RWDsmoke

Your photo looks good so unless you have a lot of verticle play in the shaft I don't think that is the problem. I ran an ltx intake for over 10 years on my 86. When you install the distributor and you are not aligned with the oil pump drive you can see how much gap you have between the distributor and manifold. That tells you the minimum engagement. The oil pump takes a lot of pressure to turn, if it was not engaging far enough and allowed to slip it would beat the crap out of the oil pump drive shaft and the end of the distributor shaft. Pull the distributor and look for marks.

AZSP33D

Disassembly and inspection of the engine should help you with the cause. Your questions about engagement have been answered, vertical play should be minimal, unless the distributor had issues or improperly set up.

yakmastermax

Finally got around to pulling the distributor...

Looking down into the motor it looks like the top bits of the oil pump driveshaft ears got sheared off. The distributor side oil pump drive tang is intact but has some marring marks on it...


So the big outstanding question, was this the result of the converted LT1 Intake manifold distributor mounting boss being out of spec, or the cheap $45 small cap distributor being out of spec, or some other error, perhaps installer error?

I am still confused because thinking way back when I was trying to get this distributor to drop all the way down... it wouldn't drop down that last 1/8" or so but it wasn't actually touching the intake manifold... it was floating in the intake manifold hole, which to me seems to imply that the fitment issue was independent of the converted LT1 intake manifold base?

What do yall think? I am going to grab another small cap distributor to check fitment with ASAP.

yakmastermax

Okay so I did a bit more work on things... I think I have an idea what is going on.

I ended up pulling the oil pump and oil pump intermediate driveshaft. I also got a brand new oil pump drivshaft from the parts store. As you can see in the pictures, the driveshaft that failed got the top of its ears sheared off, presumably due to too little engagement with the drive tang on the distributor.

I reinstalled the oil pump along with the new driveshaft, and dropped the distributor down. The distributor is now basically seating all the way on the custom adapter plate.

From the underside it looks like I am getting solid engagement between the oil pump, the intermediate driveshaft, and the drive tang, however as you can see in the video there is a LOT of vertical play in the intermediate shaft. I would say about 1/2" of vertical play. That doesn't seem right to me.

I pulled the converted LT1 intake manifold, and double checked the "height" measurements at the edges of the distributor hole as compared to my TPI intake manifold base. This is the height or thickness from the flat underside of the manifold that seals against the top of the china wall, to the topside surface of the manifold that the distributor mounts too. I took the measurements on either side of the distributor hole since the whole area is at an angle relative to the flat top of the chine wall. Here are the measurements:

TPI:
1.064"
1.164"
1.40" Diameter hole

Converted LT1:
1.110"
1.230"
1.40" hole Diameter

Okay so the converted LT1 intake is taller by 0.046" on one side of the distributor hole, and 0.066" on the other. The result also is an angular error of 0.8 degrees. The TPI intake base has an angle of 4.09 degrees while the converted intake is measuring a distributor pad angle of 4.9 degrees.

To eliminate the oil leak from the distributor mounting area I also used a 1.50" thick Moroso distributor gasket shim spacer, so not counting the angular error, just simple vertical error, it seems like the setup might have had the distributor oil pump drive tang riding about 0.200"-0.250" higher than factory. This reduced oil pump drive engagement I am almost positive is what resulted in the oil pump drive ears being sheared off, and the oil pressure going to zero as the oil pump stopped being driven.

I haven't done the trig because the geometry sorta confuses me but I am confident that the 0.9 degrees angular error in the distributor mounting pad angle results in additional vertical error that ADDS to the 0.200"-0.250" from the shim gasket and the pad height-thickness, further decreasing oil pump drive engagement.

What this means for cam gear wear and what this means for the engagement of the helical cam gear... I honestly don't know... I am curious what yall think. I guess I am hoping that due to the size of the helical cam gear and the nature of helical gear engagement, this angular error and the vertical error aren't actually problematic? Assuming they aren't, then all that needs to be addressed is the oil pump drive engagement.


Okay so solutions... as yall can see in the video the driveshaft vertical play is way too much. I could remove the distributor mounting pad adapter plate and machine it down perhaps 0.100" and also try to correct the angle. I could alternatively work with a distributor that has one of those adjustable collar stops... I am sort of leaning towars that solution as it would allow me to dial in the cam gear engagement as well right?

Lastly maybe there are slightly longer oil pump driveshafts? That would solve the oil pump driveshaft engagement issue, but might not do anything with the cam gear engagement error if that is an issue...


What do yall think!?

The good news is that inspecting the intake manifold gaskets it appears LT1 intake conversion wasn't causing any oil/air/water leaks at the cylinder head to intake manifold sealing surface, so that is good!

I would like to salvage this project if possible...

Also quick question, the car was limped home after the oil pressure went to zero, probably about 20 minutes of driving total. Since then I have started it a handful of times to move it in and out of the garage to work on it. Oil pressure has been zero and the engine has been making a racket that entire time... are the cylinder heads dead? Valves, valve seals, full roller rockers, valve springs? Are these components safe to reuse?

Thanks!

https://youtu.be/2yFPSZwA-sk?si=SUaWU7dbnubcscHg








Edit:

I found this little blurb
"Is it more for the gear mesh or for the oil pump drive? I think the spiral gears can tolerate a lot of vertical variation. If you look at the wear pattern on the distributor gear it looks like you could move it up and down quite a bit as long as the entire pattern is on the gear and not running off the end. The oil pump drive engagement seems much more critical since bottoming out the shaft is very destructive and only engaging by a hair won't last long either. There can be lot's of variation with block decks, cylinder head machining, and intake manifold machining so the distributor seat on the manifold can move around a lot. Those bronze distributor gears all seem to wear out the same no matter where the wear pattern is vertically"

yakmastermax

Little update...

