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Rebuilding a 300HP 327

Bo Dillingham

Well-known member
Jun 23, 2001
Cortland, NY, 13045, USA
1965 crimson pearl (2002 cadillac?)
It is my intention to rebuild the 300/327 in my '65 over the winter. I do NOT intend to set a new land speed record, nor do I intend to build a show car. What I want is a reliable street machine a little hotter than the factory made it.
My own personal choice for carburation would be a Holley Spreadbore, but I could be convinced otherwise by the right argument.
What I am looking for is either a list of recommended parts (Cam, lifters, rings, bearings, intake manifold, carb, exhaust headers) or perhaps a kit that contains the whole setup (or nearly all of it). The catalogues that I have recently collected show some rebuild kits, etc. but You guys (and gals) have been very patient and helpful to me so far, so I trust your information more than others.
Thanks again,


Do you know what your cruising rpm will be at 55-65 mph? What is your rear end ratio. I have some good ideas on camshafts if I know this. Your carb choice is a good one and will give you good all around drivability and throttle response . An Edelbrock Performer intake would be a good match.

If your crank and rods are good I would have them reconditioned and use them. They will be fine for a mild street engine. You can't beat Clevite 77 bearings also. Silv-O-Lite hypereutectic pistons are a very good and economical choice. They are stronger and more stable than cast and much lower priced than forged or many other hypereutectic pistons. Speed Pro or other quality moly rings and ARP rod bolts and other fasteners should be used throughout. Don't use old main and head bolts. Also spend the money for a quality timing set such as Cloyes Tru Roller.

As for heads. if your stock heads are good and you don't have any problem buying gas in your area that the 10.5:1 compression likes, use them. I would suggest hardened exhaust valve seats for unleaded gas and new valve guides with a high quality valve seal. Options would be to mill the rocker stud bosses for screw in studs and guide plates. Or you could tap and install screw in studs without the hex on them at home. Then you could use the self aligning rocker arms from GM Performance Parts and not need the guide plates or the machining operation. Other options would be to have the ports matched and the bowl area under the valves blended to unshroud the valves. This will make a difference in performance. If you want to drop compression a little for fuel concerns use a thicker composite head gasket. It may drop by 1/2 to 1 point. GM part # 3927142 is a good all around performance valve spring that doesn't require any special machining. Cast roller tip rockers will require guide plates and poly lock rocker nuts with the set screw won't fit under Corvette valve covers.

I recommend the needle bearing pilot bearing GM part # 14061685 and a high volumn oil pump.
like GM 14044872 with a brazed on pickup.

Convert your stock distributor to electronic or use a HEI if it fits the firewall and add on a MSD6A box. You will see a big difference.

I may have missed a few things but this will get you a good street/cruising engine without spending a bunch on high profile parts that won't fit the profile of a mild performance engine..


p.s. I'm going to go ahead and recommend a cam based on what I have said above and a 3.36 to 3.70 rear gear. It is GM Performance Parts camshaft and lifter package (mfg by Crane) part # 12353918.
12353918 - Camshaft Kit Price $136.75

All "marine" and off-road small-block Chevy V8. Compression ratio 8.75:1 to 10.5:1, 2600-3000 cruise RPM, basic RPM range 2000-4500 RPM, 6500 RPM attainable with proper valve springs and lifters.

Technical Notes: Kit contains one camshaft and 16 tappets. These are hydraulic flat tappets.

Duration@.050" Lift Intake 214 deg exhaust 224 deg;
Lobe Centerline 112 degrees
Lift intake .442" exhaust .465"

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