campbellerman

i just found out that my 1990 305 tpi has 187 tbi heads on it i have base timing set at 8 degrees and i am getting a little spark knock and bad gas mileage will it run better if i set timing at tbi stock 0?? thanks for the help in advance

CamaroIROC88350

iTrader: (1)

I believe the factory set timing is 6 on most TPI cars. Try reverting to six and use a flasher to do it too.

campbellerman

but it has the tbi heads instead of the tpi heads so will it still run fine at 6 degrees?

CamaroIROC88350

iTrader: (1)

If you have a TPI intake why do you have a TBI set of heads if you don't mind me asking?

To answer your question on the TBI's I'm not certain.

Do a search on here for your answer. I'm sure you or I could find it if we wanted to.

Let me know what you find.

campbellerman

the engine was replaced in '98 with a rebuilt from advance auto. it has the l98 cam but the '187 swirl port heads

CamaroIROC88350

iTrader: (1)

Here you go, read through this thread about TBI related material. I'm not a TBI guy but I hope you can find what you need in this sticky.

https://www.thirdgen.org/forums/tbi/...check-out.html

campbellerman

i will read it thank you for the help

CamaroIROC88350

iTrader: (1)

Here is another thread talking about swirl port 187 heads.

https://www.thirdgen.org/forums/tbi/...heads-why.html

CamaroIROC88350

iTrader: (1)

I posted a 2nd link for you below. Sure, anytime.

CamaroIROC88350

iTrader: (1)

Based on some quick reading I see that the 187 head is the worst of all our heads for the SBC engine. If you could you should go to a better aluminum head such as L98 aluminum heads or the L98 iron heads if you're on a budget. But you could keep your current heads I suppose.

305sbc

iTrader: (3)

The TBI heads require a very conservative timing curve in comparison to what is in your TPI EPROM.
You may have to run 0* initial or even a little less to prevent spark knock.