That particular adapter never had a gasket under it in factory applications.
GM Block Mounted Bypass
- Thread starter garageman402
- Start date
That's the one I'd go with, and it bumps the filter bypass setting up from the OEM which isn't a bad thing. Most spin-on filters these days have a bypass valve set around that range, or even higher.
garageman402
$100 Site Donor 2026
Most spin-on filters made for some GM applications do not have bypass valves.
Some people block the bypass with a cap screw thinking they just invented the wheel.
If you’re one of those, forcing all the oil through the filter, use a #9100 Duramax filter that has an internal bypass.
Look inside - No, I actually never looked inside any of the filters, so I didn't see the pleats or core condition. Probably should have but never did.
Sealing face etc. - Different engine family (Pontiac V8) but exact same sort of mechanism and the disc material sure seems the same, I have seen that disc missing a chunk. But no, not in my BBCs (or SBCs) and I also haven't seen or heard of the spring losing pressure... but to be honest I have never compared before / after on that spring with any measuring instrument eg. trying to use a typical valve spring pressure measurement jig etc.
If I didn't have an original GM one, I'd probably buy the Melling one, I am a Melling fan from way back, all their stuff, pumps, intermediate shafts etc. That Summit one (120115) looks like a Melling, the part number on the body is even the same so maybe that one is ok too? Whatever you go with just be careful with the two bolts you end up using. If the head is too big (as in too tall) the filter might tighten up against them. I have always used the GM bolts and they are a little more shallow than a regular hex head or Allen head bolt. No washers, just a couple drops of blue Loctite and you are good to go.
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- Sep 1, 2024
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The Melling picture shows it sand blasted everywhere even the thread, and is the filter thread steel or aluminum?
garageman402
$100 Site Donor 2026
Ya I didn’t like the picture at all. I would hope it’s a steel thread, but brands change over time. Melling is the big name in oil pumps but they could have sold off their other product lines? Even the cheaper Allstar looked better.
Think a lot of the newer GM engines got rid of the built-in filter bypass valve.
I actually had a 1971 402 in my 1967 Chevelle. The factory oil filter adapter with bypass was replace with an adapter without a bypass. No problems…just ran high perf oil filter (70 PSI oil pressure all the time). All 396 engines beginning in 1970 were actually 402 cubic inches. 396 block with .030 over bore. Chevy didn’t want to drop the 396 name through 1972 in Chevelle, Nova, and Camaro. Trucks and some full sized cars and station wagons called them 402 and 400. Even when there was a 400 small block. Not sure why….
I’m duplicating an older post here. With the 1972 Caprice you could get a 400 small block or a 400 ( 402 actually) big block. The small bock was a 2 bbl Turbo-Fire, and the big block was a 4 bbl Turbo-Jet. The small bock had 170 HP and the big block had 210 HP, and 240 HP with dual exhaust. Both were referred to as a 400.
garageman402
$100 Site Donor 2026
Well, I took off the old one & it had a gasket, but not the type you'd think, seems GM engineers feared the gasket breaking up & getting in the clean oil stream, so they put the gasket on the outside of the bypass. Looks like a little bit of the tab on the left has already broken off.
The new Chevrolet Performance item came in a GM bag with a gasket, but not quite the same as original, I think I'll use it though.
I rigged up a testing method using a plastic milk jug with water for weight, & a cut off pencil to actuate it, crude, but I got some numbers.
Getting it to balance & take all the weight was tricky, but I got it to free-stand so my hand wasn't inadvertently taking any weight. The one where you see the numbers is the new one.
I have some raw data that maybe the mathematicians here can figure out psi values:
The old one started to open with 20oz, opened half way with 22oz, fully opened with 24oz.
The new open did not open with 20oz, opened a little with 22oz, fully open with 24oz.
The opening is 7/16" diameter, the bore inside is 25/32" diameter, the platform has a little wiggle room, maybe 1/32" smaller than the bore, spring travel 21/64".
The old one was torqued down pretty tight, it's base is bowed now. When I put the new one in I'll use Loctite Blue (or should I use Red?) & just snug the bolts in. Yes I bought new bolts, lol.
Edit: You think the "EN" stamped on the new gasket means "Engine Side"?
The new Chevrolet Performance item came in a GM bag with a gasket, but not quite the same as original, I think I'll use it though.
I rigged up a testing method using a plastic milk jug with water for weight, & a cut off pencil to actuate it, crude, but I got some numbers.
Getting it to balance & take all the weight was tricky, but I got it to free-stand so my hand wasn't inadvertently taking any weight. The one where you see the numbers is the new one.
I have some raw data that maybe the mathematicians here can figure out psi values:
The old one started to open with 20oz, opened half way with 22oz, fully opened with 24oz.
The new open did not open with 20oz, opened a little with 22oz, fully open with 24oz.
