How do I know if I have a 2 bolt or 4 bold main 454

[MBlaster]

The boat is a 90 Carrera with a stock hardin marine 454.
TIA

[Fiat48]

Look at where the oil filter goes. You will see a large pipe fitting above the filter. Now to the left of that.....if you see another large fitting (that was for an oil cooler on 4 bolt blocks) then you have a 4 bolt main block.
BUT....just because you do not have this second fitting to the left does not mean you do not have a 4 bolt block.
Sorry if that sounds as confusing as it was to type.

[Panic Button]

Drop the pan... :cry: SOMETIMES by the block number you can look it up, and is it a MK4, or Gen 5? I think all Gen 5's were 4 bolts.

[SmokinLowriderSS]

I believe you are correct that all Gen 5 & 6 blocks are 4-bolts. Mk 4's are hit & miss. The only SURE way is drop the pan.
On a side note, I have been loaned a recent "Chevy Hi Performance" magazine by a co-worker. In it is an article that shows how 1 maqchine shop figured out how to convert 2-bolts to 4-bolt mains. No loss in strength and NO REPLACEMENT CAPS. Uses the stock 2-bolt caps. Interesting article. I will be copying all the info in it to my computer and will give to anyone interested. Just haven't decided where to post it at in here yet.

[ssmike]

I'd take a look at the main caps...... :argue:

[fastsanger]

or just pull the timing cover and you can see the front main cap :rollside:

[wsuwrhr]

or just pull the timing cover and you can see the front main cap :rollside:
yea OK. Everyone would have two bolt mains.
nice
Brian