I have a 89 305 tpi auto car with 60k on it. I am putting in an 87 iroc 350 cam and 1.6 rockers and upgraded pushrods. During the swap I'm installing headers and under drive pulleys.

my question is will my cam swap be a fit and run perfect without any other modifications or special parts? Any other parts that are recommended for the install? thanks Brian

 

nothin?

 

You should take a serious look at replacing your heads at this time if you're looking for more power. You're going to be getting close to having enough of the engine stripped out with these mods. I can't tell if headers actually do anything for you w/o better heads. Search my recent post on the 305 header change, those guys saw no increase. The cam might buy you something, and better catbacks might get you something, but not sure if the headers will w/o better flow out of the heads.

This is what I'm starting to surmise, still investigating.

 

Should be a lil bit of an upgrade with that cam and work fine as the 305 manual TPI got the 350 spec cam in 91-92 I think. Id upgrade my springs as well. The 081 heads are actually pretty decent heads. Id say you should push 230-240+ hp with a good set of headers and 3in exhaust with this setup.

 

I already have cat delete and full exhaust. I know big hp is not gonna be made on the 305. I would be happy to reach 275 hp on this motor. But everything I am doing has both motors in mind. I'm searching for heads as I have a factory 350 I would like to build down the road. thx guys

 

ALL 305 TPIs got the L98 350 cam in 1990.

 

Ran across this earlier: http://gmtips.com/3rd-degree/dox/tips/tips.htm

http://gmtips.com/3rd-degree/dox/tips/cams/cams.htm

"All 305 TPI (LB9) engines (1985-1992) came with one of two basic cam grind profiles. An easy way to identify the type of cam on an LB9 car is to look at the tach: the lesser cams have a yellow line at 4500 and red line at 5000; the hotter cams have a yellow line at 5000 and red line at 5500. All camshafts 1987 and later use hydraulic roller lifters."

Here some good links to head info:

https://www.thirdgen.org/forums/tpi/...ml#post5933683

Check link with the guys from WI who warn about flow going down w/ bigger valves....

This guy says Dual Cat's have higher HP engines. Wonder if Dual Cats got the bigger cam? http://www.ls-guy.com/lb9/

Just answered my Duat Cat question : http://www.3rdgenformula.com/90/90technical.htm

 

Interesting stuff. I read this same info last week and discovered I have the weaker cam as I have the yellow line at 4500 in my 1986 IROC TPI. I was disappointed at first, lol.

 

As was mentioned before, If you're going to labor over a cam swap, it might be wise and do a head swap as well. They sorta go hand in hand for generating power... RE-tearing into the center of engines ain't like building legos, unless your lucky

 

Just ran across this, not sure if it makes sense, but food for thought: http://www.goingfaster.com/driverseat/formhist.html


"Power choices for 1990 remained the same with some notable improvements. The LB9 5.0 liter TPI V8 got the same cam regardless of choice of automatic or manual, producing 210bhp and 285 lbs.-ft. of torque. If the hotter G92 package was ordered, horsepower for the manual (only) backed LB9 jumped from 210 to 230bhp and torque increased to 300 lbs.-ft. The B2L still produce 240 bhp and 340 lbs.-ft. of torque this year. The B2L was still not available with a manual transmission."

 

ALL speed density LB9s got the L98 cam regardless if it was Auto or Manual.