Posted By: Hot 340
Siamese Bore R3's for Street Use - 08/14/09 07:52 PM
Do you guys drill them between the bores for better cooling or no?
Siamese Bore R3's for Street Use
Posted By: HerboldRacing
Re: Siamese Bore R3's for Street Use - 08/14/09 08:24 PM
The whole point of a siamese bore block is to allow you to have bigger bores due to lack of water jacket between cylinders. These are really expensive blocks... and the thought of drilling out water passages between bores make me want to cry.
Give the block to me!
Give the block to me!
Posted By: B3422W5
Re: Siamese Bore R3's for Street Use - 08/14/09 08:41 PM
I am pretty sure Chevy 400's were siamese bore, and they have logged hundreds of thousands of street miles 
Posted By: Hot 340
Re: Siamese Bore R3's for Street Use - 08/14/09 08:47 PM
Quote:Thanks Don, just read some stuff in Jim Szilagyi's book that said it should be done, but some of his other info made me question his techniques...a little outdated maybe.
I am pretty sure Chevy 400's were siamese bore, and they have logged hundreds of thousands of street miles
Posted By: Leon441
Re: Siamese Bore R3's for Street Use - 08/14/09 09:11 PM
Some blocks have been drilled between cylinders. You drill at an angle back to the water jacket. If you look a lot of the circle track heads had water passages drilled between cylinders. Most head gaskets have two small holes between cylinders this is where the hole starts and is angled about 45 degree towards the water jacket.
Simply because you are asking I would say do not do this. This mod is for someone who is fully aware of the problems they may cause and what bore they can get away with after doing this.
Leon
Simply because you are asking I would say do not do this. This mod is for someone who is fully aware of the problems they may cause and what bore they can get away with after doing this.
Leon
Posted By: dizuster
Re: Siamese Bore R3's for Street Use - 08/14/09 09:50 PM
Quote:
Simply because you are asking I would say do not do this. This mod is for someone who is fully aware of the problems they may cause and what bore they can get away with after doing this.
Leon
Maybe you could enlighten us all...?
As I understand it, the holes are not there to flow water> They are mainly just steam escape holes. The holes can be very small, and should not effect strength much at all. All low deck R3's I've seen already have this done. The only one's I've seen that don't have the steam holes are tall decks...
Mopar doesn't put any further bore limitations on a tall deck then they do a short deck?
Posted By: cbarracuda
Re: Siamese Bore R3's for Street Use - 08/14/09 11:35 PM
All chevys have steam holes in the 400 block
Posted By: DemonDust
Re: Siamese Bore R3's for Street Use - 08/15/09 02:11 PM
Quote:Quote:
Simply because you are asking I would say do not do this. This mod is for someone who is fully aware of the problems they may cause and what bore they can get away with after doing this.
Leon
Maybe you could enlighten us all...?
As I understand it, the holes are not there to flow water> They are mainly just steam escape holes. The holes can be very small, and should not effect strength much at all. All low deck R3's I've seen already have this done. The only one's I've seen that don't have the steam holes are tall decks...
Mopar doesn't put any further bore limitations on a tall deck then they do a short deck?
The reason for the bore limit is because once the holes are drilled, you can't get the max bore out of the block anymore. You need to keep enough metal between the piston and steam jacket so you don't blow thru
Posted By: Anonymous
Re: Siamese Bore R3's for Street Use - 08/15/09 09:37 PM
i drill the 3 lower holes. (most blocks already have the center hole between the middle cylinders drilled) as well as the heads. just like a chevy 400.
Posted By: dizuster
Re: Siamese Bore R3's for Street Use - 08/16/09 11:13 AM
Quote:
The reason for the bore limit is because once the holes are drilled, you can't get the max bore out of the block anymore. You need to keep enough metal between the piston and steam jacket so you don't blow thru
Obviously if you drill a big hole in the wrong spot it can cause weakness issues. But done properly, I don't see how it can hurt much unless you're really trying to get every .001" of bore you can out of it.
Like I said short deck R3 blocks already have steam holes right from Mopar. Tall deck R3's do not. But Mopar doesn't put any different bore limitations on either...
Posted By: DemonDust
Re: Siamese Bore R3's for Street Use - 08/16/09 02:29 PM
My R5 also has the steam holes in it, but they Look to be in a different location than the few R3 race blocks I've come across..
Posted By: Leon441
Re: Siamese Bore R3's for Street Use - 08/16/09 03:02 PM
Here is a pic of my old 9.600" deck R3 bored 4.245". There would have been no issue with steam holes at this bore as they start from a 4 O'clock position and are angled 45 degrees from the deck surface entering the water jacket.
The issue with this block if had had steam holes "may" have been when repairing the block with sleeves. This block had two next to each other on #6 and #8 that worked well.
Leon
The issue with this block if had had steam holes "may" have been when repairing the block with sleeves. This block had two next to each other on #6 and #8 that worked well.
Leon
Posted By: Leon441
Re: Siamese Bore R3's for Street Use - 08/16/09 03:05 PM
This is a pic of my 358WC R3 9.00" deck block. This block has a 4.200" bore. The pic is not that good but the steam holes are there between all cylinders.
Posted By: Leon441
Re: Siamese Bore R3's for Street Use - 08/16/09 03:12 PM
Here is a pic of a stock block 69' 340 that was done before there were better blocks. It is sleeved and 3/4 filled bored 4.125". No steam holes and driven on the street when it was 4.100" bore.
Posted By: lowell66dart
Re: Siamese Bore R3's for Street Use - 08/16/09 07:37 PM
That book about building big inch smallblocks that came out a few years ago has some info about drilling siamese R3 blocks.