View Full Version : 350 piston in a 327?

01-14-2009, 11:49 PM
Trying to find a suitable set of pistons for my little 327 combo.

63 vintage 327 block, current virgin bore, most likely to be bored to 0.030".

Stock ground 0.010 327 steel forged crank, 5.7" SJ H beams.

63cc 462 Fuelly heads with 1.94" and 1.60" valves, bowl and short turn ported and deshrouded inlet valve.

Chasing 8.5:1 or less compression to suit my vintage 6/71 GM blower running 10psi. Topped with a modded 850dp, covered by a garlits Enderle type scoop. Should look bitchen and make solid 450+hp

Trouble is, low comp 327 forgies are really thin on the ground here in Australia, and even hard to find online. So I was wondering if I could run a 350 type Hi-Comp or flat top piston, and mayber deck the block 0.050".

Anyone tried a 350 piston in a 327?

I think I can make it work at the top of the bore, but worried about the piston falling out at the bottom of the bore or hitting the crank.

Anyone...? Anyone...? Stories? Failures? Sucesses?

01-15-2009, 12:09 AM
The difference in compression height between these two engines is over .100, so decking the block .050 still leaves you with too much deck height to give you any realistic compression. Trying to find pistons for these older engines used is getting harder all the time. I can just imagine your problems in Oz. You can always step up to the pump and order from Jegs or Summit as an alternative.....

01-15-2009, 12:54 AM
My compression calculator says with a -4cc piston, 0.100" down the hole, 8.0:1, so with a small lump, 8.2:1 could work out not too bad for comp.

I can get a set that works, out of Summit for around $850ish. But i dunno, my locally available hardcore 383 pistons are barely half that, weigh less and are a heap stronger, so I guess its the stubborn arse in me that wont open my wallet that far yet, for just a piston.

01-15-2009, 01:00 AM
check out PAW, I'd bet they have 327 pistons for a reasonable sum.

01-15-2009, 07:56 AM
I'd look in a Chevy dealer parts catalog, people laugh, but they carry a load of good performance parts at the right price most of the time.


01-15-2009, 08:06 AM
Using a 327 dished piston with a big chambered head is better. It will ping like a popcorn popper that far down in the hole. Try to keep it coming up within .010 of zero deck and use a .030 gasket. With a big chambered head and a dished piston you should be down in the low 8:1 range. KB makes a dished 327 piston. The blower is going to make up for the "lesser" heads.

If you aren't running more than 3-4 lbs of boost, a Chevy cast piston will live with good gas and a tight quench. All cast pistons are not created equal though. The factory ones have steel reinforcing struts that alot of "rebuilders" don't. I wouldn't doubt that GMPP still stocks the dished 327 cast truck piston. The 327 needs popups to get over 10:1 as it was with 63cc heads. A flat top motor wasn't but barely 9:1.

Shifty Shifterton
01-15-2009, 08:17 AM
Are you hung up on using the old heads?

Buy aftermarket heads with larger chambers and even better runners. Use cheaper pistons. Sell old heads to offset cost. End up running harder and spending less.

Better heads would also let ya turn down the boost and get equivalent power, thus being nicer to parts and easier to tune & find fuel

good luck

01-15-2009, 08:28 AM
Like BillBallingerSr said, mis-matching components like that is just going to open up a big 'ole can of worms that will cause more headaches than anything.

Droping the slug that far down the hole will cause the piston to loose it's quench. You will also loose swirl causing un-even burn which will cause serious carbon buildup,,, resulting in hot spots and ping.

I understand where your trying to go here, but if the 327 pistons are seriously that much of a problem for you, it might not be too bad of an idea to moth-ball your vintage motor and buy/build a belly-button 350 with cheaper off the shelf parts.

01-15-2009, 08:29 AM
Are you hung up on using the old heads?

Buy aftermarket heads with larger chambers and even better runners. Use cheaper pistons. Sell old heads to offset cost. End up running harder and spending less.

Better heads would also let ya turn down the boost and get equivalent power, thus being nicer to parts and easier to tune & find fuel

good luck

AFR or World Sr's in the 200-210 port range would be good, I haven't looked in awhile, but I think they offer a 72-74cc head. Much better solution. Someone with a '63 Vette would like to have those heads, I bet it would probably wash all said and done.

motor mikey
01-15-2009, 10:00 AM
I checked my speed-pro catalog and they make a 327 blower piston that is forged. Only problem is that it uses a 5.80 rod. Also could use a 5.85 rod will work with either. should put you around 8-1 cr.

Shifty Shifterton
01-15-2009, 11:56 AM
The reason it uses a 5.8 rod is it's a 350 piston designed around a 5.7 rod. Sounds like the same piston he's asking about, more or less

01-15-2009, 12:28 PM
Contact ( Tell the customer service rep. exactly what parts you have and what you intend to use the engine for and they can make exactly what you need. You already have a steel crank and aftermarket rods so the custom pistons are all that you need. They might have a shelf piston that is ready to ship.

01-15-2009, 12:28 PM
Speed -Pro pistons are made in India now, and they are junk. Last set of new Speed-Pros my nephew got for a customer project, he said they looked like they had been machined by an 8 year old with a machete, chattermarks, the pin boss wasn't even straight. Mocked it up with one and it was .002 crooked front to rear on the pin axis. They use KBs nowfor mild builds, Ross or Wiseco for the high end stuff.

Von Rigg Fink
01-15-2009, 12:49 PM
wow i had no idea that 327 pistons were so hard to find...
Ive got 16 of them
8 of them are in use:cool:
but the other 8 are K.B. Hypereutectic Pistons still in the box:D:cool:

probably more than 10 years old and never been used

01-15-2009, 01:21 PM
Use a Forged 350 Flat top piston . Been there, done that, many times.Be sure the piston uses the stock ring groove.
I know it's hard for you guys out of the country to get parts but the blower will like a set of 202 valves. Try to stay with a long duration cam but mild /low lift cam. Isky makes some really nice SB blower cams.If you do decide to go with new pistons, "Probe" makes a reasonablly price piston for your application. Paul

01-15-2009, 01:34 PM
Oh Yeah I forgot to say. I like to run 7.5 CR on my blown motors... it just makes them easier to tune. Paul

Unkl Ian
01-15-2009, 01:37 PM
Anyone tried a 350 piston in a 327? has 327 pistons.

01-15-2009, 05:50 PM

Didnt think that many people would be interested.

Pretty keen to keep my fuelly's, they are period and in really good nick. Cam is a fairly fat solid for a little motor, 242@0.050 110*centres. Actually, lobe centre might still be a little tight for the blower. Planning on running 10psi ish.

Paul: Not quite sure, Have you run a 350 piston in a 327? Did it work?

Definately want new pistons. I think I will just buy the dish top 327 forgies from summit, dont want to shell out for them, but I think it will save the headache later.

Whats the probe piston? I dont have a probe catalogue handy.