[Nyairguard]

How much can be removed from deck before you need to cut your intake manifold? And how would you check if you need to lay on and feeler gauge?


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[Tom Vaught]

Not sure about a recommendation for cutting the deck vs intake manifold on a stock block.

I will say I was worried when I had .030" cut from the 9.5" deck height IA block to get my BB Chebby connecting rods where I wanted the pistons to be.
I was running a fabricated intake manifold. Tom S has had a bunch of Pontiac Blocks built. Maybe he knows.

Tom V.

[tom s]

I only learned .125 is WAY too much to have cut!Tom

[b-man]

Have the minimum amount machined off the deck to make it square with the world.

Measure it (your machine shop can handle this) and buy your pistons with the correct compression height to put the pistons within .005” of the deck.

This way you won’t end up doing a bunch of extra machining and you get a custom piston made to the most ideal specifications.

If you have already purchased your pistons then you’ll just have to cut the block the amount needed to achieve whatever deck height you’ve decided on and roll with it. Custom pistons do cost a bit more initially but make the build go smoother all in all.

[tooski]

I had .025 cut off the deck to get a zero deck with the Speed-Pros. KRE heads. Had both Edelbrock T II and stock intakes on. No trouble for me. You may or may not.

[Cliff R]

Your good for most blocks and head to a total of about .050-.060". Beyond that you may have to elongate the holes in the intake and or remove some material from it.

I much prefer to buy pistons that end up about .015-.018" in the holes at TDC (with the connecting rods being used) vs compensating for "short" pistons that end up WAY down in the holes at TDC.

In other words do the math and try to get where you need to be before just randomly ordering parts, mocking it all up, then finding out you are .030-.050" (or more) in the holes at TDC. I've had that happen a few times here when customers rounded up all their parts then dropped everything off to be assembled. I had to put a quick stop to all that back when I was still doing engines here.

Instead I've have them drop off the block, crank, heads or complete worn out engine and let me select the parts for it instead.

I remember one engine in particular where the owner insisted on buying EVERYTHING himself. He Googled to the brink of extinction to find the absoute LOWEST price on every single component. Just about every single part came from a different supplier offering the lowest price with "free shipping". He even found a complete balanced spinning assembly with a forged crank, rods and high end pistons at a very reasonable price. When I mocked things up the pistons were almost 1/8" in the holes at TDC......yikes!

That is NOT a good scenario when you have to contact the seller and return the pistons because the entire spinning assembly was already balanced. Of course the seller got their panties all wadded up about it and had some choice four letter words for me since I'm stuck right in the middle of it. To make it even worse the seller was also a Forum member here and followed me around for years looking for a flaw in my armor so they could bust my balls at every possible opportunity.

Valuable life lessons learned with these sort of things.

Anyhow the manufacturer of pistons will have the pin height in the specs so you can compute the crankshaft centerline distance and buy the rods and pistons to get you where you need to be first time around. You don't want to get right at or super close to TDC because very small cuts are difficult when it comes to decking/squaring these blocks........FWIW......

[hurryinhoosier62]

Originally Posted by Cliff R

Your good for most blocks and head to a total of about .050-.060". Beyond that you may have to elongate the holes in the intake and or remove some material from it.

I much prefer to buy pistons that end up about .015-.018" in the holes at TDC (with the connecting rods being used) vs compensating for "short" pistons that end up WAY down in the holes at TDC.

In other words do the math and try to get where you need to be before just randomly ordering parts, mocking it all up, then finding out you are .030-.050" (or more) in the holes at TDC. I've had that happen a few times here when customers rounded up all their parts then dropped everything off to be assembled. I had to put a quick stop to all that back when I was still doing engines here.

Instead I've have them drop off the block, crank, heads or complete worn out engine and let me select the parts for it instead.

