96 Beretta Project

[1988GTU]

I'm just wondering if you may have an issue with air pockets randomly entering the system and not being able to prime itself out when you do use the juice. The dead heading of fuel to the 6 lines with fuel can trap air or become stag with aged fuel over time... unless you use it on a regular basis.

Pull up to the ole supermarket at night and do a few hot laps. LoL jk

[3400-95-Modified]

Well In reality the dead headed line is only going to be around 2ft long total... Its coming off the factory feed line and going directly to the regulator and then to the solenoid, shortest run possible. The chance of enough air getting caught in there that would even cause an issue is very slim... And this is where the bang button would come in, Obviously there is a purge solenoid to purge the air from the nitrous line and yes I could do the same with the fuel side if I had a place for that purged fuel to go,(not cool to just spray that on the windshield like the nitrous is) and seeing I don't have a catch can or return line for it the other option is activating the system for a spit second to purge all the lines and ensure fuel is up to the solenoid.

Looking online my design isn't very far fetched from many others out there except for they typically run one very large fuel pump and two parallel regulators, one to feed a carburetor and another to feed the nitrous system... NEITHER is return type too so they would have the same chance of developing air bubbles like your suggesting.

I guess the biggest question here was would a carb regulator work when it's fed from the pressure side of a return system... I can't seem to find that answer anywhere.

[robertisaar]

would a TINY orifice at the highest part of the feed line be possible? because that would allow trapped air to bleed off into a return line pretty quickly, fuel would slowly get cycled as well.

[3400-95-Modified]

On the 12psi line? I'm sure it could but then I would have to setup some sort of return system to work with it. I think there is too much thought going into possibility of air bubbles in this system than the true question. I mean I'm only using this system when at the strip where it will be properly purged before use and sit for short periods of time between use... Other than that who cares if air pockets up after the low side regulator when I'm driving it... its not going to hurt anything.

[caffeine]

You could probably purge the returnless line back into the regular return line

[45es]

I guess the biggest question here was would a carb regulator work when it's fed from the pressure side of a return system... I can't seem to find that answer anywhere.

Without knowing your fuel pump's curve or the regulator's specifications, you will only be able to make a guess. If it were me, I would pose that question to Holley. Contact their technical service @ Technical Service: 1-866-464-6553 or www.holley.com

[3400-95-Modified]

Well I plan on using Aeromotive regulators so I contacted them a few days ago regarding this and still haven't received a response.

[3400-95-Modified]

On to other discussion...

After going back and forth with Marc last year about DR timing chain and oiling issues we came up with a few solutions to try and ensure that the chain gets sufficient oil.

One is modifying the cam bearing to have two holes in it since the aftermarket SBC bearings you get you don't use the #1 in the pack because its too large, you only use bearings 2-5 all of which only have ONE oiling hole in it. One replacement 3400 bearing that Marc found had the two holes on the front #1 bearing like the factory ones do, AS well as a groove cut in the 3 O'clock position hole to allow for oil to make it out to the thrust plate and timing chain assembly. I will be drilling the second hole in my cam bearing as well as making a slight groove to direct more oil out that way.



Then next thing is recessing the bearing into the block as it's done by the factory to allow clearance between the bearing and the thrust plate seeing how the holes on that don't always line up very well with the cam/bearing gap.

You can see the recessed bearing compared to the block face here.



It's hard to see in this photo, but the gap between the cam and bearing is not centered in the holes for the thrust plate... They drilled those holes I believe on the same diameter as the block cam journal, and not the actual journal size on the cam itself.



You can see how the oil stains are pretty well cut in half in relation to the block cam bore ID and not the bearing ID.



You can see in this diagram Marc drew the diameter of the bearing ID in relation to the plate, then a cross section of the sprocket, plate bearing and cam with the bearing flush mount, then recessed and then finally recessed with oiling holes drilled into the cam sprocket.



I will be doing the last cross section because I also drilled 4 holes in the DR upper sprocket.. I mean it can't hurt to direct the oil to the center of the chain rather than the backside only.







