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  #16 (permalink)  
Old 10-11-2010, 11:56 PM
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Quote:
Originally Posted by bigdog7373
I say keep it a 350 because a 355 will use more fuel. Just put a nice cam in it and get the heads ported. You could also run a 4bbl instead of tbi if you want.
a 355 is not gonna use anymore gas then a 350 with the same specs, Nice cam and not a huge one, His van has Vortec EFI (CSFI, OBDII) not TBI (OBDI)

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  #17 (permalink)  
Old 10-12-2010, 01:24 AM
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Quote:
Originally Posted by techinspector1
Some L31 heads had a hardened exhaust valve seat installed rather than using an induction hardened seat. Some clown along the way has concluded that this is a "major restriction". BULL HOCKEY!! Other than a good valve job, leave the heads alone in the ports. You'll do more harm than good
Amen. I have a stout marine engine that consistently runs 5500 RPMs and makes 330 hp, and I have bone-stock vortec heads on it... one of them is a 906 and the other is a 062. The differences are so minimal that I didn't worry a heartbeat about it.

... especially when I'm jamming across the lake at 65 MPH with two barefoot skiers hanging off the gunnels.
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  #18 (permalink)  
Old 10-12-2010, 04:12 PM
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I was going to smooth the intake runners with 80 grit but if that is too smooth i'll just leave it alone. I will have it apart for a little while so I may just polish the exhaust side just out of boredom!

I was planning on getting a 3 angle valve job also.

The lift on the cam I was looking at was .474 in/ex. do you think I would need to pin the rocker studs for that using the springs you mentioned?

I was planning on keeping the stock rocker arms as well.

So all in all, do not touch the intake ports but i can clean up the exhaust side! Do not use a cam with over a .500 lift unless I want to have a bit of machine work done. A mild cam is overkill but will help.

How about the combustion chamber? It has that step below the spark plug. Would you grind it down and smooth out the chamber?

[QUOTE=techinspector1]Intake runners need to retain the stock rough casting finish, which aids in keeping fuel in suspension in the intake fuel mixture charge. The exhaust runners can be polished to a mirror finish if you have the time and effort to do it. Don't change the shape or size, just polish out the casting roughness. Be advised though, that I would only do this on a $10,000 and up engine build, not on a daily driver motor. Don't waste your time matching the intake ports to the gaskets. You may do more harm than good.



Have your shop put as many angles on the valves and seats as you can afford. If they'll do it and you can afford it, put a 101 angle job on them. Of course I'm being facetious, but the more angles you use, the better the flow is, all other things being equal.
Stock valve spring diameter is around 1.250" on stock L31 heads. When you install a cam with more lift, you usually increase the diameter of the valve springs to facilitate more travel if you cannot find enough travel with a stock diameter spring. Here's an interesting quote from Crane Cams...


Crane Cams offers some special valve springs in standard diameters which eliminates having to machine the cylinder heads. For example, a small block Chevrolet engine can use spring kit part number 11309-1 to handle .550" to .600" valve lift. The 85-00 302 Ford hydraulic roller engines can use spring kit part number 44308-1 to handle .550" lift."

Here's a Crane spring and retainer kit for the L31 heads that drops right into place with no machining....
http://www.summitracing.com/parts/CRN-10309-1/


1.5:1


The stock rockers are stamped steel rail rockers that have a recess in the tip to hang down around the tip of the valve and keep the rocker in place over the valve tip. There are several makers of roller rockers with recessed roller tips that will work on the L31 heads and stock pressed-in studs. There is a limit though, to the pressure of the valve spring that you can use before you begin pulling the studs out of the heads. Mr. Gasket makes a stud pinning kit to keep the pressed-in studs in place with stronger springs......
http://www.summitracing.com/parts/MRG-806G/
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Old 10-12-2010, 04:18 PM
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Good to know about the timing chain!!! I wouldn't switch to anything other than maybe an upgraded spider assembly. once it's all together i will take it to be run on the dyno and then have a reflash made for it to make sure it is running clean.

Quote:
Originally Posted by FastOrange
This is what i would do.

