I'm new to posting but have been a member on the site for a couple months, anyways, i have recently swapped my 305 TBI to a 350 TBI (L98), and i have a very noticeable knock after my car warms up, to the point of where it will then die, i am currently running a stock 305 chip so i know that is bad, would this be cause strictly by the 305 knock sensor or could it be timing or what? thanks for any advice, hope to start posting more often.

 

You need a 350 knock sensor and esc module. Your stock sensor will not cut it. Get ones from a LO5 350 TBI caprice car. You will eventually need to get into chip burning as well. In the meantime try to get your hands on a "cop car chip" found in certain carpice cars. That chip will be close to what you need pending you kept that motor stock. Are you using a L98 short or long block?

 

Using the Long block, bored .030, a mild cam (not sure on specs yet, guy i bought it from said "1 over stock") not sure what that means totally i'm not very knowlegable on cams yet, im running 305 heads at the moment, (till i can afford 350 heads)

also ESC a.k.a. PROM? sorry if newb question, just trying to straighten out terms. Do i still want a "caprice cop car" chip w/ an upgraded cam and being bored over...or should i bite the bullet and invest in a custom chip?

I'm only 17 and still paying off the engine so the best affordable options would be nice to hear....thanks again!!

 

I only suggest the cop car chip when people go with a 350 TBI that is pretty much left stock. Anything else requires chip work (the chip is the PROM) not found from aftermarket sources. The best way is to bite the bullet and learn how to do it yourself. You can get all of the stuff for under $250. You need a 350 ESC (electronic spark control) module to get the car to run correctly when you switch displacments with TBI systems. More importantly is the correct knock sensor.

 

thanks for the fast response, where can i find an ESC module? E-bay? Junkyard? New?

 

All three. I would go new just for reliabilty sake. Just ask for the ones on 350 TBI b-body cars (caprice/impallas). Make sure you have the right knock sensor as well. Try a few searches. You may get some part numbers and or other ways of getting these parts.

 

I did a few searches and DID find some helpful tips, [B]except where to find an ESC module, i had a friend of the family check(used to own a garage) check with his parts dealer, and she just laughed when he told her what i was doing and the parts i would need to get it running top notch, but she said she would keep her eyes open and check around for me. Also, i was offered a 78 350 two bolt main out of a 70's Van for $50, (with heads), what are you opinions on this, i figured i buy it, and get the heads redone by a guy i know for $100 and use them on my L98 (to replace the 305 heads im running). Any opinions?

 

There are 2 parts of the van motor that need to be destroyed by crushing and/or melting down as soon as possible, because they are responsible for that motor's awesome 170 HP output:

• the heads
• the cam

The heads are among the candidates for the worst ever made for the SBC. Far less potential than your 305 heads; unless your 305 heads are the ones off the TBI motor, in which case, they're about equal..... at the bottom of the heap.

If you're using the L98 long block, then you have L98 heads, since it includes the heads (that being the definition of a long block); those are fairly decent heads, far far better than the van heads.

If you don't know what heads you have, get their casting number, as that will tell everything that there is to know about them.

 

The guy i bought it from had the L98 heads for it, but when i took them to get them redone, they had two HUGE cracks running out the center, and i did not have anywhere near the cash i needed to buy a new set so i just took the heads off my old block, got them redone and put on and i was told itll give me awesome compression till about 4,000-4,500 rpm. And i figure itll buy me some time till i can afford new 350 heads.

 

Those 305 heads may be better than the 350 heads.

 

the ones off the van or the ones off the block? how much better performance would i get to port out the 305 heads? would it be worth it?

 

The L98 heads are leaps and bounds better than the van heads. The van heads are horrible and should not even be re-used on a motor. For the most part the only 305 heads to stay away from are the 187 LO3 heads. The 416 and 081 heads will work better when ported but will still keep some of the power out of your final equation.

 

so would i be better off to eventually scrap the heads (305) and get a set of camel backs? or even find another f-body 350 and take the heads?

not sure on the 305 heads, could be LO3's or LB9's....not sure i'd have to check the casting numbers

 

I would suggest vortec heads as a future replacement. It all boils down to what you want the car to do.