'97 350 Lt1 putting in an '87 gmc

[Gr8HallaFamer]

Looking for some advice and have a few questions. So I have a 67 model carb. engine in my truck now but want to put in this 5.7 Lt1 I have. I was wondering if my current radiator, in tank fuel pump, 700r4 tranny, torque converter, flywheel, power steering box, brake booster Would work with the Lt1? Also if anyone else has done this if they might have a few pointers and advice on this would be appreciated.

I have all of the wiring harness and ECM all in great shape nothing was cut when pulled. It's a complete engine with all accessories

 

[Bextreme04]

An 87 would have originally come with a TBI, so you should have a baffled fuel tank. You can get a fuel pump from a 96+ GMT 400 truck to run the correct fuel pressure and it will bolt right into the factory sending unit. I think everything else would bolt right over. The cooling system is reverse-flow. What application and year is it from? I'm assuming you are talking about 92-97 LT1 with Tuned port injection right? Its not a great fuel injection system....

 

[Gr8HallaFamer]

The Lt1 is out of a 97 formula firebird. This one isn't tune ported. I'm not sure about the baffled fuel tank. After googling it i found the 87 does not have that. My 87 truck had the TBI in it but I pulled that out a long time ago to run a old school 327 double hump heads and mild cam. The 700r is original too it's hooked to my 327 now also I'm still using the same fuel pumps that's original to the truck. I just put a fuel regulator in line.
From some stuff I found with Google's help is that the Lt1 isn't internally balanced so it needs a balanced flywheel is that correct? I wish I could remember if my current torque converter is the original to the truck but can't remember if it is. Maybe I could look at the flywheel on summit's site for the firebird and compare it to my trucks factory flywheel. Maybe that might help a little.

 

[RoryH19]

Yes an 87 will have a fuel tank setup for FI.
You just need higher volume pump.
By balanced flywheel are you referring to a manual? The autos usually have a light weight one. Does the engine still have the flywheel?
The 700r4 and 4l60e have the same footprint. The 700r4 is TV cable shift while the 4l60e is electronically controlled.
The LT1 should also be multiport injected. Tuned ported end by 92 for the f-body.

 

[Frankenchevy]

You’ll want a flexplate. I believe that engine is internally and externally balanced. Someone here will confirm or dispute that, but if you put the vehicle type and year that the engine came out of into rockauto or summit—it should point you in the right direction for which flexplate to get.

 

[Frankenchevy]

And yes, the 87 tanks are internally baffled and the same torque converter will work. Many flywheels come dual bolt pattern, but just confirm the spacing of your torque converter to the flexplate your looking at.

 

[bucket]

The flexplate for an LT1 will come up different than an '87 truck simply because the LT1 was used in cars and had a 153 tooth flexplate while trucks had a 168 tooth flexplate.

All '86 and newer had a weight on the flexplate. If you had a 327 installed, it will not have a flexplate compatible with the LT1.

 

[Gr8HallaFamer]

I know i mentioned flywheel in my previous post but I meant flexplate. I think one is for the manuals and other for autos. Lol my bad

No Rory the Lt1 doesn't have the flexplate. Bextreme04 gave me an idea for fuel pump. Also I have my cable kick down on my 700r now but I think it'll be to short and I'll have to get one for firebird.

Thanks frankenchevy for confirming the torque converter. Also I will check what flexplate rockauto shows for the 97 firebird.

Thanks bucket for the teeth counts. I seen on rockauto had a 153 count for the 97 firebird for 39.00 so this flexplate should work for me? I have the original starter for the Lt1 too.

 

[Gr8HallaFamer]

Seem like this should be an easy swap since most my stuff now will cross over. I think my only big issue is getting the correct flexplate and fuel pump. Those are easy to change. Just need to get the correct ones.

 

[1987 GMC Jimmy]

See, now this is an interesting swap. I think I’d use an OBDI harness from any early F Body/Camaro, I know W Bodies have the same style of ECM so you could (conceivably) yank the harness out of an old FWD car that used the 440-T4 in 1990 or before, and repin anything that was different. That way you could control everything, including lockup on the 700R4, without having to reflash anything. You’d need ECM 16159278 for this route, and there might be flaws with my approach. I’m just brainstorming for how I’d do it.