I remember one engine in particular where the owner insisted on buying EVERYTHING himself. He Googled to the brink of extinction to find the absoute LOWEST price on every single component. Just about every single part came from a different supplier offering the lowest price with "free shipping". He even found a complete balanced spinning assembly with a forged crank, rods and high end pistons at a very reasonable price. When I mocked things up the pistons were almost 1/8" in the holes at TDC......yikes!

That is NOT a good scenario when you have to contact the seller and return the pistons because the entire spinning assembly was already balanced. Of course the seller got their panties all wadded up about it and had some choice four letter words for me since I'm stuck right in the middle of it. To make it even worse the seller was also a Forum member here and followed me around for years looking for a flaw in my armor so they could bust my balls at every possible opportunity.

Valuable life lessons learned with these sort of things.

Anyhow the manufacturer of pistons will have the pin height in the specs so you can compute the crankshaft centerline distance and buy the rods and pistons to get you where you need to be first time around. You don't want to get right at or super close to TDC because very small cuts are difficult when it comes to decking/squaring these blocks........FWIW......

Cliff, this is WHY I have a block decked and align honed before I purchase a single part. Once the block is decked and the main saddles are align honed I know precisely what my block deck height is going to be.

[Cliff R]

I don't do either but it's still a good plan.

I will NOT use a block that needs line bored/honed. If the block has "moved" or not thru thru the center of the main bores or other line bore issue or problem, and the crank doesn't turn freely with two fingers (no rear seal installed) I woln't use it. I'm NOT saying here there is anything wrong with line honing and such, I've just had a few issues with machine shops NOT doing a good job and throwing more problems into the equation. In other words, from what I've seen with this sort of thing is that it's better to trust the work Pontiac did 50 years ago vs what a machine shop is going to do for you today. It's also rare to find a Pontiac block that isn't true thru the main bores right to start with. In all the years I built them can only remember a couple that didn't make the grade in that area. Same with having crankshafts machined. More come back WORSE than when you sent them out, so do your homework in that arena before you send out a crank that needs more than just polished and put back in service. I was actually lucky in that deal as I found the BEST crankshaft machinist on the planet early in the game and used him for every single engine I built here with absolutely ZERO issues anyplace. Sadly, like many other folks who do excellent work he retired a few years back, which was fine with me because I was done with engine builds anyhow and had also moved on to other things that pay the bills with a LOT less effort on my part.

Anyhow, back to zero decking. I used to have the blocks bored, bring them back to the shop, then go thru the process of mocking things up to determine how much to remove when decking/squaring for zero deck height. Of course that can lead to some "oh-chit" scenarios if you happend to buy pistons that were a bit shorter than they should have been!

Got better at it over the years and did the math instead. This simply involves measuring cranksahft center line to the existing deck and buying rods and pistons that would only require a small amount removed from the deck to square things up. This means only one to the machine shop instead of two. Of course you need to double and triple check your math, but every single build I did in that fashion came out dead nuts on the money when we checked them right before final assembly......

[Formulajones]

Basically what that all boils down to is ya gotta find a good machinist you can trust.
All your block work is based off the main saddle so if that isn't straight you can guess how the rest is going to turn out.

I'm of the other side of the coin than Cliffs experience, I've rarely had a block that didn't need caps machined and align honed. And with Pontiac blocks getting harder to find it's not like you have a lot to choose from.

Find a good machinist.

[Formulajones]

Cranks are another deal all together. Most machine shops, even the good ones, don't have a crank machine. Most shops send the crank out to a crank grinder mainly because of several reasons.

The machine is big
It's expensive
And it takes good machinist to run it which is a full time job by itself.

So it again comes down to finding a good machine shop where you can trust your guy knows who does a good job on cranks and trust his judgement on where he sends it.

Here in Arizona I think there are only 2 or 3 crank grinders in the entire state but there are probably 100 machine shops. I know Paul had his favorite that retired a few years ago. Not sure where that crank machine went. Point being there usually isn't a bunch of choices.

