Not sure if this has been covered, but while looking for Type IV hot rod parts, I've seen the options for using stock, Type I or Chevy rod journals?

Is it a matter of cost for using Type I or more options?

Same for Chevy?

This is a little sideways answer. On the 6 cylinder engines there has been an ongoing concern over the quality of the bearing material. Some of it is prematurely wearing out. When I built my 6 engine we installed “Chevy” bearings as they don’t have the quality issues and I did not want to tear the engine down to replace bearing because the material south.

And the selection of rods is much greater (and price lower) when you make the switch.

Great question regarding the use of Chevy bearings. So for someone like myself that don't know any, whats involved with the crank new rods and cut the crank bear larger or?

Main or rod bearings?

It's mostly to get a lighter rod, but also for a choice of rod lengths. The stock T4 rods were made for trucks and weigh a ton, so are hard to spin to high RPM's. You can weld and offset grind a 66mm crank for T1 rod sizes and get a 78.4mm stroke, giving you 2270cc's with 96mm cylinders along with a much lighter rotating assembly. CB T1 H-beam rods are good, cheap and in whatever length you want. Even their forged aftermarket T1 I-beam rods are good, strong enough, and even cheaper. Or Chevy if you prefer.

Rod bearing have been the main issue,the white metal appears to delaminate of the non-ferous backing,Glyco ones appear to be most effected,these have been used in T4 motors but you don't seem to see them as much now.
The word is that prices for NOS shells has gone up price due to the fact the older stuff wasn't giving issues.
One of top 911 engine builders on Pelican won't fit Glyco's anymore and use's USA made ones,can't remember the brand offhand.

Sorry for the ignorance, what Chevy rods are folks referring to. Are the rod journal diameters identical to Type IV or is an undersize grind used ??

With the sixes, it is all the rod bearings that cause concern. If you think about it, the mains have it much easier than the rods that are slamming at TDC. Mains are happily running with plenty of oil and lower forces at play.

They are used for larger than stock stoked cranks, such as the most common 78mm and 80mm stroked cranks.

Type 1 journal makes a stronger rod journal due to the larger journal size, but at the same time the rod is also narrower, helping clear the one T4 cam lobe.
It also has a large section of readily available, relatively cheap rods.
Because of the larger T1 journal base circle, this makes the strongest stroker crank/rod combo.

Chevy rod journal is actually a misnomer as it is really a buick rod journal.
After 78.8mm you can no longer clear the one T4 cam lobe with a T1 journal, so the the chevy rod journal is used because of the smaller base circle.
Again there is a fair number of rod sizes and they are inexpensive.

With both T1 and chevy rod journals you still must use a cam with a reduced base circle.

It's lower cost, and more options that drive it.
As Mark said, when you go full stroker, you cannot even find the parts, or make them fit...so you start in another direction.

We had (still have) one motor that used rabbit rods.
Smaller diameter big end, fit in the case and cleared the camshaft.....with some grinding..

Rabbit rods are nothing new, the type 1 crowd tried this back in the day as a case clearance free stroke crank/rod option.
Problem is the journal is too small weakening the crank, the VW crank with only 3 big journals makes it prone to flexing at higher RPMs.
Rabbit rods were abandoned, in early 80's by the type 1 crowd, because of a high failure rate.

Bearing quality, and big end rod to cam clearance are the biggest contributors.

The strongest cranks have 2.165" T1 journals, but these have the least clearance to the cam lobes. The best quality rod bearings are found in the H series for the 2" Chevy.

The 2.0 T4 journal has the best clearance, but no try- metal bearings are available for them.

The 2" chevy is the most versatile all around, and has the best overall qualities or anything thats off the shelf.

Today we have gone to Honda journals on most builds, despite it being the most expensive route possible.

All I have currently are 1.7 motors, if I decide to stick with the shorter stroke setup, am I going to run into the same problem with my crank and rods? (no good bearing choice)

Do you even bother with the smaller stroke motors based on the 1.7/1.8 crank and rod?

And if so, I know people build 1911(s?) using the 1.7/1.8 crank and rods, how about a larger diameter piston/cylinder setup?

Honda Journals?

