LS engine swap info

[Scotts Elle]

There are a few links that have since expired or are dead at the beginning of this thread. Also, many pictures are linked to "free" hosting accounts that require the hosting person to sign up for third party hosting. Can anyone please provide the vacuum check valve fitting for the brake booster? The fitting I have for the LS motor is larger than the barbed check valve on the existing booster.

Also, does the coil power feed provide 12v while cranking on a stock 67 engine harness? Wiring diagrams are not very clear. I have my LS installed and it cranks but will not fire. I have fuel pressure, VATS was disabled and base tune loaded. Data logging while cranking doesn't show much.

[aggie91]

Originally Posted by Scotts Elle

There are a few links that have since expired or are dead at the beginning of this thread. Also, many pictures are linked to "free" hosting accounts that require the hosting person to sign up for third party hosting. Can anyone please provide the vacuum check valve fitting for the brake booster? The fitting I have for the LS motor is larger than the barbed check valve on the existing booster.

Also, does the coil power feed provide 12v while cranking on a stock 67 engine harness? Wiring diagrams are not very clear. I have my LS installed and it cranks but will not fire. I have fuel pressure, VATS was disabled and base tune loaded. Data logging while cranking doesn't show much.

Definitely check and clean the injectors. I experienced the same no fire issue with an engine that had set for a good while. Had power every where I needed and the coils where firing when they should. Ended up pulling all 8 injectors and ALL of them where stuck. Cleaned them and made a harness to cycle each one with a drill battery to make sure they clicked open and closed before reinstalling them. Put them all back in and the truck fired up the first crank...To clean mine, I pulled them out, pulled the o-rings off and soaked them in a pan of berrymans carb cleaner over night. I had to tap most of them on a hard surface to get them to cycle while applying 12 volts. I also sprayed brake clean in each one with it held open with the battery and blew thru each one to get all the gunk cleaned out of them.

As for the 12v coil wire, it should have power while cranking. Make sure it is not a resistance wire or has a resistor inline. This wire needs to be a full 12v for the PCM. That is how I have my '65 wired, I just replaced the coil wire with a regular 16 ga wire from the plug on the firewall all the way to the PCM.

If you followed the lt1swap.com rework, then you should have already made the relay/fuse block that tlorber talks about.

[Scotts Elle]

Thanks all. I did end up checking the coil wire and it was hot during cranking. There was 2 issues (of course, 100% was me rushing and missed things). The crank position sensor was only lightly pushed into it connector. I had set it there a week or so back and thought, "I will pull the starter later to plug that in". Being hidden, I completely missed it.

The other issue was the Holley returnless in tank pump was wired in reverse. When I tested the fuel system before installing the motor, it worked great. All lines pressured up to 60psi, no leaks... When I installed the connector and wired the relay for its final install, I reversed the leads. I heard the fuel pump kick on so I thought it was fine when I was trouble shooting. I was going to pull the injectors and noticed that the fuels didn't release any pressure. That's what tipped me off.

Anyone know the brake booster check valve part number? The hose is larger on the intake that the original hose to the stock booster.