-KEEP the Vortec CSFI
-build the engine, Make sure to use a SINGLE row timing chain, not a double, there is a wheel in behind the timing cover to trigger the crank sensor, a double row will be to thick
-Get the PCM tuned for you specs, and you should be good to go.

I would NOT get rid of the EFI, makes no sense ot go to cabr in a van that sounds like it gets daily use.
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Old 10-12-2010, 04:48 PM
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Quote:
Originally Posted by chucksrt
I was going to smooth the intake runners with 80 grit but if that is too smooth i'll just leave it alone. I will have it apart for a little while so I may just polish the exhaust side just out of boredom!
If you have it apart and want to then clean up the ports with an 80 grit roll, it will help slightly and it takes determination to mess it up with a tootsie roll. Just try to clean up the casting and not make it any bigger than it has to be to get clean and you'll be fine. The most material you'll remove from the ports is about 5-10 cc's, which actually puts that port at an ideal size AND one that is common for aftermarket vortec castings.


Now if you're talking about using a carbide bit, then you can get into some trouble, but its actually kinda hard to mess up with a tootsie roll.

Also, 80 grit is NOT too smooth. I don't know where this too smooth idea came from but there has never been any evidence to show even a mirror polish being too smooth. There is evidence to show where roughing up a port has helped but it is in cases of oversized ports with dead spots. A vortec head doesn't have dead spots- which is why it works so well.
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  #21 (permalink)  
Old 10-12-2010, 06:15 PM
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high five fast orange, your not named after the hand cleaner are you? I see way to many people on here that are always wanting to get rid of the efi which makes no sense to me. I can't say makes no sense, I believe it is the older guys that have dealt with carbs all their life and efi is just something they don't want to try and tune or have tuned. Apples to Apples the efi will always out perform.
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  #22 (permalink)  
Old 10-12-2010, 06:16 PM
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[QUOTE=chucksrt]I was going to smooth the intake runners with 80 grit but if that is too smooth i'll just leave it alone. I will have it apart for a little while so I may just polish the exhaust side just out of boredom!

I was planning on getting a 3 angle valve job also.

The lift on the cam I was looking at was .474 in/ex. do you think I would need to pin the rocker studs for that using the springs you mentioned?

I was planning on keeping the stock rocker arms as well.

So all in all, do not touch the intake ports but i can clean up the exhaust side! Do not use a cam with over a .500 lift unless I want to have a bit of machine work done. A mild cam is overkill but will help.

How about the combustion chamber? It has that step below the spark plug. Would you grind it down and smooth out the chamber?

Quote:
Originally Posted by techinspector1
Intake runners need to retain the stock rough casting finish, which aids in keeping fuel in suspension in the intake fuel mixture charge. The exhaust runners can be polished to a mirror finish if you have the time and effort to do it. Don't change the shape or size, just polish out the casting roughness. Be advised though, that I would only do this on a $10,000 and up engine build, not on a daily driver motor. Don't waste your time matching the intake ports to the gaskets. You may do more harm than good.



Have your shop put as many angles on the valves and seats as you can afford. If they'll do it and you can afford it, put a 101 angle job on them. Of course I'm being facetious, but the more angles you use, the better the flow is, all other things being equal.
Stock valve spring diameter is around 1.250" on stock L31 heads. When you install a cam with more lift, you usually increase the diameter of the valve springs to facilitate more travel if you cannot find enough travel with a stock diameter spring. Here's an interesting quote from Crane Cams...


Crane Cams offers some special valve springs in standard diameters which eliminates having to machine the cylinder heads. For example, a small block Chevrolet engine can use spring kit part number 11309-1 to handle .550" to .600" valve lift. The 85-00 302 Ford hydraulic roller engines can use spring kit part number 44308-1 to handle .550" lift."

Here's a Crane spring and retainer kit for the L31 heads that drops right into place with no machining....
http://www.summitracing.com/parts/CRN-10309-1/


1.5:1


The stock rockers are stamped steel rail rockers that have a recess in the tip to hang down around the tip of the valve and keep the rocker in place over the valve tip. There are several makers of roller rockers with recessed roller tips that will work on the L31 heads and stock pressed-in studs. There is a limit though, to the pressure of the valve spring that you can use before you begin pulling the studs out of the heads. Mr. Gasket makes a stud pinning kit to keep the pressed-in studs in place with stronger springs......
http://www.summitracing.com/parts/MRG-806G/
Im running .489 Lift without pinning the studs.

