I am looking at buying 1991 Trans Am with a 305 TPI. It has 113,xxx miles on it. I want to make the car a driver and one of the things I need to is rebuild the motor. I want to set it up stock. What do I need to do, being my first real engine build up? Does the cam need to be replaced? If so, where can I get a stock one? Will everything work as factory if the motor needs to be bored out? Will the bigger pistons affect the TPI system at all? What sensors need to be changed and which can be reused? Any suggestions for labeling wires, cleaning the TPI unit, and the build in general would be greatly appreciated.

 

I would start with a 350 short block and go from there. Allen

 

I thought about going 350, but decided agianst it. I want the better gas millage from a 305, plus I want to keep the car as stock as possable. I just want a nice looking driver. The big thing I need to know is what to do about the cam. I here people say you need to replace it and others say you can reuse the cam. I would end up replaceing the water pump, oil pump, oil pan, radiator, belts and hoses. What elses needs to be replaced?

 

If you want a solid 305 with good gas mileage it is not hard. Build a new engine with a pair of Hypereutectics, LPE or ZZ4 cam, port the intake and Plenum, get larger runners and a set of Vortec or World S/R Torquers heads. And yes you will still get like 23 mpg at least on the highway. I know because my friends ZZ4 350 gets 23 mpg highway. So a 305 could do better.

 

I believe he'll need more than a pair. Maybe four pairs?

That extra MPG or two the 305 may get on the highway may not be a great tradeoff for the lower power output.

Maybe telling the kid in the 4.6L Mustang that just smoked him "Yeah, but I'm getting better gas mileage than a 350!!!" will help the bitter pill go down easier.

I'd go with a 350, mild cam like the LPE 219 stick, and small-port aluminum heads such as the ZZ4s. The tiny <170cc intake ports are a great match for long-tube runner TPI.

My rebuilt L98 with flat-top hypereutectic pistons, ZZ4 heads, and an LT4 HOT cam pulled over 25 MPG on flat Interstate consistently (GPS verified) and ran 13.19 @ 103mph in the 1/4mi on the same software that passed NJ treadmill emission inspections. Not much to complain about there. On two long road trips, I was within 0.5gal each refill compared to the '95 TA with 6-speed trans I was benchmarking against. Power production flattened out above 5000rpm, but that's the compromise.

 

Sorry to hijack the thread but I tried private messaging kevinc and it wouldn't work. Were their any problems with the installation of the heads and cam? What else would be need for the install? How much time and money should be set aside for the installation excluding tuning? What's the powerband and have you gotten it dynoed? TIA for any response. Again sorry for hijacking the thread.

~Roger

 

I had to turn PM off, too many "how do i swap and ls1 into my iroc!!!!!1!!!???" messages arriving. Yes, that's an actual quote sadly.

The L98 rebuild survived four hard seasons of drag racing, road courses, and street use. The shortblock was sold to a fellow road courser still with the honing crosshatches visible in the bores. (go Amsoil go)

Best dyno run w/ the long-tube TPI:
http://www.mycar.net/mafb/registry/d...id=963&ref=det

The only problem happened towards the end of season 4 when one of the old-design FelPro 1003 head gaskets separated a fire ring, and it started ingesting a bit of coolant. Even then it ran fine, just killed two O2 sensors before I tracked down the problem.

The engine went together all in one project, it wasn't a heads/cam swap, so I'm not much help in terms of estimating a swap.

Materials are new ARP head bolts, Permatex thread sealant w/ Teflon, head gaskets, timing cover gasket, and the usual stuff.

 

Has felpro revised the 1003 head gasket or is there another part # that has taken its place? I was about to order a set untill I read your post.

 

Thanks for the fast response!! Those are some nice numbers and I can bet the LS1 setup is even better! I've got one more question, who'd you order the heads from? Ok a few, did you keep the stock tpi plenum and base or was it mildly modded? I think that's all the questions. Thanks!

~Roger

 

Yup, and it's easy to distinguish the old design from the new.

The old one is the traditional blue embossed surface, the new is black with blue sealant beads around the coolant passages.

No known instances of fire ring failure on the new design that I'm aware of.

Pay attention to your quench height before ordering these...they're pretty thick. I'd had my block zero-decked, so I could run 0.041" or whatever they were...way too much on a stock block with the pistons 0.025" in the hole. I'd go with the thinner FelPro 1010 or GM replacemetn L98 multi-layer steels.

 

I ordered the heads from SDPC2000.com but any GM dealer can get them. They come fully assembled w/ hollow LT4 valves, LT4 springs good to 0.525" lift, ready to go if you don't want to port/polish them. (I didn't)

I used an Accel base, and polished up the stock runners and plenum. 52mm throttle body upgrade from skulte.com topped it off.

The ZZ4 heads have 90deg intake bolts as in pre'87 design, so it's a planning consideration if you're using an '87+ intake. The Accel intake had both angles and slotted holes so it goes either way.

 

Hey Kevin, how do I swap an LS1 into my lawn tractor?

 

Lets make that into a sticky on the boards.