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Engine Swap Advice, Which Block?

2K views 21 replies 11 participants last post by  MUSTANG65FBK 
#1 ·
Hello everyone,

Im about to start and engine build and was hoping you all could chime in with some advice on which block I should pick up.
I was able to get my hands on a 1978, 302 for $40. It happens to be in pretty good shape but now that I have it / now that I have seriously started looking into internal parts, im thinking it would be better to jump up in size? Ive seen some people take a 351w and turn that into a 406. I was thinking this would be a good engine to shoot for, build wise, because of the torque it can make and the horse power. Both seem to be high enough but wont push the block to its limit. I was leaning towards doing that but was hoping for some impute? Stay with the 289? Move to the 302? Jump up to the 351w? Jump up again with the 351w and turn it into a 406? or... something totally different?

I know that the engine must fit the conditions it will be used for so to fill you in on that, I plan to use my car on the street for fun on nice days but would like the opportunity to get into autocross down the road. My car still needs to have some of the spider webs massaged out if you know what im saying. Needs new shocks, leaf springs, probably a brake upgrade... ect..ect.. So the autocross plan is downnn the road. Mostly in town use now.

I am planning to over build the engine and run it at less than what it is capable of to try and keep it lasting a long time. H-beam rods, forged crank, ARP bolts top to bottom..ect. Its going to be a slow build, mostly due to cost but I want to make sure that I start at the right place before spending any money.

Thank you guys!
 
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#2 ·
I believe you're referring to a 408w, but that's the route I'd go depending on your budget. I have a 351w in my 65 fastback, it has 450hp/tq and I absolutely love it. There are some trade offs though... the 351w is typically cheaper to build as opposed to a 302 or 302 based stroker like a 331 or 347 but you have to buy a specialty swap header, I went with the JBA mid length swap headers and they fit great but it's pretty tight getting to the spark plugs or working on around the motor. Increasing the hp by almost double will also give you other problems, mainly suspension and drivetrain. You'll have wheel hop, a drivetrain, if stock, that wasn't meant to keep up with that kind of power. What kind of budget do you have, what's your goal in terms of power and do you have a 351w block picked out already? Are you wanting to build it yourself? I bought my crate motor for $3500 because I didn't have the time, knowledge or tools/space to build a motor. If you're looking for as much horsepower as possible for as cheap as possible I'd maybe recommend a 351w stroker crate motor or building your own if you can. If you're looking for 300-400ish hp/tq than I'd maybe stick with a 302 based motor as that's well within safe hp range. But a 351w with aluminum heads, intake and lightweight internals is actually lighter than an all cast iron 302... food for thought. Just depends on what you want and how much money you've got
 
#6 ·
The engine clearance was something I was wonder about.. My car is a factor C4 but once this new engine goes in I will also swap over to a manual of some kind. My goal when I decided to build and engine was to get as close to 500hp/500tq as I could but everything I have been reading has said the 302, (regardless of how well its built), will grenade if pushed past around the 400hp/tq point? Maybe not right away but from what I have been reading, they will not last for a long time. My goal is to build something that will last a long time. So I have to drop my power point goal to like 390hp/390tq or change block I think. (I know in real life hp and tq will probably never be equal but I want to pull and much out of both as I can)

CMEFLY said he is pushing past that 400 marker point and it sounds like his engine is doing fine with really good numbers. So I could be totally wrong about that 400hp/tq point as being the danger zone. Does anyone know where that point is?

Money is less of and issue as im going to do this slowly and will take the costs as they come. Id rather build it right one time with good parts than many time with cheap parts.
 
#4 ·
Since you are in Wa State I would go through Brian at ADPerformance. All you need is a 302 based 347. The 408W are great but they are a little tight in the 65/66 cars. ADPerformance is in Redmond so you can pick up an assembled shortblock or longblock. Brian has a strong reputation for building great engines. Stay with a Cast Scat crank , I beam rods and a good forged piston. You do not need H beam rods and a steel crank. You will split the block before any of those parts give out. I have a mild built 347 that dynoed 460HP and 440TQ on a dyno known for being stingy with the numbers. That is a lot of power in a light 65/66 Mustang.
ADP SBF Comp Street Shortblocks : AD Performance, Your Source for Longblock Performance Parts
 
#5 ·
Since you are in Wa State I would go through Brian at ADPerformance. All you need is a 302 based 347. The 408W are great but they are a little tight in the 65/66 cars. ADPerformance is in Redmond so you can pick up an assembled shortblock or longblock. Brian has a strong reputation for building great engines. Stay with a Cast Scat crank , I beam rods and a good forged piston. You do not need H beam rods and a steel crank. You will split the block before any of those parts give out. I have a mild built 347 that dynoed 460HP and 440TQ on a dyno known for being stingy with the numbers. That is a lot of power in a light 65/66 Mustang.
ADP SBF Comp Street Shortblocks : AD Performance, Your Source for Longblock Performance Parts

Ill have to check him out. So your making 460/440 out of 302 cast iron block with built internals? Thats pretty much my goal numbers with my build but I want to make sure that the parts I put in will be able to handle that kind of abuse. Kind of the reason I thought the 351w would be a better starting point since its a little more robust. Ill have to call that builder.

