Piston/ block choice

I know this has been asked many time, but searching the archives I couldn't find a good answer. I got three blocks, a 455 already .030 with light rust, a standard bore 430 and a standard bore 455(1970).Its for a 69 stage one, don't have the original block or trans so number matching is not a option, trying to decide what block and what pistons to use. It will just be a street car, but the heads I have are ported cast iron with stage one valves. I was concerned about valve shrouding if I use the 430 even bored out . I have a old spx2 cam, aluminum intake and holley 850 dp. I had ran this combo in a street/ strip car with the wiseco pro tru and it was stout, but I do not have any experience with forged pistons like the speed pro- Any thoughts, prices, where best to buy pistons , etc...

 

I'm going to ask the machine shop,but I think the one with light rust will have to be bored again. I trying not to go to wild with a 470 or more for the street. This car is going to be driven alot

 

Most forged pistons (Not Speed Pro) are .038' over so the .030" over block gets bored again anyway.
Have both 455 blocks sonic checked for cylinder wall thickness and use the best one.

The best priced forged piston and ring set is Autotec.
http://www.buyracingparts.com/pisto.../autotec-455-buick-forged-dished-pistons.html

The TA_1611B Spherical dish pistons are also a good choice

Speed Pro pistons are heavy and the quality control is not so good.

 

The speed pro's have been made off shore for many years; I sent a set back about 4 years ago because their weights were all over the place and finish was bad. I ultimately used the Weisco Pro Tru, +038 bought on line for about 600 bucks with rings. Used stock rods prepped well and I think that combo is fine for the street. I used a mild TA cam, new stock rockers and spent some money on iron heads with a stg 1 conversion and mild porting. Its in a 36 ford, and is plenty for the street. The car is stupid fast and I race a low 10 second drag car so my seat of the pants dyno is accurate. Don't get carried away and spend 10K. You can make plenty of torque with a mild combo with decent head work and that's what you need for the street. Just my 2 cents.

 

Thanks for the info everyone, going to the machine shop tomorrow and discuss with them. Ill probably stay away from the speed pro and maybe go with the wiesco again

 

I hate to pop bubbles but Diamond, JE, Wiseco, and a couple of other companies just got bought out. :-( Gib-Tech pistons is what I would opt for.

 

What is your personal experience with Gibtec? How many sets have you ordered?

 

Sold more recently than April, 2017?
https://performanceracing.com/news/...cquires-diamond-pistons-and-trend-performance

Sounds to me like the company that owns JE and Wiseco (and others) bought Diamond more than a year ago.

 

464,470,482 all are a 4.350 bore. being .030 now you can get to .038 with just hone, its alot of hone, but to setup bore then hone might be more.

I have protru in my race motor it's in the 725ish hp area. maybe a touch more. you can find them online for around 450ish with rings. stk rods will work for what your doing but figure total cost including rod bolts b4 opting to redo them, you can get molnar plug and play for a little over 600......super nice part.

make sure the bottom end in square, well oiled. depending how well the heads flow will be the key. the true honest hp from a 464,470,482 will be minor at best. the big benefit to the later combos is getting super close to 0 deck without having to cut the block alot which saves alot of backdoor hidden unexpected machining to get the heads and intake to line up correctly.............but a piston sitting at 0deck for a street motor isn't a major concern, especially with iron heads since you have to worry about knocking. the aluminum heads will run more compression on the same octane with less knock and detonation.

there are some thing that need done and some your ok to save some money on for a street motor. but you need to make sure the block, crank, and rods you have are good pieces to start with first, then select the rest of the parts after you know where they stand and what is needed to get you what you need/want

 

I don't care about selling anyone pistons, but I have to comment here..

Deck clearance with an iron headed engine, with optimized pump gas compression (around 10-1) is critical. More deck clearance makes the engine more likely to detonate, and the smaller the cam is, the worst this gets. "zero deck" does not have a major influence on HP production (it's about 10HP per .010 in the hole) but it has a major impact on a combos detonation resistance. I learned this the hard way over the years, cost me thousands.. don't make the mistake of trying to "save money".

Pistons for a stock rod/stroke combo, with compression distances less than 2", are simply the wrong parts. Been that way for 40 years now. Monkey see- Monkey do engineering is how we got pistons with those specs in the first place.

Buy the correct parts for the job. I believe TA has an offering now with the correct Compression distance, or you can order them direct from Auto-tec, or call me if you need help figuring it all out.

JW

 

I know if a piston sits too far down like how the stk 75 pistons did it cause issue. but I guess I didn't know the closer to 0 you get the less chance of knock you have?

 

Yup, neither did I, till I got an expensive lesson on the Buick 455, and part throttle detonation with excessive deck clearance. You have to run very little initial timing, and an extremely slow advance curve to avoid it.

The more "mild" the entire combo is, the worse this is. Low HP engines, with tight converters and low numerical gear ratios put a lot more strain on the motor at part throttle, where detonation is most likely to occur.

JW

 

This is a very intereating subject.
My 455 is .040 over for 4.35 bore.
Speed pro pistons from 10 years ago.
Piston I think .050 in hole.
Calculated compression was 9.3 to 1 w the 10.0 to 1 pistons so far down. 1973 heads. Small valve.

 

I have had slight detonation at times.
Where is best investment to save my engine.
It runs well and have a new quadrajet power carb to put on.

 

That is simplest step.
Thanks man.