Hey Guys!

I'm working on my mom's 89 Firebird again. Its an LO3 and it blew a head gasket. It makes brown antifreeze continually so I'm pulling it down to the short block to breathe some new life into it.

I've been gathering parts up and here's what I've got so far:

Vortec fuel pump (previously installed by me in 2010 when I bought the car off of craigslist) that supplies much higher pressures and flow than the stock TBI pump

081 TPI cylinder heads from a good running 1988 Trans Am that got scrapped due to rust issues

exhaust manifolds from a 1990 Trans Am (not sure what casting they should be but hopefully they're not the same as what I have now) with y-pipe. They look suspiciously like TBI parts and if they are then I wasted money. Grrrr......

An LT1 camshaft? I don't know what flavor of LT1 cam I have because I can't find the OEM part number on it. What I did find was this: GMPT BC 17 779, then at the bottom 779 18f 1031, then 35400 0031*

I don't know what any of those numbers mean. It looks like the cam in the LT1 articles on our forum, no fuel pump lobe and seems to have a long pin coming out the front. I'd just like to know, ball park, what I have. I'm sure its better than the LO3 peanut cam no matter what it is.

Next up to buy are the gasket sets, TBI adjustable fuel regulator and the various little exhaust pieces to get this thing on the road and happy.

I am anticipating that I'll have to increase the fuel pressure a little to compensate for a more free flowing cam, heads, and exhaust. I'll start tuning after I have it running again to make it perfect.

One other thing, my guy at the machine shop says the last LT1 cam he swapped into a small block had a different firing order or something like that? I told him I'd never heard of that and planned on printing out one of our articles on an LT1 cam swap and giving it to him.

Any suggestions? Anybody know what those cam numbers mean or what cam I have?

Thanks guys!

 

As far as I know, all stock GM LT1 cams have the standard firing order. An aftermarket LT1 cam can be ground with the LS1 firing order (4/7 swap?).

If you use the TPI 081 heads the PROM will require a re-do as those heads require a bunch more spark advance then the TBI swirl port heads. Along with a bunch of VE table work to get the fueling back in line (from heads & cam).

RBob.

 

Sounds like good advice so far, thanks!

I was reading in the LT1 cam swap article that I might need an initial advance of 8 degrees or so just to get it to start? Anybody have any experiences with that?

As far as the PROM burning goes, I think I'm ready to tackle that. I don't fully understand all the ins and outs of it yet, but there's no time like the present to get it done.

 

I screwed myself by not knowing the proper casting numbers for the big exhaust manifolds ahead of time. Great. I now have an extra set of boat anchors...AND a useless y-pipe

I hate learning these lessons the hard way

 

779 is a Vortec truck cam. My 97 Express had the 779 cam.

 

Right on! So now at least I know something.

That's still better than the LO3, yes? I've read on this forum that the vortec truck and the B-Body LT1 have similar specs, is that true, too?

Thanks for the input!

 

Some years they had the same exact cams. The L31/B-car LT1 and even L99 4.3 used the same cam.

191/196° @.050"
.414/.428" lift
111° LSA
106° ICL

The stock TBI L03

179/194° @ .050"
.350/.385" lift
109° ICL
108 or 106° ICL I forget which

 

If I were in this position I would probably hunt down a "395" Marine cam.

196/206 @ .050"
.431/.451
109° LSA
106° ICL

With 1.6:1 rockers on a Vortec 350 with the Ramjet EFI it makes 350 hp.

 

Thanks for the info!

 

Thanks again for the info. I'm keeping the vortec cam because its better than what I have and I already have it now.

I'm in the process of getting a burn on a chip to start out the tuning for the car now.

I've also got my L98 manifolds, my OEM 88 IROC-Z cat back, a magnaflow 3" cat, and I just purchased a MAC y-pipe from Hawks. Mom's car will have a little more pizzaz, so thanks guys!

 

Don't forget to shorten the cam gear locating pin on the cam. Sometimes they can be tapped in further, other times they need to be cut shorter.

RBob.

 

Will do. I plan to just stand the OEM peanut cam next to this one and make them match.