462 build, help with static and dynamic compression

Now I'm faced with a decision. I've got money wrapped up in the short block already with having the block bored, the pistons(albeit used), haveing rods recon'd w/ ARP bolts, new rod bearings and having crank turned 10/10, blah blah blah and what not. I'm faced with having to spend another $1200-$1500 for new rods, pistons and crank work. Or is it more cost effective to have the block shaved the .050 and mill the heads/intake?

To be clear, I'm not saying I'm not willing to pony up the cash for the new rods, pistons and crank work if it's what HAS to be done. I'm just curious if I'd be OK or save some coin buy shaving the deck and heads/intake, and then go the BBC rod and JW piston route on the next build.

Just trying to weigh all options and keep an eye on cash at the same time, considering I already have some coin invested. Thoughts?

 

Not that I've built a ton of engines, but I personally am not a fan of milling heads or intakes for fit due to block issues. That's a one way street and if you bust your block or decided to sell off the parts, they are modified in a way that doesn't make them a simple bolt on deal for other blocks.

 

The cheapest change at this point is to get the longer Pontiac rod that Jim suggested and modify them to fit your pistons and crank.
you would only have to deck the block .025" or less and your done.

http://www.summitracing.com/parts/ESP-6625PP3D/

Don't forget to check the dish volume in every piston to be sure they are close to being the same.

Paul

 

geez, all these issues, it is enough to make me want to sell off my buick parts and just drop in a chevy engine. My car isn't a numbers matching car or anything, and reading all this makes me wonder what the hell I am doing it for.

I have those speed pro pistons at +.040, factory rods, a new set of ARP rod bolts and stage 1 iron heads.

 

I get a little overwhelmed with it myself. Its just another hurdle and a few things to overcome. If these were Chevys or Fords they'd be easy, I'm not a fan of always taking the easy road. Don't sell you Buick stuff just to put in an easy Chevy motor...stick with it, I am!

 

Well, I'm not overly worried, but still, it seems overwhelming sometimes. With the high gears I have, 2:74, I don't anticipate this engine getting up too high in the RPM range, maybe 5000 -5500 max, so a lot of these issues are probably not going to raise their ugly heads.

Maybe I should just look at buying a set of connecting rods that have already been machined and are a good match, doesn't TA sell those?

 

Well, maybe I am worrying too much then. My cam has about .500 lift and non-ported stage one heads so I guess I am reading too much into this thread.

Thanks for talking me off the ledge.

 

That would be just fine for me.

Thanks for the responses.

 

Sorry to butt in, but have a question for JW. On your 470 what rod length are you using and what is the CH of your piston?
Thanks Rick

 

Rick

Rods are 6.800, compression height is 1.775

Crank stroke is now 3.95

We run a longer rod to reduce cylinder wall loading.

JW

 

Is 1.775CH the norm for a Buick piston? Jim thanks for all the inof.
Thanks Rick

 

Rick

The CH is about .200 less than norm because the rod is 6.8 instead of the 6.6 stock lenght.
but Jim has the CH adjusted so very little needs to be taken off the deck for zero clearance.

The new stroke is 3.95, so taking half of that stroke, add 6.8 rod length plus 1.775 CH = 10.55
On an untouched stock 10.57 deck heigth 455 block that leaves only .020" for zero decking which should be enough to straighten up most blocks.

Paul

 

Yup, that is really the heart of the matter, when it comes to the need for all this milling, to achieve optimal deck clearances.

IN looking at the specs..

Most aftermarket Buick pistons have a compression distance of 1.975..

So if we do the math, with a stock rod and crank, assuming the "factory lengths and dimensions", we find that that 10.570 block has to be 10.525 to achieve zero deck.. it has to be milled .050.

That TRW/Speed pro Piston that Collin has, is supposed to be 1.985 in compression distance.

Now, in reality, the blocks are actually a little taller than 10.570, typically about .002-.004 on the LH bank, and up to .008 on the passenger side.. this what we have seen over the years.

And when you resize the factory rods, you shorten them a little bit.

I just did a shortblock for a board member, with his factory rods and 2362P pistons. And in reality...

Deck height, for zero deck, was 10.514.

Anything beyond .030 typically requires something else to be cut, to fit the intake manifold.. this problem is made worse by us now using thicker composition gaskets on the aluminum intakes. What you will see is that when you drop the intake on, the threaded hole in the head is way at the bottom of the intake bolt hole.

I have seen some intakes that someone actually slotted the holes, so it would fit.

Apparently the fact that the ports were no longer lined up, either didn't occur to him, or he didn't care.

It's really not that complex.. Mill the block a minimum amount to square and straighten it, and we have found over the years that .020 will do the trick. Often times just a .010 cut will leave pitting on the deck, around the water holes.

Then get the right length parts to go in the holes.

Saves a lot of time, effort and money. This was not possible with the "production" or HP forged pistons on the shelf for a 455 Buick, until 2009, when we put together the 470 combo.

I know, I lived it for a decade in the business of building HP Buick 455 engines.
JW

 

Would using a 0.020" shim headgasket help any with the issues associated with decking? One would only need to deck say 0.025" or so

 

I was wondering what rod and piston combo you were using. I have an earlier AMP 470 and its different than yours, 6.635 rod and 1.940 piston. Just doing a little checking. Thanks for all the info

 

I'm gonna cc the pistons Thursday, I'm curious to see exactly where they are. Then I'll drop em back in and check to see how far they are in the hole on more than one cylinder to verify rod length as sugessted bt JW.