305 Dying

[SLICK78]

Well guys the stock 305 in my 78 is knocking something bad...so I have been trying to come up with a cheap but reliable solution since this is my current DD. I found a 89 350 tbi with 10k on fresh rebuild for 200, then comes the problem of re-using the stock exhaust. I have found that I can plug the block dipstick provision and reuse my 305 pan with the dipstick in the pan so I can retain the stock exhaust manifolds. my question is this is the 89 tbi 350 a roller motor and if so what would be the biggest cam I can put in it with out needing head work and a stall. Also tbi heads accept regular sbc intakes correct? thanks for the help guys.

 

[t5montecarlo]

check to see if it has provisions for a mechanical fuel pump.

 

[SLICK78]

well I have a good 400 sbc that I am more interested in putting in it but it is a 72 model and never had the valve covers off so I think I will drag it home and pull it apart to inspect it....Side note not in nearly as big a hurry now got it up on the freeway after work and the knock went away so I am thinking it is a sticking lifter or something even after I shut it down for 30 min or so and fired it back up the "knock" is gone so I dont know what to think

 

[Doober]

Have you pulled the intake? All TBI engines I've seen have been flat tappet. You can still put a reasonably sized cam in a factory roller block... the LT4 hot cam is .492" and can be used with a stock roller setup.

Being that I've been going through this process myself, know that:
A melonized/'composite' distributor gear may be required, and they're NOT cheap (think $80+, most I've seen are over $100).
A factory roller cam-specific timing set is needed, and they're at least double a regular timing set (cheapest I found was $50 for a stock replacement). If you use a cam button along with a strong enough timing cover you can use a regular timing set, just buy a retrofit roller cam instead of factory roller (the difference is the nose on the cam is machined for the retaining plate on the front).

 

[SLICK78]

well after reading you other answer to my question about the heads I am pretty sure I am gonna pass on the 350 and just pony up and build my 400... I noticed yesterday and re-confirmed this morning that my current 305 is only making the "knocking" sound on cold start ups and after it gets hot it goes away I will try when I get out of work to video the sound...Thanks for the help guys!

 

[Doober]

You don't have to use a roller of course If the 350 has 10k on a rebuild it may be a better deal... if the 400 hasn't ever had the valve covers off you may very well be going through the entire machining process, including possibly getting better heads for it, etc., I'm just thinking out loud.

 

[SLICK78]

man I am so torn as to what to do... On one hand I really want to put in my 400 but I know I could get the 350 in now and I have no idea when I could get the 400 put together an in

 

[DOUG213XRJ]

I would go with the one that would get the Malibu running the easyest and cheepest

 

[SLICK78]

but the condition of the 350 is unknown I was told they pulled it because of a leaking intake which leads me to believe the bearings were washed with anti freeze....so I am gonna just build my 400 since I am pretty sure my 305 just has a sticking lifter so I think I got some time as I would like to do the 400 with a gear and od trans all at the same time...but we will see haha I could blow it all over the road today on the way home from work

 

[Damon]

Truck TBI engines are flat tappet. Car TBI engines use roller cams. The truck block MIGHT be a roller cam block (it's kind of a crap shoot- some were, some weren't), but even if it is a roller cam block it will have a flat tappet cam and lifters in it.

TBI heads are the weirdo 87-up bolt pattern. The center two intake bolts are "stood up" at a steeper angle than earlier heads. You can modify an earlier intake to fit, but I wouldn't bother. The 305 heads off your old engine would work just as well as the factory TBI heads.

If you can build up that 400 in a reasonable timeframe I agree taking a pass on that 350 TBI engine would probably be a good idea. If you just need something to throw in it real quick to get it running, then pick it up, swap your 305 heads and intake onto it and drop it in.