Can I put Pistons in backwards?

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Can I put Pistons in backwards?

Post  Andre.servin on June 20th 2015, 5:57 pm

Hey how's it goin! Got a question about my 460 Pistons and connecting rods.

I pulled a 460 out of a 77 f250, which I intend to drop into my torino.

The engine appeared really clean and still showed cross hatching in the cylinder walls, it was bored .060 over and the odometer on the truck read 150,000 miles.

The engine most likely still ran good, Im guessing it wa rebuilt maybe at some time around 80,000 miles or a little more on that truck before it landed in the wrecking yard.

I took it to my machinist and told him I wanted the block magnafluxed and to inspect the heads as well as the Pistons. If they where still good, which they should have been, I wanted to reuse them and just home and re ring the engine.

Block and heads checked out fine as well as the Pistons. Cool ordered my re ring kit and cam and timing chain.

Upon installing the Pistons and rods into the cylinder bores I noticed that had almost no rod clearance and that the engine was extra hard to crank by hand.

It has what I believe to be stock style ford Pistons. As they are stamped with a ford logo.
The connecting rods are also stock ford ones labeled 1-8.
I assumed all was well an installed them with the piston arrow up top facing towards the front of the block on all Pistons. After having trouble turning the crank by hand I took the caps off and noticed that my connecting rods where installed into the Pistons with the chevy/Chrysler cylinder order. 1,3,5,7/2,4,6,8 vs 1234/5678

So the bevel edge on the connecting rods are not facing the crank journals but the other rods.
I'm not sure I my machinist removed the rods at some point in time and put them back in that cylinder order. Or if whoever rebuilt that engine at some point in time did it and all my machinist did was clean them up and see if they where still good.

If I where to turn them around so the piston arrow is facing the other direction vs front of the block, I can line the rods up perfectly to the crankshaft so the beveled edges are towards the crank vs towards the other rod. But then the piston arrow will be pointing the opposite direction and I'm not sure if that's a problem.
Thanks!

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Re: Can I put Pistons in backwards?

Post  69F100 on June 20th 2015, 6:11 pm

Yes the piston can be installed wrong the rods should be numbered 1 thro 8 and should be installed to.the  cylinder number

Yes the bevel should be to the crank right now you should be able to swap sides with the front on back.
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Re: Can I put Pistons in backwards?

Post  Andre.servin on June 20th 2015, 6:33 pm

Cool sounds great! So Piston direction doesn't matter as long as it's in the correct cylinder and the rods are correctly installed to crank?

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Re: Can I put Pistons in backwards?

Post  butterbean on June 20th 2015, 7:22 pm

what about the valve relief's they should be facing the front!!!
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Re: Can I put Pistons in backwards?

Post  69F100 on June 20th 2015, 7:33 pm

If the pistons are facing right but rods bevels are wrong then swapping piston sides will correct the bevel problem and keep the piston facing forward. Keep the pistons on the same journal swapping sides should fix your problem. One other thing you should do before taking a engine apart it to mark the rods where they go so everything stays balanced.
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Re: Can I put Pistons in backwards?

Post  Andre.servin on June 20th 2015, 8:58 pm

Okay so don't just turn the piston around in the same cylinder but put it in the opposing cylinder?

Example:
Piston and rod for cylinders 2 and 6. Install #2 in number 6, and #6 in number 2?
That way the piston is still facing forward and the connecting rod bevels are against the crank counterweights.

So virtually install 1234 into 5678 and 5678 into 1234?

Just trying to follow this the best I can so I don't ruin anything hahah

Yea I should have marked them but oh well, it's already past that point. I guess I figured the factory marks where good enough.

I believe my Pistons have dual valve relief notches. I'll try and post a picture.

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Re: Can I put Pistons in backwards?

Post  rmcomprandy on June 20th 2015, 8:58 pm

Pistons with a pin "offset" are often installed reversed intentionally for a little less parasitic horsepower loss from wall friction.  The down side is more piston slap and noise.

It is VERY important to install the rods in the engine correctly... no matter how they are installed on the piston as long as the notches are in the correct location.

SO, yes ... just switch sides.

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Re: Can I put Pistons in backwards?

