oil pump to distributor rod

[ejw 71]

Is the intermediate rod that connects the oil pump to the distributor on a 348 the same as the one used in a sbc? Thanks, Ed

[Ronnie Russell]

Ed, rod is big block. I think IS-77 Melling. Double check that, I m going from memory.......

[ejw 71]

Thanks Ron, I'll get one at local parts store.

[GOSFAST]

The 348/409 uses the entire SB setup. Both the pump and the driveshaft. Melling's part number is IS-55A for the shaft and M-55A for the pump! The shaft number has the steel sleeve. This pump number is the same one used in the Z-28's and the Vettes. Thanks, Gary in N.Y.

P.S. DO NOT use any of the recently manufactured SB pumps from Melling. They're having breakage issues with the new(er) castings. If you need a pump get the ones that have the 5 digit part numbers.

[ejw 71]

Thanks gary, I'll take the BB shaft back to parts store. Ed

[Ronnie Russell]

Uh oh, I have about a dozen 409s out there with big block oil pump drive rods. What to do, what to do??? :dunno

[GOSFAST]

Uh oh, I have about a dozen 409s out there with big block oil pump drive rods. What to do, what to do??? :dunno

Hi Ron, you made me go back to Melling to double check here. The part number for the pump is correct, the M-55A, and the part number for the shaft, IS-55A is correct also, however, that is not the shaft number for the SB. The SB shaft is a number IS-55E. But it is also not the same number for the BB's which is the IS-77. My apology! Thanks, Gary in N.Y.

P.S. Im have no way to know if the IS-55A (348/409) and the IS-77 (396/454) is the same length, possibly. I can't get to Melling tonight.

[BlueSwede]

Sorry!

I´m with Ronne Russell on this!
It is the big block rod you should use.

Been there done that and it was not funny to take the oil pan of again.
The lokal distributor in Sweden also said the SB would work.

Check this link to the "interchange part "of this forums page,.. other good to have info also :rolleyes:

http://www.348-409.com/348409interchange.html

:deal :D

[Ronnie Russell]

Who will break the news to ejw71??? I dont have the heart. Hope he does not have pan glued on yet. :doh

[GOSFAST]

I sent an e-mail to "ejw" to try to save him any extra work. Here's how it goes straight from Melling. The SB drive shaft is 5.960" long, the 348/409 shaft is 6.480" long and the BB is 6.720" long. Melling claims the BB will fit in BUT is actually 1/4" (.240") longer than the required shaft and MAY cause other issues down the road. Downward pressure on the oil pump gears for one. It would also become more of an issue where any head/intake milling was involved, thereby lowering the distributor housing.

As I stated earlier, if "ejw" asks for the part number IS-55A he will get the correct shaft. However, if he simply asks for a SB shaft he will get the shorter one. The part number I posted is correct according to the guys at Melling! Thanks, Gary in N.Y.

P.S. I do try to keep the info I post on these forums as accurate as possible with respect to part numbers and applications but sometimes the best plans just don't work out!

[Ronnie Russell]

Gary, So what you are saying is the IS-55A is 348-409 only. I have been down the road a long way with IS 77 and have never had negaitive issues, however , it sometimes takes 1, sometimes 2 nylon gaskets ( spacers) to obtain perfect fit. I did not know Melling made a dedicated 348-409 drive rod. From now on I will order the IS 55A. Thanks for the information.

[GOSFAST]

Hi Ron, let me try to "confuse" everyone a little further here. This is all directly from Melling. If you "play around" with these units you may want to record this info.

The 1958 thru 1965 348" in Chevrolet TRUCKS ONLY use the M55/M55A pump and an IS-55E driveshaft.
This is the steel-sleeved piece and it measures 5.960" long. Here is part of the confusion, the "mix-up" if you will, this part number IS the standard SB Chev driveshaft!

The 1958 thru 1961 348" in Chevrolet CARS ONLY use the M55/M55A pump and an IS-55A driveshaft. This is the steel-sleeved shaft also and measures 6.480" long.

The 1961 thru 1965 409" in both Chevrolet CARS and TRUCKS use the M55/M55A and the IS-55A driveshaft, again, the steel-sleeved number and 6.480" long.

The BBC driveshaft, the IS-77, measures 6.720". You can "see" the .240" difference between the IS-55A and the IS-77. This is most likely the reason, as I stated, for "shimming" the distributor.

You can always get through to "Melling-Tech" at 517-787-8172. Thanks, Gary in N.Y.

P.S. To sum it all up, the pumps are ALL the same, 348"/409" car or truck. The shafts are all the same, 348"/409" in the cars only. The change is in the 348" truck's pump-driveshaft's only. I would assume from my own info here that there's a difference in the 348" TRUCK distributors, BUT, I'm not certain. I would say to be very careful in "Marine" applications also, there might be more part numbers there.
The M55 pumps and the M55A pumps are identical except for the "pink" high-pressure spring, part #98015, in the "A" pumps. You should use the "A" pumps in most "W" units AND most SB's. Thanks again, Gary!

