200 Con Rod

[mugsy]

I guess this is a rant, "WTB" and a plea, all in one!

I picked up, last year, a '66 200 short block from a guy on another forum. He bought a '66 ragtop to put a v-8 in and was parting out what he didn't need. So I bought (real cheap) basically the short block. The guy told me the engine ran and he was told by HIS seller that it had a "recent" rebuild. So the guy who sold it to me could not vouch for the completeness, etc.

Well I have started to take 'er apart to check the previous rebuild work. First thing noticed was the #1 piston was about 55-60 thou down the bore. All the rest averaged about 30 thou! So I took the pistons out, and to the best of my meager ability with a caliper, I measured the rod length, it is 20 thou shorter than rods #2-#6 !!! And the "date" code cast into #1 is C1DE and for #2-#6 the date is C3DE. #2-#6 lengths are within the tolerance from the shop manual too.

I also weighed the piston assemblies (rod, bearing, piston, pin,rings) and for #2-#6 they are all with in 4 grams of eachother. I think that is pretty good :roll: But #1 is close to 20 grams lighter

So my rant is why someone who assemble an engine with mismatched parts!!! I'm assuming that the engine would run poorly with lower compression on ONE cylinder and be a little out of balance with ONE piston/rod lighter. OR are these number within tolerance?

There got that off my chest! But now I need a single standard length connection rod . Can anyone help?

tanx

 

[xctasy]

I'd consider making changes to another rod of similar depth. All 144 and 170 rods should in theory be longer than the 200 rods, but that date code indicates that you may have an early 170 1961-ish rod (C1DE) closed and ground to suit. My written lengths are 4.755 and 4.80, from memory, but I have no idea what number castings they had. If the 144, 170 and 200 rods were the same, they should have a similar code number.

The Ford Six Performance book is the diffinative Tulmud on these things.

I'm not certain, but I think that may cover the differences.

The stock rods sat at around 4.71" for the 200 six. The 144/170 rods were
placed in blocks with pistons of different heights, and strokes of different lengths.

When a rod is closed and ground, it is shortened and lightened. The rod pin may be bored with a degree of freedom of up to 50 thou or more, so this could be what has happened. There are depth gauge readings you can take to see if this is what has happened.

Our Aussie rods got an AR prefix, so an Aussie ADC1DE may not be the same as yours.

Hope this helps.

A gram out can be a 1 ton cyclic load banging a crank at 6000 rpm, so biff the lightest rod, and find another heavier one. The earliest ones should be forged, so another junked 200 should be the source of a good candidate.

 

[CobraSix]

tanx,

sounds similiar to me. i bought my latest 200 from a guy who bought the car and soing a V-8 swap. The previous guy "rebuilt" it a few years prior. Yeah...right...

Slade

 

[66Sprint6]

Hey,
With that first rod being an early 60's 170 rod, could I use some with my pistons to lower the compression when I turbo? Would that be smart to do while saving up for new dished pistons , or should I just stick to the rods I have in my 200 and get better dished pistons. Maybe even both, lol? What ya think about that?
Matt

 

[mugsy]

I knew a guy who had a 360 in a '72 Plymouth Duster and he claimed to have balanced his piston/rod within a hundredth of a gram. That sounded a little excessive. But if they should be within one gram then I now have my next weekend project!!

When I left the pistons/rod at the machine shop the guy there stated that they normally don't press off pistons to be re-used. They only keep the rods, so he doesn't know if the pistons will be in good enough shape to be re-used. I will go there in a couple of hours and see if he was successful :roll: .

I didn't think about resizing the big end to make the lengths match. I'll discuss that with the shop.

Tanx for the help so far!

 

[xctasy]

Hey,
With that first rod being an early 60's 170 rod, could I use some with my pistons to lower the compression when I turbo? Would that be smart to do while saving up for new dished pistons , or should I just stick to the rods I have in my 200 and get better dished pistons. Maybe even both, lol? What ya think about that?

Just info to help you.

I'm not certain about the rod lenghts. I suspect that, if the 170/144 rod is diferent, it is most likely longer than an 200 rod.

The lowering of compression was done on Ford engines by allowing the piston to sink down in the bore. I personally think this was a concession to wide variances in the rod, crank and pistons lengths. Mark P did an awesome sum-up of the squench Ford designed into the combustion chamber, and blue printed a head and gasket using a standard tin gasket. His background is Ford ignitions, so he has most likely forgotten more about engine ignitions than we will ever learn about engines!

