First time swap. LQ9 into 95 OBS

[Mickeymotormount]

You can "T" it if you want. The pumps are the same. It's just the reservoir that houses the pump that's different.

Since I didn't want the crowded look of more than one return hose going to the pump, I chose to use just one hose. Unfortunately, I chose the wrong return nipple.

Before I realized I had made the mistake of dumping the return to the top nipple, I searched around and found a pump from a 2000 Silverado with a 4.3L V-6. Upon looking at that pump, and similar pumps from the OBS series, that's when I realized I had made the mistake. All the pumps without Hydro boost brake systems dump return fluid to the center of the pump. Hydro boost pumps have 2 returns: One to the center of the pump and one to the top. The center return is crucial to keep the pump from cavitating(aerating the fluid).The upper return is merely a secondary return. As long as the primary(center) return is used, there could be more than one secondary return.

So, needless to say, I installed the V-6 pump since I had crimped and brazed the center return nipple on my original 6.0 pump.

[kewljay223]

ok cool. im gonna go the T route even though there will be a few extra hoses but i will keep them short so it wont bother me.

i havnt done anything as i been working 14hrs the last few days and still have two more to go. but i did get more parts ordered the other day including a ls1 pan. parts from summit will be here tomorrow and the pan... hopefully by friday. if not ill have enough to keep me busy all day friday.

[gagliano7]

worked on it today. but was only able to work on the fuel tank. ran into a few issues. only one major one tho and that almost made me flip.... i thought i was gonna have to buy another fuel tank!!!

here it is about ready to put in the newer style assembly from 96-98 trucks.


EEEEEEEVVVVVVIIIIIDEEEENTTTTLLLLYYYYYYY.......... GM thought it was a good idea to change the size of the opening on top of the tank rather than just keep it the same for the next 3 years untill they changed body styles..... the new assembly will not fit!!!! not even close. luckily nobody was around at the time i tried to install it. there might have been some injuries.

so after a little rant, i sat down and studied both assemblies to see if i could come up with anything. and i think i did. my dilema was that i needed a higher pressure pump AND a pressure sensor which the old unit doesnt have. but i had luckily already bought the 381 pump that i thought i was gonna need before i realized i could just use the pump from the newer assembly which i asked about a few pages back. so i knew i could install that. problem 1 solved. now on to the pressure sensor. the old unit uses a vent hose that goes to the gas cap to relieve fuel pressure when the tank heats up on OBD1 vehicles. OBD2 has a pressurized tank which eliminates that hose and now has a pressure sensor. BAM!!! thats when it hit me. use the vent hose to supply the pressure sensor. so i removed the sensor from the new unit, got some arb fittings to adapt it from 5/8 to 1/4" and some fuel hose and put the sensor on the end. i will have to mount the sensor in the framerail somewhere. but as long as there are no leaks, this should now make the tank pressurized and i dont see how the referee could care thats its not mounted on the unit itself. it should still read the pressure just fine. heres the new rig... looks kinda ghetto but i think it should work. Please tell me if im not seeing something


i know this doesnt apply to most of you but since there is VERY LITTLE info on CARB legal swap "how to's" im trying to keep my thread as detailed as possible on how to hook up all the nessesary smog equipment for anyone else trying to do this kinda swap since im going through hell and back to figure it out on my own.

ill be working more on the tomorrow. hope to get the vapor canister, vent solenoid and wiring all mounted and hooked up so that the tank portion is finished. i hate trying to crawl under this damn truck!!

Just to let you know which i might be to late there is a rubber boot that goes on the bottom of the pump which i don't see in your picture to help with vibration for longer pump life.

[kewljay223]

Just to let you know which i might be to late there is a rubber boot that goes on the bottom of the pump which i don't see in your picture to help with vibration for longer pump life.

yeah your right. i dont think i put that on since i dont remember my kit coming with a boot. it had more of a sleeve that i think was meant for the newer style unit. but that tank is not coming back down... haha i figure since the original lasted for almost 20 years without it, this should go for quite a while (fingers crossed). but thanks for the heads up, if it fails ill know why and how to fix it.

so i got my LS1 oil pan yesterday. wahoo! so you know what i did today. pulled that motor back out and put the pan on. along with other little things but my day mostly consisted of pulling the motor and putting it back in. haha yay.... talk about fun. that part that sucks the most is that it looks exactly the same as it did when i started this morn! all that work and it looks like nothing even happened. so i dont have any really good pics. but it was so worth all the effort seeing that pan higher than the crossmember. here are a few pics that i did take.


LS1 vs truck pan. so worth the cost/hassle. very easy change over.

took a look around and im very pleased to say that it is super clean inside there. i was a little nervous to look...

the pan on the block right before we dropped her back in. i also thought this was a good shot for those confused out the flexplate ordeal. i had a nice chat with forum member "bstill" who cleared the issue right up for me. YES you can use the dished flexplate but if you have the EARLY 4l60e's the torque converter has a shorter snout which requires the use of the spacer but it is placed on the back of the flexplate rather than in front. all it does is support the snout of the torque converter.

anyway, thats it for today. tomorrow the plan is to get the exhaust built up. that will take a while. ill keep ya updated. hopefully i can fire this thing by end of friday.

oh yeah, anybody know whats up with the oil filter from the truck pan not fitting on the ls1 pan? the threads are different. why would gm make a diff filter? what am i supposed to get? one for a 98-02 camaro/firebird?

[kewljay223]

ok well i was just doing some researching and it seems like the part numbers are the same for the oil filters.... idk why my filter wont thread on?? it felt like it was cross threading or something. ill look closer tomorrow, maybe i damaged the threads somehow... damn that would suck. ill let ya know

[kewljay223]

anybody know how to hook up the heater hoses? on the old tbi, there was an outlet on the water pump and an inlet on the back of the intake. then new motor has two hoses on the water pump on a Y-fitting, and from the diagrams it looks like one went to the heater core and the other went to the overflow tank (idk what the purpose for the overflow. should i just cap that since ill have one from the radiator?) where do i connect the return hose from the heater core to the motor??? i cant find any diagrams that show where the return hose goes.

[bobbylog]

[kewljay223]

sweet. does it matter which one is connected on which line of the heater core i.e. is there a directional flow through it or no? from your pic it looks like the supply hose is going to the nipple on the passenger side and the return on the driver side. is that correct? thanks alot for the pic.

[kewljay223]

well i got some more done today. was able to get the oil cooler lines ran, fuel lines ran and power steering lines too. after that it was on for the exhaust. im not pro so it took me way longer than at a shop but hey, didnt cost me anything but my time and i like welding so no big deal. was able to get everything up to the 2nd o2 sensor. still need to get the hangers mounted but im done with it for now until i hear what it sounds like as is.

im happy cuz all the major stuff is finally over. now its just a bunch of little things that im going to try and bust my ass on tommorrow cuz id really like to fire her up by the end of the day. wish me luck!

[kewljay223]

oh and i still dont know what to do about the oil filter. i checked the part numbers for the truck, camaro and corvette and they are all the same. but the filter will not thread on the new pan. it works just fine on the truck pan but it seems the threads are just slightly bigger on the new one or the pitch is different. i think i remember reading that a different filter was required if you bought the aftermarket gm "fit into anything" pan. could that be the one i need? idk what to do. i even tried taking it off the pan and i just cant. its on there reeeeeaaalllly good. any suggestions?

EDIT: BAM!!!!!!! http://ls1tech.com/forums/generation...r-adapter.html WTF GM!!!! i mean really? what is the purpose for changing the threads? who the hell does this benefit? this kind of BS frustrates me.