Double P.S. DO NOT USE ANY RECENT "NEW" CASTINGS FROM MELLING WITH THE M55/M55A PART NUMBERS. These castings are having "breakage" issues. They "lightened" the new pump body weights as per G.M. specs! In the photo those pumps have the identical part number. The one with the screen welded in place is from "old" inventory, the "bare" pump just came in the door and is going to be returned, we will not be installing these new castings in any future builds!

http://i16.photobucket.com/albums/b28/GOSFAST/PES%20Engines/th_Melling-SBOilPumps.jpg (http://i16.photobucket.com/albums/b28/GOSFAST/PES%20Engines/Melling-SBOilPumps.jpg)

[Ronnie Russell]

Gary, Thanks for the information. This is the first I have heard of any w-head engine using small block drive rod. (348 truck) , but then I dont get out much. Not to doubt Mellings, but I would like someone to measure an old 348-409 drive rod to make sure it is the same as Mellings information. I always throw mine away because I know that I will not use. Too important not to be 100% sure. Probably everyone else knew of the IS55A except me. The M55A is a high pressure pump, as you said. I dont use high pressure pumps in w-heads because of poor drain back. Again, no problems over the years. I guess it is , " to each , his own." And for the M55 casting problem,,, Why hasnt Melling issued a re-call?? Why are these pumps still available at all vendors??? Again, thanks for your time to post.

[Ronnie Russell]

Thanks gearhead. That would confirm Garys info. IS 55A is the way to go,, Will order 3 or 4 for stock. :)

[TomO]

Great Info!!!! Oil Pump shaft was on my list of things to buy.

TomO

[skipxt4]

Gary and Ronnie: Can I add some more confusion to this topic? Years ago, back in the middle 90's I bought a 348-409 oil pump rod from LGC. (Tag # on pkg. 19/46A, GM part # on pkg. 3998289 w/ Plastic Sleeve). Anyhow, since I decided that I will use a HV oil pump, I purchased a steel sleeve oil pump rod from Summit. This model is a Moroso # 22080 Heavy Duty Replacement for BBC, exc. GEN. V/VI. Both of these shafts are around 6 1/2 in. long, not counting the extra length of the sleeve.:clap Also, to Gary. My oil pump is a Melling M55 HV. In the box was a tag that says, This pump has a new look due to a new housing and cover design. The changes improve the pump on original stock applications. The date on the tag is Aug. 05. The pump has USA stamped on it. Don't know if thats a good thing or not. :scratch Skip:)

[ejw 71]

Boy, I sure didn't mean to cause all the confusion. I've ordered a IS-55A melling rod and have a new M-55 melling oil pump. Nope, hadn't installed the oil pan. How about a melling number for the inlet screen. Thanks to all for getting to bottom of this, Ed

[GOSFAST]

Gary and Ronnie: Can I add some more confusion to this topic? Years ago, back in the middle 90's I bought a 348-409 oil pump rod from LGC. (Tag # on pkg. 19/46A, GM part # on pkg. 3998289 w/ Plastic Sleeve). Anyhow, since I decided that I will use a HV oil pump, I purchased a steel sleeve oil pump rod from Summit. This model is a Moroso # 22080 Heavy Duty Replacement for BBC, exc. GEN. V/VI. Both of these shafts are around 6 1/2 in. long, not counting the extra length of the sleeve.:clap Also, to Gary. My oil pump is a Melling M55 HV. In the box was a tag that says, This pump has a new look due to a new housing and cover design. The changes improve the pump on original stock applications. The date on the tag is Aug. 05. The pump has USA stamped on it. Don't know if thats a good thing or not. :scratch Skip:)

Hi Skip, go back and look at the photo of the pumps side-by-side. Those are the identical part numbers. I repeat, DO NOT USE THE PUMP PICTURED ON THE LEFT SIDE, it's not a matter of IF it will break, it's just a matter of WHEN.

And I'll also say this once more, DO NOT USE HV PUMPS UNLESS YOU HAVE ALUMINUM RODS OR VERY BAD BEARINGS, period. Contrary to rumor, an HV pump WILL drain a pan, at least quick enough to keep the oil supply from the screen. Also, I've put this on these forums before, these HV pumps help shorten both timing chain and cam/distributor gear life, and require more HP to drive the pump.

I'll put another photo here showing a very simple modification to the lower distributor band on the housing to help feed add'l oil directly to the gears. This "mod" cools the gears and lets them live longer. This is not a new tip, we've done it for years now. It's in the "Crane Cams" catalogue.


Ron, also in reference to the "drain-back" question, the Hi-Pressure (M55A) pumps DO NOT pump any more oil than a standard M55. The volume is identical. The "pink" pressure relief spring that is standard in the "A" pump allows the system to reach into the 65#/70# range before it releases the pressure. Thanks, Gary in N.Y.

