big block chevy fueling for your IDIT+!!

[BullDiesel]

Currently running the big block pump with the original idi pump arm, running great got 1,100 miles on it so far with no problems.
Actually getting slightly higher fuel pressure than the first fuel pump, idles at 8.5 psi and when driving normally stays at 7 psi.
@wix51085 I think you hit the nail on the head with your explanation of the problem with the first fuel pump.

 

[hce]

Steeling pictures from the internet. The two pumps are old vs new IDI. The black one is for a pontiac v8.

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[jwsfarrier]

Great info guys! Keep up the good work

 

[wix51085]

In case anyone wants to try and make the short OG pump arms some day. They're 14ga. These dimensions are very close but still approximate. With these being pressed out of sheet metal there's some variation. The side view was made by tracing the pump arm and scanning it then making it proportional to the 1/4" hole. Not ideal, but difficult to model otherwise with my basic abilities. Should totally be close enough given the tolerances though.

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[DougBoy66]

How close would this Ford model be? GPH and pressure are what you would want. Just didn't know if anyone had already checked it out

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[hce]

How close would this Ford model be? GPH and pressure are what you would want. Just didn't know if anyone had already checked it out

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The arm on a FE pump does not appear to go high enough. Holley also stakes the arm pivot so arm replacement is a pain. Carters appear to have a pin that could be driven out.

 

[wix51085]

Swapped the arm in to the Summit pump today. Here's the arm I took off compared to the IDI arm. I think stuff moved a little or the camera is exaggerating the difference of the two arms on the end. When I was playing around with calipers and looking at them in person they're extremely close. Either way, the difference is negligible compared to tolerances in this part of the pump. No fitment issues on install.

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If you want to be a cheapskate like me, use one of the 110 GPM Summit Racings pumps (SUM-250020-1, SUM-250022-1, SUM-250024-1). The cheapest one is SUM-250020-1 right now for about $77. I think I mentioned before but my housing was stamped with the part number for the Holley. It's like store brand Dr. Pepper but for lift pumps.

The best way I found to disassemble the IDI pump to steal the arm is by drilling a hole in the corner on the back side of the pin. (Took me two tries to find where to drill. Ignore the other hole) Then you can punch it out with minimal effort.

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For removing the staked pin on the new pump I used a punch and hammer to try and push the staked metal back. Then I used put a flat punch under the pin and whacked it with a hammer until it popped out. This took awhile as I was trying to be careful not to damage anything. This worked fine but I don't recommend it and wouldn't do it again. If I was going to do this again I would just drill holes in the back of the pump like I did to remove the IDI arm. Really no harm in having holes there since they get covered by the pin and you could fill them with JB weld, tig them shut, or tap them and stick a grub screw in there if you wanted.

I didn't take a picture taking the arm off the new pump but here's a pic of where I put the flat punch and beat on the end to pry it out. Again, don't really recommend this.

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Stuck the IDI arm in the new pump and staked it in. As you can see, I got a little crazy on the staking trying to push a whole bunch of metal over like it originally was and I broke some pieces off. Some of this was due to poor technique and some of this was due to metal being strained from pushing the previously staked metal back with a punch when I removed the arm. Drilling a hole in the back is better.

After breaking a couple tiny chunks off I ended up just staking it in with a pointed punch like you'd do on most other staking jobs. Plenty sufficient and it's in there nice and snug. All the forces are pushing the arm down and out anyways. There's nothing that should be trying to pull the arm in to the motor and defeat the stakes.

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As a note, I used the pin from the new pump too. The pin on the original pump was a little shorter. Could probably still use the shorter one anyways though if for some reason you needed to.

I'm waiting on a couple fittings for fuel lines so not in the truck yet.

 

[jwsfarrier]

Forgive me if you already explained this. Will the long IDI arm work or do you have to use the short one? Thanks!

 

[wix51085]

@jwsfarrier For this style of pump with the shorter neck (which is what almost all of the aftermarket high GPM pumps appear to be) the long arm isn’t a direct drop in. You have to modify it by cutting approximately 1/2” out of it and welding it back up. But you have to be very careful to only shorten it length wise and not height wise too or it’ll mess up the pump travel. I drew a little diagram of that issue on the last page.

Alternatively you can try one of the 80gph Summit pumps. Those appear to be longer necks and I strongly suspect the longer arm will be a direct drop in to those.

I was going to experiment with that but will pass the torch to the next guy for now. Got other stuff to work on and more fun ways to burn $100.

 

[wix51085]

You’ll have to use your imagination a little here because these are both short pump arms.. But imagine the bottom one is the long pump arm you’re talking about.

I would line up the pin hole of the chevy arm you’re scrapping with the longer IDI one you want to use. Cut both of them at the same spot like this and weld the left side of the chevy arm to the right side of the IDI arm. That way should make all the dimensions correct.

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There’s also the issue of the return spring being different be. Idk what the best solution is for that but can go back a few pages to see how Bull Diesel did it.

 

[Clb]

You guy be 100% on those weldments.
Keep after it.

 

[jwsfarrier]

Thanks wix51085 for all the info and your R&D with this. I have a carter pump laying around with long arm I will mess with and try to find one of the shorter style arms in the meantime. Thanks

 

[wix51085]

Only a month later and I finally got to start my truck for the first time with the new frankenpump. Unfortunately was held up by a series of delays on a radiator from Jegs.

(Not to brag too much, but after cancelling my order for a Champion I found a Fluidyne radiator listed for $415 on SRIPerformance. As I suspected, no one had ordered one of these radiators from them in a really long time and their price was far out of date. Shout out to them being cool and letting it go for $480 and me being cool and not bringing up contract law to force the $415. I'd tell everyone to jump on that deal but they have since updated their price to $635.)

Anyways, a little bit of cranking and everything primed up quick and it starts and idles like a champ. Have a few things to put back together as I did a lot of deferred maintenance all at once but should be roadworthy soon. Now I'm even more motivated to get to the DMV for title, reg, and plates.