Questions about going from 302 to 408

eric n · May 14, 2005

Hey guys, I have a year + (hell maybe 2) til my gt500 gets here. So I was thinking about maxing out my current 66. Going from a lowly nicely modded 302 to a 408 seemed like a way to increase hp. Now I'm not much of a mechanic but other than a standard short block, what will I need.

I'm already aware I'll need a different oil pan, intake, distributer and ofcourse gaskets. but what other major components (stuff that costs $$$) will I need. I'm pretty sure this will nickle and dime the heck out of me. But a little warning ahead of time might just talk me out of it.

HuKares · May 14, 2005

You'll need basically the whole engine new. Sure you can reuse the carb and the heads but would you want to? If your going to a 408, you're going to want to get parts that are optimized for your new setup instead of being restricted by your old 302 parts flow characteristics. Well, I guess you can use the aircleaner, water pump, timing cover, and some accessories too. Overall though, it's a big leap.

eric n · May 14, 2005

HuKares said:
You'll need basically the whole engine new. Sure you can reuse the carb and the heads but would you want to? If your going to a 408, you're going to want to get parts that are optimized for your new setup instead of being restricted by your old 302 parts flow characteristics. Well, I guess you can use the aircleaner, water pump, timing cover, and some accessories too. Overall though, it's a big leap.

I hear you, but I was under the impression that my trick flow heads would be good to go and my bg 650 would also be up to the task. I'm looking at a shift point around 6000 to 6500. Am I way off base?

thanks for the input.

HuKares · May 15, 2005

eric n said:
I hear you, but I was under the impression that my trick flow heads would be good to go and my bg 650 would also be up to the task. I'm looking at a shift point around 6000 to 6500. Am I way off base?

thanks for the input.

They would work. You'll make more power and it will come much sooner, but the power will also start to level off sooner than it did on the 302. If you check my sig. you'll see that I'm using a 750 carb on a 331. You may want to go to a 850 for you application or bigger depanding on how radical you want it to be. As for the heads, they are a step up still from stock 302 or 351 heads but you may want to go bigger. One advantage of going with TFS, they can be ported out quite a bit and flow equivalent to AFR 205 heads. Though not cheap, Fox Lake Racing does these port jobs on their CNC machine and will freshen up the heads at the same time. The owner used to work for TFS before Summit bought the company and then he went off on his own. I'm running a set of Track Heats with their stage 1 CNC port done.

grego37 · May 16, 2005

wont you need to dump the 302 and start with a 351w to make a 408windsor stroker motor?

eric n · May 16, 2005

grego37 said:
wont you need to dump the 302 and start with a 351w to make a 408windsor stroker motor?

Absolutely, that is what I was alluding to when I said, "other than a SHORTBLOCK, what other parts will I need" I may not have been clear. I'm ultimately trying to figure out what parts I can re-use. I was hoping heads and carb would be up to the task, as that is another 1500 that I'd rather avoid spending.

Bullitt · May 16, 2005

i think your heads will be fine, and your carb may very well be.

the 240ish CFM that the TFS heads flow is plenty to support 450ish HP. i don't know what your goals are, but that's respectable power.

you WILL see good gains by increasing carb size and heads because you're pushing a lot more air with a 408 vs a 351. if you're spending the money to spin a 408 to 6500 RPM, porting those heads and changing the carb shouldn't be too out of the question...

grego37 · May 16, 2005

I have a 408 windsor stroker with a Holley 830 DP. and Edelbrock victor jr. if this helps.

Id consider going to a single plane intake like a victor Jr or? with the 408 you'll have all the bottom end torque you could ever want, and then some. do what you can to increase the top end rpm perf / flow

65ShelbyClone · May 16, 2005

eric n said:
I'm already aware I'll need a different oil pan, intake, distributer and ofcourse gaskets. but what other major components (stuff that costs $$$) will I need. I'm pretty sure this will nickle and dime the heck out of me. But a little warning ahead of time might just talk me out of it.

You'll also need a pump pickup, headers, possibly accessory brackets(?), belts, harmonic damper(if diff than your 302), and probably more I forgot. Your carb and heads will work for the time being, but going larger will free up more power. Heads will cost, but you can get good used Holley 750DPs for less than $150.

Keeping your old stuff will make for a torquey 408.

eric n · May 16, 2005

Bullitt said:
i think your heads will be fine, and your carb may very well be.

the 240ish CFM that the TFS heads flow is plenty to support 450ish HP. i don't know what your goals are, but that's respectable power.

you WILL see good gains by increasing carb size and heads because you're pushing a lot more air with a 408 vs a 351. if you're spending the money to spin a 408 to 6500 RPM, porting those heads and changing the carb shouldn't be too out of the question...

Thanks for the intel! I gotta assume there is someone in central or So CA who does quality precision porting on Trick flow heads. Any suggestions?

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