Jayson_305

Hey all, i have a 85 trans am and im looking to do a cheap 350 build. I’m looking around and ive come across a few center bolt head 350’s. Im curious to see if those engines will accept the older (early 80’s) perimeter bolt style heads. Thanks in advance!

Tuned Performance

iTrader: (92)

The will only have one bolt pattern unless there aftermarket heads such as afr. There are adapters to put perimeter on center bolt heads.

Tuned Performance

iTrader: (92)

https://www.ebay.com/itm/26570837934...mis&media=COPY

WildCard600

I think OP is asking if the heads will bolt to the block.

Tuned Performance

iTrader: (92)

gotcha, yes later swirl port or vortec ect will bolt to a earlier two piece main sbc.
you will need a different intake manifold depending on heads or elongate the center holes. Lt1 / lt4 heads bolt on but have a different cooling system so don’t use those.

Jayson_305

I’m looking to get a later style sbc and use 80’s High output 305 heads. The old school stump puller type build. The engine is out of an 89 or so camaro with tpi. I’d ditch everything but the block and use a set of 305 ho heads. I’d keep the perimeter bolt setup i’m just more concerned about them bolting up to the block

TransamGTA350

iTrader: (2)

The older heads will bolt to the newer block. If the newer motor is a 350TPI, the heads will flow better than the 305HO heads. The 305 heads have 58cc chambers vs. the 350 heads 64cc, so you will need to be careful of too high of compression ratio.

If you're trying to reuse the 85' 4bbl intake manifold, it will bolt right up to the perimeter bolt 305 heads. However, you can elongate the center intake bolt holes and adapt the manifold to the center bolt head intake bolt pattern.

I would leave the 350 block and heads together and just adapt the intake manifold.

The newer motor will have a 1 piece rear main seal compared to the 2 piece on your 85'. 86' and later SBC's were all 1-piece rear main. You will need to use a flywheel or flex plate for the 1 piece rear main.

Jayson_305

From what i’ve heard that setup will run 11:1 compression and run just fine on 93 pump gas. It’s just a rowdy streetable engine going into my trans am, backed by a t5

Tuned Performance

iTrader: (92)

I see so many issues with this post

Jayson_305

Explain, i’m open to learning. This whole idea was brought upon me reading about 305 heads on a 350. Thought it was something different and affordable

TransamGTA350

iTrader: (2)

10:1 is generally considered the upper limit on pump gas. Some have gone higher successfully, but that’s with careful component selection and a very good understanding of static vs dynamic compression ratios, cylinder head flow and burn properties, cam selection and tuning.

Jayson_305

From the reading i’ve done there have been plenty of sbc’s running similar compression ratios on 93 octane pump gas.

TransamGTA350

iTrader: (2)

Best of luck with your build. Hope it works out for you.

Jayson_305

I appreciate the help!

TTOP350

iTrader: (8)

Thevold 305 heads on a newer 350 will work but won't run as well as the stock tpi 350bheads. Not worth it