I recently bought a 400 small block engine bored out 30 over. I have the complete engine, even all the new parts I need to reassemble it. I got it for $800. I feel it was a good deal. All the machine shop work was done by the other owner. Boring, honing, etc...even had the heads rebuilt with new valves. Crank polished...Block was cleaned and magnifluxed...new bearings, freeze pugs, gaskets...etc.etc. Well, you get the idea. EVERYHTING was done.
He even had new pistons put on the original rods. However, he had dished out pistons installed that will only put out a lame 7.5:1 or 8:1 compression. I just bought a new set of flat tops that will bring it to a more respectable 9.75:1 or so.
This is my question:
I called a machine shop and asked if they would remove the old pistons and install new ones on the original rods. The guy told me to save my monew and just heat the rods with a torch and tap out the old pins holding the piston in place and then reverse the process and "tap" in the new ones. i had been told that this procedure is a no-no...they NEED to be press fit to avoid damaging the rods..
Is he right?...is it possible to heat and tap them out..I am skepticale and would like othe ropinions...thanks.

My 406 SB has something like -22 dished pistons with the 45 degree chamfer around them and 64 cc heads now that I took my old -461 big valve heads off that were 66 cc's and my CR. was like 9.5 with the -461's.

You MUST be running 76 to, and I think GM even made 80 cc heads, get that low a CR.?????

pdq67

That should be done by a machine shop and when you have them of check the pistons for weight to make sure they are the close to the same weight and while the pistons ore off check them for bend and twist as we see alot of shops that do not do this procedure which I think is very important area to look at.

I recently bought a 400 small block engine bored out 30 over. I have the complete engine, even all the new parts I need to reassemble it. I got it for $800. I feel it was a good deal. All the machine shop work was done by the other owner. Boring, honing, etc...even had the heads rebuilt with new valves. Crank polished...Block was cleaned and magnifluxed...new bearings, freeze pugs, gaskets...etc.etc. Well, you get the idea. EVERYHTING was done.
He even had new pistons put on the original rods. However, he had dished out pistons installed that will only put out a lame 7.5:1 or 8:1 compression. I just bought a new set of flat tops that will bring it to a more respectable 9.75:1 or so.
This is my question:
I called a machine shop and asked if they would remove the old pistons and install new ones on the original rods. The guy told me to save my monew and just heat the rods with a torch and tap out the old pins holding the piston in place and then reverse the process and "tap" in the new ones. i had been told that this procedure is a no-no...they NEED to be press fit to avoid damaging the rods..
Is he right?...is it possible to heat and tap them out..I am skepticale and would like othe ropinions...thanks.
=
No, you cannot heat them to take them apart.
With press fit rods you do not heat them to remove the pins, you press them apart.
You do heat the pin end of the rod to install the new pistons though.
I know of no machine shop that would consider pressing the parts back together anymore.

That said unless you have done it a few times I would highly suggest you do not practice on the parts you are going to run.
As Carl said, take them to another machine shop than the one who gave you this "advice" & have them installed correctly.

Yep, I agree 100% with Mike above!!!!!!!! :thumbsup:
Also, which heads are you going to use? If they are heads with combustion chambers around 64cc, you will be just fine on pump gas. But with 76cc heads, you will be happier with flat tops. ;)

I appreciate all the advice...You confirmed my opinion on it...gonna call somebody else to have it done.
the heads are 76cc's...that is why i went to the flat tops. With that size head and dished out tops, the compression wouldn't cut it.
thanks again

22cc of dish on a 64cc headed 400 is 9.78:1, not sure about flats probabaly higher than you think.

UM ,Mike ,heres what you posted on your 406 dyno question:
406 SBC
KB 22cc dish pistons zero decked, 64cc heads static comp @ 9.78:1

So which is it 9.78:1 on a 406 or a 400 ??

He didn't say if he was 0 decked or not.

I sure hope nobody follows the crap they've been showing on Horsepower TV these past few weeks, although it is entertaining to watch.

Nothing like using a torch to get the rods glowing red before installation, never mind doing the same to the crank sprocket. :rolleyes: What a bananahead that socalled machinist is.

Personally, I cannot believe there is a machine shop left on earth that would even think about recommending something like that :(

I recently bought a 400 small block engine bored out 30 over. I have the complete engine, even all the new parts I need to reassemble it. I got it for $800. I feel it was a good deal. All the machine shop work was done by the other owner. Boring, honing, etc...even had the heads rebuilt with new valves. Crank polished...Block was cleaned and magnifluxed...new bearings, freeze pugs, gaskets...etc.etc. Well, you get the idea. EVERYHTING was done.
He even had new pistons put on the original rods. However, he had dished out pistons installed that will only put out a lame 7.5:1 or 8:1 compression. I just bought a new set of flat tops that will bring it to a more respectable 9.75:1 or so.
This is my question:
I called a machine shop and asked if they would remove the old pistons and install new ones on the original rods. The guy told me to save my monew and just heat the rods with a torch and tap out the old pins holding the piston in place and then reverse the process and "tap" in the new ones. i had been told that this procedure is a no-no...they NEED to be press fit to avoid damaging the rods..
Is he right?...is it possible to heat and tap them out..I am skepticale and would like othe ropinions...thanks.

To give an answer anywhere near accurate we need more information.

What is the measurement from the deck to the top of the piston?
How thick is your head gasket.
Accurate measure of dish in the pistons.

I agree with Tom; a 406 with "stock" dish pistons and 64 CC heads will give you a compression ratio that you will be happy with.

Flat tops with 4 valve relief, .025 deck height and .040 head gasket and 64 cc heads yield about 11:1.
Same setup with 76 cc heads, 9.78:1.

Dish pistons, .025, .040, 64cc, 9.1:1.
Dish pistons, .025, .040, 76cc, 8.1:1.

The actual numbers will vary depending you your actual deck height and head gasket used.


Verle

To give an answer anywhere near accurate we need more information.

What is the measurement from the deck to the top of the piston?
How thick is your head gasket.
Accurate measure of dish in the pistons.

I agree with Tom; a 406 with "stock" dish pistons and 64 CC heads will give you a compression ratio that you will be happy with.

Flat tops with 4 valve relief, .025 deck height and .040 head gasket and 64 cc heads yield about 11:1.
Same setup with 76 cc heads, 9.78:1.

Dish pistons, .025, .040, 64cc, 9.1:1.
Dish pistons, .025, .040, 76cc, 8.1:1.

The actual numbers will vary depending you your actual deck height and head gasket used.


Verle

Does anyone pay attention to when these questions were asked & answered :D

Look at the dates,, these questions were asked well over a year ago,,
Plus the original poster already stated which heads he had,..
Again a year & a half ago,, ;)

Doh !!!!!!!

Mike and Bill,

My 406 short rod TRW pistons have the really deep dish w/ I think shallow 4-notches and a great big 45 degree chamfer around their dia.

This is the -22 cc dish 406 piston, isn't it?

I've got their TRW part number squirreled away out in the garage somewhere??

pdq67

Mike and Bill,

My 406 short rod TRW pistons have the really deep dish w/ I think shallow 4-notches and a great big 45 degree chamfer around their dia.

This is the -22 cc dish 406 piston, isn't it?

I've got their TRW part number squirreled away out in the garage somewhere??

pdq67

Sounds like it but a number would help :p

I have a listing for a TRW L2352F with a .083" dish 4vr having 14 cc's volume. Dunno if that's the piston PDQ is talking about.

Funny how a post can pop back up and I'll just ASS-U-ME that it's current LMAO. My point was valid about the HP TV wizard bringing the rods to near melting point before installing the piston, YIKES.