Early 72 LT-1 Engine specs.

[Duke W.]

Re: Early 72 LT-1 Engine specs.

For 1971 SAE gross ratings were primary, and net ratings were listed parenthetically. In 1972 only net ratings were advertised.

It could be that the SAE net standard was not yet completed by the time information had to be published for the 1971 model year in late 1970, which could explain why 1972 net ratings were somewhat lower for engines that were basically the same configuration as 1971 other than minor carb and ignition calibration, which usually have little, if any, effect on peak torque and power.

Another example is the Vega L-11 engine (140 CID, 2-bbl., special camshaft) that was included with GT package. For 1971 the gross/net horsepower ratings were 110/93, but the net rating dropped to 90 for '72.

Both years had AIR but slightly different carb and ignition calibrations, which is the primary difference between the '71 and '72 LT-1s.

Technically, new emission standards don't go into effect until Jan 1 of each year. Most mfgs. meet the standards at start of production, but I think it would have been legal to use 1971 certified engines until the end of the calendar year even if the car had a 1972 VIN.


Duke

[Tom L.]

Re: Early 72 LT-1 Engine specs.

Joe, I had brought this issue up a while ago after finding something interesting about the HP ratings of my '72 LS-5. It went nowhere at the time. However after seeing this post and the buildsheet Marc provided I back to check my AIM to see if there were similar descrepencies for the LT-1.

I attached the page from my '72 AIM for refrence. It lists the following:

Base (K code): Gross HP 270 and a Net HP of 210

LT-I (L code): Gross HP of 330 and a Net HP of 275.

LS-5 (L code): Gross Hp 365 and Net HP 285

None of these ratings are published in anything I have read. What Marc and others suggest about GM not having all thier ducks in a row in terms of what to publish and what to publish and what to print on early order and build sheets. My other thoughs were that the influence that insurance companies led GM to fudge actual HP ratings to please them. It is well known that this has been done in the past. Hope this helps.

[Terry M.]

Re: Early 72 LT-1 Engine specs.

I think they did, I was looking in the pocket spec guide vol-2, which shows two different codes for the 72-LT 1 (CKY and CRT w/K19). Now looking in vol-1 of the spec guide it states that none of the CRT code motors were ever produced. Hopefully Terry M will jump in on this one, as he would know way more about this than I. But the CKY code is for the 72-LT 1, rated at 255hp.
Lynn

So far only one CRT engine has been reported, and none of the judging manual team has had an opportunity to see it. If there is one, there were probably more, but we haven't seen them yet.

[John H.]

Re: Early 72 LT-1 Engine specs.

Could the engine be build to 71 specs ??

Marc -

Highly unlikely - each engine configuration had to be emission-certified, including a 50,000-mile durability schedule, and the emission calibrations and certification were different from '71 to '72 for the LT-1; selling a '72 LT-1 with '71 LT-1 calibration would be a violation of federal law.

[Warren F.]

Re: Early 72 LT-1 Engine specs.

I believe you'll find that the carburation and timing specifications are different for the '72 model from the '71 LT-1 and quite possibly the distributor is calibrated differently. This is what I was informed, that made the 20 net hp difference in the two years.

[Craig B.]

Re: Early 72 LT-1 Engine specs.

Warren is correct jetting was reduced by I believe 2-3% and static timing advance from 8 degrees to either 4 or 6 degrees inorder to meet 1972 emission regulations. Gross H.P. for the '72 LT-1s was either 312 or 315 but quite sure it was 315. I think the reason your car shows '71 specs on the paperwork is because GM didn't have meet 72 specs until 1-1-1972 and the paperwork hadn't caught up with the actual build yet. With all the articles I've read both in factory books,parts books, and magazine articles on LT-1s, I have never heard of someone ending up with a '71 carburator or distributor in a '72 LT-1. If you want to apply '71 specs to your '72 LT-1's don't drill out the jets, buy new from Holley, and buy GOOD points Mallory or Blue Streak would be good choices.

[Craig B.]

Re: Early 72 LT-1 Engine specs.

Marc, in addition to my remarks yesterday and sometime to dwell on it, I believe the reason your build sheets show the engine horsepower of a '71 rather than the correct '72 numbers is because the selling dealer tried to order your car as a '71. When a '71 was no longer available, the customer ordered the '72 but no additional order was submitted for the '72. When the build sheet was created from the '71 order, the clerk probably transcribed exactly as written from the dealer order sheet and since there was no longer any 330HP motors available there was no necessity to correct the error.