455 1975 rebuild w factory iron heads

Hi Guys,

First of all, as I’m new on this forum I would like to say hello to everyone.

I’m doing a full rebuild of BBB 455. Unfortunately/fortunately it’s from 1975 so cylinder heads have large combustion chamber, i.e. 76 cc if I’m not wrong. I'm using ARP bolts, TA parts for oil pump etc.

What I would like to get is some decent power (definition is quite relative) so something close to 300-350hp. Anyway this engine will rest in a car which will be used for cruising, so good runner is what I’d like to get.

I know that the easiest/best way would be just to buy cylinder heads with smaller combustion chambers… but for now I’d like to stay with factory cast iron heads from 75 as shipping of such heavy parts from US is pretty expensive and my heads are already at machinist... My engine currently have CR 8:1.

Despite new cam, which I think will be 212 TA or at worst 112, I’m stuck with selection of aftermarket pistons. I’ve found post of Derek (http://www.v8buick.com/index.php?th...r-is-there-a-better-year.314594/#post-2617519) who said that flat top pistons with stock 75 heads could be something for a good runner and I’d like to try this direction.

TA performance have cheap pistons (1607) which are adv. as 8.5:1 and 10:1 CR. I’m waiting for their answer on dish volume of the latter one but I’m pretty skeptic and don’t expect anything lower then 20-22cc. Alternatively, I could use Wiseco PTS543AS (https://www.cnc-motorsports.com/pts543as-wiseco-flat-top-pistons-12-2-1-4-313-bore-buick-455.html) pistons which have only 8.43 cc of dish volume. This could at least in principle shoot CR up to something around 10.1:1. Those pistons are manufactured in two sizes, i.e. std and .04 (resulting in 464). My cylinders have pretty small wear, but everything is up to the machinist, how much material he will need to take out to make them perfect. I hope it will be just minimal touch but can happen that I will need to buy larger pistons. I think that going to 40 overbore could be too much as this will be engine for cruising and should last long. Moreover, engine was running fine before rebuild so I’d like to save some founds and not go to sonic check.

I could also cut heads by something around 0.04 and put TA pistons…


What do you guys think about it? Will it work with Wiseco pistons? or cutting heads would be a better solution?

Any advice is much appreciated.

Here in Poland (Europe) it’s impossible to find someone who knows anything about Buick engines.

Maciej

 

Welcome from NY,I'm sure somebody will chime in to give you some good advice about what to use with what.75-76 heads are not really that good for performance,personally,as you stated,steel heads are very heavy,but Elderbrock head are much lighter then steel or TA aluminum heads,but for usage here I do prefer TA heads.Bruno.

 

Those wiseco piston using a .04 gasket and 76cc heads sitting .020 below deck will net you about 10.5:1

I have them in my 464......4.350 bore..... .038 over bore.....this is very common size in the buick world, gets you to a better selection of rings.

I wouldn't have any issues using them......just don't put them in with too much clearance they can be noisy that way.

There are "better" choices out there but for the money see ing they come with rings and pins and your not looking to get max compression they could fill the void in your compression and be friendly to wallet.

They are 4032 material I believe, which I feel for a street setup is a better choice as it doesn't expand like the more purer 2618 does.

But that is just my opinion

 

We have a good number of Europeans on this Board.

 

You do have “The Cannibal” a Buick parts person, in The Netherlands.

https://www.buick-riviera.com/RickBax.html

 

Thank you very much for all answers.

I will probably go with the wiseco pistons and 38 overbore as suggested by Ben.

Thank you Larry for advice. Truly speaking, I don’t think that I will ever switch to aluminum heads. Wiseco pistons will seat about 0.03 below deck but it’s not yet measured. Depending on the straightness of the block maybe it will be milled, if yes, I could cut this 0.03 easily and quite cheaply.

 

Keep in mind that drastically cutting heads or block can cause intake fitment issues, and require new pushrod lengths to be determined

 

What size overbore is too large? Or better put, what's the minimum wall thickness to sustain a long-lived block?

I've heard stories of folks saying blue blocks are thicker-walled, but after reading Jim's take on this there seems to be no real trend. Apparently my 70 block with Jim was 40 over from some time ago, and he commented on how thick the walls still were, but I have no idea how thick is thick enough, or too thin.

Do folks with boost experience have any take? I thought the more general take was to keep compression down due to forced induction, but unsure about wall thickness considerations.

 

Thanks, Larry - thought I perused that thread enough but seems not fine enough.

Sounds like Jim likes .140+ on pin sides prior to boring, but likely tough to find that block, and certainly no less than .100 before boring. I guess we'll see what mine spec out to, and go from there!

 

Thanks guys. So I’ve decided to do a sonic check of the block and I would like to share results with you. Maybe they will be helpful for someone.

Results (minimum obtained values) are given in the following order: major thrust side, minor thrust side, front (of the block) pin side, rear pin side.
cyl. #1 0.213 0.242 0.209 0.193
cyl. #2 0.197 0.310 0.219 0.160
cyl. #3 0.248 0.252 0.130 0.191
cyl. #4 0.230 0.301 0.174 0.141
cyl. #5 0.256 0.248 0.138 0.154
cyl. #6 0.252 0.299 0.192 0.114
cyl. #7 0.232 0.244 0.161 0.232
cyl. #8 0.248 0.241 0.209 0.213

What is worth to note is that the minimum value for major thrust side (cylinder #2) is 0.197 and minimum for rear pin side (cylinder #6) is just 0.114. Those numbers are pretty satisfying especially that this is the block that I have and need to live with. However, what is worth to mention about the sonic check is precision. I’ve got gauge which has an accuracy of +- 0.1 mm (0.004”) + some deviation due to the user. I did several measurements going through the whole block again and they were pretty repeatable.

Now I need to decide if to go with 0.038 overbore + wiseco pistons, which can give me min. thickness at the pin side of 0.091 (including possible deviation due to measurement accuracy). Or to go with TA pistons with overbore of 0.02 and CR 10:1 (TA1607). I’ve found that compression height of those pistons is 1.997, while still, I’m waiting for answer from them on dish volume but should be something around 22cc. With the Wiseco pistons I could go to CR 10.4:1, while with the TA assuming their volume of 22cc to around 9.4.

Ben mentioned that those Wiseco pistons can be loud with too large clearance and I’ve found that JW had an issue with their wrong (too low) diameter resulting in too lose clearance and making them loud.

What do you think about using TA pistons? How drastic performance drop vs wiseco pistons you would expect from them? Just to mention that the engine will be put into Riviera 72.

Using the opportunity, I would like to ask you about an opinion on the timing cover. I’ve inspected it and found some pittings/scratches at the inner surface of oil pump (see attached image). What generally, you would do with it for a street engine (with not high hp)? Replace with TA cover right away? or give it a try? Obviously, I will have a new pump with booster plate, regulator and shim kit. I didn’t check the oil pressure before tearing down the motor but there was no signal (lamp) indicator of low oil pressure at idle (I don’t know what is the threshold value at which it should turn on).


Thanks a lot!

Maciej

 

Maciej I have those pistons in my motor Jim is right on.The first build they were ok after the 2nd time around maybe a little to much hone they are loud when its cold. In summer they are not to bad, to do all over again I would have used something else. hope this helps