AznDrgn

Pending some body repairs on my newly acquired '83 944NA I'm going to rebuild the engine and I had a few questions about cross drilling the crank. I know it isn't really neccessary thing to do but this car is going to be a daily driver until I find another car and then it will become a track car.

-When you cross drill the rod journals do you drill cross drill all 4 or just the #2 journal?
-Cross drilling vs Perpendicular drilling anyone know if one is better than the other?
-Roughly what does it cost to get this done?
-Who does it? I know Huntley Racing used to do it but they are out of business now so I need another option. I'm sure any machine shop can do it but I don't really want to hand my crank over to someone who is not experienced with the 944 or at least porsche's in general.
-Lastly can anyone reccomend some good machine shops in the Northern Virginia/ southern Maryland area? The only one I know of is Intersport and I didn't really have a great experience with them the last time I used them and would rather not repeat such an unpleasant experience.

Thanks in advance

hosrom_951

-When you cross drill the rod journals do you drill cross drill all 4 or just the #2 journal?

All 4

-Cross drilling vs Perpendicular drilling anyone know if one is better than the other?

Do a search on this, i believe that Perpendicular was a better method

-Roughly what does it cost to get this done?
-Who does it? I know Huntley Racing used to do it but they are out of business now so I need another option. I'm sure any machine shop can do it but I don't really want to hand my crank over to someone who is not experienced with the 944 or at least porsche's in general

A proper shop (Lindsey racing) does this for ~$150+ depending on what else is needed and options you choose.

BoostGuy951

Why not? A crank is a crank. Knowledge of the 944 is not going to make a difference in the drilling and chamfering of the hole. Do you know what Lindsey does with the crank? They take it to an everyday Oklahoma machine shop.

Danno

I know of two local shops in my area that can do the crank-drilling work for less than $100. That also includes polishing all the journals too.

AznDrgn

So it looks like any old machine shop should be able to drill my crank for me and I should be expecting to pay around $100-$200 for it to get done. I did a search on perpendicular drilling and the only thing I came up with was the article from Huntley Racing saying that it was better. Can anyone who has drilled their crank either cross or perpendicular chime in with their opinion? My next question is how big should the newly drilled hole be? I did a search and it seems some people think that the area of the two holes should not exceed the area of the original hole where as others don't think it matters. Anyone have any opinions as to which way to go? Just to be sure that I've got things right when you perpendicular drill the crank when the piston is at TDC the new hole is facing up and when your at BDC the hole is at the bottom right?



I just got the brake booster and clutch master out of the car so I can now see the part of the rotten firewall and so far it doesn't look as bad as I thought it would. I will be cutting a section of the firewall out of my parts car and welding it in place and then add supporting braces to the back side. Hopefully I can have the motor rebuilt and the body ready to go for some early spring drives.

Zero10

Hmm, is the original hole welded closed or something when it is perp/cross drilled? Otherwise you will always increase the area of the holes...

AznDrgn

As I understand it the holes are left open to increase oil flow to help keep the bearings lubricated and cool so they don't spin. Only thing I don't get is that if you increase area you lose pressure which is bad in the long run as well. Has anyone done any sort of research into how much volume and pressure our oil pumps are capable of and what the release pressure of the OPRV is?

jharding

Your crank may already be cross drilled. My 83 944 (mfrd 7/83) had a cross-drilled crank and forged rods. That engine was definitely stock and never rebuilt before I got my hands on it.

AznDrgn

jharding to my knowledge no production 944's destined for the regulart market had cross-drilled cranks. The forged rods were standard for the early 944's. It would be really sweet if my motor did have a drilled crank but I kind of doubt it since if it was a factory thing the '83 cranks would be quite popular and I'm sure some of the members here who moonlight in parting out 944's would know about it. Are you sure there is no chance of someone pulling the crank on your motor to drill it in the past?

jharding

I bought my car with approx. 110,000 miles on it. The car came with a stack of receipts from three previous owners (including the original window sticker!). Other than belts, rollers, waterpump, and a few sensors, there was no mention of motor work in any of the receipts. When my friend and I tore it down it had no evidence of previous work. The headgasket looked original and was paper thin in a couple of spots. The rod bearings had a good amount of wear on them, and there was a lot of crud around the oil pump. We were originally going to pull the engine to reseal it. It had so many oil leaks it looked like a Harley! While the engine was out we decided to check the headgasket, and then it led to an entire rebuild. My friend has a very early 83 944 (mfd 2/82) that had a cross drilled crank in the original engine.

So did Porsche design those cranks originally, decided it wasn't worth the extra cost, and just used up the inventory? I don't know, but at least two early cars I've seen have them.

BC

Danno - can you tell us where these machine shops are and what thier names are?

hosrom_951

Maybe it is because where i live, but when i asked my specialist regarding cross-drilling/lighting/Knife edging the crank, he said that a specialist should do the work, not just a good machine shop.

If that is true, then it would be great if someone (Danno ) would show the correct prep-drilling/cross-drilling proceedures for the 944 crank for future reference.

Matt Sheppard

Last '83 engine I took apart had a cross-drilled crank as well. It's crank and rods are what I rebuilt my motor with. I thought when I discovered it that maybe he had the bottom end completely redone before I got it, but that was really not very likeky.

Ahh, the power of community. Thanks for the data point. Another reason to horde '83 engine cores.

AznDrgn

well it seems that we've all learned something today, early '83 cars came with cross drilled cranks and forged rods. Definately a big plus!!! I guess I'll have to tear mine down to find out what I've got.

Tom Carson

has anyone used an '83 crank in a late block? I thought post '83s were changed because of the extra crank pulley for the power steering. someone needs to confirm they are interchangeable. I didn't think they were…I really thought the post ’83 cranks were slightly longer