to measure things and great techniques! So if the cylinder and head surfaces are new I shouldnt lap them? What about the balancing of the parts? It doesnt seem too much of a expense but I'm sure they are very busy guys and would take some time to get in the que! It's not gonna be a racer but more of a stock driver. Bill

[raygreenwood]

Cylinder and head should always be lapped together new or not. Balancing can be done by any competant shop....but some spend more time and are more complete than others. Check around. The more extensive the balance ...the better...and more expensive. They will need pistons, wristpins, rings, clips, crank, rods and flywheel to do a complete job. Ray

[DeathBus]

Cylinder and head should always be lapped together new or not. Balancing can be done by any competant shop....but some spend more time and are more complete than others. Check around. The more extensive the balance ...the better...and more expensive. They will need pistons, wristpins, rings, clips, crank, rods and flywheel to do a complete job. Ray

Ive had luck in both directions, when just replacing rods i usually dont get the whole assembly balanced. Make sure you mic EVERYTHING. If you just have to replace bearings, you dont really need a balance. If you replace pistons AND rods, I would say balance the assembly. I usually use a KNOWN GOOD WRIST PIN, check the bushings on the rods, if there is any wiggle, get some rebuilts.

[raygreenwood]

The problem I have found with pistons of late....is that the pistons , pins etc....are not tolerance grouped by any means....like they used to be. Also, if you have had your rods re-sized.....they are no longer balanced.

It may not seem to be much....but every little bit counts. Most good shops can balance down to a gram per rotating assembly (piston, rod, rings and crank throw) or less. They generally have issues getting balanced on the new piston sets. They need the pins and clips. Some times its as simple as swapping rode, pins and pistons all around. Sometimes it takes working the rods, trimming inside of a pin...or shaving the pistons. Ray

[DeathBus]

The problem I have found with pistons of late....is that the pistons , pins etc....are not tolerance grouped by any means....like they used to be. Also, if you have had your rods re-sized.....they are no longer balanced.

It may not seem to be much....but every little bit counts. Most good shops can balance down to a gram per rotating assembly (piston, rod, rings and crank throw) or less. They generally have issues getting balanced on the new piston sets. They need the pins and clips. Some times its as simple as swapping rode, pins and pistons all around. Sometimes it takes working the rods, trimming inside of a pin...or shaving the pistons. Ray

Have you been using MAHLE pistons? I understand they changed their production to China?

[raygreenwood]

Actually....my new engine will be using the 90.5 domes from Repco (new Zealand) with rebored stock cyls. They are relatively close copies of Mahles.
I have also been looking into....possibly the use of the Karlschmidts (possibly an odd spelling of Kolbenschmidt?) that are used in Saabs. Very very nice pistons. Most are dished, but are very thick so could be trimmed to flat tops. Ray

[vwbill]

So do the parts need to be tested in a dynamic way or just the weight of the objects to reach equal componants on each side of the crank?
Can you weigh the objects in a water displacement setup and try to match them by taking a little off? Do they mostly take weight off the pistons? Is there a problem with having equal weight in a axis off the center of the rods and pistons, so you need to balance the parts off a center line? What about the rings? I thought they were already matched?
Does the crack cause alot of flex with being out of true to a axis or is the big part the flywheel since it is so far out of the center turning point?
Why I'm asking is can you actually do the weighing/balancing yourself or is that really not something you should try? Can you assume(LOL) any parts are usable through caliber readings, i.e. the crank? Thanks Bill

[DeathBus]

So do the parts need to be tested in a dynamic way or just the weight of the objects to reach equal componants on each side of the crank?
Can you weigh the objects in a water displacement setup and try to match them by taking a little off? Do they mostly take weight off the pistons? Is there a problem with having equal weight in a axis off the center of the rods and pistons, so you need to balance the parts off a center line? What about the rings? I thought they were already matched?
Does the crack cause alot of flex with being out of true to a axis or is the big part the flywheel since it is so far out of the center turning point?
Why I'm asking is can you actually do the weighing/balancing yourself or is that really not something you should try? Can you assume(LOL) any parts are usable through caliber readings, i.e. the crank? Thanks Bill

In all respect to Ray, dude you dont have to go through all of this to build yourself a good running motor. Take the parts you have and build the engine. 99% of the time the engine will run like a watch. You are not building a high performance revver, you are building a STOCK type 4 engine. I have built several motors that were never "blueprinted" and they ran just fine.

