View Full Version : Need a oil filter bypass valve

Bulltear Ad
Bulltear Ad

01-10-2009, 08:37 PM
Hey guys,
My engine builder says my '74 304 didn't have an oil filter bypass
valve in it and I can't find one anywhere. It's all rebuilt and will be ready to go as soon as I get that valve. Anybody have one they will get rid of?
Also, my timing cover was worn out so I found one on Ebay.
Bought it and saw it was made in China. Is that the Crown crap I read about on this forum?
If so, That was a wasted $200.
Thanks for any advice and especially if anybody will sell me a bypass valve!

01-11-2009, 09:37 AM
As far as I know, All the new aftermarket timing covers (even sold from Mopar dealers) are made by Crown. There were several batches where the machining of the oil pump shaft hole was so far out of tolerance that the distributor wouldn't go in once it was installed on the motor. That's why MC here at Bulltear started checking EVERY ONE that he sells for proper fit. I want to say the failure rate was over 30% on one batch. Yours might work, it might not.

The oil filter bypass was eliminated on later production engines, maybe mid 80s. Since they were eliminated, I doubt anyone stocks the parts. You can get a new replacement filter adapter here at Bulltear without the bypass, or have your machinist just tap and plug the hole. The bypass allows unfiltered, dirty oil back thru your engine, so you're better off using a quality filter (I like Napa Gold or Wix) and no bypass.

If you really want to keep it. Email me your snail mail addy, and I'll send you the parts.


01-11-2009, 10:20 AM
Performance American Style sells them, they are directly from Mopar...


01-11-2009, 10:45 AM
I don't know if you're in a hurry but I've got a used oil pump in working condition that I'm not gonna use? I'm from canada

01-11-2009, 01:13 PM
you looking for the flap and the spring and the ring to hold it in place

01-13-2009, 08:00 AM
Thanks, guys. If it'll work by plugging the hole and eliminating the bypass altogether, that's what I'll do.
I've had a hell of a time with this engine. First rebuild kit I ordered never showed. Finally got my money back and ordered another one and they sent me marine pistons with it. Got those replaced and then the machine shop took forever and now its been sitting waiting for a bypass valve. Can't wait to get the old Jeep back on the road.
My ex-wife's son is rebuilding a Javelin, If he ever needs any advice, I'll send him here, you guys know your AMC's.
Thanks, again.
If my engine guru says we gotta have a bypass valve, I'll get back to you.

01-14-2009, 10:22 AM
what is the difference between standard pistons and marine pistons? thicker casting, ring spacing, dome? I have never seen the two side by side so i dont know the difference.

01-14-2009, 12:46 PM
I really don't know if there is a difference. Its been too long for me to remember what the deal was. (other than they didn't fit) I'll ask my buddy who's doing the engine again and get back to you. Dave, the machine shop guy who was boring the block to fit the pistons took one look and said "These are not Jeep pistons." He may have even knew they were marine. I don't remember.
what happened was the person who filled my order transposed two digits in the stock number and I got marine pistons with my Jeep rebuild kit.
Thanks for the photo, Fuzz401, and for answering my need for parts, tufcj and mkzmomo, and the link to performance american style, dwloop. I shoulda came here a long time ago.

01-19-2009, 08:39 AM
I asked Bob, my engine guru/Harley/Mopar/Cat mechanic about the marine pistons and he said my AMC engine wouldn't like marine pistons very much cause they are LOW compression. As is very low. So there you have it.

01-19-2009, 09:37 AM
Those could be low comp forged supercharger pistons! What part # do they have on them? I may have a use for them if your willing to sell them.

01-20-2009, 08:11 PM
I'll see is I can find the #s and mic the diameters for you. I don't even know what engine they are for or whether its inboard or outboard.

01-21-2009, 09:59 AM
Clevite part # 224-2321 030 (.30 over)
9-1491HT 030
They mic at 4.023" diameter (Give or take)
That's with digital calipers and I tried to get them squarely in the center of the wrist-pin holes but I ain't swearin its perfect.
They are cast not forged I think.
If they were forged I could tell right?

01-22-2009, 09:37 PM
If they were forged they wouldnt be Clevites :wink:

Those come up as hypereutectic pistons

01-22-2009, 11:18 PM
You can get a new replacement filter adapter here at Bulltear without the bypass, or have your machinist just tap and plug the hole.


Bob, got a pic of both/where I can plug this hole (360)?

05-13-2009, 09:25 PM
Look what I got from MC today. So, do I just remove the oil filter and stick it on or ..... haven't even looked at the process yet.

Thanks MC

05-14-2009, 07:16 AM
Remove the oil filter, remove the threaded nipple, replace the stock parts with the new piece. Pretty simple.


05-14-2009, 07:18 AM
I never have done this and what stock peices. Where would be a good place to get them?


05-14-2009, 11:14 AM
The stock piece looks like the part in your hand. It's already in there. Take it and the little fiber valve out, throw them away, and put in the piece in your hand.

It will be pretty obvious once you take off the filter.


05-14-2009, 01:51 PM
Sothrow the fiber away & do I have to take the assy off the Jeep or just unscrew the fliter then nipple. Pics.

Thanks Bob

Bulltear Ad