Rebuild 327 365hp

[Mike L.]

I was just told that I couldn't get my 327-365hp matching numbers motor rebuilt to spec because the compression would be too high and I would need to run it on aviation fuel. Is this correct?

[Patrick H.]

Re: Rebuild 327 365hp

No.
Find a new engine builder.

[Leif A.]

Re: Rebuild 327 365hp

As Patrick stated...get a new engine builder. When I rebuilt my L79 327/350hp, I used pistons that slightly raised my compression ratio from stock (Keith Black hypereutietic pistons). Never any need for any fancy av gas or racing fuel. I run Chevron 93 octane and never have an issue with detonation or pinging...runs terrific!

[Mike L.]

Re: Rebuild 327 365hp

Thanx Patrick!

[Mike L.]

Re: Rebuild 327 365hp

Thanx Leif, I'm already on it!

[Jimmy G.]

Re: Rebuild 327 365hp

There is some truth in what he told you. It will run but not at peak levels. Unless you are going to race it, I would recommend lowering the compression about a point. With that 93 Ethanol (heaven forbid) will work all day long. Ask another builder than make up you mind.

[Michael J.]

Re: Rebuild 327 365hp

I had my original '64, 33K mile, L84 rebuilt to factory specs and have not had any problem with it. I run 90 octane ethanol free gas in it. I am at 7000 feet, so the need for higher octane is not present here and that offsets some of the high compression in the SHP engines, but even when I take it to the low country, like Texas, it runs great, I just have to set the idle down since there is so much oxygen at those low altitudes vs. where I tune it.

[Patrick B.]

Re: Rebuild 327 365hp

I would certainly use modern composition head gaskets because they a better head gaskets, but they also have the benefit of lowering the compression slightly because they are about 0.040 thick instead of about 0.020 for original steel head gaskets. I think sealed power still sells the original TRW type forged pistons for 11:1 327 engines. Bear in mind than an over bore raises the compression so the composition head gaskets would offset an over bore.

[Daniel D.]

[Richard G.]

Re: Rebuild 327 365hp

When I rebuilt me last motor I too thought I would raise the compression with the overbore. And that would have been true if the piston manufacture hadn't lowered the compression height on the piston. (Sealed Power)
Evidently to account for blocks that have been decked.
I recommend reading the small print and watching the compression height closely.

[Duke W.]

Re: Rebuild 327 365hp

I've consulted on a number of 327 rebuilds. For all mechanical lifter engines I recommend the LT-1 cam. The connecting rods are weak and should be replaced. The Eagle SIR 5700 is a good choice and a set is only about $250. It's the least expensive insurance policy you will ever buy.

The OE type replacement pistons, L2166F will typically yield a CR of close to 10.5 depending on deck height, which is a BIG variable, and head gasket thickness is used to "tune" the CR into the target range. For about half the price the Keith Black KB157 will be a few tenths lower with the same gasket and will allow an aggressive spark advance map even on relatively low fuel octane, like California 91 PON.

Massaging the cylinder heads will increase peak power about ten percent, peaking at about 6500 with a little rolloff to 7000 and a valve train limiting speed of 7200 with properly setup OE valve springs.

I'd be happy to discuss with you... best to do by phone... late afternoon/early evening Pacific time. I turned of the message machine due to all the junk calls, but I'm usually around.

Duke
310
327
5527

[Mike L.]

Thanx Jimmy!

Thanx Michael.

Thanx Patrick.

Thanx Daniel.

Thanx Duke. I'm no mechanic but everything you said makes sense!