P.S. If you guys are not certain about something in this area please give Melling a call, like I said they are "good" people! (Ask for George in tech)

http://i16.photobucket.com/albums/b28/GOSFAST/PES%20Engines/th_Distributor-Mod.jpg (http://i16.photobucket.com/albums/b28/GOSFAST/PES%20Engines/Distributor-Mod.jpg)

[Ronnie Russell]

Gary, Thanks for your reply. Guess I look at things a little differently. My fault. It would seem to me that #70 psi would pump more oil than #50 through a particular orifice. The lower pressure spring by passes at #50 ( estimate) allowing only that pressure. The higher pressure spring does not bypass until #70, allowing 70# psi at some point. I do believe your opinion of the HV pump is correct, but a little strong. There are hundreds, if not thousands, HV pumps out there doing a good job. As far as Mellings reputation........ I called their tech line a few months ago and told the guy I had a 55A pump that I wanted to convert to std. Pressure. Not only did he tell me what spring to use, he popped one in an envelope and mailed it to me at no charge. What kind of company does that nowadays??? Very few. Thanks again for your input.

[models916]

When I built my engine I talked to Melling tech as to what pump to use. This is what they sent me. Better safe than sorry. Use the HV unless you are positive you dont need it and your engine will never wear out.

Here is some info from Melling:

High Volume Pumps: Advantages, Myths & Fables

Most of the stock automobile engines are designed to operate from idle to 4500 RPM. The original volume and pressure oil pump will work fine in this type of application. As the demands on the engine increase so does the demands on the oiling system and pump.

The oil pump's most difficult task is to supply oil to the connecting rod bearing that is the farthest from the pump. To reach this bearing, the oil travels from three to four feet, turns numerous square corners thru small holes in the crankshaft to the rod bearing. The rod bearing doesn't help matters. It is traveling in a circle which means centrifugal force is pulling the oil out of the bearing.

A 350 Chevy has a 3.4811 stroke and a 2.111 rod journal. The outer edge of the journal travels 17.5311 every revolution. At 1000 RPM, the outer edge is traveling at 16.6 MPH and 74.7 MPH at 4500 RPM. If we take this engine to 6500 the outer edge is up to 107.9 and at 8500 it is 141.1 MPH. Now imagine driving a car around a curve at those speeds and you can feel the centrifugal force. Now imagine doing it around a circle with a 5.581, diameter.

The size of the gears or rotors determines the amount of oil a pump can move at any given RPM. Resistance to this movement creates the pressure. If a pump is not large enough to meet the demands of the engine, there will not be any pressure. Or if the demands of the engine are increased beyond the pumps capabilities there will be a loss of oil pressure. This is where high volume pumps come in; they take care of any increased demands of the engine.

Increases in the engine's oil requirements come from higher RPM, being able to rev faster, increased bearing clearances, remote oil cooler and/or filter and any combination of these. Most high volume pumps also have a increase in pressure to help get the oil out to the bearings faster.

That is what a high volume pump will do. Now let Is consider what it will not do.

1. It will not replace a rebuild in a worn-out engine. It may increase pressure but the engine is still worn-out.

2. It will not pump the oil pan dry. Both solid and hydraulic lifters have metering valves to limit flow of the oil to the top of the engine. If a pan is pumped dry, it is because the holes that drain oil back to the pan are plugged. If the high volume pump is also higher pressure, there will be a slight increase in flow to the top.

3. It will not wear out distributor gears. The load on the gear is directly related to the resistance to flow. Oil pressure is the measure of resistance to flow. The Ford 427 FE "side oiler" used a pump with relief valve set at 125 psi and it used a standard distributor gear. Distributor gear failures are usually caused by a worn gear on a new cam gear and/or worn bearings allowing misalignment.

4. It will not cause foaming of the oil. With any oil pump, the excess oil not needed by the engine is recirculated within the pump. Any additional foaming is usually created by revving the engine higher. The oil thrown from the rod bearings is going faster and causes the foaming. This is why high performance engines use a windage tray.

5. It will not cause spark scatter. Because of the pump pressure there is a load on the distributor gear. The number of teeth on the oil pump gears determine the number of impulses per revolution of the pump. In a SB Chevy there are seven teeth on each gear giving 14 impulses per revolution. At 6000 RPM the oil pump is turning 3000 RPM or 50 revolutions per second. To have an effect on the distributor, these impulses would have to vibrate the distributor gear through an intermediate shaft that has loose connections at both ends. Spark scatter is usually caused by weak springs in the points or dust inside the distributor cap.


High volume pumps can be a big advantage if used where needed. If installed in an engine that does not need the additional volume, they will not create a problem. The additional flow will be recirculated within the pump.


www.melling.com

[skipxt4]

Gary: I'm happy to announce that my oil pump does "Not" look like the one on the left side of your picture.:clap I'm not doubting your knowledge on engines in any way, shape or form. But I am gonna stick with the HV pump. As everyone knows, these W engines have a few peculiarities. One of them is their oiling system. Small block and large block chevys have larger oiling passages feeding the main bearings. The 348-409's are a little inadequate, compared to them. This is my reasoning for going with a HV pump. Back when I first joined LGC they used to have decent articles, in their monthly magazines. One of them was drilling out the passages in the lower part of the block, above the oil pan mounting area on 348-409's. I believe 348's and 409's can benefit from a larger volume of oil. Thanks for the tip on the failure prone oil pumps. Skip :)