That's what I am going for.
The nv4500 is ready
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
L18 8.1L swap resource thread
- Thread starter Larry
- Start date
The nv4500 is ready
I’m on FB, but, not on it.
There are several 8.1/496 groups active on FB.
Many, many people all asking similar questions. I do not respond as I don’t want a presence on FB. Just interesting how many people are having similar troubles/questions.
ie: What transmission can I use? Can I use a manual transmission? what flywheel will I need?
Can I “not use” the DBW, and use a TPS/IAC? What Throttle body do I use in this case?
All questions we’ve answered here.
There are several 8.1/496 groups active on FB.
Many, many people all asking similar questions. I do not respond as I don’t want a presence on FB. Just interesting how many people are having similar troubles/questions.
ie: What transmission can I use? Can I use a manual transmission? what flywheel will I need?
Can I “not use” the DBW, and use a TPS/IAC? What Throttle body do I use in this case?
All questions we’ve answered here.
If you look at your cable throttle where the linkage hooks up you’ll see there is an extra lug where the cable for a cruise control servo cable attaches. I’m not currently aware of anybody that makes a cable specifically for a th350 to 8.1, but you might be able to figure something out with something like what I used on my 5.3 install with a 700r4 using a cable throttle. Bowtie overdrives had a cable with an end that used the lug for the cruise cable (which looks the same as the 7.4 cable throttle typically used on our 8.1 installs). It also had the length to reach the forward mount location of the throttle vs a central mount for an older tbi or carb setup.
What I don’t remember is what the trans end looked like because my memory has me thinking the Th350 and 700r4 cables are different in that end. But that’s where someone could get creative and get one of each and make them go together in some way.
Or you just get a nv4500 and do the sex change operation now and not worry about messing with an antique 3-speed automatic that was never intended to be behind a big block of any style.
I fully recognize you probably just want to get the truck running and driving but if a 5-speed is the ultimate goal, I wouldn’t waste my time fooling around with the slushbox.
Having blown up 2nd gear in the th350 in my Nova with a basic 350 with a mild cam in it I can venture to guess the trans won’t live long without serious upgrades behind an engine that makes 455ft/lbs of torque stock.
The FB peeps would have to read and possibly search. If they could read and search they would have found this thread. I'm constantly amazed at the info that people cannot even google search. If I didn't have a commercial interest, my social media usage would be entertainment only. And maybe keeping up with some news since it does seem to be a good outlet for a few interests, if you have a fine BS filter.
Having raced a TH350 built to the limit of what's practical and stopped our engine development at maybe 400hp, I would agree. Of course I also kept a 700R4 alive behind a 504 BBC that wasn't stock at all but it was very built with a full manual VB and I drove it like I wanted it to live most of the time. Again, not the right way.
I think I’m having a fuel pump pressure issue.
Truck keeps backfiring, loudly! Through the exhaust, during starting.
I just replaced the pump as the first one quit, after only running the engine for >5 minutes.
This last one it ran the engine for about 15 minutes, still works, but, it still backfires loudly through the exhaust on startup.
It will not maintain pressure. Both are/were AC DELCO units, but, pushing through an Evil Energy 10micron inline filter.
I’m about to order up the Evil Energy in-tank pump, that’s rated at 80 PSI continuous. And let the stock regulator do its thing.
Thing is making me nuts!
I’m usually really good with these kinds of problems, but, this time has me stumped.
Truck keeps backfiring, loudly! Through the exhaust, during starting.
I just replaced the pump as the first one quit, after only running the engine for >5 minutes.
This last one it ran the engine for about 15 minutes, still works, but, it still backfires loudly through the exhaust on startup.
It will not maintain pressure. Both are/were AC DELCO units, but, pushing through an Evil Energy 10micron inline filter.
I’m about to order up the Evil Energy in-tank pump, that’s rated at 80 PSI continuous. And let the stock regulator do its thing.
Thing is making me nuts!
I’m usually really good with these kinds of problems, but, this time has me stumped.
Not a fan of Evil Engery.
Cycle the key 2x then start see if it does better.
Cycle the key 2x then start see if it does better.
Did that, still back fires.
It’s honestly got me thinking my problem might be that 10 micron filter.
It’s just too “thick” for the pump to push the fuel through.
It’s honestly got me thinking my problem might be that 10 micron filter.
It’s just too “thick” for the pump to push the fuel through.
Could be. Isn't that one an AN fitting filter? If so would be easy to by pass
10 micron isn't much.
My 6.2 diesel has a 10 then a 2 micron and diesel is thicker than gas
That’s what I was thinking. So, I’m going to try a completely different aftermarket pump. Probably try that Evil Energy 80PSI EFI intank pump.
I just installed that pump in my ‘75. Been working great.
You think you have a fuel pressure problem, but what pressure is it running? Key on prime? Idle?
Before I would go through the effort and expense of another pump I’d put a gauge on it. 8.1’s will not run with fuel pressure below 45 psi. Low 50’s and it’s definitely lacking power due to the lean condition.
I will toss this in for the experience. With all my fuel pump problems when they start getting weak and putting out less pressure I’ve never once had it backfire through the intake. It has a noticeable lack of power and stumbles under load but not once has it popped back through the intake. Plus as pressure gets too low it just stalls.
The popping reminds me of an ignition issue. Which I totally get it’s pretty hard to screw up the plug wires on an 8.1. But those coil harness can be plugged into the wrong bank (which it may not run at all) or the plugs to two coils are swapped on one bank.
My thought being if fuel pressure is above 60psi at key on and running it’s most likely not a fuel delivery issue. Then I’d double check the coil wiring.
Before I would go through the effort and expense of another pump I’d put a gauge on it. 8.1’s will not run with fuel pressure below 45 psi. Low 50’s and it’s definitely lacking power due to the lean condition.
I will toss this in for the experience. With all my fuel pump problems when they start getting weak and putting out less pressure I’ve never once had it backfire through the intake. It has a noticeable lack of power and stumbles under load but not once has it popped back through the intake. Plus as pressure gets too low it just stalls.
The popping reminds me of an ignition issue. Which I totally get it’s pretty hard to screw up the plug wires on an 8.1. But those coil harness can be plugged into the wrong bank (which it may not run at all) or the plugs to two coils are swapped on one bank.
My thought being if fuel pressure is above 60psi at key on and running it’s most likely not a fuel delivery issue. Then I’d double check the coil wiring.
Oh that would be ugly, I would have to ohm out every wire to coils from the ECM. I guess I could. It would take some doing.
It doesn’t back fire into the intake, it back fires into the exhaust.
I was thinking it was an ignition problem as occasionally it will momentarily stall the starter, like it fired too early. Then backfire, then start.
It seems to run smooth enough.
I’ll check the fuel pressure again with thin new pump, see what it is, then make a determination.
I agree that if I had the banks swapped it probably wouldn’t even run. But, the possibility of having a cylinder swapped is there. Now I’ll have to go look. If any are, it’s probably only 2 as it does run, fairly smooth.
I reved it up last week it backfired through the exhaust on deceleration.
I reved it up last week it backfired through the exhaust on deceleration.
I don’t think you should need to ohm out the circuits. I’d have to look at the schematic again but I remember there being a unique color per cylinder. Should be pretty quick to match up. Middle two cylinders would be the easiest to flip by accident.
If you have access to a scan tool where you could monitor the misfire counter that would point you in the right direction to the offending cylinder.
