Modifying 670 head chambers - Page 6

turbo louie · 02-11-17, 12:45PM

As you see in the videos when the journal spins it will initially ride up the side of the bearing, also at this time it is going to start dragging the oil in between the journal and the bearing, basically acting as its own pump. As the RPM increases it builds pressure and pushes the journal over with a oil film called the wedge and where the load zone occurs. During high loads there is a possibility of pushing through the oil wedge and having metal to metal contact(not good). The modification will bring the oil delivery closer to where the oil wedge and load zone occur, and decreasing the chances of squishing out the oil under load.

Good article that talks the same points I did, and has some graphics

http://www.epi-eng.com/piston_engine...e_bearings.htm

This is the same website but at the home page, book mark it because it has a lot of good engine info

http://www.epi-eng.com/piston_engine...y_contents.htm

I really like this mod, and think if I had it done when I was spinning my 4 cylinder 7200 rpms that it would of had a better chance of living longer. Im going to try applying this mod to a bearing shell in stead of the block, just incase if I do it the wrong way it wont chance taking any integrity away from the block. I will try to make the mod edge free by using rounded cutters so it wont impose any stress risers in the altered area...

Mb125 · 02-11-17, 04:28PM

Bearings for the 3.8

turbo louie · 02-11-17, 07:16PM

So they do the 3/4 deal as well. Is it just the 2 ? Or do all the bearing have that mod?

Mb125 · 02-11-17, 10:22PM

All the bearings have it

turbo louie · 02-11-17, 11:30PM

I wonder if they did that to my caddy engine..

Dragncar · 02-17-17, 01:10AM

Quote:

Originally Posted by EC

You really believe that?

For the most part, hell yes. Talking to a guy who has some Tenn boy E heads on a 400. Near .600 lift roller, 3200-3400 stall, good gears, 1st gen bird, Victor/Tomahawk. Runs freaking 12.2s.
You can run 10.90s with home ported iron heads on a 400. This cam was custom ground by them for him.
SD 272 48s and a RAIV cam beats that.
E heads have a big throat/bowl and its hard to make a 400 run with them.
One reason Dan Whittmore (RIP) asked for some smaller chambers from Edelbrock when they called him asking what they should make for a Pontiac aluminum head.

Dragncar · 02-17-17, 02:01AM

Quote:

Originally Posted by Mb125

At least GM caught on. They started doing it right at the factory on the GM 3.8 blocks.

Thats because the oiling system on Buick V6s sucks. Long oil pump pickup that runs the length of the pan, bleeds oil pressure around the lifter bores.
Thats why they always blew up in the Indy 500 with "Roberto Guerrero" driving. Setting the top MPH, then blowing up 2/3 they way through the race.

JSPONT · 02-17-17, 03:55PM

Yes I have seen turds any heads. This is why the combo is so important.
People spend a ton of money on parts that are a proven combo, then wonder why there car is so much slower than the person who has the same combo.
Then you find out, the cam was not degreed, forget porting, they don't gasket match the intake and heads, then throw a carb on and do not even own a jet kit or a timing light.....
It does take some knowledge and experience to get a car to run its best.

Dragncar · 02-18-17, 03:10AM

Quote:

Originally Posted by EC

So because 1 person (yes im aware there are a couple more) built a turd you think iron heads are better? There are LOTS of iron headed turds out there also!!

The Pontiac world is littered with 400s with E heads that are turds. Been happening since they first came out.
There is a long list of them that have showed up at my track not to beat even my junk. Some with 4.25 cranks too. There is a guy with a 455 E heads RAIV cam, 12.40s. I tell them stuff, they either listen or do not. My pal with the 400 in a iron headed second gen that ran 11.0-10.90 with 62s, 10-1 CR. Engine lasted 3-4 years. Mine is at 27 and its last pass was its best ever. 56 lbs hot oil press. Plenty of folks have called it a reliable Beast. I tell them when the old girl lets go they should put a plaque on the spot where it goes.
The car I am talking about had heads and cam done by Tenn boys. WTF?
Ace ran 9.30s in a not so light 2nd gen (pretty fast EC right) with a 400, E heads sand rolled by SD to right at 290cfm, kept the velocity up, one of the fastest NA not crazy CR 400s I know of. 400s need velocity. Huge flow hurts, not helps many folks.

turbo louie · 02-18-17, 08:46AM

Quote:

Originally Posted by Dragncar

The Pontiac world is littered with 400s with E heads that are turds. Been happening since they first came out.
There is a long list of them that have showed up at my track not to beat even my junk. Some with 4.25 cranks too. There is a guy with a 455 E heads RAIV cam, 12.40s. I tell them stuff, they either listen or do not. My pal with the 400 in a iron headed second gen that ran 11.0-10.90 with 62s, 10-1 CR. Engine lasted 3-4 years. Mine is at 27 and its last pass was its best ever. 56 lbs hot oil press. Plenty of folks have called it a reliable Beast. I tell them when the old girl lets go they should put a plaque on the spot where it goes.
The car I am talking about had heads and cam done by Tenn boys. WTF?
Ace ran 9.30s in a not so light 2nd gen (pretty fast EC right) with a 400, E heads sand rolled by SD to right at 290cfm, kept the velocity up, one of the fastest NA not crazy CR 400s I know of. 400s need velocity. Huge flow hurts, not helps many folks.

So spin the motor higher and there's your lost velocity !

turbo louie · 02-18-17, 12:36PM

You build a 400 to spin to 8000-8500 with a E head and put the right cam in it what do you think is going to happen? Then do the same with any D port and what will the comparison be ? !

JSPONT · 02-18-17, 01:26PM

Quote:

Originally Posted by turbo louie

You build a 400 to spin to 8000-8500 with a E head and put the right cam in it what do you think is going to happen? Then do the same with any D port and what will the comparison be ? !

All true. It's about the combo. It's a puzzle you need the pieces to match.