putting a 502 in an '87 suburban

[FlatBlackBurb]

okay so i have a chance to get my hands on a 502 gm performance parts engine with about 40k miles on it for 1500 bucks or so.

http://www.gmperformanceparts.com/EngineShowcase/index.jsp?engId=HT502&engine=HT%20502&sku=88890534&engCat=bb

theres a link to the engine. im pretty sure its an EFI fuel injection, thats what the guy who has it said, only problem is i have a TBI system. how hard is it to switch the two? he said he has the complete wiring harness i just want to know if its that involved. like what needs replacing etc etc.

im not too impressed with the 350 i have now. not much power. what kind of power increase can i expect to get with this engine? im running 4:10 gears with 36's and a turbo400 tranny. the guy said it spins 38's easy.

so whats involved with swapping these engines out? is it worth it? has anyone done it before?

thanks

 

[54inches]

It should have the same placement as a regular BB.

It will fit no mater what.....

 

[FlatBlackBurb]

yeah but what about the different type of fuel injection? EFI instead of TBI? whats involved with the wiring harness? and all the electrical crap? also the ECM

 

[54inches]

It should have a stand alone computer.

 

[bowtiepower00]

In addition to being a carbed replacement motor, the HT502 was also offered as a replacement engine for TBI 454/4L80e equipped trucks (notably the 454SS, but HD trucks too), complete with GM PROM replacement and CARB exemption. The cam is tiny and computer friendly. Dimentionally, it will be the same as any other BBC, the only drawback to the GM 502 block is that it has no provision for a mech fuel pump, but since you're going FI that shouldn't be an issue. If it has GM FI on it, it will be TBI. You will be probably be able to use your current computer, but you'll have to find a 454 throttle body and possibly do some wiring mods to swap the TB unit out for your SBC one. Edelbrock offers a conversion kit to make it's TBI multipoint conversion work with the 502, but that's a whole nother bag of worms there. If it's aftermarket multiport, you're on your own.

I would grab the FI with the motor if you can. It will save you headaches in the long run. BBC TBI stuff is hard to find and expensive.

$1500 is a good deal for that motor though. It's about $5500 new.

Lots of BBC TBI and FI knowledge over at 454ss.com.

 

[midnight]

It should have a stand alone computer.

I second that. Usually those crate FI engines are designed to work with a seperate computer and wiring harness.

 

[vortec]

snatch that thing up. worst case scenario, you sell it for a profit.

 

[bowtiepower00]

The only GM BBC crate offered with a stand alone computer is the Ram Jet 502. The engine may have a standalone computer with it, but if it does it's not going to be a GM one.

Still a good deal for a torquey motor, though.

 

[Greg72]

The HT502 is a LOT less sexy than the regular 502s.....

Very restrictive heads from what I remember.....I have a comparison chart for all the 502s in my gallery link. GM uses different scales on their dyno sheets deliberately to make it harder to make direct comparisons between the HT502 the 502HO the RJ502 and the ZZ502.

 

[bowtiepower00]

Yes, the HT502 does have small port heads, but they really aren't a limiting factor for a low RPM torque motor. In fact, they will produce better low RPM numbers than the rectangle ports offered on other 502's. The biggest reason the HT makes such low numbers is the cam. It is tiny. With a cam swap, and perhaps a little work to the heads, it will make a solid truck engine. The HT cam is small enough to be TBI friendly, however.

For a musclecar, no, it's not a good choice. But for towing or moving a lifted rig with large tires it will definately get the job done.