I think any time you let the piston sit down shallower by using a shorter rod or piston, you increase the prospect of detonation because of the greater area of hard, hot edge of block becomes a source of early ignition. More power and better detonation resistance is gained using a piston that comes close to the top of the block. Find a head with 58 to 62 cc's of chamber volume, or the taller gaskets. I favour a composite gasket because it reduces the risk of a hot fire ring creating an early igniton of the fuel air mix, but a good engine builder may have other ideas.

 

[mugsy]

Latest update:

The #1 and #2 pistons were pressed off of the rods without any problems. I measured and weighed the pistons/rings; they were about 1 gram apart I measured the rods and yes, they are 0.020 inches different in centerline to centerline distance AND they are about 18 grams different in weight

So I am in the hunt for a single 200 con rod!!!! 8)

I have an early version of Dennis' and Dave's book, in it they do not give the length of the 144 rod, only the 200/170 rod.

Matt: if you can find a SET of C1DE rods then it might help with the compression ratio on your turbo motor. I used the calculator on the Falcon Six web site, the 0.020 difference in height lowers the compression ratio by roughly 1/2 a point. Don't know it that is enough to help with detonation.

 

[66Sprint6]

Thanx for the help guys,
I am always looking for a good cheap way to lower compression and more importantly, fight detonation before I can afford to build up the block to take large amounts of boost.
Matt

 

[ASMART]

Shorter lighter rods?? Combine that with shorter pistons,block milling, adj push rods and you get a shorter lighter block with lighter recipricating weight. You could get custom shorter push rods to to lighten the valve train weight load. That would mean less spring pressure needed for the same red line. Hmmm.

 

[addo]

Mugsy, for the amount of grief in looking, vs the certainty of it all, go find a full set of rods. Close, hone, balance, polish and peen away. Then do the piston masses.

Regards, Adam.

 

[simon]

are 200 and 250 rods being reproduced, or are there just remanufactured available?

I found myself unable to obtain any information on that. Yet...

 

[xctasy]

You can get used 5.88" 1971 to 1992 Aussie 250 rods by the bucket load in stock and longer (1997 to date) 6.06" length, or even use Tempo/Topaz 2.5 HSC four cylinder ones (6.00") as a stand in. These fit US 250 engines.

As for the 200, there are no cost effective changes for US 200 blocks. You must use 144/170/200 rods. Your stuck with what you can find second hand. Some are cast, most are forged.

There are other options but they are expensive:-

1. custom ones from 2.0 Pinto (needs a crank grind and bushing to fit the bigger wrist pin bore to a shallower custom piston) . 5" tall, needs a 1.245" 305 Chevy custom piston.

2.or SBF 302, but they need a lot of work on the crank to fit. 5.09" tall, needs a 1.155" piston. The SBF rod is too narrow, and would need changes to the crank grinding to centre on the rod.

3.There is no exact match without a piston change.The longer rods from Ford I6 based 2.3 HSC ohv valve engine would need a custom piston 0.795" compression height piston, definately not cost-effective.

4. A 188 Aussie I6 5.37" rod would need a 0.875" piston,

5.and the 221 I6 rod, about 5.14" tall, would need a 1.105" tall piston.

These last three rods are straight drops in with very expensive pistons!

 

[Anonymous]

I have two sets of 200 rods that are shot peened and polished, sized and checked for straightness. they are also balanced to 1/2 gram. I have $125 in each set and would sell them for that. I have the balance sheets for each set from the balance shop also.

Todd

 

[mugsy]

Todd,

As they say, "timing is the secret to life". I ordered a single rod from a parts store late last week. $31 is the dammages. It should be here today or tomorrow. I'll be checking it to make sure the dimensions fit/match my motor. If the thing is not what I want/need, I'll PM ya and we can go from there.

Thanks,
Keith

 

[Anonymous]

You are going to want to balance that rod with the rest of your set to make sure that you dont have a severe balance problem. Good Luck

 

[mugsy]

PB,

You're right. I'm going to have the other 5 pistons removed from the rods and then balance the rods AND pistons out. I should be picking up the rod at the parts store this evening and will measure the centerline distance BEFORE I walk out of the store. 8)

I am also putting in new rings, so the pistons need to be match as well. This is starting to be fun!!

Mugsy