mich2112

iTrader: (1)

Searched here and Mortec and Internet. Didn't find a definite answer.

14102183

Thanks, Mike Jones

F-BIRD'88

late 305 TBI swirl port heads.

Limited high performance head. The funky shape and swirl vane
in the intake port promotes high swirl and turbulance but restrict
high lift flow.

Best used on low horsepower low rpm motors.
They work well for that.

NTChrist

Some people say that the swirl can be ground out to increase flow. I haven't seen any numbers to back this up, tho.

mich2112

iTrader: (1)

Thanks F-BIRD88:

Could you tell me the best roller cam to use with my engine I'm building? 88 Iroc-Z

block: 14093638
heads: 14101083

I don't want to have to spend a lot on machine work on the heads. I also dont want to change to heads that require external EGR or Vortec manifolds.

I will be using my stock TPI.

Thanks, Mike Jones

F-BIRD'88

Not a lot of info.

What size motor? what rear gear ratio? what stall converter.
Are you going to port those heads. Will you be raising compression ratio? are you going to modify your tpi Porting, Runners. Headers? etc.
All this needs to be considered when selecting a cam that will compliment these mods.

Cams by themselves are poor power adders. But work well
when combined with other mods that increase airflow thru the motor.

Something with 204 to 216 @.050" duration and .450 to .500"
lift will work well with home/ported "083" heads.
maybe with 1.94 x1.60 valves.
try some higher ratio rockers arms.
Just don't get too carried away with duration.
TPI motors are midrange torque motors.
A larger than stock TPI cam will increase power at the high end of the rpm range, usually at the expence of low end torque.
You want to get one that has relatively low overlap (wide lobe separation (112/114) to be Computer friendly.
You can browse the different EFI friendly cams on Crane, Comp
and Crower cams internet sites.
How about a ZZ4-350 take off cam with 1.6 intake rockers.
check out www.competitionproducts.com There is a new GM hyd roller for like $49 that would work well with 1.6/1.7 rockers on a mild TPI like yours. PN #264HP
Just be sure to get a valve spring that can control the valvetrain.
The different cam manufacturers all ahve tech lines you can call/ email to get the right stuff.
You could also buy this 264HP cam just for the core and send it to Comp
Cams or Crane to be reground with a custom EFI grind that is matches to your buildup plans.

kfoley

I have a set of 901 heads (I think that's the casting number, they're late 80's early 90's swirl ports) that I'm porting (experimenting with). I'm grinding out the "swirls" and if I don't bust through a wall, I'll get them flowed to see if it actually worked. Does anyone know if I will have any problems grinding all that stuff out, or is there plenty of meat to take out?

F-BIRD'88

Grind away you really have to grind quite a bit to go thru.
You can epoxy up any boo boos any ways.

If you wanted to be creative you could epoxy Putty fill the bowls
and ports
which have poor shape for high flow and recontour them.
Its actually real easy to work with the stuff.
You can't do any harm there. You could have a good look at some vortec's or Darts or Brodix etc to see what port shape
is favoured. Might just create the best "Super Stock" cheater head going.
I say grind 'em out and putty them up with temperary modeling putty. or window dumb dumb.
do a few ports differently with different design shapes.
Take the "experimental head(s)" to someone with a flowbench and flow the different ports you created with the putty.
If ya find on you like that flows, just copy it in Epoxy putty on the rest of the intake ports. Epoxy putty is quite durable on intake ports. Go nuts and have fun.

kfoley

Sounds like a plan. I've already ground the "swirls" down even to the valve guide, but couldn't do much until I got my cutters, since then I haven't had much time to work on them. Where can I get epoxy putty and how much does it usually cost?