I read that the 302 block is likely to grenade once you pass the 400hp/tq marker point? Any one know where you can safely run a 302 cast iron block if the internals are built? I want to get more than a few years out of my build.
 
#7 · (Edited)
There are no hard numbers, so that's hard to answer, and there are many factors that affect it. In the end, if you're going to be making much power, a 351 is safer. Think about what you said. You've heard 400 is the breaking point, so you're going to shoot for 390??? It doesn't work that way. They're all different. I've seen them hold way more and....... less.
 
#10 ·
since you want to autocross the car ultimately, my recommendation is to build a 347 from the 302 block. the reason here is better balance because you dont have as much weight on the front end of the car as you would with the 351w based engine. and yes i know you can add aluminum heads and cut the weight of the 351w down to about what a stock 302 weighs, but then lets compare aluminum head motors against aluminum head motors, the 302 is still going to weigh less with aluminum heads than the 351 will by the same amount as before. so 400lbs for an aluminum head 302 vs 480lbs for an aluminum head 351w. my vote is still for the 302 based engine.
 
#18 ·
I went the 351w route over a 302 as the 351w, at least at the time of my build, was the better option. The reason for that is that the 351w can usually be built for considerably less than the 302 built stroker and it starts off with 75ish hp/tq more. Yes it is wider and is a little more difficult for clearance issues/headers, but as said, get aluminum heads and intake, light weight internals and get as much power as possible for considerably less money and with less weight than a cast iron 302. If you're looking for 500ish hp, go with a 351w based motor
 
#11 ·
I was going to say when this thread started that autocrossing a 289 with aluminum heads would probably be a blast. Old school dirt trackers around here say they used to like a 289 over a 302 on a short track because the 289 would "spin up quicker". I'd autocross the crap out of a 289 after lightening the car as much as practical.
But I see things have escalated to 500HP so nevermind and by all means, a stroker kit in 351W. I like 351's too.
 
#15 · (Edited)
HA. Too many choices now. Not so many years ago it was not like this. Lots of things nobody is talking about too.

If you go with a 351W block based engine, just make sure you get the engine swap headers made for it. It still may not fit depending on how much fatigue there is in the old shock towers. They might have to be massaged.

The other big item to put on your list if you push any build up into the 400 torque range, your stock C4 will have to go. Ah, you planning a manual swap. Even if you swap to a T5 you can't swap to a regular T5 because they aren't built to hold this much torque either. It will need to be a something or other built up one like a TKO and not even a world class T5 will hold up with 400 torque. I have a friend running a T5Z(whatever that is) behind a 351W/427 in a fox mustang and he is afraid to hammer on it because he doesn't think the tranny will hold.

You will need to plan on swapping to a 9 inch rear end respectably built to handle the horsepower you are planning to make.

There is a list of chassis and suspension upgrades and various ways you can go to do that but you will ultimately need to do more to keep the car together and run a hot rod engine like what you are considering building.

I'm not trying to discourage you. You just need to know the greater implications of your horsepower decision.
 
#16 ·
Thanks guys, Ill probably build off this 302 i just got and stroke it. A few things that are making me lean that direction are avoiding the extra weight from the 351w and the extra bulky block. I didnt take either of those into consideration. I dont mind making less hp and tq when I take all aspects into account. Ill try and aim for a 350-400 ish ball park and stroke the 302 i just picked up. 500hp was more or less shooting for the stars but if there was a way to get there and still have the 302 size block i wanted to know. looks like ill just aim for less which is still fine.
 
#19 ·
As I and others have said, yes a 351w is heavier with cast iron heads. But if you do aluminum heads, intake and lightweight internals it'll be lighter than a stock 302 engine. And you'll probably want the aluminum heads anyway. It's a little bit wider and a little bit more difficult to work on but it's not horrible. Other than needing a swap header most other parts swap over. I have a 351w based motor in my 65 fastback and have no regerts ;)
 
#20 ·
Just to play devils advocate a little. You ever drive a little 65 or 66, or other lightweight car with 500 horses, or 390 for that matter? That's an awful lot of power for a car you might autocross one day. Shooting for numbers can be a fools errand if you have nothing to compare it to. There are probably a ton of 250- 300 hp/ torque cars that are scary fast and a blast to drive in any environment.
 
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