Hey guys i was just wondering ...

I have a 90 Formula with a 305TPI motor all stock.... its my new toy first one I have had with tpi. I have a chance to pick up a fairly cheap 85 350TPI motor out of a Corvette. My question is is there any differences in a 85 L98 and a 90 L98. Like do I have to change anything or do anything extra since the block is older. Thanks for your help guys, Ron.

 

Sounds like a good deal. First off you dont have a 90 L98. You have a 305, L98 is a 350.

The corvette engine is equipped with a cold start injector, commonly called the "ninth injector". Your 305 does not have this. It recieves its extra fuel via the injectors, for cold start up.

Also the corvette engine is equipped with a MAF, while the 90 305 has a MAP sensor. Two different ways the ECM calculates the proper A/F ratio. MAP measures by vacuum, and MAF actually measures the air the engine injests through thru the MAF sensor itself.

No problem with the conversion. Go with the 350. You can use your ECM, wire harness. You will have to change knock sensors. your new engine will be a speed density, instead of mass air.

I believe there are many books written on TPI conversions,even in non F-body and corvette chassis.

Dont let the corvette engine go. If it has aluminum heads, thats even better yet....Tom

 

right I knew I had to switch it from MAF sensor to a MAP sensor but I forgot about the cold start injector. I was going to use most of the parts off the 305 and just use the 350 short block... so eberything should work out ok then right? Are the runners different sizes for a 305 and a 350? And I am assuming the 350 has bigger injectors just like TBI motors. I am just new to the whole TPI thing so its gonna take me some time. Thanks again, Ron.

 

Injectors in a 305 are 19 lb.hr., while the 350 has 22 lb.hr.
The runners and all the other hardware is the same, except for the ninth injector hole in the drivers side runner.

There is some minor differences between the two plenums, due to the cold start injector.

Im not really sure, because I have never done this swap, between two different systems, but I believe you can just disable the ninth injector(someone correct me on this), or you can just switch the plenum and runner on the two engines.

Regardless no matter how you look at it the 5.7 is the way to go....Well worth the small amount of work..Tom

 

Did the 85 Vettes get the pc. o' sheit MAS too?

 

I believe they did in 85.

 

Yeck.