[raygreenwood]

Deathbus...that is quite true. But its less than 99% of the time by far. This is getting more and more so.
Not long ago....early to mid 90's, good German and good Brazillian made pistons were available. The paint marlings for both diameter tolerance group and weight tolerance group actually meant something. If the numbers on your rod caps still matched and you just slapped these in....they generally made a good running engine.

As you machine cranks....they can get slightly out of balance....not generally something to worry about. But....the pistons as of late....esecially aftermarket pistons that were made to be dropped into reborred cylinders....have had NO tolerance grouping done whatsover.

Unless you have the parts balanced...you will have no idea exactly how far out they really are. You would be stunned!
The repco pistons...and the last set of oversized replacement Kolbenschmidts I used a few years back.....(meaning both came without cylinders)....were as much as 10 grams different from piston to piston. .
The rods....if they cam from the engine you have in all one set and had only been carefully rebuilt through the years...are probably within a few grams or so of each other. Thats just "ok"....tolerable. Add that to the variances I just listed on t he pistons.....and it can get ugly.

Does this mean that your engine will run with some kind of ugly rocking? No at all. But add to this....that almost any flywheel you get will not be balanced anymore....neither are a lot of the clutch PP's....carrying balance (heavy side) punch marks.

Where this is going...is that now...if you have an engine with uprated compression and output....extra thrust....extra load.....balance is more critical. It causes heat. You can run 10-30 degrees cooler on some engines just for balance.

But its not a huge deal to get done. Take all the junk to one shop. A good shop will either have, or set up bob weights for your crank with the flywheel attached. That way...its one less imbalance. Generally...its pretty quick just to set all of the rods very close to each other when re-sizing and surfacing the sides of the big end.

The pistons...generally one or two may need to have a little taken out of the back of a dome on the mill. But...when the pistons are heavy and the differences high....having the wrist pins along and the rins and clips can make the difference between balance...or not...simply by shuffleing them from piston to piston. This is because you can only take so much out of a piston or a rod safely. I had a set a while back...that for some reason, one piston had 15 grans difference. They could only take about 7 grams out of it. So...by swapping the wrist pins around....one was about 3.5 grams lighter. By trimming an end and shuffling clips they got it down to about .7 grams.

There is none of this you need to do..and its not a hassle...and its not expensive. Just take it to a shop and leave it. It can range from as low as $65 to about $175 dollars for excellent balance. And yes...the engine will run slightly smoother...run slightly cooler...and last longer. Ray

[MGVWfan]

It may be heresy, but I've used the scale at the post office to weigh parts and adjust accordingly (not VW engine parts, though). They're accurate to a tenth of an ounce or so, and are reasonably repeatable. It's better than nothing. Won't help balancing the flywheel/torque converter or crank, though.

[DeathBus]

Deathbus...that is quite true. But its less than 99% of the time by far. This is getting more and more so.
Not long ago....early to mid 90's, good German and good Brazillian made pistons were available. The paint marlings for both diameter tolerance group and weight tolerance group actually meant something. If the numbers on your rod caps still matched and you just slapped these in....they generally made a good running engine.

As you machine cranks....they can get slightly out of balance....not generally something to worry about. But....the pistons as of late....esecially aftermarket pistons that were made to be dropped into reborred cylinders....have had NO tolerance grouping done whatsover.

Unless you have the parts balanced...you will have no idea exactly how far out they really are. You would be stunned!
The repco pistons...and the last set of oversized replacement Kolbenschmidts I used a few years back.....(meaning both came without cylinders)....were as much as 10 grams different from piston to piston. .
The rods....if they cam from the engine you have in all one set and had only been carefully rebuilt through the years...are probably within a few grams or so of each other. Thats just "ok"....tolerable. Add that to the variances I just listed on t he pistons.....and it can get ugly.

Does this mean that your engine will run with some kind of ugly rocking? No at all. But add to this....that almost any flywheel you get will not be balanced anymore....neither are a lot of the clutch PP's....carrying balance (heavy side) punch marks.

Where this is going...is that now...if you have an engine with uprated compression and output....extra thrust....extra load.....balance is more critical. It causes heat. You can run 10-30 degrees cooler on some engines just for balance.

But its not a huge deal to get done. Take all the junk to one shop. A good shop will either have, or set up bob weights for your crank with the flywheel attached. That way...its one less imbalance. Generally...its pretty quick just to set all of the rods very close to each other when re-sizing and surfacing the sides of the big end.

