Engine Forged flat top pistons from 5.0 fit a 351 build?

[PonyGTrider]

Hi all, I searched all the forums but couldn’t find anything related to my questions.
have a 306 roller with flat top pistons, 170 twisted wedge as cast, stage 1 TFS cam and TFS upper/lower intakes. This engine is running nice but I’m tempted to build a 351W but need to do that on a very constrained budget.
I want to send those flat tops to the 351W as well as the cam and heads, I will port/polish the heads before moving them on. I will send the stage 1 cam and the upper intake too. I know the lower don’t fit so need to buy one.

So will those parts from my 306 fit into the 351W block? The flat tops have valve relieves. I’m not racing my actual 306 so the pistons haven’t been stressed out too much, but will they fit without potential issues in the 351 block??? What about the rest of the parts.
Let me know if you see any future in my super low budget project, or I just forget about it.

Thank you much

 

[General karthief]

Let's see, maybe a little math here..... 306 ci ........carry the one...... Subtract this........add that..... Well that means those pistons will be flop'n around like a monkey f.....you get the picture.
i'd say no but I'm not a 'builder of engines' so I may be wrong.......

 

[LILCBRA]

Bore size is one aspect, wrist pin location is the other. From a quick search, it appears that they don't share the same wrist pin location, so they won't just swap onto 351W rods and work. There is some information in this thread that I found that could be beneficial for you.

351w / 302 pistons | Maverick/Comet Forums

Can anyone tell me the differences in the 302 and 351w pistons ? Are they interchangable ?

mmb.maverick.to

 

[General karthief]

Bore size is one aspect, wrist pin location is the other. From a quick search, it appears that they don't share the same wrist pin location, so they won't just swap onto 351W rods and work. There is some information in this thread that I found that could be beneficial for you.

351w / 302 pistons | Maverick/Comet Forums

Can anyone tell me the differences in the 302 and 351w pistons ? Are they interchangable ?

mmb.maverick.to

Now that was an interesting read, so I'm wrong, you can use a 302 piston in a 351 interesting, and I have a 351 in my ranchero

 

[2000xp8]

Use 302 parts on a 351 and you will just get an engine that is heavier and more expensive that performs marginally better than the 302.
IMO, it's pointless.
I'm in the forget about it category.

 

[PonyGTrider]

Bore size is one aspect, wrist pin location is the other. From a quick search, it appears that they don't share the same wrist pin location, so they won't just swap onto 351W rods and work. There is some information in this thread that I found that could be beneficial for you.

351w / 302 pistons | Maverick/Comet Forums

Can anyone tell me the differences in the 302 and 351w pistons ? Are they interchangable ?

mmb.maverick.to

Thanks for sharing

 

[PonyGTrider]

Use 302 parts on a 351 and you will just get an engine that is heavier and more expensive that performs marginally better than the 302.
IMO, it's pointless.
I'm in the forget about it category.

Ok thanks for sharing you opinions, I’ll consider them

 

[PonyGTrider]

Let's see, maybe a little math here..... 306 ci ........carry the one...... Subtract this........add that..... Well that means those pistons will be flop'n around like a monkey f.....you get the picture.
i'd say no but I'm not a 'builder of engines' so I may be wrong.......

I plot those figures with a tad different results, I’ll review them.
Thanks

 

[PonyGTrider]

Now that was an interesting read, so I'm wrong, you can use a 302 piston in a 351 interesting, and I have a 351 in my ranchero

Well apparently you can’t, I swear I read somewhere this was possible I guess I will multiply my research on it

 

[RaggedGT]

You have a Ranchero?

 

[General karthief]

You have a Ranchero?

Yes, long story, I'll update my thread, I will say it's really kinda a a a a ........ interesting?

 

[2000xp8]

Let me clarify my statement a bit.
I'm not speaking to the shortblock aspect of the project.
My thoughts are if you have a good 306 currently, it's certainly not worth it to take it apart, buy all the 351 swap parts (which is going to add up), pay all the machine shop labor and then reuse 302 top end parts.
302 top end parts give you close to 302 results.
Let's not forget many of these projects go sideways, so who knows what you will encounter outside of what is predictable.

You could spend some money on mild head work (valve job, springs, bowl cleanup) with port matching to the lower intake, a custom cam (for sure) and make just as much power and spend probably 80% less money and do very little work.

Maybe even consider a used vortech and leave the parts you have and just upgrade the meter and injectors.

If you really want the 351, build a stroker on the stand purpose built from the ground up.
Take your time and do it right over the next few years.

 

[PonyGTrider]

Let me clarify my statement a bit.
I'm not speaking to the shortblock aspect of the project.
My thoughts are if you have a good 306 currently, it's certainly not worth it to take it apart, buy all the 351 swap parts (which is going to add up), pay all the machine shop labor and then reuse 302 top end parts.
302 top end parts give you close to 302 results.
Let's not forget many of these projects go sideways, so who knows what you will encounter outside of what is predictable.

You could spend some money on mild head work (valve job, springs, bowl cleanup) with port matching to the lower intake, a custom cam (for sure) and make just as much power and spend probably 80% less money and do very little work.

Maybe even consider a used vortech and leave the parts you have and just upgrade the meter and injectors.

If you really want the 351, build a stroker on the stand purpose built from the ground up.
Take your time and do it right over the next few years.

Yeah you might be right, I guess I’m bored and was trying to screwup with my engine which like I said is working flawlessly. And yes you’re right
Next time I open it I’ll do the valve seats and port polish the runners and bowls of those twisted wedge.
At this point I did the port match but I only did a gasket match and I know more than one will give me the reprimand “Gaskets aren’t templates” but I did that anyways. At this point I’ll try to do a real port match between head and lower intake to have a smooth no bumps transition between both of them. But again some will say doing that will do nothing but I have a different way of thinking.
A 408 stroker build is on my plans but obviously not doable with my actual budget but it is on my plans and it will be done with the best parts I can afford.

Considering the pros and cons of my initial plans probably will have to scrap that, unless I can get a good prediction of have better results compared with what I have with my actual 306

Thanks man