You are looking at the template that comes with the high-volume oil pump for the 2.8. It is telling me to cut along the red lines which will leave a good section free-standing and eliminate one of the dimples that strengthen the fold (I think.) It seems like a lot of the baffle to remove but I don't want to try several cuts, trial and error. What are your thoughts?
Why the high-volume pump? Well, I'm tiding over this short block (100Kmiles) until I can afford a 3.4 short block, so leaving the crank and cam bearings as is (while porting/polishing heads and manifolds, and going to 1.5 semi-roller rockers). The oil pressure if I remember back to 18 months ago now was around 10 psi at idle and I thought the high-volume pump would give me a bit of margin.
Why questioning the instructions? It seems like a lot to remove compared to the increased size of the pump vs stock, when compared side-by-side. Maybe I'll get a picture of that so folks can see both together.
I was able to fit my "high volume" pump without trimming the 85-86 2.8 pan... but maybe I unknowingly installed a standard volume unit, or the pump was mislabeled. I ordered a Melling M95HV from Rockauto.
Why don't you first try installing the pan without trimming, then if it doesn't fit, trim if required?
If you're going to be cutting the stock baffle, you have to make sure that you get out all the metal and abrasive dust from the pan.
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Originally posted by olejoedad: Why are you questioning the instructions from the manufacturer of your oil pump?
It's not because a given piece of advice comes from the part manufacturer that it's good advice...
[This message has been edited by pmbrunelle (edited 11-08-2019).]
Originally posted by olejoedad: I would trim the baffle to insure an adequate supply of oil to the pickup screen.
Ah hah, I was not thinking about it that way, just from the clearance standpoint. I've got three views of the two pumps side by side and it is clear that the high-volume pump is a little bit bigger, certainly not so much so that one would need to cut so much of the baffling away. But I think I'll go with the manufacturer recommended baffle mods with a view toward the less obstructed returning oil flow ...
I suspect that the high volume 2.8 pump is actually a stock 3.4 pump....
I think the 2.8 high volume (aka the Melling M95HV) pump is the same as the later-generation stuff, except for the pump cover and pickup tube. The gear housing of the HV/later stuff looks a bit longer than the Fiero stuff, giving more displacement.
The pickup tube on the HV is the same as the Fiero pickup tube (its shape and diameter). The later-generation stuff has a larger diameter pickup tube, with different bends.
The pump cover on the HV has a smaller hole in it than later-generation stuff to accommodate the smaller diameter pickup tube.
Summary: I think that putting a Fiero pump cover and pickup tube onto a later-generation oil pump yields the 2.8 HV pump.
[This message has been edited by pmbrunelle (edited 11-08-2019).]
Another difference, perhaps due to wear on the old 2.8 pump, is that the shaft turns very easily by hand. On the new HV pump it takes a serious effort ...
Thanks for clarification. I had to trim the pan on a 3.4 swap, using a 3.4 pump. It had a larger OD pickup tube than the 2.8 pump, and a much larger pickup screen.
Originally posted by Notorio: But I think I'll go with the manufacturer recommended baffle mods with a view toward the less obstructed returning oil flow ...
If that's what you think, then would this recommendation also apply to those with stock 2.8 oil pumps?
Originally posted by olejoedad: I suspect that the high volume 2.8 pump is actually a stock 3.4 pump....
I wouldn't be surprised. I remember back in the '90s, retrofitting a 3.4 oil pump into to a 2.8 V6 became a thing. And it required trimming of the pan baffle.
Originally posted by pmbrunelle: If that's what you think, then would this recommendation also apply to those with stock 2.8 oil pumps?
Hmmmmn, that question is above my pay grade. With the OEM pump, why would GM engineers pick the baffle design they did? Is it the best balance of the many factors they were trading off? I can logically understand when they leave performance on the table b/c it is just too darn expensive to produce (e.g. ported and polished heads) but in this 'bafflng' case I'd think these design changes would have been cost neutral.