Hopefully all of this will result in a long lasting chain...

[mfuller]

Hmm......I wonder how long my unmodified DRTC (from the first run) will last?
I've got about 5000 miles on it now.

[3400-95-Modified]

Well your's at least had the grooves on the back to allow oil out from the thrust plate... My original one and the whole second run were lacking those grooves... that's why it died in 5k miles for me... at least that's the assumption.

I'm just going a bit more overboard to hopefully assist in oiling.

Only person I know of that had issues with the first run was Bob442

[3400-95-Modified]

Well got some progress this weekend....

Removed all the casting flash from the block, Went really quick compared to what I though it was going to...

Before



One in progress



Lifter Valley





After

[3400-95-Modified]

I then dug into the old motor today to look things over.

Front cam bearing was in fact extremely flush to the block which gave very little space for oil to flow out the thrust plate. Also this cam bearing set I never drilled the second hole in for the 1st bearing... Stupid me on that deal. Current chain was still in good shape, Not as tight as it was when I installed it but not loose enough to cause noise yet... And that was just a cheap Advance auto one I threw in last year sometime.







And now on to the bad news... But I think this will end well.

Time for a new cam.







Three lobes have markings of the cam face starting to disintegrate... Was nervous when I started pulling the lifters and saw some funky markings on a few... This explains the marks.

Oh Ben.... Time to spec me up a custom cam... And pushrods... And if I HAVE to I'll swap springs

[3400-95-Modified]

Got some info back from Aeromotive... Can't run a static regulator with a inlet pressure of 55, they are only spec'd for something around 20 PSI. I'll have to find another way to do a second loop...

Did some head tear down last night... and CC'd the chambers. Came up with 32cc's... Original is 32.4 so not as much removed as I thought... May still have them shave just a bit to get them in the realm of 31.5 or 31cc's. Currently the setup I have picked will result in a 10.12:1 CR... Almost a full point over what I had in the past... around 9.2:1 using the same head CC's and the rest of the stock 3400 components. I gained over the 3500's 9.8:1 by going with thinner cometic head gaskets, .051 compressed vs .060 as well as the cometic gasket bore being 95mm or 3.74 vs stock 3.8". I may get the block decked .005 but I'm not sure yet.. that would put me at 10.26 but it brings the pistons and valves closer together... Not sure on clearance needed with whatever I end up with for a new cam.

CCing...


De-buring oil drain's on heads

Before



After

[45es]

Got some info back from Aeromotive... Can't run a static regulator with a inlet pressure of 55, they are only spec'd for something around 20 PSI. I'll have to find another way to do a second loop...]

Have been following your project with great interest. The fuel system problem you are faced with is complex to say the least and trying to use the high pressure pump to supply both high and low pressure systems creates some complexities that are difficult to overcome. As you noted earlier, using a bypass to lower pressure for the low pressure side of the system can cause the whole system's pressure to drop to that level starving the injectors. You might think out of the box so to speak and look at the system in reverse. A high volume low pressure pump with available regulator can be set to the requirement of the low pressure system. Teeing off of that delivery system, a booster or high pressure pump can be installed to supply the needs of the high pressure system. Still some complexities but not nearly as difficult to overcome as what you are presently considering.

[3400-95-Modified]

I was offered two solutions by aeromotive... One was to install a stand alone fuel setup for the nitrous... Fix all but expensive... 599 is the cheapest I found and F-body specific. Next solution was to take the return from the injectors and feed that to another bypass regulator and create a 7-12 PSI back pressure on the first regulator. I asked him if this would affect the first regulators pressure at all, because if it doesn't then this may be the easiest and cheapest way to go.

Going to a pump system like you described really creates issues for my setup due to working with the stock tank, pickup and baffles right now... A free flowing siphon of 3/8 line will empty the pump chamber quicker than it can fill it up with the current way that tank is baffled... at least when it's got less than 1/2 tank in it... not sure how wll it works when it's full.