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Topic: Big Block to 502 Swap

in Forum: C3 Engines


Big Block to 502 Swap

Posted: 4/27/04 10:25am Message 1 of 8
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Has anyone put a 502/502 in their C3? I've got a 454 I'm thinking about swapping. What are the biggest issues to over-come. What Pulleys to use, Z-bar mount, Fuel Pump, Intake Manifold to fit under Stock Hood, Cooling? Thanks, Randy


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Big Block to 502 Swap

Posted: 4/29/04 6:46am Message 2 of 8
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Castle Rock, CO - USA
Joined: 4/21/2002
Posts: 179
Vette(s): 1973 T-Top 1993 Coupe
Hello Randy,

The swap should be fairly straight forward.

You will need an in-line fuel pump as there is not a place to put the mechanical pump.

You will need to replace the water pump with a "short" water pump.(If the engine you buy has a pump already on it.) There may be some minor clearance problems with the timing cover bolt heads. Alittle grinding should help.

Have the radiator rodded out or replaced with a new one. I don't believe that you need to go to any great lengths to keep the engine cool if the cooling system is in good shape.

The accessories and pulleys should bolt exactly in place.

As far as the hood clearance, it depends on your year. 68-72 should not have any problems. Their hoods are high enough to clear most intakes. The Edelbrock Performer is about the right height but whatever you choose make sure to compare it to the original for height. It shouldn't be any more than 1/4" taller. 73-74 BB intakes are actually very short. You can use the original intake on the 502 I think, but HP will suffer since the intake runners actually run uphill to the intake ports.

Good luck!

Alex

|UPDATED|4/29/2004 6:46:54 AM (AZT)|/UPDATED|



Big Block to 502 Swap

Posted: 4/29/04 9:33am Message 3 of 8
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Clifton, NJ - USA
Joined: 10/3/2003
Posts: 129
Vette(s): 1972 Coupe Ontario Orange Black leather interior LS-5; Turbo 400
Randy;

Check with the manifold mfgrs, Edlebrock says none of their dual plane manifolds will fit under the stock BB hood, the only manifold they have that will is thier Torkerr II. I'm looking at putting Edelbrocks' EFI system on my 72 BB, and figure I would need to go to a L-88 hood for clearance.

NJ BB Ken |cheers|


1972 T Top 454; "Boomer" Latest "upgrades": 1 1/8" front Stabilizer bar. Rebuilt SS calipers with O-ring pistons. Under car Chambered exhaust. Fiberglass rear spring (360lbs/in). Bilstein Rear Shocks. 3/4" Rear Stabilizer Bar. Tow hitch. Performer manifold with 600 cfm Holley. Comp Cam 262 .499 lift. L-88 Hood in process

Big Block to 502 Swap

Posted: 5/7/04 1:41pm Message 4 of 8
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That's what I've heard, as well. Thanks, Boomer. Good luck with your BB project.


Big Block to 502 Swap

Posted: 5/7/04 1:49pm Message 5 of 8
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Alex.....Thanks for your response. What is the reason I'd need to go to a Short H20 pump? Also, I was told by EdelBrock that no current Aluminum intake would fit under my stock 1969 BB Hood. The TorkerII (I've Heard) would be my only option.


Big Block to 502 Swap

Posted: 5/7/04 1:50pm Message 6 of 8
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Hot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
if you do get the l-88 hood...

the edelbrock air-gap fits nicely with a demon sitting on it.


Big Block to 502 Swap

Posted: 5/10/04 5:58am Message 7 of 8
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Castle Rock, CO - USA
Joined: 4/21/2002
Posts: 179
Vette(s): 1973 T-Top 1993 Coupe
Hello,

The short water pump is used to get the needed clearance from fan to radiator. The BB you have currently has the short pump.

The BB intakes for the 69 were not very high, but they had adaquate performance. I am assuming you have the 390hp engine. You may be able to clean up the ports and still be near the 500hp mark. Also the 68-69 Tripower will fit under the hood. You will need to match up the type port (oval or square) to the heads on the 502. I think they are oval on the 502. So the 390hp and 400hp (tripower) will be a direct fit. The 435hp tripower is a square port and should not go on the oval port head.

Alex


Big Block to 502 Swap

Posted: 5/12/04 2:31pm Message 8 of 8
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Alex,
I appreciate your response. I didn't remember if the pump was long or short on the existing motor...And you assume correctly....I have a 390 hp engine currently. Thanks, again!


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