I have seen numerous comments about the quality of the 2.5 l connecting rods. Who has actually had problems with the rods, and what were the problems? I am not a fan of the cast "armasteel" connecting rods, but Pontiac and Buick both used them in a lot of engines.
I've popped a few rods through 2.5 blocks. If you get a 1984-86 rod and a 1987-88 rod in hand and compare them. You'll see that they improved the beam, and the later rod directly interchanges to the early engine
Could you tell exactly what failed on the rods that "popped thru the side of the block". Rod beam failure, bolt failure, bearing failure? Thanks.
Yes; something broke.
Seriously, there's not much left to go on when one of these lets go, but in the most recent one I believe a bolt let go. Consequently I now use ARP rod bolts and resize the big end of all my 2.5 rods.
I believe these are the same rods used in the Pontiac 301 v8. Did they have problems with the rods? I'm not sure about horsepower, but they had a turbo version which would have loaded the rods pretty well. Is it possible that the low final drive gear (4.10) made over-revs more common?
I believe these are the same rods used in the Pontiac 301 v8. Did they have problems with the rods? I'm not sure about horsepower, but they had a turbo version which would have loaded the rods pretty well. Is it possible that the low final drive gear (4.10) made over-revs more common?
You can hope, wish, conjecture, speculate, and second-guess all you want but the fact is and will remain that the stock rods are not a good choice for performance. The 301 turbo did not really "load" the rods, it only made something like 200 hp- figure the BMEP for that. Would a 4.10 car spend more time at revs- sure, bit plenty of 2.5s have been exploded while connected to 2.84 autos- ive done it.
When you blow up a rod it is very hard to tell which came first in the failures that happen (bolts, caps, rods, wrist pins, pistons). I think the old style were breaking in half at some point and punching a hole in the block and causing an oil fire. Not sure the new ones had less failures or just less exciting ones. Larry
