Offenhauser 5489 Intake Install

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BillGrissom

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Getting around to installing the correct after-market 4 bbl intake on my 1965 Dart 273. Bought this Offy 5489 on ebay several years ago at a good price (~$120) and before shipping rates became outrageous. Good because I've seen them sell here for $250 +$80 shipping and Summit lists new ones for $540 (buy today receive in May). Perhaps they cast new ones once they get enough orders. I attach an installation manual I found. Currently I have an Edelbrock intake for 1966+ installed, which required counter-sinking the holes and using flat-head bolts w/ conical underside, which was all I could find at the time.

Three issues I've had. My question is the large 1/2"NPT tapped hole the rear where a head coolant port is normally blocked. I think the port is there so a head can be used on either L or R side, plus allows removing the sand core. It isn't factory, based on photos I've found of the 5489 manifold here, plus the OE iron manifold. I recall people doing such to run an external cooling tube to modify the coolant flow. Anyone know the whys and benfits? I cleaned it up with an NPT tap and will plug it for now. I don't plan to race and don't want to try out-thinking the engine designers.

Another problem was that the bypass port had a rusty steel nipple. Could have been cleaned in place and used as-is but I prefer stainless or brass w/ teflon tape, so figured I'd remove it like I did the steel heater nipple. As often happens, the steel tube just collapsed under a pipe wrench without turning, even after heating the aluminum a long time with a propane torch. I had to cut it flush, cut an axial slot with hand jigsaw, then peel the shell inward with a punch. That cut the threads a bit, but ran an NPT tap in to cut them bit deeper and eliminate the slot.

Another problem is that one T-stat bolt hole is stripped. Need to buy a 3/8-16 thread insert and tap to fix it. That bolt needs to be secure to support an AC bracket for Sanden compressor. Rolling my own AC brackets and will post if success.

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  • ManifoldDodgePlymouth273Engine.pdf
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Nice. I've also had a hard time removing the bypass fitting, once theer in they are very hard to get them out!
You'll have to continue this thread with the install!
 
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Bill, I have seen the rear drilled in both sides for the water passage.Connected together with AN fittings and hose.
Theory is to let the water flow instead of dead head at the rear. I guess the water will move thru the hose.
I too bought a intake that was drilled. I never used it and passed it on.
 
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I don't understand what you're after here, Bill. You seem to have overcome all of your issues.
 
... You seem to have overcome all of your issues.
Unfortunatley, issues have grown. I fixed the water pump stripped hole easy with a thread insert ($27 kit at Ace). But, when I held an intake gasket against the manifold, I find where they drilled the bypass hole is off and partly overlaps the gasket sealing surface. I wonder if that is why that intake was sold affordably on ebay, perhaps others noticed the oops or the seller stated it and I missed it. Someone skrewed the pooch on that mod. Sometimes you will drill a starting hole fine, then expand it and find the later drills changed the centerline. Best to have parts clamped in a drill press or milling machine to avoid that, but takes a lot of setup time on an angled part like this. Not sure why they thought they needed such a large hole anyway, greatly overthinking the engine designers.

I epoxied a brass NPT bushing in there and about to cut it flush, then fill w/ epoxy to try to make a smooth surface to seal the gasket. A bushing instead of a plug so I can install a Holley temp sensor there for later EFI. I'll report back w/ photos, but won't know if it seals until I run the engine. Worst-case is if there are coolant leaks into the crankcase where you can't see them until you find your oil turned milky.
 
Bill, I have seen the rear drilled in both sides for the water passage.Connected together with AN fittings and hose.
Yes, that is what I've seen on a few small-blocks, perhaps Chevy's too. No concerns with my 383 Big-Block because they don't route coolant thru the intake manifold. That makes it easy for rodders to test various BB intakes on a dyno, just leaving the metal valley-pan gasket in place. I wonder if the cross-over in the intake manifold and coolant passages within the timing cover are what define "small block", as it allows the overall engine to be shorter. In the slant-six, and I recall Chevy straight-six too, they recessed the water pump into the side of the block to keep the engine shorter to barely squeeze it into the engine bay. My 1964 slant doesn't even have room to fit a clutch-fan.
 
