Hello everyone. Not first time buick owner, but first time V8 buick owner. I know this may very well be premature, but I have a question. What is the difference between the 1971 350 and the 1972 350? the reason I ask is because I notice that the horsepower rating for the stock 350 drops about 70 hp from 1971 to 1972. I would imagine it has something to do with emissions, but what is making that difference? I recently acquired a 1972 with a 350-2 as you might have already gathered. Simply I want to just remove what is causing that deficiency. Is it the intake manifold and carb? Both years I am referencing have the two barrel, but I am not sure if it is the same model of carb or not.
I don't think it's going to be that simple. I think compression was lowered with different pistons (deeper dished). Not sure if the heads are also lower compression.
That is what I was unsure of. I was hoping it was something outside the internals. Here's for hoping...
Wasn't the compression drop between 70 & 71? I think the big difference comes from changing from Gross to Net horsepower ratings.
still surfing while I have time and not able to find the exact reason for the decrease. Just that it had to be "detuned to run on unleaded gas".
The reason for the drop in horsepower was because this was measured at the rear tires(with all accessories operating),whereas the 1971 350 was measured at the flywheel.That is the reason for the drop in horsepower.
So then if I am understanding what you are saying... Please do tell me if I am not That there is no actual flywheel horsepower difference? It is just for the next year that Buick decided to calculate rear wheel horsepower instead of proclaiming the flywheel horspower? What was Buick's reasoning behind this? And the 1972 Buick loses about 70 hp on its way to the ground? Oh, please tell me I am thinking about this all the wrong way!
There is a difference in 71 and 72... The first year I started seeing EGR and AIR smog systems was 72. I think that some 72 motors had the smog crap on them, and some did not. If you look at a 71 and a 72 intake manifold next to each other, they are completely different. You can see tunnels for the exhaust gas recirculating system (EGR) on either side of the manifild on 72's - regardless of if it was equipped with an air pump or not. Correct me if I'm wrong....
Then would a intake swap and a 4 barrel addition take car of the choke hold the '72 intake "appear" to have? The same as it might on '71? What I am asking specifically I suppose is would this make the '71 and '72 on even keel. Say if both engines from each year had the same upgrades. Like intake and carb? Or would the the '71 still have the advantage?
Not on my 72 350 intake. The biggest difference in HP ratings was in fact the change to a net rating method, instead of gross. It wasn't just Buick, it was the industry in general. Although increased use of smog equip probably played a role too.
I'm sure there were other changes involved. Generally, a car will lose 10-20% of its gross HP rating through the drivetrain. I don't remember if it was brought on by govt. regulation or insurance companies, but it wasn't a Buick decision. It was an industry-wide change. 83Stage1 edit: oops - just noticed i should read the rest of the post... uh, "What Dave said" :laugh:
Gee Adam, I'm already back in from the garage... It's cold outside! I checked it out last year, and it is a 72 casting #, and I have 72 heads also. The right rear of the intake, where the EGR valve would mount, has no provision there for it. I recall reading the reasons some intakes didn't have to have it, but I'll have to dig some more to refresh my memory.
Here's a 72 with the tunnels on the sides of the intake... I am assuming the smog stuff was ripped out of this car....
The A.I.R. system was also not on all 72 intakes. The exception is the 350 non-California cars with automatic tranny. Found the info on EGR in 72. Used on all 72 cars with manual trannys, and all cars built for California.
Cool thanks I'll store that in my brain for future picking:grin: I do know that there were differences in 72 heads from the 71's. Would this fall along the same lines as the intake?
o No: I have 72 heads. Could be the combustion chambers are larger, but I don't have any specific knowledge about them.