When this motor first died I came across a used Miniram 1205 setup and snagged it in preparation for going that direction. Recently I mailed my black anodized miniram fuel rails out to another gearhead in a trade swap for his silver miniram fuel rails.

I neglected to properly package the rails I sent him, and as a result the package came apart and one of the miniram fuel rails got lost in transit.

I am going to send his silver fuel rails back, but now I am out and don't have a full miniram fuel rail setup. Waiting to hear back from Jim at TPIS about possibly a lone single rail floating around his shop, but most likely I would have to wait until May or June and spend $400-$425 for a new fuel rail kit from TPIS...

Does anyone know if there are any other Miniram fuel rail options? 92-93 LT1 fuel rails? Does the rear crossover interfere with a small cap distributor?
could 94-96 LT1 rails be modified to work with the Miniram? What about modifying the Miniram to clear the 94-96 LT1 fuel rail front crossover?

Alternatively... maybe this is a sign to try to get the LT1 intake conversion working again? I think I know why the oil pump intermediate drive shaft ears broke... poor engagement... maybe I can redo the custom LT1 intake distributor mounting pad, and since I am building this motor on a stand now, I can check the engagement more easily before putting the motor in the car...

What do yall think?

AZSP33D

I think I have a set of fuel rails. Some extra o-rings. No regulator.

Making my own fuel rails out of blank fuel rail extrusions, as I didn't think that the Mini Ram Fuel Rails were adequate. After I got a fuel injector flow bench, it really opened my eyes to distance from input to injector influence and the detriment of pulses created by the injectors slamming open and shut.

Yeah, you only have 1/4" or less engagement looking a the witness marks on the oil pump shaft... see if ARP makes one that's 1/2" taller?

AZSP33D

Heres the set… I would keep the side that you dont need… seems like you need the one on the right.

yakmastermax

Just thinking out loud and wondering what you guys think about the Miniram vs the converted LT1 intake?

If I went with the converted LT1 intake that would free up $1200-$1400 or so....

My concern is flow and power. Am I leaving power on the table with this 383 build if I go that route. AFR 195 Enforcer 251/197 CFM intake and exhaust heads, 232/236 and 0.575" lift 112 LSA cam.
Can I port the LT1 intake myself to flow well enough to make up any difference between it and the Miniram?

Another concern is intake port matching. I think that the LT1 intake has its ports offset vertically from the AFR Enforcer 195 heads. I don't really know how to mock things up and see how much material and where it needs to be removed to get everything to match? Do I have to pull the valves and valve springs from the heads to do this sort of work? My understanding is that there are 3-4 "gen 1" small block chevy intake port "heights".

There is the old school standard that the 128, 113, and other heads follow and I think that the AFR 195 heads are patterned after. Then there is the Vortec port which is raised, the LT1 port which is raised also, maybe the same amount at the Vortec, then there is the LT4 port which is raised more than the Vortec and more than the LT1? That is the same height as the fast burn?

Should I just spend the money to hit the easy button and use the Miniram, knowing the ports line up better, and perhaps it has better flow characteristics than the converted LT1 intake?

What do yall think?

yakmastermax

Little bump!
I got my custom Mike Jones cam in. Cam card shown below. Also my AFR Enforcer 195 heads arrived thanks to forum member and 9 second ZF6 racer Jim...

Thanks to AZspeed I got a replacement set of fuel rails for the Miniram, so now that is a viable option...

But I still haven't decided on Miniram vs converted LT1 intake, so I am looking for input from yall!

The Miniram is by far the more costly option to go with, but should port match much more readily to the AFR heads. I still gotta fab up fuel line connections for the Miniram as well. My main thing is that if I went with the converted LT1 intake I could put the $1200-$1400 of the Miniram into some other aspect of the car, and I would have a more custom hot rod setup which I like, plus I think it looks cooler.

The LT1 intake on the other hand I think has some serious port mismatch issues with the AFR Enforcer 195 heads. I believe there is a 0.100" or potentially more lip at the top of the head intake port due to the raised intake ports on tbe LT1 manifold.

I am confident now that I could get these ports to match by hand porting the AFR heads to have taller ports... but what if this does more harm than good?

My understanding is that even if I enlarged the AFR head intake ports and LT1 intake ports at the gasket mating surfaces to both be wider, taller, and to match, there might be some weird velocity issues if the CSA at the gasket surface was larger than the upper part of the LT1 intake runner tract? Is that correct?
So in order to do it right I would have to open up the LT1 intake manifold runner tract all the way up into the plenum to have a CSA equal to or larger than the CSA that I achieve at the gasket surface in order to get the AFR heads to port match the 0.100"-0.125" raised LT1 intake ports?

Maybe it is better to just use the Miniram?

Also does anyone have a part number for an set of extra thin small block chevy intake manifold gaskets? I would open the ports up to gasket and port match regardless, but the thinner gaskets should make the port matching easier when it comes to getting the vertical alignment of the LT1 raised intake port vs the AFR Enforcer 195 Gen 1 SBC intake port height.




Thanks guys!

Jeepman1

I have a question on setting initial timing after a cam install. Do you know the starting timing setting for the LT1 with my distributor? I have a similar setup to the OP, 90s LT1 with MSD 8366 distributor on a modded stock LT1 intake. I have a stock LT1 rotating assembly with non keyed crank hub and unmarked harmonic balancer. I have the aftermarket opti spark hole cover plate with timing mark installed.

With the engine at TDC, my thought is to mark the balancer at 0 degrees off the pointer and then mark out the degrees based off measurements from a different balancer (same circumference).

So I think I can get relatively close on my marks but I am unsure what the starting initial timing setting is since this is all set with the Optispark presets.

Any advice is appreciated.