Post  Andre.servin on June 20th 2015, 9:14 pm



Heres a picture of one of my Pistons fro
When I first pulled the engine. Sorry it's backwards and a little poor. It's the only one I can find in my phone an I'm currently at work so I would have to wait to get home to take a solid photo but here's apicturenof one in the engine

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Re: Can I put Pistons in backwards?

Post  Andre.servin on June 20th 2015, 9:18 pm

It has the dual notches in the Pistons.

Okay I apprectiate everyone's answers to my post and I hate to sound like an idiot but I'm a little confused.... When you say switch sides do you mean switch sides as in put piston number 2 into cylinder number 6?

Or do you mean simple install the piston back into the same cylinder but with the arrow facing towards the back of the engine vs the front. That way everything is still in the same cylinder and the rods are oriented correctly, just the piston is turned 180 around.

Sorry for the confusion on my behalf!



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Re: Can I put Pistons in backwards?

Post  supervel45 on June 20th 2015, 9:57 pm

I would put the rod marked #5 in cly. #1, and the rod marked # 1 in cyl. #5, and see if they are right with the notches facing the front. I am assuming the machinist used the Chevy firing order also. If they are positioned properly, switch 6 and 2, 7 and 3, 8 and 4, checking them as you go.

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Re: Can I put Pistons in backwards?

Post  Andre.servin on June 20th 2015, 10:34 pm

Okay sounds good I will do that.

Doing this switch won't ruin anything?

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Re: Can I put Pistons in backwards?

Post  supervel45 on June 20th 2015, 10:47 pm

I won't promise anything. I think if the rod bevels are towards the crank and the notch's to the front you should be OK. I would check the rod side clearance of all your rods. It's a good thing you caught the problem before you tried to run it for sure.

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Re: Can I put Pistons in backwards?

Post  Andre.servin on June 20th 2015, 10:54 pm

Checking the rod clearance is how I figured it out!

Okay will do and then report back!

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Re: Can I put Pistons in backwards?

Post  Andre.servin on June 21st 2015, 6:03 am

So here's what happened.

I performed the swap on #2 and #6. Switched the sides, it corrected the problem and the arrow is still facing forward.

#3 and #7 where already installed correctly. I left those alone.

#4 and #8 - piston and rod #4 is backwards so the swap would work on it. ISSUE being #8 is installed correctly. So swaping these would make the same issue with just the opposing piston and rod (4). Only way to fix this one is to turn piston #4 around but then the arrow is facing the rear of the engine on that cylinder vs the front.

#1 and #5 - same issue as 4 & 8, #1 is installed correctly... #5 is backwards. Only way to correct this one is to turn #5 around but like wise the arrow will be facing the rear.

Can I just turn the Pistons in the cylinder? Or should I simply just take them all out and go to the machine shop and just get the rods switched so everything is lined up 100% perfect?

I would like to get going already on my project, this would delay me until the machinist is done with the switch, which I'm kinda tired of being stuck on the engine. I do want the engine to work good so if it's possible to turn them around in the cylinder with no negative side effects then I will do that. If not I will just yank them all out in defeat hahah

Btw I don't believe my machinist installed the rods. I feel he simply just cleaned the Pistons and rods to inspect if they will still work. I noticed on the picture I took before assembly whoever ire built it prior to just simply throughs the connecting rods in any order on the crank. They just made sure the bevel was to the crank.

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Re: Can I put Pistons in backwards?

Post  bosshoss on June 21st 2015, 6:12 pm

As long as you have four rights and four lefts it doesnt matter which hole the piston goes in. Given the choice between running a piston backwards or a rod backwards I would have to choose the piston however it is not ideal. I would worry about offset and piston to valve clearance etc. like I said..
Mix and match them however you need to but make sure the rods are correct...

If it was me and i still had a couple that were backwards I would take them in and have them switched.

dkp
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Re: Can I put Pistons in backwards?

Post  Andre.servin on June 21st 2015, 7:14 pm

Yea i decided to just settle this debacle and take out the 4 that where installed backwards and I'm taking them to the machine shop on Monday

That way every rod and piston are where they should be and everything will be as intended. Sucks but oh well, better to do this now then encounter some issue of some sort some torino down the road later.

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