An example there are at least 5 machine shops up here in Prescott, 3 others I know in Sedona and Cordes Junction, They all send cranks to Phoenix, there isn't a crank machine up here. One of my neighbors was a crank grinder and owned the machine. He lived in Payson at the time, retired and sold the machine to someone in Phoenix.

[hurryinhoosier62]

Originally Posted by Formulajones

Basically what that all boils down to is ya gotta find a good machinist you can trust.
All your block work is based off the main saddle so if that isn't straight you can guess how the rest is going to turn out.

I'm of the other side of the coin than Cliffs experience, I've rarely had a block that didn't need caps machined and align honed. And with Pontiac blocks getting harder to find it's not like you have a lot to choose from.

Find a good machinist.

Been preaching this the entire time I’ve been posting on here( seventeen years), but I still see people posting on how the machine shop screwed something up. The problem is automotive machine shops are disappearing. There are TWO machine shops in the Louisville area I would actually let do work for me. At the best of the two the machinist is nearly ninety, but his work is impeccable. The second the machinist is a mere seventy-five years old. Not enough young men or young women have to “fire” in their bellies when it comes to automotive machining. To start a shop is incredibly expensive, even with used equipment. The only advice I would give someone on finding a good machine shop is to ask their customers. They are your best source as to the quality of the machine work that particular shop puts out. Remember that QUALITY machine work is NOT cheap.

[tom s]

Im lucky,found my shop from Joe Sherman.He had been doing Joes work for years before his passing.The owner has his 2 sons working the shop.He over sees every job they do.It will be left in good hands when he hangs it up.They do EVERYTHING in house except crank grinding.Does everything form Dsl to Lambo work.Tom

[soupman]

My machinist got close to zero deck, he was adamant that I leave .005 above zero deck. He said in case I ever have to machine the deck again for whatever reason, there will be some material left to work with. I was ok with his reasoning.

[Formulajones]

Originally Posted by soupman

My machinist got close to zero deck, he was adamant that I leave .005 above zero deck. He said in case I ever have to machine the deck again for whatever reason, there will be some material left to work with. I was ok with his reasoning.

That's perfectly fine and common practice

[Formulajones]

Originally Posted by hurryinhoosier62

Been preaching this the entire time I’ve been posting on here( seventeen years), but I still see people posting on how the machine shop screwed something up. The problem is automotive machine shops are disappearing. There are TWO machine shops in the Louisville area I would actually let do work for me. At the best of the two the machinist is nearly ninety, but his work is impeccable. The second the machinist is a mere seventy-five years old. Not enough young men or young women have to “fire” in their bellies when it comes to automotive machining. To start a shop is incredibly expensive, even with used equipment. The only advice I would give someone on finding a good machine shop is to ask their customers. They are your best source as to the quality of the machine work that particular shop puts out. Remember that QUALITY machine work is NOT cheap.

When I was younger and living in Cincinnati I had a good friend, a very smart engine builder, who's brother ran his own machine shop. He did quite a bit of work for me then, and was always busy with circle track engines. He was the go to guy for a lot of racers. I was just lucky at the time to be surrounded by people like that. Dad liked using Tony Bischoff. Anyone in the car hobby worth anything knows who he is and his reputation, goes without saying.
When I moved to Arizona first place I spent a lot of time was the dragstrip, and asked a lot of racers who does their machine work. That was a good place to start but a little luck came my way, and I met Mike, a member here.
Mike got me in touch with Paul Carter so I paid a visit. This was after I had used a couple other machine shops by then. It became clear pretty quickly why Paul was the better choice and I thank Mike for that. So I drive 3 hours each way to Tucson to see Paul and pass right through Phoenix on the way that has more machine shops than I can count.

[Half-Inch Stud]

I had a 455 "zero-decked" and it went well. I think the Machine shop process was to put a straight shaft in Mains to get all 4 corners to level front-to back. Mill, jerk to block 90* and mill again.