How do you make it work with the TIV?

1.7/ 1.8 and Type 1 VW are all 2.165" journals, the difference is the bearing/ journal width. The TIV is wider.

I only used the stock 1.7/ 1.8 journals when building class limited race engines, mostly for SCCA.

Honda journals are made to work with an open checkbook, a billet crank and billet rods, where strokes over 84mm are a reality.

And basically IMHO at the price point where in a 914 you may as well build a /6.

BTDT.

I don't disagree, but for most of the applications that these engines go into, a six is not an option.

So question:

If the 2.0L crank is made by just turning a 1.7/1.8L crank journal down to 50mm while offsetting the center correctly, Why cant I send a slightly damaged 1.8L crank to a crank turner and have them turn it down to a 2.0L crank?

If that were the case it would seem that "stock forged" cranks should be more plentiful for 2.0L than for 1.7/1.8.

And where is the best place to find stock crank bearings and undersized rod bearings these days?

You certainly can. Just make sure you can get the metal treatment correct. I don't know what the hardness specs/heat treat/surface treatment are on the rod journals, but I'm pretty sure they're kind of important.

Oh, and you might have to muck around with the oil passages as well.

--DD

Here, these are the options, with pricing: http://dprmachine.com/products/crankshafts-type-iv/

They're welded up and then re-machined and ground. Good work, recommended.

So what if:
1 - I am limited to stock 2.0L engine for vintage racing.

2 - I want a lighter rotating mass for lower reciprocating forces at higher RPM

Would there be an advantage to taking a 1.7/1.8L crank and having it turned down to 71mm stroke but 2.0" journals so that I can use the chevy rods?

Can the crank be JUST turned down for this, or would I have to have it built up via welding first?

Can I get the chevy rods in the correct length to keep my displacement stock while finding lighter parts than the stock conn-rods? (if the rods are too long, I just need to shim the jugs?)

Don't know the rules but can you use a 1.7/1.8 66mm crank and bigger pistons?
You can get a crank offset ground and use OS bearings. I know that's only .030-.040 but every cc counts.

The issue with going to a smaller journal (add high RPM) is you will have more crank flex. The VW configuration of two opposing rod journals in between the main bearings is it's prone to flexing. That's why VW cranks were all forged, VW would have loved to been able to use a cast crank, way cheaper to make. Yes they did try and IIRC the mexican beetle did have cast (new casting technology) but they were still marginal for anything other than stock 1600cc engines.
Personally I would have the crank welded and use the CB type one rod over a smaller journal.

I am currently running a stock 2.0L crank now (50mm), so using the 2.0" chevy journals would be larger than I have now by .8mm.

And if the chevy rods are lighter, then that reduces the forces on the crank.

So if I am doing my math right:
1.7L crank has 66mm stroke and 55mm journals.
2.0L crank has 71mm stroke and 50mm journals

If you cut the 55mm journal down by 5mm towards the out side only, then the stroke is 71mm and the 2.0L rods fit

If you cut the 55mm journal down by 4.2mm towards the out side only, then the stroke is 70.2 mm and the Chevy rods fit.

So if you want 2" journal rods and a 71mm stroke, you have to weld some on the crank before turning.

Widely available bearing will work. Don't get mired down in perfection that's unattainable. Obviously there are better and worse bearings. But if you don't want to build a $12,000 engine, accept that the stock bearings are available and will give a sufficient service life for a street driven car.

A small investment can get you a good used 2.0 crank and rods. So it's hard to justify a 66mm stroke crank. But like all engine design, it depends on what you want out of the engine and what your budget is. Generally, spend all your money on heads, and then use what's left on the other parts. Also keep in mind the Cascade Effect®. When one part 'grows', getting bigger and better, the other parts must grow with it.

Keep in mind the Cascade Effect®. If you go over 96mm bore, you really need to take a good look at your head choice. Combustion chamber shape, spark plug location, valve size, port size, etc.

Chevy or T1 aftermarket rods no difference in weight, in fact the T1 rods may be lighter. I prefer the CB T1 rod over the Scat (chevy).

Like I said, I'd personally go with the combo that give less flex in your app.