Do you need to deck the block if not using MLS HGs???

sizemoremk

Registered User
Hey guys!

I am wondering about somethings here now that my engine is at the machine shop.

Money is tight, as when I bought this engine, I was under the impression it would be plug and play, but specs dictate that the custom pistons and rods must be fit into a new block with a new crank, along with lots of machine work on the block.

I am currently leaning the drection of conventional HGs, with ARP headstuds, and will get the head surfaced for straightness... Is it necessary to eck the block also, if using the conventional felpros?

I was trying to wait for the cometics, but I will let that wait till the next build...

I am really wanting to use the convential HGs as a safety net, so perhaps I would blow the HG instead of something in the shortblock...
At least whilst I git-R-tuned and dialed in.

So the basic question is, does the block warp enough to require decking???

I know I could ask the machine shop, but they don't have my replacement block yet...

I am just trying to get my estimates together...

Thanks
 
sizemoremk said:
Hey guys!

I am wondering about somethings here now that my engine is at the machine shop.

Money is tight, as when I bought this engine, I was under the impression it would be plug and play, but specs dictate that the custom pistons and rods must be fit into a new block with a new crank, along with lots of machine work on the block.

I am currently leaning the drection of conventional HGs, with ARP headstuds, and will get the head surfaced for straightness... Is it necessary to eck the block also, if using the conventional felpros?

I was trying to wait for the cometics, but I will let that wait till the next build...

I am really wanting to use the convential HGs as a safety net, so perhaps I would blow the HG instead of something in the shortblock...
At least whilst I git-R-tuned and dialed in.

So the basic question is, does the block warp enough to require decking???

I know I could ask the machine shop, but they don't have my replacement block yet...

I am just trying to get my estimates together...

Thanks

Yes it could be warped, besides that the factory finish was lousy. Get the block resurfaced while your at the machine shop. If your ever going to do it, now is the time to switch over to MLS gaskets.

David
 
Yes, the block can warp. Most of the time not enough to require resurfacing in and of itself. IMO, there is another consideration if you want a nice, long-lasting rebuild. As machined from the factory the block decks probably aren't parallel with, or square to the crank bore. Then because the boring bar indexes on the block head surface, the bores won't be perfectly aligned with the crank centerline. Some blocks will be close but some will be off enough to cause stresses and bearing alignment issues.
So, have the block align honed, block decked to the crank centerline before boring. Now the question arises about the smoothness of the block deck and only you can decide if you want to make it smooth for Cometics at this time or not. John
 
David Neibert said:
Yes it could be warped, besides that the factory finish was lousy.

David,

I spun a couple of bearings and am now doing a short block rebuild. By looking, I can tell that the heads have already been into, so how can I tell if the block's deck has been resurfaced already as well? Can you help, or maybe anyone else? Take care.
 
AnnivSpeCpe said:
Yes, the block can warp. Most of the time not enough to require resurfacing in and of itself. IMO, there is another consideration if you want a nice, long-lasting rebuild. As machined from the factory the block decks probably aren't parallel with, or square to the crank bore. Then because the boring bar indexes on the block head surface, the bores won't be perfectly aligned with the crank centerline. Some blocks will be close but some will be off enough to cause stresses and bearing alignment issues.
So, have the block align honed, block decked to the crank centerline before boring. Now the question arises about the smoothness of the block deck and only you can decide if you want to make it smooth for Cometics at this time or not. John

You're absolutely correct as I ran into that problem on my block.
The passengers side of the block was .007" higher in the rear than the front.
Then that same block deck was tilted .0075" towards the fenderwell. The block deck was'nt warped it was machined that way from Ford. The drivers side deck was fine, but both decks were taken down .008" because thats what it took to straighten the crooked deck.
 
MIKE 38sc said:
You're absolutely correct as I ran into that problem on my block.
The passengers side of the block was .007" higher in the rear than the front.
Then that same block deck was tilted .0075" towards the fenderwell. The block deck was'nt warped it was machined that way from Ford. The drivers side deck was fine, but both decks were taken down .008" because thats what it took to straighten the crooked deck.


Is that really bad?

I guess I will put decking in the budget then!

Thanks!
 
Well that puts each of those 3 cylinders at different compression ratio's, not to mention with the head tilted that way it affects the flow into and out of the cylinders.
The engine came from Ford that way and it did run for 128,000 miles. I just figured that since I completely tore the car down for a full up restore that I was going to put everything back as it was supposed to be.
Yes I'm compulsive and very anal about details :eek: thats why its taken over 4 years to build my car. :( That and lack of time. :(
 
MIKE 38sc said:
Well that puts each of those 3 cylinders at different compression ratio's, not to mention with the head tilted that way it affects the flow into and out of the cylinders.
The engine came from Ford that way and it did run for 128,000 miles. I just figured that since I completely tore the car down for a full up restore that I was going to put everything back as it was supposed to be.
Yes I'm compulsive and very anal about details :eek: thats why its taken over 4 years to build my car. :( That and lack of time. :(

I agree with above but I am more concerned with the bore squareness with the crank. If the boring bar is used on the block that has a factory "tilt" of .007" at the head surface, compound that by several more thou at the bottom of the bore. This will cause the rod bearings to not be "square" on the crank throw and may be the cause of stories of spun bearings on nearly new engines. John
I don't know if the factory indexes on the block deck when they originally bore a block. The factory may take measures to insure the bore squareness to the crank centerline. However, when you rebore with a boring bar mounted to the deck surface you will not be following the factory bore anymore and imparting an error in your new bore. Some of these factory "tolerances" are why one engine runs like crap and another one is a winner from the factory. Thus the reason for blueprinting in the first place.
 
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AnnivSpeCpe said:
I agree with above but I am more concerned with the bore squareness with the crank. If the boring bar is used on the block that has a factory "tilt" of .007" at the head surface, compound that by several more thou at the bottom of the bore. This will cause the rod bearings to not be "square" on the crank throw and may be the cause of stories of spun bearings on nearly new engines. John
I don't know if the factory indexes on the block deck when they originally bore a block. The factory may take measures to insure the bore squareness to the crank centerline. However, when you rebore with a boring bar mounted to the deck surface you will not be following the factory bore anymore and imparting an error in your new bore. Some of these factory "tolerances" are why one engine runs like crap and another one is a winner from the factory. Thus the reason for blueprinting in the first place.

This is a very good point. The factory possably uses a machine which index's off the crank bores, so even if the deck is cocked the bore will be straight with the crank.
However many machine shops do not have one of those very high dollar machines and so bolting down a boring bar to a cocked deck will result in a bore not being sqaure with the crank. That most certainly can cause the bearing problems mentioned.
Talk to a good machinist about factory tolorances and you'll be horrified by what you hear. Factory tolorances are pretty sloppy and AnnivSpeCpe is correct in saying that explains why 1 engine runs better than another straight from the factory.
 
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