Ok Im not to sure about this and I only thought the LT1 was a 350 but here is what someone is saying

gm made the 4.3 and a 3.90 bore 305 that was lt1 style that cam in roadmasters and caprices. aries motor came out of a 95 roadmaster because i went with him to get it. it is a "w" code motor and the bore was measure when the headgaskets were changed and cam installed. still has the stock iron "w" code heads.


Any detail on this one guys?

 

It was not a 305. It was a 265 CI (4.3L) called the L99. It had a 305's 3.74inch bore but the short stroke of a 327. A 305 is 5.0L, not 4.3. General rule of thumb is 1 Liter = about 62 cubes.

You could theoretically make a 305 LT1 with an L99 block and a 350 crank, but other than to just be different or to keep under a max displacement in a racing series, there's really no point in it.

 

Was it in the roadmaster?

 

61.024 to be exact

I think they got iron headed LT1's just like the Impala/Caprice.

-Corey

 

The L99 was iron headed....the chambers are different and I think the valve sizes were smaller, don't reallly remember.

But it came in the Roadmaster, Caprice and the rare Olds wagon. It was 225hp or 230 I can't remember.

 

All roadmasters had LT1 350s.

 

Some interesting info about the "Baby LT1" in this article.

 

The chevy 305 has the same stroke as the 350: 3.48". The L99 has a 3.00" stroke which if you used the L99 crank in an LT1 (350) block, you would have 302 cubes.

 

The 4.3l L99 was used ONLY in the Caprice and was 200hp/245ft.lbs. it used the same cam as the iron head LT1s that was the only motor available in the Roadmaster, Fleetwood, and Impala, the LT! was avaialable in the Caprice as well. The Olds wagon was dead before the LT1 went into the b-body so it never got one or an L99.

From the outside you need to look at casting numbers to tell it apart from an iron head LT1. It seems to show the same durability as the LT1, I pulled mine and replaced it with a Roadmaster LT1 at 110K, you would not believe how good the inside looks.

 

Did a little math. OK, what am I missing here? I know the 265 ci from the mid 50s, had a stroke of 3.00", and a bore of 3.7(5)". This combo generated 265 ci. The L99 has a 3.7(4)" bore. That does not compute to 265 ci. So, what is correct, the 3.74 bore, or the 265 ci designation?

 

If you get up this way you are more than welcome to my old L99 block, I think that is the best way to resolve that question. I tried to measure with a calipers but don't think it was accurate enough to bother with.