The pistons...generally one or two may need to have a little taken out of the back of a dome on the mill. But...when the pistons are heavy and the differences high....having the wrist pins along and the rins and clips can make the difference between balance...or not...simply by shuffleing them from piston to piston. This is because you can only take so much out of a piston or a rod safely. I had a set a while back...that for some reason, one piston had 15 grans difference. They could only take about 7 grams out of it. So...by swapping the wrist pins around....one was about 3.5 grams lighter. By trimming an end and shuffling clips they got it down to about .7 grams.

There is none of this you need to do..and its not a hassle...and its not expensive. Just take it to a shop and leave it. It can range from as low as $65 to about $175 dollars for excellent balance. And yes...the engine will run slightly smoother...run slightly cooler...and last longer. Ray

I just got the Idea that Bill was making out to be a helluva lot more than it needs to be. I use a good digital scale to weigh my parts. I have found generally that the rebuilt rods I have been getting are within wieght tolerences, as are the same for the MAHLE piston and cylinder sets. I am fortunate to have had all standard measured cranks, so no machining there. I do think that getting the flywheel balanced is a good idea and something I will probably start doing.

[DeathBus]

Deathbus...that is quite true. But its less than 99% of the time by far. This is getting more and more so.
Not long ago....early to mid 90's, good German and good Brazillian made pistons were available. The paint marlings for both diameter tolerance group and weight tolerance group actually meant something. If the numbers on your rod caps still matched and you just slapped these in....they generally made a good running engine.

As you machine cranks....they can get slightly out of balance....not generally something to worry about. But....the pistons as of late....esecially aftermarket pistons that were made to be dropped into reborred cylinders....have had NO tolerance grouping done whatsover.

Unless you have the parts balanced...you will have no idea exactly how far out they really are. You would be stunned!
The repco pistons...and the last set of oversized replacement Kolbenschmidts I used a few years back.....(meaning both came without cylinders)....were as much as 10 grams different from piston to piston. .
The rods....if they cam from the engine you have in all one set and had only been carefully rebuilt through the years...are probably within a few grams or so of each other. Thats just "ok"....tolerable. Add that to the variances I just listed on t he pistons.....and it can get ugly.

Does this mean that your engine will run with some kind of ugly rocking? No at all. But add to this....that almost any flywheel you get will not be balanced anymore....neither are a lot of the clutch PP's....carrying balance (heavy side) punch marks.

Where this is going...is that now...if you have an engine with uprated compression and output....extra thrust....extra load.....balance is more critical. It causes heat. You can run 10-30 degrees cooler on some engines just for balance.

But its not a huge deal to get done. Take all the junk to one shop. A good shop will either have, or set up bob weights for your crank with the flywheel attached. That way...its one less imbalance. Generally...its pretty quick just to set all of the rods very close to each other when re-sizing and surfacing the sides of the big end.

The pistons...generally one or two may need to have a little taken out of the back of a dome on the mill. But...when the pistons are heavy and the differences high....having the wrist pins along and the rins and clips can make the difference between balance...or not...simply by shuffleing them from piston to piston. This is because you can only take so much out of a piston or a rod safely. I had a set a while back...that for some reason, one piston had 15 grans difference. They could only take about 7 grams out of it. So...by swapping the wrist pins around....one was about 3.5 grams lighter. By trimming an end and shuffling clips they got it down to about .7 grams.

There is none of this you need to do..and its not a hassle...and its not expensive. Just take it to a shop and leave it. It can range from as low as $65 to about $175 dollars for excellent balance. And yes...the engine will run slightly smoother...run slightly cooler...and last longer. Ray

I just got the Idea that Bill was making out to be a helluva lot more than it needs to be. I use a good digital scale to weigh my parts. I have found generally that the rebuilt rods I have been getting are within wieght tolerences, as are the same for the MAHLE piston and cylinder sets. I am fortunate to have had all standard measured cranks, so no machining there. I do think that getting the flywheel balanced is a good idea and something I will probably start doing.

Bill email Steve at Serrano Auto Parts in Torrence California

gscco@msn.com

he can get you anything you want. Rebuilt rods, pistons and cylinders, bearings for a GREAT PRICE and its good quality stuff. He might even be able to sell you a reground Type 4 flywheel.