496 building advice needed
#1
Junior Member
APPRENTICE
Thread Starter
Join Date: Oct 2004
Posts: 19
496 building advice needed
We are in the process of putting together a parts list for a 496 that will be in our dragster. I will have to use stock heads for the first couple years. I need advice on pistons, cams, lift and expected HP of this engine. Thx M
#4
Senior Member
RACING JUNKIE
Join Date: Sep 2007
Posts: 4,137
IF THE SKY IS THE LIMIT BUY SOME GOOD HEADS. By the time you fix up old stock heads you will be half way to a good set.
14-15 TO 1 COMPRESSION, SOLID ROLLER AROUND .750 LIFT WITH dur @.050 270-280 range 112-114 LSA VICTOR 454-R
JMO although I would probably ask an engine builder. Use the rectangular port heads.
14-15 TO 1 COMPRESSION, SOLID ROLLER AROUND .750 LIFT WITH dur @.050 270-280 range 112-114 LSA VICTOR 454-R
JMO although I would probably ask an engine builder. Use the rectangular port heads.
#5
Senior Member
SENIOR BUILDER
Join Date: Dec 2005
Posts: 117
Originally Posted by Tod74
IF THE SKY IS THE LIMIT BUY SOME GOOD HEADS. By the time you fix up old stock heads you will be half way to a good set.
14-15 TO 1 COMPRESSION, SOLID ROLLER AROUND .750 LIFT WITH dur @.050 270-280 range 112-114 LSA VICTOR 454-R
JMO although I would probably ask an engine builder. Use the rectangular port heads.
14-15 TO 1 COMPRESSION, SOLID ROLLER AROUND .750 LIFT WITH dur @.050 270-280 range 112-114 LSA VICTOR 454-R
JMO although I would probably ask an engine builder. Use the rectangular port heads.
#7
Senior Member
EXPERT BUILDER
Join Date: Mar 2007
Location: Michigan
Posts: 379
Skys the limil just have to use stock heads !!!
Start with a good block, Go with a good billet crank, a set of aluminum GRP rods with the best bolt they offer, set of diamond or JE Blower pistons gas ported and buttons with about 13 to 1 compression, a good blower cam from comp cams around a .750 lift with a 7-4 swap, top all of it with a 871 supercharger with around 10 lbs of boost with enderlie bird catcher on alcohol approx 1200 HP. 8) 8) How you doing ???
Start with a good block, Go with a good billet crank, a set of aluminum GRP rods with the best bolt they offer, set of diamond or JE Blower pistons gas ported and buttons with about 13 to 1 compression, a good blower cam from comp cams around a .750 lift with a 7-4 swap, top all of it with a 871 supercharger with around 10 lbs of boost with enderlie bird catcher on alcohol approx 1200 HP. 8) 8) How you doing ???
#9
Junior Member
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Thread Starter
Join Date: Oct 2004
Posts: 19
ok thanks this is good info.. The two sets of heads I have are 781 and 049 oval ports. What do you think of these? My rods are Eagle H beams 6.385. I will get a Lunati 4340 4.25 crank soon. With the stock heads what advice and what HP can i see with these? Is there any issues with too much crank case pressure when running high compressions? Thx
#10
Senior Member
DYNO OPERATOR
Join Date: Jan 2004
Location: central Illinois
Posts: 459
496
049/781 oval port cast heads are the best stock heads. However, even mnoidified, they will hold back a 496 engine above 5500 RPM.
To do them right you need to add 2.250"/1.880" valves, unshroud the bowls, port match, have bronze guide liners installed, mill the decks, add good rocker studs and guide plates. Then figure in good valve springs, titanium retainers and 10 degree locks. But they will still be less than 290 CC intake ports. Too small.
A set of RHS/Pro Topline 320 aluminum bare heads can be bought on RJ if you look for $1000. They will take the same parts but the machine work will be done already. They will make 75-100 more HP. And they will have resale value.
If you have to use stock heads, sell your 2 sets and buy a set someone else already spent their hard earned money on doing all of the above, for about $500.
To do them right you need to add 2.250"/1.880" valves, unshroud the bowls, port match, have bronze guide liners installed, mill the decks, add good rocker studs and guide plates. Then figure in good valve springs, titanium retainers and 10 degree locks. But they will still be less than 290 CC intake ports. Too small.
A set of RHS/Pro Topline 320 aluminum bare heads can be bought on RJ if you look for $1000. They will take the same parts but the machine work will be done already. They will make 75-100 more HP. And they will have resale value.
If you have to use stock heads, sell your 2 sets and buy a set someone else already spent their hard earned money on doing all of the above, for about $500.