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-   -   f-bird'88 lift rule 350-vortec (http://www.hotrodders.com/forum/f-bird88-lift-rule-350-vortec-139608.html)

DENCOUCH 05-30-2008 09:40 PM

f-bird'88 lift rule 350-vortec
 
After reading these posts for I dunno how long, I am going to do one of T-bird's suggested builds centered around the Isky lift rule camshaft and Vortec heads.

I was gifted with a low-mile crate 350 that I tore into today. No piston ridge but I found that it has those awful dished pistons. For some reason I was believing it had flat top pistons.

My goal today was to measure the deck height in order to insure I had the proper quench with my .015 steel shim head gaskets.

I want flat top pistons. I need flat top pistons! What is the next step?

It seems I should continue to tear it down to the block & drop it off to be hot tanked.

Should I have them make a pass over the deck to insure it is flat?

Should I have them take a bunch off to aid in my quench pursuit?

Should I go ahead a order the pistons so the holes can be fit to them?

The bores look absolutely great, no harm to be seen, so I am not thinking of an overbore.

CNC BLOCKS NE 05-31-2008 05:22 AM

The only problem with stock bores is that GM does not plate hone their blocks and a stock engine don't build the cylinder pressure that a performance engine will build and maybe and issue later on.

If you take a block with with round cylinders and set a torque plate on it and measure the bores you will see up to .004 distortion from low to high between the cylinders.

If you are going to bore the block have the decks squared to to insure a true 90 degrees to the crank and a tue 45 degrees from the crank and cam center lines.

Good luck with your build Carl

F-BIRD'88 05-31-2008 10:24 AM

If the stock bores were that bad then the stock OEM motors would never pass an emissions test. (blowby and oil contamination would give huge unburned hydrocarbons) They tend to pass strict emissions tests so the ring seal quality must be pretty good.
Check/measure the dish volume of your pistons. (its not that hard to do) If they are -12 to -15cc mill your vortec heads .040" and install with with the .015" shim gasket. the stock 350 pistons should be .025" below deck @ TDC or close to it.
Your cr will be between 9.6 and 9.8:1 finished with a 58-60cc head volume.
Thats plenty enough compression for a street motor.

GM doesn't recomend flat milling more than .040" off the deck of these heads.
The physical flat mill limit is the stock intake valve seat edge.
You'll be fine at .040".

About the only way to keep it low buck.

F-BIRD'88 05-31-2008 10:41 AM

1 Attachment(s)
To find the volume of a beveled dish in the piston top you need to calculate the averaged volume of the major dish and minor dish volumes.

Measure the dish depth and the two dish diameters with a dial caliper and short straight edge. I can help ya with the math.

I've never seen a vortec head pull the pressed in rocker studs with 1.26" springs and .450" lift. Leave the rocker studs alone or just drill and roll pin them if you're going to loose sleep.

CNC BLOCKS NE 05-31-2008 10:52 AM

Quote:

Originally Posted by F-BIRD'88
If the stock bores were that bad then the stock OEM motors would never pass an emissions test. (blowby and oil contamination would give huge unburned hydrocarbons) They tend to pass strict emissions tests so the ring seal quality must be pretty good.
Check/measure the dish volume of your pistons. (its not that hard to do) If they are -12 to -15cc mill your vortec heads .040" and install with with the .015" shim gasket. the stock 350 pistons should be .025" below deck @ TDC or close to it.
Your cr will be between 9.6 and 9.8:1 finished with a 58-60cc head volume.
Thats plenty enough compression for a street motor.

GM doesn't recomend flat milling more than .040" off the deck of these heads.
The physical flat mill limit is the stock intake valve seat edge.
You'll be fine at .040".

About the only way to keep it low buck.

Have you ever measured a block with a torque pate installed??? As I posted stock engines don't build alot of cylinder pressure compared to a performance engine.

Look at a set of stock pistons they blowby all the way to the oil rings.

Here is a link to look over for you as a non beleiver of using a torque plate.
http://www.camaros.net/forums/showthread.php?t=58964

F-BIRD'88 05-31-2008 11:13 AM

Quote:

Originally Posted by CNC BLOCKS NE
Have you ever measured a block with a torque pate installed??? As I posted stock engines don't build alot of cylinder pressure compared to a performance engine.

Look at a set of stock pistons they blowby all the way to the oil rings.

Here is a link to look over for you as a non beleiver of using a torque plate.
http://www.camaros.net/forums/showthread.php?t=58964

CNC: I don't doubt or question you skills and knowledge on proper race engine block preparation or the value of using a torque plate when honing,

I don't even know if GM hones the blocks with a torque plate attached or not, I'd bet they do. I'll ask some one that works on the line at GM St. Catharines ( Glendale Engine Plant) next time, if they do or.....

Again not doubting the torque plate stuff - torque plate honing works... but those pics tell me that motor ran hot. (blueing on the bores) or did you blue mark the bores before honing???
The bottom end noise problem indicates multiple critical dimentional issues which required your attention.

CNC BLOCKS NE 05-31-2008 11:28 AM

Quote:

Originally Posted by F-BIRD'88
CNC: I don't doubt or question you skills and knowledge on proper race engine block preparation or the value of using a torque plate when honing,

I don't even know if GM hones the blocks with a torque plate attached or not, I'd bet they do. I'll ask some one that works on the line at GM St. Catharines ( Engine Plant) next time, if they do or.....

