building a 290
68javelin
08-14-2005, 11:45 PM
Hey i just got a 68 javelin with a 290 for a pretty good price. I plan to super charge it years from now and go all motor for now, what do i need to do first before i supercharge it without hurting the engine? In order please. :P
MrPbody
08-15-2005, 02:04 PM
I'm not sure what you're asking. What are your goals?
68javelin
08-15-2005, 04:23 PM
What do i need to do to the engine before i super charge it? Such as bore, stroke, forged pistons, ect... In order in which you would do first if you were building it. 400+ hp is my goal.
MrPbody
08-16-2005, 09:13 AM
Building a "blower" motor is a whole different animal than a non-charged engine. There are a few "extras" to consider.
The Rambler has a pretty stout crankshaft, so I doubt you need anything special there. The connecting rods are also a quality piece. You mention "stroking". Not practical with the Rambler (no readily available aftermarket cranks). If the little 290 isn't enough, consider a 360 (AMC, NOT Dodge) or 401 (both bolt right in). A 343 or 390 would do it, as well.
High quality, light-weight forged pistons are called for. We recommend Ross for the custom application. Compression ratio should not exceed 9:1, and 8.5:1 more desired. Have the top ring moved "down" about .125", to at least 3/16". make sure the piston maker knows you plan to supercharge.
Head preparation is also key to performance in a blower engine. Contrary to popular belief, a supercharged engine will gain more, proportionally, with good porting, than a normally aspirated engine. We use Pontiac intake valves (2.11" dia, flat head and 30 degree face) and exhaust valves (1.77" dia, flat head, 45 degree face). These valves improve low-lift flow and are the correct length. They also have the 11/32" stem diameter, making them a tad lighter than the originals.
Cam is VERY important. A good cam for a blower, will not yield good performance in a non-blown application. It would be adequate, but not much more. Avoid tight LSA's and high overlap. Something with a 114 LSA is desired for a street motor with a blower.
Always bore a block for new pistons. A "fresh" bore will allow the rings to seal up well, and provide maximum life for pistons. Have a deck plate installed for boring/honing.
New ARP rod bolts and a good balance job will complete the bottom end work.
If you have more specific questions, feel free. You're also welcome to e-mail me (PM doesn't work on my machine). [email protected]
The Rambler has a pretty stout crankshaft, so I doubt you need anything special there. The connecting rods are also a quality piece. You mention "stroking". Not practical with the Rambler (no readily available aftermarket cranks). If the little 290 isn't enough, consider a 360 (AMC, NOT Dodge) or 401 (both bolt right in). A 343 or 390 would do it, as well.
High quality, light-weight forged pistons are called for. We recommend Ross for the custom application. Compression ratio should not exceed 9:1, and 8.5:1 more desired. Have the top ring moved "down" about .125", to at least 3/16". make sure the piston maker knows you plan to supercharge.
Head preparation is also key to performance in a blower engine. Contrary to popular belief, a supercharged engine will gain more, proportionally, with good porting, than a normally aspirated engine. We use Pontiac intake valves (2.11" dia, flat head and 30 degree face) and exhaust valves (1.77" dia, flat head, 45 degree face). These valves improve low-lift flow and are the correct length. They also have the 11/32" stem diameter, making them a tad lighter than the originals.
Cam is VERY important. A good cam for a blower, will not yield good performance in a non-blown application. It would be adequate, but not much more. Avoid tight LSA's and high overlap. Something with a 114 LSA is desired for a street motor with a blower.
Always bore a block for new pistons. A "fresh" bore will allow the rings to seal up well, and provide maximum life for pistons. Have a deck plate installed for boring/honing.
New ARP rod bolts and a good balance job will complete the bottom end work.
If you have more specific questions, feel free. You're also welcome to e-mail me (PM doesn't work on my machine). [email protected]
Automotive Network, Inc., Copyright ©2026