Unfortunatley, issues have grown. I fixed the water pump stripped hole easy with a thread insert ($27 kit at Ace). But, when I held an intake gasket against the manifold, I find where they drilled the bypass hole is off and partly overlaps the gasket sealing surface. I wonder if that is why that intake was sold affordably on ebay, perhaps others noticed the oops or the seller stated it and I missed it. Someone skrewed the pooch on that mod. Sometimes you will drill a starting hole fine, then expand it and find the later drills changed the centerline. Best to have parts clamped in a drill press or milling machine to avoid that, but takes a lot of setup time on an angled part like this. Not sure why they thought they needed such a large hole anyway, greatly overthinking the engine designers.

I epoxied a brass NPT bushing in there and about to cut it flush, then fill w/ epoxy to try to make a smooth surface to seal the gasket. A bushing instead of a plug so I can install a Holley temp sensor there for later EFI. I'll report back w/ photos, but won't know if it seals until I run the engine. Worst-case is if there are coolant leaks into the crankcase where you can't see them until you find your oil turned milky.
I dont know about expoxy being able to seal up. I would source or fab up an aluminum threaded bung and have it welded in place.
 
I used the JB Weld High Heat epoxy which you knead by hand to smooth at the cut bushing. I also used it at other ports to smooth the slightly pitted surface, as shown. It becomes very hard so can be tapped and withstands 500 F so "should work". Strange that one coolant port doesn't align well with the metal intake gasket. Was the casting off? The Fel-pro gasket kit appears to be on for 273 engines (predates 318?) though box was open so perhaps I swapped gaskets long ago. I ran a coating of Permaseal Gasket Maker1 around each coolant port and coated bolt threads since the tapped holes are open to the crankcase. It is gummy and cleans up in ethanol, so seems like a thicker version of Permatex Gasket Sealant (purple goo) which might be butyl rubber. I didn't have the end gaskets, but unsure they are needed or even best. I ran a thick bead of the Permatex Ultra Grey shown. After torquing to 23 ft-lb, the gaps at the ends were very small and the sealant almost squashed out, so "should work".

Glad I bought Grade 8 bolts since that torque felt higher than expected for 5/16" bolts. I had to use temporary bolts at the front since didn't notice those must be longer. Felt like they would fail so stopped torquing at 20 ft-lbf and will swap to G8. Ditto for the coolant port bolts where I first used stainless bolts but felt like they were stretching so swapped to G8.

Sharp eyes will notice the glitch at the front bypass port. It is 3/8" NPT instead of the 1/2" NPT of the later Edelbrock intake I had on there (had to booger the mounting holes and use flat-head bolts). I made the mistake of using the later alum water pump which has a matching 1/2" outlet. To adapt, I used a 3/8" NPT-F to 1/2" copper tube adapter and 3/8" NPT-M nipple. The alum w.p. was to match the only radiator I could get at Autozone at the time long ago. Not a good path since causes many other issues - alum w.p. is 1" thicker so fan gets closer to radiator and pulleys no longer align, had to remark TDC on damper, no brackets for TRW p.s. pump so had to change to Federal, etc.

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Looking real good. It looks like the repair turned out well!

I love that JB weld high heat. Also JB weld original is an awesome product.
 
I love that JB weld high heat. Also JB weld original is an awesome product.
Yes, I googled for info on best epoxy and watched youtube tests. The original JB Weld tied for best in strength and adhesion. The "fast cure" epoxies were horrid, not even bonding tight to metal surfaces. I was going to go to Ace to buy original JB Weld, then saw I had the unopened "High Heat" one on the shelf and it seemed the best choice for filling surfaces in cast aluminum as it bonds well and becomes very hard. It starts hardening quick so had to screw the fitting all the way in within 2 minutes after mixing.

I forgot to mention that I used a stainless steel T-stat housing (ebay), with a silicone rubber gasket from Real Gaskets of TN. They make similar silicone gaskets for the oil pans and valve covers of all my Mopar engines which I used (slant, SB, BB). A bit pricey (~$30 oil pan), but worth it if they last forever as claimed. They began by making gaskets for airplane engines (more critical). I also have a head-gasket kit for a 5.2L Magnum engine which appears to have silicone valve cover gaskets, so perhaps that was standard for those. Looks like they'll fit, but the cork gaskets I have on there still look OK.
 
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If you don't really need the hole for a sensor or whatever, why not just take it to a welding shop and get them to weld an aluminum plug in it and then smooth it back down on the sealing surface? Seems like that would be a more reliable repair.
 
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