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-   -   Looking for advice on 454 or 502 (https://www.offshoreonly.com/forums/general-q/297296-looking-advice-454-502-a.html)

sceptre155 05-30-2013 09:30 PM

Looking for advice on 454 or 502
 
Looking for some feedback on which avenue to take.

I have a 454 efi with a bad crank that needs a rebuild. I just bought a rebuilt 502 long block thinking I could just swap parts and flash the ECM for the 502. Well it turns out the 502 has rectangle intake ports and my mpi is oval. So that won't work. Here is where I'm not sure which direction to go. The 454 heads won't work on the 502, chambers are to small and the 502 has high dome pistons.

Do I rebuild the 454?
Buy new heads for the 502 and use my 454 efi setup?
Buy another efi setup for the 502?
Swap the 502 over to a carb setup?
Is it possible to convert my oval port efi setup to rectangle intake ports?
How big a pain is it going to be to program the ECM for my setup? The 502 is suppose to be around 425 hp

Not trying to throw a ton of money at this, each option seems to be another few grand. But either way ill have some parts to sell.

Thanks for any advice in advance.

rumrunner29 05-30-2013 10:21 PM

Personally, I would just build a 502 carb motor and be done with it...two years ago I had both my 454s rebuilt and if I had it to do over I would have bought a set of used 502s...I would have been happier....just my .02

cp5899 05-30-2013 10:30 PM

I agree. Throw an carb and intake on and be done. Much better starting off with a 502 over the 454. To put the oval or round port intake on the 502 would be a waste.

phragle 05-30-2013 10:52 PM

Ebay seems to think that the 454 and 502 mpi intake is the same part....

sceptre155 05-31-2013 05:19 AM

What all is involved with switching to a carb setup? Do I need a new wiring harness? Can anyone recommend a intake and carb setup that works decent without breaking the bank?

cp5899 05-31-2013 06:23 AM

I did the conversion earlier this spring. I bought a victor jr intake and a Holley 850 carb. I also bought a thunderbolt 4 wiring harness and distributor from someone on here. After that, just bolt it all on and go. The harness and distributor can be had on hear for very good deals. Think I paid $75 for all of it.

I ended up going with a blower so still have the carb and intake sitting on the shelf. If you decide to go that way pm me and I would work you a deal for the carb and intake setup.

sceptre155 05-31-2013 07:12 AM

What comes with the Thunderbolt wiring harness? I need an ignition module of some sort correct?

cp5899 05-31-2013 08:39 AM

Yes. I bought mine on here. It came with dist, harness and module. Unplug the old one and plug in the new one.

MILD THUNDER 05-31-2013 09:09 AM

If you have a complete long block 502, do the carb/intake setup. IF your 454 was a 385HP mag, then you'd have the rect port intake like the 502 mag. But you obviously had a 7.4L 310HP MPI version with vortec heads.

sceptre155 05-31-2013 09:53 AM

I'd like to run the 502 to be honest. I've been looking around for a 502 mpi setup too, just seems to be bad timing. I found one setup for 700 but its a mefi 1. And has had the intake etc... all ported. So I'm kinda dragging my feet. Feedback?

Otherwise its buying intake, carb, wiring harness, distributor and ignition module. Did I miss anything?


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