F-BIRD

We buy alot of new blocks form GM and NO they do not plate hone their blocks and we have seen quite a few of the crate engines out of cicle track cars and have gone though them and those are not plate honed either.

Stock engines run very lean compared to a performance engine and there is very little byproduct from the combustion proccess.

Over the years we have done a few rebuilds for friends and have gone through the blocks the right way line hone, deck, bore and plate hone and the engines have run better then they did when they were new and the fuel milage improved alot as well..

On other thing to remember that GM bores the cylinders off the pan rails Which is not very accurate, Some time take a depth mike and measure the depth of the main housing bores from the pan, We have found that the pan rail and the crank center lines are off a lot. Would a guy ever deck of the pan rail ?? GM blocks are machined very crude compared the Bowtie blocks.

curtis73 05-31-2008 11:38 AM

Regardless of how GM does it, you won't be able to rehone your block without going oversize in some way. The block was honed to fit your pistons, then the rings wore it larger, then honing it again will make it bigger yet.

The deck should be checked for flatness, but if you don't need to shave it, don't. No need to make the decks thinner if they don't need to be... just like you're not anxious to overbore unless you need to. With flat tops .020 in the hole plus your .015 gasket will make a nice tight quench.

Most good shops wait for the pistons to come in so they can measure that specific set and do final honing for your pistons.

F-BIRD'88 05-31-2008 11:41 AM

One day I'm going to do the plant tour there and see just what they do.
They build the LS V8 motors and the V6's there. Used to do the Gen 1 vortec V8 motors before. My friends dad was a lead hand there years ago and would know exactly what they do/did...don't. Used to get us lots of cool SBC engine parts for building our hot rods, way back.

I don't doubt for a minute that you can and do improve on GM's crate motors but I'm assuming this posters motor is low mileage and in good overall condition and should be fine for a low buck budget build up. Got to keep the costs in check or its no longer a "budget build."

CNC BLOCKS NE 05-31-2008 03:41 PM

Quote:

Originally Posted by F-BIRD'88
One day I'm going to do the plant tour there and see just what they do.
They build the LS V8 motors and the V6's there. Used to do the Gen 1 vortec V8 motors before. My friends dad was a lead hand there years ago and would know exactly what they do/did...don't. Used to get us lots of cool SBC engine parts for building our hot rods, way back.

I don't doubt for a minute that you can and do improve on GM's crate motors but I'm assuming this posters motor is low mileage and in good overall condition and should be fine for a low buck budget build up. Got to keep the costs in check or its no longer a "budget build."

I didn't see any where that this was a budget build!!!!

In most cases budget builds don't come out as good as non budget engines as have seen quite a few budget engines over the years that other shops have built on a budget and the customers are not happy with the results and in most cases they were promised they would be happy with the power. So we have seen more then one guy rebuild there engine the right way.

But remember we get calls on the bad ones not on the good ones.

CNC BLOCKS NE 05-31-2008 03:54 PM

Quote:

Originally Posted by curtis73
Regardless of how GM does it, you won't be able to rehone your block without going oversize in some way. The block was honed to fit your pistons, then the rings wore it larger, then honing it again will make it bigger yet.

The deck should be checked for flatness, but if you don't need to shave it, don't. No need to make the decks thinner if they don't need to be... just like you're not anxious to overbore unless you need to. With flat tops .020 in the hole plus your .015 gasket will make a nice tight quench.

Most good shops wait for the pistons to come in so they can measure that specific set and do final honing for your pistons.

It's important to have the decks square to the main line and a true 45 degrees from the cam and crank center lines.

We have seen blocks that shops bore off an unsquared decks and in most cases if the block won't go .060 because it didn't pass a sonic test its know junk.

If your going to have a block machined for performance use do it once right as it makes for a much better running engine in the end.

Ther are a lot of shops out there doing shorty work because thay don't have the proper equipment to do it right, Don't get me wrong building a bone stock engine you can get away with a lot but building performance engines the substandard machine work will show up after a while.

There is a right way to do things and I guess there is a semi right way LOL.

machine shop tom 05-31-2008 06:17 PM

1 Attachment(s)
You guys done yet?



tom

DENCOUCH 06-01-2008 12:38 AM

Piston choice
 
Ok, so what I am going to do now is:

1. have the block decked JUST enough to make sure Ihave it indexed 90 degrees to the crank.

2. have a flat surface for optimum sealing for the .015 steel shim head gasket.

3. have the heads checked for flatness and milled if needed. Perhaps .020.

4. I am considering an .30 overbore to fit a set of pistons. I have seen these and am wondering if they are ok or not. I was looking for something with less than +7.00 cc. +5 cc sounds good if I want to keep the compression up.
These Pistons from Summit.


It seems silly to me to get a .015 head gasket, mill everything & then go to a +7 cc flat top piston.

I need help with this guys, there is so much stuff to keep track of.

Stroke 06-01-2008 07:14 AM

You need to set a goal, a realistic goal. Then, no matter what you use, or how you go about getting there, make your goal. IMO those are el cheapo cast pistons, and sure they'd work, but what is it you are going to do with this engine? You could throw them in and add some cam along with some budget priced stuff and get what you want, or, go whole hog and make it exactly what you want without worry. First thing though, you need a specific goal for this engine and need to know where it is going to spend it's life, happily.

NXS 06-01-2008 07:20 AM

Quote:

I am going to do one of T-bird's suggested builds centered around the Isky lift rule camshaft and Vortec heads.
got a link to what you are talking about?


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