Piston Selection

[FreeBeeTony]

How's this for a piston to use on my Vortec rebuild?

​

 

[Scott Danforth]

do they come with rings? or is that the $49 extra?

if they come with rings, not a bad price.

did you call competition products?

 

[FreeBeeTony]

Rings are $49 extra.
Will call competition today....thanks.

Hope to drop the block and crank at the machine shop tonight.
Plan on posting a build sheet before I buys parts.

 

[alldodge]

Do note the compression listing at zero decking

You know there were several watching your engine build listing, adding another thread can only hurt by limiting those watching

 

[FreeBeeTony]

Compression says 9.6:1 w/ 64cc heads......is this too high?

Trying not to have too many topics under one thread.
Thought I would start a "Rebuild Thread" when I am all settled w/ parts and start building........not a good idea?

 

[alldodge]

Compression says 9.6:1 w/ 64cc heads......is this too high?

Note they are using .040 as the example and compression listing is at zero decking. Your plan was to use a thinner head gasket and .015 decking. This is their estimates. Need to look at all the numbers. Use the compression calculator to verify

Trying not to have too many topics under one thread.
Thought I would start a "Rebuild Thread" when I am all settled w/ parts and start building........not a good idea?

For the same reason that a question just happened here, if I would not have seen the thread the question would not have been asked. Will agree most long threads will not get many NEW folks looking at it, but keeping ones around that might bring something up. IMO all questions are good, some more then another. If you have multiple threads then you may also get the same questions asked again, but then again some may not pay much attention either, its your call and my opinion

 

[FreeBeeTony]

Looks like Jegs has the best prices so far for pistons, cam, springs and rings.

 

[Scott Danforth]

Compression says 9.6:1 w/ 64cc heads......is this too high?

Trying not to have too many topics under one thread.
Thought I would start a "Rebuild Thread" when I am all settled w/ parts and start building........not a good idea?

9.6 with vortec heads is fine. that is one of the magical things about the vortec head and the swirl effect.

you can even bump your base timing to about 12 BTDC at 9.6 with vortec heads

 

[FreeBeeTony]

Machine shop recommended something like below:

He didn't like the Keith Black pistons.
These Speed pro have a comp height of 1.548 and a volume of 5cc.
If I mil the deck 0.01 (giving me 0.027 deck clearance) and use a 0.025 gasket I will have a 0.052 quench and a comp of ~ 10.13:1. (I used a 4.04 for the bore).

 

[scoflaw]

wouldn't buying a short block for short money make more financial sense. 84 Grady doesn't sound like a race boat. Is it really worth the effort ? Time to kill, dollars to burn ?

 

[FreeBeeTony]

Hoping dollars are ~comparable.
Don't mind turning a wrench..........will keep me busy over the winter!

 

[alldodge]

I think the pistons will be fine, just note around 10 your looking at 89 octane

 

[scoflaw]

So to recap, you don't know the condition of your block, crank and rods, and you are shopping for pistons ? Can't review with all the threads you got going on, but remember you had your heads rebuilt ?

 

[FreeBeeTony]

Not buying any parts yet.........just shopping.
Waiting to hear from machine shop before buying anything.

 

[Scott Danforth]

make sure you weigh the speed pro pistons before you balance. what was supposed to be a matched set varied by 25 grams from low to high. they did replace the two heavy pistons, however that is my experience.

my last set of forged Wiseco slugs for the BBC were 1 gram difference between the low and high in the batch of 8

I would wait for the machine shop before picking slugs and I would get the tops cut vs going with 10.13:1 or find different slugs

if your crank and rods need love, you can get a stroker kit for less than touching your existing rods and crank.

 

[FreeBeeTony]

Had a conversation w/ the machine shop tonight re: piston selection.
​He was still pushing the flat top w/ 4 valve reliefs (~7cc volume)
​I was still pressing for the KB193 pistons LCQ w/ 12cc Dish.
​I think I made the right choice and went w/ the KB pistons........will give me the quench I want and still keep the comp reasonable (~9.6).

​I have learned a lot here......he seems stuck in the past.

​Plan on decking the block 0.010 and getting a 0.025 gasket for a 0.040 quench.

​The machinist seems to think I am wasting my time w/the quench.
​I don't have any experience w/ it.........going by what I have learned here which makes sense.

Any comments?

 

[alldodge]

I think your machine shop was in the right direction, and decking the block is good but maybe not so much down. Here is a very, VERY good read to consider: Start on post 17 by ICEDDPPL and read thru

https://www.offshoreonly.com/forums/general-q/350917-timing-vs-afr-vs-egt-2.html

 

[FreeBeeTony]

AllDodge Thanks, that was a VERY good read with some great info.......
But, if I went w/ the flat tops w/ the 4 VR I felt my compression would be too high.
After learning about quench and the LCQ pistons I decided to go w/ those.

During the read, I would say any engine could be prone to detonation or pre-ignition.

I hope I'm not making a mistake w/ the LCK Pistons........already ordered them.


These are the pistons........Jegs has them cheaper but didn't have a pic.

 

[Bondo]

After learning about quench and the LCQ pistons I decided to go w/ those.

Ayuh,.... Personally, I believe yer headed the right way, Tony,.....

With tight quench, detonation happens at much higher comp. ratios,....
But,...
It won't stop detonation from a lean condition,....
Care for the fuel system is still something to pay close attention too,...

 

[FreeBeeTony]

Thanks.
I did some more reading today and it looks like the top ring on these pistons needs a larger gap........that may be the reason for some failures.
My machinist said he saw some with the tops separated from the bottoms.