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302 with 351 parts what combo.

4K views 17 replies 9 participants last post by  CJR09 
#1 ·
I have currently got a 302 prity much standard other then the cam, good compresion (I think) and I have also got the crank rods and pistons from a running 351, what is the best combo and what would I have to do to any of the parts?
Thanks
 
#2 ·
you can go a few ways

351 bottom end with either 302 or 351 heads
302 heads will give a higher compression so youll have to run good fuel and good ignition
you could also run different compression height pistons with either heads to give desired compression
or use after market heads if you can afford it
there are also 4v and 2v heads and valves ( different size valves and ports ) to consider also
you can use 351 crank with 302 rods also with a piston to suit which is a common combo with the 351 heads which gives increased compression also
maybe have a talk to your local engine builder or machine shop
it comes down to money /power / how much you do yourself / and who you listen to

have fun deciding
 
#4 ·
Keita said:
I have currently got a 302 prity much standard other then the cam, good compresion (I think) and I have also got the crank rods and pistons from a running 351, what is the best combo and what would I have to do to any of the parts?
It all depends on your budget, and for how long you can survive without your ride.

What kind of condition is the 302 and the 351 in ?

If the 351 is still running, then you can do a compression test.

You can also build up the 351 while you continue to drive the 302, then spend one weekend swapping them over. This way you can take your time building the 351 to suit your needs and your budget.
 
#5 ·
I want to spend the absolute minimum as the accountant (my wife) has got me on a tight budget of what I can spend in total on my ute and there is a few other things that I want to do. I also fergot to mention that it is running stait gas and so I would like it to stay that we. The ute is only a toy I have a work car. so time out of action isnt a major other then space at home.
 
#8 ·
Keita said:
It seems the best/cheapest option is to just change the crank to a 351 crank. So I realy dont need all the parts that I was getting. Dose anyone have a good 351 crank that I can buy for minimum cash???
Not quite. Just changing the crank will put your pistons thru your heads. The 302 rods are longer. To use these rods with the 351 crank means u need shorter pistons to suit.

351 crank plus 302 rods plus stubby pistons = zero deck height
 
#10 ·
Keita said:
So what I need is 351 crank, 351 conrods, 302 pistion, 302 head. Is that right?
Well, yes. 302 and 351 share the exactly the same piston from standard. You can also say "i need a 351 crank, 351 rods and cleveland pistons,302 head " if you want. Or you could also say "351" cleveland pistons as well. Its hard to explain in writing :whoaa:
 
#11 ·
pistons come in many sizes

for a compolete rebuild


main,big end,cam bearings
new pistons /rings and block bored to suit each piston
crank checked and possibly machined for trueness
pistons / rods weighed to match
the whole bottom end balanced together - pistons,crank,rods,balancer,flexplate /flywheel
all these parts cleaned and inspected and checked and double checked for sizes and clearances when building
for higher revs a decent set of rod bolts and shot peening or other method to reduce the internal stresses of rods
new cam to suit your application
heads maybe done up - ss valves , seats ,springs etc

the price adds up
 
#12 ·
?
Why do you need another 351 crank and rods? You already have them, don’t you?
?

Keita said:
. . . I have also got the crank, rods and pistons from a running 351 . . .
The cheapest way to go is to drop the 351 crank and rods and pistons into your 302 block, assuming the pistons are the same size as your 302 bores. If not, then you’ll be up for some new cast pistons with rings. Hopefully a hone is all that’s needed to prep the bores before assembly.

Have the 351 crank bearing surfaces checked, then buy new bearings to match their size.

If it was me, I’d spend a little more now to do the job right, because it will save you having to pay more later on.

I’d get a new cam to suit the extra cubes. The following link refers to a cam that I use with my straight gas 351, and it works very well on the street with stock auto and rear end ratio. Heaps of tyre turning torque from such a mild profile.

http://www.fordforums.com/showpost.php?p=1197665&postcount=27

You’ll also need new hydraulic lifters. If your timing chain is worn, then have it changed. Your motor will run smoother. Better to do it while the cam is being swapped.

The 302 heads work very well with gas, and you will hear and feel the results of the extra compression.

Check your heads, because the valves may need to be re-seated and the springs may need to be replaced.

Don’t rush the job and DON’T cut any corners, otherwise before you know it, you’ll be pulling the motor out again and forking out more cash.
 
#13 ·
G'day,
reading this with much interest.
From my understanding, is that in the states they have 2 types of head...(damm wish i still had the article)
Basically it was the difference between the 4v and 2v heads.
4v clenched chambers?
2v better sized ports. (more practical for street use)
Then they spoke about the aussie heads which had the best of both worlds.
This was all for 351.
so where does the 302 head fit in?

Cheers
Jas

PS they also listed US suppliers of rebuilt aussie heads
 
#14 ·
I think this is how it goes . . .

There are 4V quench (rare and expensive now), like the ones used on the GTs, and 2V quench, (used solely on the 302C).

All others are 4V open or 2V open chambers.

The 302 Cleveland (only made in OZ and which should be referred to as the Geelong 302), only has a 3 inch stoke, so the smaller chamber delivered a comp ratio of around 9.2 to 1.

Fitting one of these heads on a 351 (with their 3.5 inch stroke – extra swept volume), delivers a C/R of between 10.5 and 11.0, depending on the block’s deck height, machining of the heads, piston valve relieves and gasket thickness.

Ford Australia made a few subtle changes to improve the flow characteristics of their new 302 heads, (designed to be unveiled in the XA model), because the US design was restricted by the narrow shock towers of their Mustangs.

The shock towers of the XA are wide enough to accommodate a big block, but not as wide as the XD/XE engine bay.

Can someone please correct me if I am wrong.
 
#15 ·
jas24zzk said:
G'day,
reading this with much interest. From my understanding, is that in the states they have 2 types of head...(damm wish i still had the article) Basically it was the difference between the 4v and 2v heads.

4v clenched chambers?

2v better sized ports. (more practical for street use) Then they spoke about the aussie heads which had the best of both worlds. This was all for 351. so where does the 302 head fit in?
Cheers Jas

PS they also listed US suppliers of rebuilt aussie heads
Quench not clenched.

Someone like Davis can explain why this design quenches the flame front and is supposed to reduce pre-ignition.

Yes our 302 heads are sort after in the US, though not so much now that there are so many alloy offerings on the table.
 
#16 ·
Keita said:
I have currently got a 302 prity much standard other then the cam, good compresion (I think) and I have also got the crank rods and pistons from a running 351, what is the best combo and what would I have to do to any of the parts?
Thanks
ACL do a piston for using the 302 rod with a 351 crank, but i priced a set up at repco and there a jaw dropping $774,
speed pro also do a set but i cant find a part number hence no price
 
#17 ·
jas24zzk said:
G'day,
reading this with much interest.
From my understanding, is that in the states they have 2 types of head...(damm wish i still had the article)
Basically it was the difference between the 4v and 2v heads.
4v clenched chambers?
2v better sized ports. (more practical for street use)
Then they spoke about the aussie heads which had the best of both worlds.
This was all for 351.
so where does the 302 head fit in?

Cheers
Jas

PS they also listed US suppliers of rebuilt aussie heads
Dont quote me, but i think the heads your reffering to are the type that I have on my 351c (XD - Ex interceptor) They are Stamped as 4V, have 4V chambers but have 2V inlet/exhaust ports. And if thats so, I'm swimming in the bastards. All of my blocks came with these heads.
 
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