I also wouldn’t be tempted to convert to coil-per-cylinder if it doesn’t have that already. I have to have an old school distributor in the cars I proactively seek out, but if I had a gun to my head, I’d still do the optispark because at least your spark source is consolidated, one of the main pros of a distributor anyway, and the aftermarket seems to have ironed out a lot of the kinks that were occurring in the 90s. They’re actually really precise.

 

[Gr8HallaFamer]

See, now this is an interesting swap. I think I’d use an OBDI harness from any early F Body/Camaro, I know W Bodies have the same style of ECM so you could (conceivably) yank the harness out of an old FWD car that used the 440-T4 in 1990 or before, and repin anything that was different. That way you could control everything, including lockup on the 700R4, without having to reflash anything. You’d need ECM 16159278 for this route, and there might be flaws with my approach. I’m just brainstorming for how I’d do it.

I also wouldn’t be tempted to convert to coil-per-cylinder if it doesn’t have that already. I have to have an old school distributor in the cars I proactively seek out, but if I had a gun to my head, I’d still do the optispark because at least your spark source is consolidated, one of the main pros of a distributor anyway, and the aftermarket seems to have ironed out a lot of the kinks that were occurring in the 90s. They’re actually really precise.

That might be to much for me. I'm just kinda learning as I go. I looked up some some stuff on the 440-t4 but seems like more than I might can handle. I was hoping to use most of what my truck already has and if the ecm need reprogramming have that done since it'll be easy to do.

 

[Rusty Nail]

The flexplate for an LT1 will come up different than an '87 truck simply because the LT1 was used in cars and had a 153 tooth flexplate while trucks had a 168 tooth flexplate.

All '86 and newer had a weight on the flexplate. If you had a 327 installed, it will not have a flexplate compatible with the LT1.

Good catch Cubo. LT1 flexplates are different!

I support this swap 100% and I'm very interested. Pokin my nose into other people's LT1 swaps, it's my opinion based upon my previous intelligence gathering, that if it were ME, I wouldn't dream of not installing a damn fine aka super cool/really good Optispark and water pump unit before I spent dime number two. Suuuuurrre seems like the right place to start. Good luck!

 

[Gr8HallaFamer]

An 87 would have originally come with a TBI, so you should have a baffled fuel tank. You can get a fuel pump from a 96+ GMT 400 truck to run the correct fuel pressure and it will bolt right into the factory sending unit. I think everything else would bolt right over. The cooling system is reverse-flow. What application and year is it from? I'm assuming you are talking about 92-97 LT1 with Tuned port injection right? Its not a great fuel injection system....

I know you mentioned a different fuel pump but I was also told that a 255 LPH
Walbro GCA758-2 - Walbro Electric In-Tank Fuel Pump would work? Would it fit in the factory sending unit. What has got me on this one is I can get a new one for 40 bux which is more than 50% off. But if it don't fit I don't need it.

 

[Bextreme04]

I know you mentioned a different fuel pump but I was also to that a 255 LPH
Walbro GCA758-2 - Walbro Electric In-Tank Fuel Pump work? Would it fit in the factory sending unit. What has got me on this one is I can get a new one for 40 bux which is more than 50% off. But if it don't fit I don't need it.

I think the answer is yes it will fit, but lots of people have been complaining about reliability with them lately.

The OEM ACDelco EP381 is the correct pump for that application and will fit your stock sender. It's $87 at rockauto. There are equivalent Carter or Delphi pumps for $20-50 also. https://www.rockauto.com/en/catalog...ban,7.4l+v8,1303108,fuel+&+air,fuel+pump,6256

I'm using the EP381 in my swap because it came in the donor truck

 

[Gr8HallaFamer]

I think the answer is yes it will fit, but lots of people have been complaining about reliability with them lately.

The OEM ACDelco EP381 is the correct pump for that application and will fit your stock sender. It's $87 at rockauto. There are equivalent Carter or Delphi pumps for $20-50 also. https://www.rockauto.com/en/catalog...ban,7.4l+v8,1303108,fuel+&+air,fuel+pump,6256

I'm using the EP381 in my swap because it came in the donor truck

Ok I'm going to go with the EP381 thanks for your input