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351 XE on LPG
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Thunderoo said:
When i had my clevo built i bought a kit which had a 351 crank...302 rods...and hypertech pistons with adjusted gudgen pin height...the pistons were very short in the skirt area compared to the normal pistons, but this set up also strokes it out to a 387.
A 351 crank, (regardless which rods and pistons are used), will ONLY deliver a capacity of 351 cubic inches UNLESS the crank has been off-set ground, but then it wouldn't be able to fit Cleveland 302 rods. Chev rods are normally used with these off-set cranks and the resulting capacity is 377 or 383 with a 30 thou over-bore.

I'm sorry, but I think somebody is pulling your leg or you have your facts mixed up.

A 4 inch bore and a 3.5 inch stroke CANNOT deliver 387 cubic inches.
 

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XB GT'S ROCK !
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Rhett said:
A 351 crank, (regardless which rods and pistons are used), will ONLY deliver a capacity of 351 cubic inches UNLESS the crank has been off-set ground, but then it wouldn't be able to fit Cleveland 302 rods. Chev rods are normally used with these off-set cranks and the resulting capacity is 377 or 383 with a 30 thou over-bore.

I'm sorry, but I think somebody is pulling your leg or you have your facts mixed up.

A 4 inch bore and a 3.5 inch stroke CANNOT deliver 387 cubic inches.
Intersting. Im not dissagreing with you....but i will be haveing a chat whith the company i bought the kit off ! Thanks. But now you can buy kits from Scat which stroke 351 c to a 420..!
 

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Thunderoo said:
Intersting. Im not dissagreing with you....but i will be haveing a chat whith the company i bought the kit off ! Thanks. But now you can buy kits from Scat which stroke 351 c to a 420..!
Feel him out, because if he did pull the wool over your eyes, he make make up a new story as he goes. First find exactly what he did use so he can't say "oh, i meant chev rods"!!!
 

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XB GT'S ROCK !
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TruBlu351 said:
And welcome aboard Thunderoo!

You should easily have a low 13 Falcon there! What diff gears you running?
Thxs very much....ive been useing the other Ford forum for some time now, and ive just been told by a guy who ive just meet yesterday through the forums to view each others car, that there is another Ford forum...so i signed up. Unfortuneatly im running 2.7........The engine has only done 500 klms...but she still lights em up with the tall diff.

 

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Hey, nice car. The black & silver is a great colour combo.

I'll withdraw my statement about easy low 13's now that you have the 2.7 cruiser gears!! Get some 4.11's into 'er :hehe:
 

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XB GT'S ROCK !
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xdclevo said:
Feel him out, because if he did pull the wool over your eyes, he make make up a new story as he goes. First find exactly what he did use so he can't say "oh, i meant chev rods"!!!
Tryed to get in contact with the guy that i bought the kit off.....but suprise suprise...i couldnt get in contact with him. So i rang Engine world ( Port Macquarie ) and Currie Brothers ( Taree ) And both of them said that the 351 crank and 302 rods with the small skirt pistons and the changed height gudgen pins "DO NOT INCREASE THE CAPCITY OF THE ENGINE" ( Looks like im going to have to change my signature LOL ) One place said that this combo will increase tourqe by 10 - 15 % from the standard set up, and the other place just said it will increase tourqe well above the standard, one place said also it makes them more reliable as when the clevo gets worked a bit they can split cylinder walls...and the 302 rods decreases the strain on the cylinder walls. So...im a little dissapointed now, but it all goes away when i jump in her and fire her up !! Rhett is 100% correct...to stroke the clevo's chev rods are used.!! Thanks for the heads up guys !!
 

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XB GT'S ROCK !
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RAVEN said:
that car is tough mate !
Thanks very much.....did i tell you how much black is to keep clean !!!!!
 

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351 XE on LPG
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Sorry to introduce the disappointment mate.

I just love your ride and engine bay !

The good old XB! . . . (back when body lines had class and character, not like the computer generated 'bubbles' we have on the roads today)

I agree with TruBlu.
The diff ratio will stop your XB from achieving its full potential.

I find it useful to be able to calculate the revs you'll be pulling using different combinations. This way you can match everything to suit your cam's power band.

I've developed the following tool for running what-if scenarios . . .

http://www.fordforums.com/showpost.php?p=1103251&postcount=1

Hope you find it useful.
 

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Death by Ford
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Thunderoo said:
Thanks very much.....did i tell you how much black is to keep clean !!!!!
Nice XB there Thunderoo:hy:. You are right about the black, one of my XB's is painted black and it's also a pain to keep clean. In summer on 40+ days i can roast chickens on my parcel shelf :priest: .
 

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It increases the length of the connecting rod from 5.780" to 6.02".

It increases the nearness of the piston pin to the top of the piston.

It increases the reduction in dynamic compression ratio of engines with camshafts with a good bit of valve overlap.

It increases the piston dwell time at/near TDC.

It increases the reduction of dwell time at/near BDC.

It increases the weight of the connecting rod used in the rotating assembly.

It (probably) increases the reduction of weight in the piston used in the rotating assembly.