Dont touch the Spark plug area of the Combustion chamber, in fact, i would just clean it up, dont do any grinding down there.

Im using the standard Comp spring with a damper, no machining and im running .489 lift, so far so good.
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  #23 (permalink)  
Old 10-12-2010, 06:37 PM
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Do you know the part # of the springs you used? Or the Spring rate? Yeah, I am not trying to go radical. I just want more HP/TQ and want to help get better fuel economy as well. I figure If I am going to pull an engine apart I might as well pump it up a bit too.

I have no real plans to do anything other than drive it! But I have been known to do last min. crazy things like find a deal I can't refuse like a supercharger kit off craigslist. So If i'm going to build it, I want it ready for whatever may or may not come! (Just an example of the craziness in my head!!)

Im running .489 Lift without pinning the studs.

Dont touch the Spark plug area of the Combustion chamber, in fact, i would just clean it up, dont do any grinding down there.

Im using the standard Comp spring with a damper, no machining and im running .489 lift, so far so good.[/QUOTE]
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  #24 (permalink)  
Old 10-13-2010, 12:22 AM
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Quote:
Originally Posted by crussell85
high five fast orange, your not named after the hand cleaner are you? I see way to many people on here that are always wanting to get rid of the efi which makes no sense to me. I can't say makes no sense, I believe it is the older guys that have dealt with carbs all their life and efi is just something they don't want to try and tune or have tuned. Apples to Apples the efi will always out perform.
Missed this earlier, actualley i currently have a Carb on my 1994 Chevy C1500, couldn't afford a proper tune for TBI at the time, im currently saving up for a MPFI system. Im only 18, so no Carb nostalgia here, also my name is because my truck is Orange and a joke about the handcleaner

Last edited by FastOrange; 10-13-2010 at 12:36 AM.
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  #25 (permalink)  
Old 10-13-2010, 12:34 AM
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Quote:
Originally Posted by chucksrt
Do you know the part # of the springs you used? Or the Spring rate? Yeah, I am not trying to go radical. I just want more HP/TQ and want to help get better fuel economy as well. I figure If I am going to pull an engine apart I might as well pump it up a bit too.

I have no real plans to do anything other than drive it! But I have been known to do last min. crazy things like find a deal I can't refuse like a supercharger kit off craigslist. So If i'm going to build it, I want it ready for whatever may or may not come! (Just an example of the craziness in my head!!)

Im running .489 Lift without pinning the studs.

Dont touch the Spark plug area of the Combustion chamber, in fact, i would just clean it up, dont do any grinding down there.

Im using the standard Comp spring with a damper, no machining and im running .489 lift, so far so good.
[/QUOTE]
i used Comp Cams #981-16 Springs i also used the matching Comp retainers and locks, now i would recommend you go for the beehive springs, i used these cause i bought them for my TBI heads before i found a deal on my Vortec's.
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  #26 (permalink)  
Old 10-14-2010, 01:22 PM
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Awesome info! Thanks for the part # for the springs!
I think I'm going to get the following done
Polished rods, forged pistons, rotating assy balanced, mild cam and new roller lifters, springs and retainers, single row timing chain, polish exhaust side of head and maybe 80 grit intake side, 3 angle valve job and maybe pin the rocker studs. I will upgrade the spider and once it's running have it dyno tuned. Family cruiser or not, this is the only thing I am able to build until I find a toy to play with.
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  #27 (permalink)  
Old 10-14-2010, 09:07 PM
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why would you polish the rods?
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Old 10-14-2010, 09:17 PM
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Do a stock rebuild and save your extra money for something else. Its a van......
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Old 10-15-2010, 07:10 AM
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polished rods remove casting and rough areas where cracks can form.

I know it's a van but I plan on keeping it for a while. I would rather enjoy what i drive.
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