Re: LT1

Hi Joe,

no numbers visible on the alternator pad, looks like the block has been decked. Are they repeated anywhere else or do I have to wait until I pull the sump to see if it's a 4 bolt. I have been told that LT1's had a forged crank, do you know if this is correct?

Thanks for your time

Mark

Bigjfig wrote:

Hi Milhouse,

did any of the truck engines have double hump heads? I know there are many possibilities, but there are a few things such as the alloy valve covers which look like the real thing, that make me wonder.

cheers Mark

Milhouse wrote:

Nah, none of them did. They just did one engine-per-displacement; instead of a 220hp 350 and a 280hp 350, it was just 292, 307,350, 396 (depending on the years, heh). Just read your other post where the block had been decked...if I were you I'd at least pull a valve cover and get the head numbers. It's a start, at least. :)

Milhouse

Both the LT1 and the 300 hp 350 had double hump heads. Possibly even the same casting numbers. The LT1's however were fitted with the 2.02" intake, and 1.60" exhaust valves. The passenger car motors had 1.94" and 1.50" valves. Lt1's were originally equipped with "pop up" pistons in 1970, which yielded a compression of 11 to 1. The 300 horse motors had flat tops. If the motor was rebuilt it probably had shorter pistons installed to accommodate modern lower octane gas. Lt1's came with mechanical advance only distributors, so there would be no vacuum advance hose. They also originally came with a Holley 780 cfm Vacuum secondary mounted on top of a Aluminum dual plane high rise manifold. If you have all these things you probably have an original Lt1. However we are talking about an engine that's been around for over 30 years. Many of these things could have been changed by previous owners. Hot Rodders are known for not wanting to leave anything alone. I hope this helps. - Gary

ASSUME it's a garden variety 350 and not a "home run". Buy as such. In that fashion, if and when it's not, then you won't be disappointed.

Ask the seller to prove it to you. Tell us what he claims. Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 26k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 141k and still going.... '80 T/A project car...

It was part of a package deal, An acquaintance was short of cash and offered me an unused set of alloy heads (Pro-Topline) complete with good quality valve gear. The price was pretty sharp, but when I was hesitant he threw in the 350 to seal the deal. As I was not keen on taking the Camaro off the road for longer than I have to (I love cruising in the old girl), the second motor gives me a chance to build something quicker than stock without messing up the numbers matching original unit. He made no claims at all about this 350, there are just a few things that made me wonder when I started really looking at it.

Mark

Bigjfig wrote:

Yeah, I'm going to lift a cover, curiosity is getting the better of me. Living way down here in New Zealand, Chevy info is scarce, so this newsgroup is a goldmine for me. :-)

Mark

Milhouse wrote:

Altough there is a chance they were not original, I've seen "double hump" heads on many vehicles, including trucks, from mid 1960's until