It likely increases the controversy in discussing rod lengths and what is better/worse/best/good enough.


:davis:
 

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I am going to be building my 351 soon for my xw if I use the 302 rods with the 351 crank do I still use the standard 351 pistons
 

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I am going to be building my 351 soon for my xw if I use the 302 rods with the 351 crank do I still use the standard 351 pistons
You should start a new post in the correct section with your question rather than tag on to an old post , better chance of getting a reply .
 

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I found out today from the original owner of my new coupe that he thinks the guys who did his engine put 302 con rods on the 351 clevo thats in it for some reason to increase something...what would this be?
Yes, I realize this thread is over 14 years old.

That depends on WHICH Ford 302 rods are meant by "302 con rods":
  1. 302W, 302W-HD: length between centers = 5.090 inches;
  2. Boss 302: length between centers = 5.150 inches
  3. 302W-TA, Boss 302-TA: length between centers = 5.315 inches (used only in racing applications)
  4. 302C: length between centers = 6.020 inches
  5. For comparison and contrast, the OE 351C connecting rods are 5.780 inches long between centers.
With a stock 3.500-inch stroke and no wristpin offset, this means:
  1. The rod:stroke ratio is 1.45429: 1, the wristpin centerline is 3.340 inches above the crankshaft centerline at BDC, and the compression height required to put the crown of the piston 9.190 inches above the crankshaft centerline at TDC is 2.350 inches.
  2. The rod:stroke ratio is 1.47143: 1, the wristpin centerline is 3.400 inches above the crankshaft centerline at BDC, and the compression height required to put the crown of the piston 9.190 inches above the crankshaft centerline at TDC is 2.290 inches.
  3. The rod:stroke ratio is 1.51857: 1, the wristpin centerline is 3.565 inches above the crankshaft centerline at BDC, and the compression height required to put the crown of the piston 9.190 inches above the crankshaft centerline at TDC is 2.125 inches.
  4. The rod:stroke ratio is 1.72000: 1, the wristpin centerline is 4.270 inches above the crankshaft centerline at BDC, and the compression height required to put the crown of the piston 9.190 inches above the crankshaft centerline at TDC is 1.420 inches.
  5. The rod:stroke ratio is 1.65143: 1, the wristpin centerline is 4.030 inches above the crankshaft centerline at BDC, and the compression height required to put the crown of the piston 9.190 inches above the crankshaft centerline at TDC is 1.660 inches.
The 302W, 302W-HD, Boss 302, 302W-TA and Boss 302-TA crankshafts featured crankpins having a nominal diameter of 2.123 inches; like the 351C, the 302C crankshafts featured crankpins having a nominal diameter of 2.311 inches. Use of the smaller crankpins lowers bearing speed, but could present a strength issue in extreme-output applications relying on a modified OE cast crankshaft; however, modern forgings are sufficiently inexpensive that this shouldn't be a problem.

Ford has (and non-Ford makers have) used ridiculously tall pistons in production engines with cast cranks and rods, without significant issue; however, the shape of the piston is critical in every application, so make sure each of your pistons has the correct profile. The shape of your piston will determine where is the critical point; as this can vary by manufacturer and piston design, it isn't presented here: it's the point that MUST remain fully captured by the bore, to prevent the rocking of the piston. Conceivably, tall pistons may have a sort of hourglass profile that allows the wristpin to be pulled halfway (or more) out of the cylinder at BDC.

Taller pistons are (obviously) heavier; therefore, they will not allow revs to go as high as would a shorter piston. On the other hand, shorter rods work better with high-lift, short-duration camshafts when the heads are generally regarded as being "too big" for the application -- which is pretty much the 351C-4V story in shorthand.

There is no "magic" rod:stroke ratio; however, inefficiencies do both multiply and accrue. Having so stated, the axiom "there's no replacement for displacement" applies. Given the context, here's the take-away: for a crown height that is 9.190 inches above the crankshaft at TDC (assuming zero wristpin offset, perfectly indexed bores, etc.) --
  1. A piston having a compression height of 1.240-inch can be used with a 3.500-inch stroke and a 6.200-inch connecting rod, for a 1.77143:1 rod:stroke ratio; with a 4.030 bore, that's 357.2 cubic inches (5,852.74 cc); however also,
  2. A piston having a compression height of 1.240-inch can be used with a 4.000-inch stroke and a 5.950-inch connecting rod, for a 1.48750:1 rod:stroke ratio; with a 4.030 bore, that's 408.2 cubic inches (6,688.84 cc) -- and MAYBE
  3. A piston having a compression height of 1.240-inch can be used with a 4.340-inch stroke and a 5.780-inch connecting rod, for a 1.33180:1 rod:stroke ratio; with a 4.030 bore, that's 442.9 cubic inches (7,257.40 cc) -- and if you bump that up to a 4.200-inch bore, you've got 481.0 cubic inches (7,882.60 cc).
The object in the above 3 examples isn't to present the absolute extreme one-off case, but to show a long-rod 351C with a couple of alternatives fitted into the same block with the same deck clearance.
 
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