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View Full Version : Engine Clearance ???



BlueNun
06-18-2007, 08:34 PM
Whats up everyone
I wanted to say thanks to the response I received about my fuel pump question over the weekend. Now I have another question. I am building a 468 Chev for my Tahiti. I bought a 2 bolt 454 studded with callies caps, line honed,fresh bore FULLY arp studded for $250 (buddy ownes a machine shop)
Anyways I was doing some thinking and I am guessing that a jet pump (mine is the new JI Berk.) puts a pretty good constant load on an engine way different from a car. So should I give the bore a few thou. extra clearance to help with heat in the cylinders?? I am looking at the Mahle piston packages with the anti friction coating and a Dan Olsen oil cooler to help combat extra heat. This isnt gonna be a race motor more like a very stout lake boat. So what should I do in advance to help my engine last longer and not have any heating issues????
Here is a few pics of my boat. Its a 84 Tahiti (full stringer)with a brand new JI pump. I paid $600 for it with a tandem competitive trailer. So far I have repaired and reglassed the stringers and bilge and built a new axle for the trailer. Tell me what you think
Jason
http://i95.photobucket.com/albums/l132/swat2380/Boatpictures042.jpg
Here is after I repaired the stringers reglassed and then I used a truckbed liner kit
http://i95.photobucket.com/albums/l132/swat2380/104_0966.jpg

396_WAYS_TO_SPIT
06-18-2007, 08:39 PM
Nice boat!!!! Keep us updated. Your gonna have some fun with it;)

steelcomp
06-18-2007, 09:12 PM
The trend is to add a few thou (couple thou) but not due to the extra load. You're running cold water constantly through the water jackets, and that dosen't allow for as much cyl. expansion, yet you're heating the piston basically the same. Hot piston, cold cyl = more clearance. Talk to your machinist friend about how much. It's pretty arbitrary. Oil cooler is a good idea.

shaun
06-19-2007, 12:37 AM
For my build i purchased JE/SRP pistons so i contacted them to see what they recommended. With a open cooling system that picks up cold water they recommended i run a extra thou of clearance in the bores, my bore came out to be 4.311 (454 .060 over).
I would call and talk to the piston manufacture and see what they say...

ck7684
06-19-2007, 04:11 AM
Be sure to get an oil temp gauge. You dont want the oil to stay too cold either. It needs to heat up enough to "burn out" any moisture from condensation...look into the clearances for marine and dont forget to look at ring end gaps also...good luck with your project!! That's one sweet looking boat!!
P.S. I am currently refreshing mine up also :D