Oil bypass upgrade options for a higher compression 2.4S rebuild?

blau911 · 08-05-2008, 11:08 AM

Guys,
Just getting ready to put together a 2.4S with 2.2S P&C's. Curious to know what my best and most cost effective options would be in regard to doing the oil bypass upgrade? I understand that upgrading to a 1976-84 oil pump is recommended by Wayne in his book. Wondering where I could get one and how much they go for? I would look at EBay but I want to make sure I get a good one.
Or is there another option?
BTW, I am looking to use this as a fast street car, not a weekend racer.
Any words of advice from someone who has been there and done this would be greatly appreciated.

Eagledriver · 08-05-2008, 11:16 AM

There are many 2.7 engines that have died due to pulled headstuds that would be good donors for your pump. I suspect a WTB thread on the used parts page would get you one. Also places like parts heaven. New is probably available from sources such as Pelican. You can get a good idea of the condition with a visual inspection. Look at the gear teeth for scoring and wear. Compare the backlash with the pump you have. I would definitly to this upgrade.

-Andy

304065 · 08-05-2008, 11:36 AM

New pumps are not available without the integrated sump screen. A Carrera pump will work, but requires use of the bulge sump plate which is not original looking.

I used an SC pump in my '66 901/05, had the oil bypass mod done. Price was about $225 and I took the pump apart to check it to be sure it hadn't ingested debris. The usual dismantlers have these pumps available.

BK911 · BK911's Garage

The original pump should still work, and will be better than not doing the mod.

At least this is what I heard from somebody, who heard from somebody.

304065 · 08-05-2008, 02:17 PM

Hmm, the whole point of the oil bypass mod is that the scavenge section was made smaller and the pressure section larger, due to a lower oil level in the case. Using the original pump would still work but you lose the advantage of a bigger pressure side.

BK911 · BK911's Garage

I hear ya John, and I definitely agree a later pump would be better. But do you think doing the mod with the old pump would be better than not doing the mod?

Intuitively I would think the old pump with the bypass would still circulate more oil and reduce the sump level. Stock seems to work fine, so making it a little better for ~$25 in parts and 15 minutes of labor seems worth it to me.

Shoepop · 08-06-2008, 07:49 AM

Just looking @ both it would seem removing the screen/housing from a Carrera pump would be a 5 minute job with a dremel.

304065 · 08-06-2008, 08:01 AM

Quote:

Originally Posted by Shoepop

Just looking @ both it would seem removing the screen/housing from a Carrera pump would be a 5 minute job with a dremel.

Perhaps, but you would want to do it alongside an SC pump. The pipe has to fit through the hole in the sump screen and there's a very specific angle on the end. That said, you could probably swap the old pipe and re-swage it inside the new pump.

Henry Schmidt · Henry Schmidt's Garage

The point of the by-pass mod is to redirect the by-pass oil to the inlet side of the pressure stage of the pump instead of dumping it back into the engine. This mod is beneficial with any pump. If you intent to use your old pump you can have it modified to flow approximately 15% more oil. Many shops do this mod and Supertec is one of them.

Eagledriver · 08-10-2008, 04:28 PM

While I suppose the mod will improve the scavenging of the case even with the old pump, there doesn't seem to be a problem with scavenging on these early engines. The mod will do nothing to improve the flow of oil through the bearings, piston squriters and cams unless you upgrade the pump or have Henry modify it.

-Andy