Engine Builders Advise Needed
Thread Starter
Drifting
Joined: Mar 2009
Posts: 1,461
Likes: 361
From: Monson MA
Engine Builders Advise Needed
I have a NoM 1968. I am doing a full restoration. The 327/350 will need a rebuild. I have asked a coulpe of shops for guesstimates (if thats a word) for the rebuild. Compression ratio comes up and I am told my two that the ratio should be dropped from 11 to 1 down to 10 to 1. Another says 11 to 1 will be OK. They all say I will need to run 93+ oct. in either case. My question is which path to go with: 10 to 1 or 11 to 1. I would like to keed it original at 11 to 1 but not if I will have to play with the timing and other adjustments to keep it running. My wife will be driving it when complete and I do not what reliability issues. I look forward to any input.
Thanks, Peter
Thanks, Peter
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
I would set it to the side and pick up a 383 but if that's not practical for you. Rebuild it with the correct pistons and cam. As long as your heads are fitted with harden seats they will be OK. Your compression can be backed off by installing a thicker head gasket. It's creap and easy to put back to stock if need be
Good Luck
Good Luck
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
You indicate NOT original motor (NoM) and it'll get driven ... so why sweat keeping an original compression ratio when a high ratio is likely to cause headaches?
Gas is crappy now; do you expect its quality is likely to improve? ... In future (but excluding E-85), do you expect hi-octane gasoline will be become more or less available?
Yours probably has iron heads ... suggest put scr at 10:1 OR LESS.
If you have 327 heads w/ about 64cc chambers ... a thin-shim fel-pro 1094 gasket & stock uncut deck and +thirty-over flattop piston will put scr right about 9.6 to 9.8:1.
a good hypereutectic flattop +30 327 piston is sealed power p/n H660CP30
a good forged flattop +30 327 piston is sealed power p/n L2326F30
Gas is crappy now; do you expect its quality is likely to improve? ... In future (but excluding E-85), do you expect hi-octane gasoline will be become more or less available?
Yours probably has iron heads ... suggest put scr at 10:1 OR LESS.
If you have 327 heads w/ about 64cc chambers ... a thin-shim fel-pro 1094 gasket & stock uncut deck and +thirty-over flattop piston will put scr right about 9.6 to 9.8:1.
a good hypereutectic flattop +30 327 piston is sealed power p/n H660CP30
a good forged flattop +30 327 piston is sealed power p/n L2326F30
Last edited by jackson; May 7, 2010 at 11:04 AM. Reason: miscalced scr
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
You indicate NOT original motor (NoM) and it'll get driven ... so why sweat keeping an original compression ratio when a high ratio is likely to cause headaches?
Gas is crappy now; do you expect its quality is likely to improve? ... In future (but excluding E-85), do you expect hi-octane gasoline will be become more or less available?
Yours probably has iron heads ... suggest put scr at 10:1 OR LESS.
If you have 327 heads w/ about 64cc chambers ... a thin-shim fel-pro 1094 gasket & stock uncut deck and +thirty-over flattop piston will put scr right about 9.6 to 9.8:1.
a good hypereutectic flattop +30 327 piston is sealed power p/n H660CP30
a good forged flattop +30 327 piston is sealed power p/n L2326F30
Gas is crappy now; do you expect its quality is likely to improve? ... In future (but excluding E-85), do you expect hi-octane gasoline will be become more or less available?
Yours probably has iron heads ... suggest put scr at 10:1 OR LESS.
If you have 327 heads w/ about 64cc chambers ... a thin-shim fel-pro 1094 gasket & stock uncut deck and +thirty-over flattop piston will put scr right about 9.6 to 9.8:1.
a good hypereutectic flattop +30 327 piston is sealed power p/n H660CP30
a good forged flattop +30 327 piston is sealed power p/n L2326F30
Cubes over compression for the future.
Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
Sounds like you are not hungry for more power. If all you want is a driver, I would stick the original engine in a corner and just put a basic crate 350 in. Paint it orange and nobody will be able to tell the difference except the accessory holes in the heads. $$ wise this will be much cheaper than all the work required to rebuild it and fix the heads for hardened seats. Last "stock" rebuild I did had almost $800 in heads alone with valve guides, seats, valve job, etc. If you do rebuild it, I would vote to drop compression.
Last edited by markdtn; May 7, 2010 at 12:27 PM.
Thread Starter
Drifting
Joined: Mar 2009
Posts: 1,461
Likes: 361
From: Monson MA
You indicate NOT original motor (NoM) and it'll get driven ... so why sweat keeping an original compression ratio when a high ratio is likely to cause headaches?
Gas is crappy now; do you expect its quality is likely to improve? ... In future (but excluding E-85), do you expect hi-octane gasoline will be become more or less available?
Yours probably has iron heads ... suggest put scr at 10:1 OR LESS.
If you have 327 heads w/ about 64cc chambers ... a thin-shim fel-pro 1094 gasket & stock uncut deck and +thirty-over flattop piston will put scr right about 9.6 to 9.8:1.
a good hypereutectic flattop +30 327 piston is sealed power p/n H660CP30
a good forged flattop +30 327 piston is sealed power p/n L2326F30
Gas is crappy now; do you expect its quality is likely to improve? ... In future (but excluding E-85), do you expect hi-octane gasoline will be become more or less available?
Yours probably has iron heads ... suggest put scr at 10:1 OR LESS.
If you have 327 heads w/ about 64cc chambers ... a thin-shim fel-pro 1094 gasket & stock uncut deck and +thirty-over flattop piston will put scr right about 9.6 to 9.8:1.
a good hypereutectic flattop +30 327 piston is sealed power p/n H660CP30
a good forged flattop +30 327 piston is sealed power p/n L2326F30
Team Owner
Joined: Jul 2004
Posts: 40,404
Likes: 791
From: Redondo Beach, California
A suggestion for a little more power. Put a crank for a 350 cubic inch engine in it. Of course a close inspection will reveal a balance weight on the engine crank damper and a balance weight on the flywheel. Solution? Have the crank internally balanced and use the damper and flywheel from a 327. No one will ever know.
Didn't the 350 hp/327 engine in 68 have a 10.5:1 compression ratio?
My vote is that 11:1 is a little high for today's pump gas. If this were a weekend fun car, you could use pump gas and a couple gallons of race gas with 11:1. For a no hassle, daily driver my vote would be for 10:1.
Didn't the 350 hp/327 engine in 68 have a 10.5:1 compression ratio?
My vote is that 11:1 is a little high for today's pump gas. If this were a weekend fun car, you could use pump gas and a couple gallons of race gas with 11:1. For a no hassle, daily driver my vote would be for 10:1.
Instructor
Joined: May 2008
Posts: 154
Likes: 3
From: Indiana
Twinpack, I have a numbers matching 68. 327 / 300 hp. When I rebuilt mine I did put a little more power into it by using newer heads and a cam slightly bigger than the 327 / 350 engine. I have 10.5:1 compression an it's fine but I wouldn't go any higher. As someone above mentioned, consider putting the numbers matching engine on the side (stored for the next owner) and build an engine you will have fun with. I don't race and I don't beat my car but I like to get into it now and again. It's never enough power. So if you are going to remove yout engine and rebuild, do yourself a favor and build it big the first time.
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