K 1500 350 in 305 out / NEED HELP!

Hey guys, I took a 305 out of my 1990 k1500 P/U and instaled a 350 out of a 1989 Chevy Suburban. I used the 305's intake/TBI and distributer. It also has an after market timimg cover. So the questiuons I have are Where are the timing marks suposed to be, at the side of the cover or at the top? Secondly, Does it matter that I used the intake/TBI, and distributer from the 305? Or is it just that I need to change the ECM (computer)
Thanks

The intake and such shouldn't matter but i think you have to have the 350 tbi injectors. You can just buy the injectors you don't have to buy a whole new assembly.

I have a 90 with the 350. The timing marks should be in the same place as the 305. With the engine at TDC, the timing mark will be on the right side (kind or 1 or 1:30 on a clock).

The ECM is the same as the 305; however, you will need a PROM for the 350.

//2000CAYukon

Now I have another question... What is a prom?

Programmable Read Only Memory, it is in the ECM and contains information such as engine size and so forth.

What do I have to do to change the PROM? I guess I need to purchase the Chip, but how do I install it?

What do I have to do to change the PROM? I guess I need to purchase the Chip, but how do I install it?

http://www.tbichips.com/instructions.htm

//2000CAYukon

Well after going throught a pile of research... It's the injector's I have to change. My PROM is set up to handle 305, 350, and 454ci motors. So if anyone knows how the he// I find the right injectors/or TBI for a 350 please do tell. I have been told that there are 7 different injectors for a 1990 GMC truck. So here we go again.

Well after going throught a pile of research... It's the injector's I have to change. My PROM is set up to handle 305, 350, and 454ci motors. So if anyone knows how the he// I find the right injectors/or TBI for a 350 please do tell. I have been told that there are 7 different injectors for a 1990 GMC truck. So here we go again.

Take a look Q1 on this FAQ http://www.tbichips.com/faq.htm It has the part number for the 350 injectors. I disagree with your comment about the PROM. They all use the same ECM (or computer) but they definitely use different programs.

I bought a set of reconditioned injectors from this guy for $89 shipped to my door http://www.injectors4u.com/

//2000CAYukon

I've used the stock 305 TB on a similar swap. We put a hot '87'ish 350(originally carbed) into a '95 C1500 with a TB adapter, and never had to change the PCM. After some timing issues(damn that brown dist. wire) and a reset, the engine couldn't be happier.

Well it looks like WE might have just figured out the problem I've been having with this swap. I put a TBI off of a 88- 89 Suburban on the truck and it seems to have solve most of the issues. I still occasionally get a check engine light but it also goes out quickly. I'd like to thank all of you for your help to this point.