I think other methods can result in a front-back slope. As if a head-milling machine was used to mill blocks.

[track73]

[QUOTE=Cliff R;6413740]I don't do either but it's still a good plan.

I will NOT use a block that needs line bored/honed. If the block has "moved" or not thru thru the center of the main bores or other line bore issue or problem, and the crank doesn't turn freely with two fingers (no rear seal installed) I woln't use it.

When I started the Pontiac hobby I read the HO "bible". It says Pontiac blocks rarely need Line boring.

[racegto65]

Originally Posted by Nyairguard

How much can be removed from deck before you need to cut your intake manifold? And how would you check if you need to lay on and feeler gauge?


Sent from my iPhone using Tapatalk

When I have cut either the block, heads or both, the easiest way i have found is to lay the intake manifold on without gaskets and check bolt hole alignment and the do the same with the gaskets in place. If the gasket causes it to change measure the gasket and cut accordingly.

[lust4speed]

I can't buy the argument that any material needs to be left on the deck in case of future problems. Original deck lasted 50+ years and only damage is corrosion from previous neglect. I suspect that the engine will be well maintained after the rebuild so we shouldn't have to worry about any future pitting. If something catastrophic happens, the deck will be the least of our worries. If only a minor boom happens and the block is salvageable the next custom pistons can be ordered with a shorter compression height.

Any port misalignment between head and intake is not good. Every thousandth removed from the deck or head will alter port alignment the same amount. The ability of getting bolts to fit when installing the manifold is the least of worries. Granted, bolts will fit through the manifold bolt holes up to almost exactly .060" offset, but at that point your intake port is sitting .060" higher than the head port. Guess we all have a different idea of how far things can be off before we believe performance is being hurt.

[Dragncar]

Originally Posted by Cliff R

I don't do either but it's still a good plan.

I will NOT use a block that needs line bored/honed. If the block has "moved" or not thru thru the center of the main bores or other line bore issue or problem, and the crank doesn't turn freely with two fingers (no rear seal installed) I woln't use it. I'm NOT saying here there is anything wrong with line honing and such, I've just had a few issues with machine shops NOT doing a good job and throwing more problems into the equation. In other words, from what I've seen with this sort of thing is that it's better to trust the work Pontiac did 50 years ago vs what a machine shop is going to do for you today. It's also rare to find a Pontiac block that isn't true thru the main bores right to start with. In all the years I built them can only remember a couple that didn't make the grade in that area. Same with having crankshafts machined. More come back WORSE than when you sent them out, so do your homework in that arena before you send out a crank that needs more than just polished and put back in service. I was actually lucky in that deal as I found the BEST crankshaft machinist on the planet early in the game and used him for every single engine I built here with absolutely ZERO issues anyplace. Sadly, like many other folks who do excellent work he retired a few years back, which was fine with me because I was done with engine builds anyhow and had also moved on to other things that pay the bills with a LOT less effort on my part.

Anyhow, back to zero decking. I used to have the blocks bored, bring them back to the shop, then go thru the process of mocking things up to determine how much to remove when decking/squaring for zero deck height. Of course that can lead to some "oh-chit" scenarios if you happend to buy pistons that were a bit shorter than they should have been!

Got better at it over the years and did the math instead. This simply involves measuring cranksahft center line to the existing deck and buying rods and pistons that would only require a small amount removed from the deck to square things up. This means only one to the machine shop instead of two. Of course you need to double and triple check your math, but every single build I did in that fashion came out dead nuts on the money when we checked them right before final assembly......

Cliff, can you explain the proper way of measuring the deck height with a 12" caliper.
I have a block that needs measuring and had it explained to me once, just want to double check.
Measure from deck to main bore. Then divide the main bore diameter and subtract ? Something like that ?
Any of you other machinists/builders can give your thoughts and doing this too if you like.
Thanks for any help, I am sure others would like to know also.