Can anyone help me find engine specs on the 1986 Mercruiser 300 tempest? I have an 86 model ski centurion 22'10" with the tempest 300. she's tired and needs a rebuild but I would like to know all the info I can before I touch anything.

I can E-mail you the specs if you'd like.

What's your E-mail?

Jeff

I also have a boat with twin tempest 300. Could you please email me the specifications as well?

My email is [email protected]

Have you found out any information about these engines? are they 350s with higher compression?

Thanks,
Jon

They were 9.0:1 compression.I'll scan the sheets and email later today.

Jeff

can I get them too please. I was looking at the original brochure for my Formula 272 LS the standard engines were 260 mercs and bigblocks were not available unless you got the SR1 but 300s were an option. I was wondering if there are any special tempest decals on the valvecovers or spark arrestor. Thanks in advance KZ
[email protected]

Could you also put me on the e-mail list?
jay21one @ yahoo . com


Yes they had a spark arrestor that said 300 Tempest on it. and I think a 300 decal on the valve covers.

I must apologize, I've been quite busy.
Tomorrow I will get to it!

Jeff

I would love to have some pics of the engine / decals

Jeff thanks for the spec sheets.
ERIKV79 AND OLMAKO20 Can one of you guys to check some casting #s. I can break down all the details for you. First I need the casting # on the back of the engine block It will be at the rear of the engine behind the distributor where the bellhousing bolts to the engine block on top left or right. Next I need the casting # under the rocker arm cover it will be between the valves. an example of the engine block # is this (14010209) An example of the cyl. head # is this (3998997) I have been told that mercruiser took the L-82 Corvette engine and made a marine version out of it. This is how I can confirm it for you. From Jeffs spec sheets we know You have a forged steel crankshaft Forged aluminum pistons special camshaft and valve springs and a 4 bolt main block. Highrise aluminum intake manifold These are the best parts GM had to offer for durability. The main thing to take from this is If you replaced the engines with run af the mill rebuilts these parts most likely wont be in them. If they are just tired with alot of hours rebuilding the motor you have is the best bet. I have all the GM books and can confirm it thru the #s. Thanks Paul. PS If we get some tempest engine decal pics maybe we can get repros made.

Sorry guys Ive been away for a bit. Yes I have the arrester cover intact and will post some pics a.s.a.p. I will also get the casting #s up as well. I too have heard the Corvette story and I know that you can buy a mercruiser intake plug from Corvette Central.