The opening is 7/16" diameter, the bore inside is 25/32" diameter, the platform has a little wiggle room, maybe 1/32" smaller than the bore, spring travel 21/64".
The old one was torqued down pretty tight, it's base is bowed now. When I put the new one in I'll use Loctite Blue (or should I use Red?) & just snug the bolts in. Yes I bought new bolts, lol.
Edit: You think the "EN" stamped on the new gasket means "Engine Side"?
garageman402
$100 Site Donor 2026
I had a 91 Camaro with the 3.1 V6, the sealing face was not evenly contacting the base, looked like it had loosened off the spring, & not sealing at all.
You think Loctite Blue is good enough? How much torque did you put on them? As I mentioned, the old one was deformed, it was on pretty tight. I'm gonna spray the threads out with brakeclean, put the Loctite on, then snug them.
Yes blue is fine (make sure all the treads are clean and dry, both the bolts and the block, your brake clean sounds good, let it dry). 18 ish ftlbs for torque (it is a fairly thin bolt). This piece is static there is nothing to work the bolts loose. As well, the filter adds tension to the bolts when spun on. You can go orange or up to red but next time you need to remove the adapter (engine overhaul etc.) it will be a struggle, not impossible, but a struggle. It is not wrong to use the orange or red if you want piece of mind, I just use blue on this component.
The old one being deformed(!!) leads me to think someone has been in there and got something terribly wrong and then over tightened it. I can't see how it could deform as it is flat on flat unless something interfered. Is there a picture of that, just curious? I would have guessed that the bolts would break before that housing would deform but I guess not.
I am also curious what was the cost from GM that you paid on it if you don't mind letting me know? I see everything from $65 to $85 online just wondering what the cost is to a regular guy like me.
Pressure (lb/in^2) = Force (lb) divided by area (in^2).
In this case, the force to crack the valve is 22 oz (1.375 lb).
The area of the bypass valve is the inside bore area that the oil acts on the valve face.
So the area of a 25/32 inch (0.78125 inch) diameter valve face is 0.479 sq-in.
P = 1.375 lb / 0.479 in^2 = 2.87 PSI (call it 3 PSI).
That seems petty low to me. This calculation is based on your measurements. Verify what the diameter of the bypass valve the oil pressure acts on. Should be more like 8-12 PSI from what I know about the built in OEM stock bypass valve on the newer LS GM engines.
UPDATE, see post below for your specific part number, which apparently is suppose to be set higher than the stock OEM bypass.
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From Summit Racing website:
https://www.summitracing.com/parts/nal-19299222/reviews
Says it should be 17-18 PSI.
https://www.summitracing.com/parts/nal-19299222/reviews
Says it should be 17-18 PSI.
garageman402
$100 Site Donor 2026
Yes, it does seem low, the part I bought was from Summit, I bought it based on that measurement. If we use the 7/16" (.4375) diameter of the actual opening, I get 9.147psi, that would crack it open, then once the entire large diameter platform gets pressure, it would open fully it seems. The new one is definitely stronger than the original one.
Maybe my method is flawed. I didn't account for the weight of the plastic milk jug or the pencil segment, which I think is negligible, but if we assume 2oz more (24oz) it makes it 3.13psi. 10psi using the 7/16" opening.
I zoomed in as seen in the your photo below, and see the face of the bypass does butt up against the 7/16 inch hole (red arrow), so that is indeed the area the oil pressure acts on.
Recalculating as done above, I get:
7/16 inch dia hole = 0.15 sq-in.
Using your 24 oz (1.50 lbs),
P = F/A = 1.50/0.15 = 10.0 PSI
In order to get 18 PSI with that 7/16 inch dia hole (with 0.15 sq-in area), the force would need to be:
F = PA = 18 x 0.15 = 2.7 lbs.
The calculated PSI is still way below the opening spec given by Summit Racing. How are you measuring the weight of the water, jug and pencil?
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garageman402
$100 Site Donor 2026
The jug is a standard 1 gallon plastic milk jug, I had 22oz. of water in it. The pencil is 1". I started with 128oz (8lb), way too heavy, poured out 64oz, still too heavy, got down to 16oz, then went up from there. Each time I used a cooking measuring cup. Here's a pic of the milk jug, I can't see it being more than 2oz though:
But once the valve is open, the entire plate is exposed to oil pressure, wouldn't that larger area count after it opens?
garageman402
$100 Site Donor 2026
Well the housing is aluminum, mounted on iron with steel bolts, maybe the heating & cooling cycles expand the aluminum more & effectively tightening the bolts' grips? Have you seen Rochester Q-Jet float bowls warp? The 2 bolts that go through to the manifold bow that housing every time.
I scraped all the old gasket material off the ends. Here are two pics, I can't post a video.....
