So I have a pile of parts that have been collecting dust and rust for several years and I think it's time to build up a backup engine for my 65. While yes my current engine is a 427 I still want to build up a fully dressed engine and have it on my start stand. If for no other reason than I'm bored or it would look cool or whatever it's something on my to do list.

This is what I have to work with;
Bare Block - 3959512 CE Std. bore large journal block w/ provisions for the lifter valley crankcase vent breather canister.
Short Block - 3970010 CE LT1 350 Std. bore (4-Bolt block, crank, rods, pistons)
Heads #1 - 3782461 original to my 327 300hp 65 Vette
Heads #2 - 3991492 Over the Counter angle plug with 2.02 /1.60 valves (heads came off above LT1 CE engine)
Intake - 3844461 Aluminum
Various L75 (300hp) and L79 (350hp) tin/brackets to include 2.5 exhaust manifolds.

I'm going to use the 3959512 CE block, 350 LT1 steel crank, 350 LT1 rods, 3844461 intake, 2.5 exhaust manifolds and engine will be dressed out to a 1965 L79. I'm "REALLY" ok with this build being a 300HP engine so if I ever do decide to or need to do a engine swap I want a engine that is mild cruiser. My gears are M20 trans and 3:36 rears.

What heads should I use, what pistons and what cam? For all intent and purposes will be a 350 cu In engine that looks like a 1965 327 350hp engine. The 492 heads have accy bolt holes.

Thanks for any thoughts you guys might have on this.

 

Since you want to retain L-79 appearance (and I assume performance characteristics) then use the L-46 cam with the 350 crank installed at the OE inlet indexing of 114 deg. ATC. Use the OE type 3911068/Sealed Power VS-677 valve springs and a truck replacement roller chain.

Look at KB pistons. Make all the measurements and use a CR calculator to target a CR of 10.25:1 if 93 PON fuel is available and reduce 0.1 for each point below 93. This should allow an aggressive detonation-free spark advance map.

The ...492 head castings were widely used as replacements for earlier big port, straight plug heads going back to the 461X. Are you sure they are angle plug? I'm not aware that they could be machined for angle plugs. I don't think that angle plug heads allow the installation of the OE heat and ignition shields. They were "off road" only, never installed on a production engine, so if they came off a LT-1 CE replacement long block, I don't think they could be angle plug.

If the heads have the standard valve size, I'm not sure if it's worth increasing to SHP size. You must also make the inlet unshrouding cut if you increase valve size, so the marginal increase in power may not be worth the increased cost.

Remember Taylor's Rule: Identical engines other than stroke will produce about the same peak power at about the same mean piston speed.

Duke

 

Thanks Duke

I could be wrong on the casting numbers of the 2.02 heads but they are angle plug heads. The back story on this CE LT1 engine, came out of a Vette I acquired in early 2005 and the prior owner got this car as a theft recovery with a missing engine in 71 or 72. He worked for a Chevrolet dealer and bought the CE LT1 long block and put it in this car so I can only assume the heads were part of this long block. Heads are in storage so I will have to re-verify the casting numbers but I do recall them being dated 1972 I think.

As for the ignition shields I will have to go dumpster dive my hard drive and see if I can find any old pictures I do recall some of the shielding being installed but not all of it.

Dennis

 

If I remember correctly, the 292 casting number head or the “turbo” head was an angle plug unit. Would be easy to get those mixed up. I guess I could Google that...

Edit: And I did. The all-knowing Google says the 292 head was angle plug, but consensus was the 492 heads were available either straight or angle. This I don’t know for sure. I have a set of worked 492’s on my ‘69 Camaro and they are washer seat, straight plug heads.

 

Ok mystery solved, the heads I have are 3991492 dated A 2 4 angle plug cast iron heads with 2.02 /1.60 valves.

3991492....70......350..........LT1,Came l hump,accessory holes,64cc, straight plug
or
3991492....70-up................over the counter,Camel hump,64cc, straight or angle plug

 

Pictures

 

I just checked my 2nd edition Chev. Power Manual, published circa 1975/6. It shows two finish machined heads from the ...492 casting...3987376, service replacement, straight plug and 336746, off-road, angle plug. I guess I just plain forgot that this casting could be machined for either plug configuration.

The "off-road" moniker for the angle plug version is because it was never emission certified on any production engine.

Duke

 

Angle plugs will allow all shielding to be installed. not really an issue.

 

That was my understanding, not that I ever did it. Obviously the ignition shielding would fit and even hide any lack of heat shielding, if not used or wouldn't fit. But it makes sense that the heat shields could be fitted as well.

 

Parts bin build of a sbc sounds like fun Mr. D. Soo many options it becomes difficult to decide on the combination. But my experience tells me that choosing the camshaft is something that needs to be done last after stroke, deck height, chamber size, piston dish are all chosen and the compression ratio is nailed.

It reads like you have already chosen heads, block and crank - most likely rods size too. So lets talk pistons and I like hypereutectic pistons because they seal so well, are light and can be very inexpensive though some are just as expensive as forged pistons if your not careful when choosing. A good place to start is the Sil-O-Vite catalog. Its takes some time to sort it out but the GM pistons are fairly well organized. Page 70 has Gen II flatop hypers (will still work in Gen I sbc and are light) with 7cc valve reliefs and 1.54" compression height under part #1489HC (hyper, coated) for $170 (Summit racing). Also a "tighter" hyper under part #3437HC with 6cc reliefs and a 1.56" compressed height for $180 (Summit racing). If you need a larger dish then I would shop Speed Pro as they have better prices on the larger dish hyper pistons.

So to get things started I would target a 9.5 or less static compression ratio and see where the build takes you from there.

Hope this can help.

 

My 357 with angle plug Phase 6 Bowtie heads sports the factory ignition shielding, and the plug boot heat shields below the ramshorns, with no problems.

 

I don't know what your intended usage is. I would use the 492s, big valves, screw in studs, hardened exhaust seats integral not pressed in. You could use flat top cast pistons and have close to 10:1.