273 302 318 340 build

[4spdragtop]

Just flipping thru both dodge and Plymouth manuals. 70 dodge 340 conrod weighs 758 grams versus 726 for Plymouth. 32x8 256 grams difference a little over 1/2 lb! Wonder why the weight difference?

 

[toolmanmike]

Here it is

 

[4spdragtop]

Thanks Mike. I remember reading about that plug a while back. Id forgotten bout it.
Thanks!

Here it isView attachment 1715108086

 

[nm9stheham]

Just flipping thru both dodge and Plymouth manuals. 70 dodge 340 conrod weighs 758 grams versus 726 for Plymouth. 32x8 256 grams difference a little over 1/2 lb! Wonder why the weight difference?

I suspect that is a mistake for Dodge Vs Plymouth. The 340's and then 360's (and then later on the 318's too) were 758 grams. The 726 gram weight started with the 273's (and maybe even the Poly 318's?), and probably just needed beefing up for the 340's torque and HP.

 

[nm9stheham]

IIRC, that plug forces the oil to divert though the filter. If not there, I don't think it causes pressure loss but the oil won't get filtered and the anti-drainback function in the filter is defeated. And being steel, I don't think it is effected by boiling; a brass one might be effected.

 

[4spdragtop]

Im thinking it could be a misprint as well. I'll weigh the #3418645 rods when I get back to work and post weights.
I stopped at Dodge today to order plug you mentioned Mike. # 3462871 but found it discontinued. Mine has whay appears to be a steel one and seems solid. If im talking to machinist I'll ask him about it.
Dealerships in US have them tho?
I saw another thread where you mentioned it crosses to Dorman #555-008. I'll get one in the next few days. I did order MP oil pan gasket kit P4452097. Hope its a good one. Only $11 so Im sceptical lol.

 

[4spdragtop]

Swung by car store, they dont have the small plug. Dorman #555-008 crosses over to Papco #260-118 so thats ordered up.
Whats a good way to remove the plug? Im thinking center punch, then drill then thread a screw in?
Suggestions?
Main bearings are full groove, but rod bearings arent. Would grooved rods be a recommended upgrade?

Thanks
Steve

 

[nm9stheham]

Look down into the top of the block, into the hole where the oil pressure sensor installs. IIRC, you look right down at the top of that plug.

If I understand your intended use, I doubt that you will be running at sustained high RPM's to justify any special rod bearings. You're not going circle track racing, right?

 

[4spdragtop]

No to circle track lol. Summer daily driver(pending fuel and tire costs) lol.
I thought it might be an inexpensive upgrade while Im "there".

Thanks for the tip on plug removal! I'll take a look at it tomorrow.
Cheers!

Look down into the top of the block, into the hole where the oil pressure sensor installs. IIRC, you look right down at the top of that plug.

If I understand your intended use, I doubt that you will be running at sustained high RPM's to justify any special rod bearings. You're not going circle track racing, right?

 

[4spdragtop]

Swung by post office and picked up head gaskets I bought from member "75 Duster 360". Thanks again Rob!
A set of used Cometic measuring 4.0795" approx. And a new set of Mr Gaskets measuring 4.1470" approx.
Block bore is 4.0695" Everything measured with digital verniers.
I think Mr G compressed thickness is .028". I gotta chk to be sure.
Machinist recommended Felpro .042"
Can anyone tell me whats recommended for bore size on head gaskets?
Al also mentioned to leave the plug at the rear main alone. In all his years he installed one and that was because the block came to him without one. So an install was a must.
Also stopped at Dodge store and picked up oil pan gaskets n seals.# P4452097. Seems pretty flimsy so we will see. Only $12 so not much lost if it craps out. After I had ordered this one I saw a reusable one from MP so I may try it.
Not much progress really lol. Next step checking bearing clearances. Try to get to that in the next week.
Thanks all

 

[nm9stheham]

If you are .030" over on a 340, then the nominal bore is 4.070" and I would use something that has a hole that is at least 4.095 or 4.100" diameter. There can be some mis-registration of the gasket bores on the cylinder bores. And while Cometics have been reused successfully, I personally would not do so on a new build; it adds in another variable or question mark in the new build.

Remind me... are you using stock, open chamber heads?

 

[4spdragtop]

Thanks for the cometic suggestion! I'll look at them more in the next week.
Heads are stock X heads. Im going to do some DIY porting on them.

If you are .030" over on a 340, then the nominal bore is 4.070" and I would use something that has a hole that is at least 4.095 or 4.100" diameter. There can be some mis-registration of the gasket bores on the cylinder bores. And while Cometics have been reused successfully, I personally would not do so on a new build; it adds in another variable or question mark in the new build.

Remind me... are you using stock, open chamber heads?

 

[nm9stheham]

OK, on the open chamber heads. In that case, the head gasket thickness is not critical for the piston-to-head clearance. So the MR gaskets would work and be pretty close to the stock thickness. I would not worry overly much on the head gasket bore being about .070" larger than the cylinder bore; you are not going to be pushing this to the limit the CR loss will be teenie-tiny and there should be no realistic issues with that small crevice.

 

[4spdragtop]

I haven't crunched #'s yet for compression. Gotta cc heads too, they havent been touched in 20 years. Other than lugged n shuffled around. Lotsa math to do yet lol.
Threw parts on scales at work today for reference.
Thanks again, much appreciated.

OK, on the open chamber heads. In that case, the head gasket thickness is not critical for the piston-to-head clearance. So the MR gaskets would work and be pretty close to the stock thickness. I would not worry overly much on the head gasket bore being about .070" larger than the cylinder bore; you are not going to be pushing this to the limit the CR loss will be teenie-tiny and there should be no realistic issues with that small crevice.

 

[4spdragtop]

I just noticed the shitty/fuzzy pics. Pistons are forged TRW 2332P .030Con rods are 3418645. Not sure if they are NORMALLY weighed with small end bushings or not??
Are these the beefier rods? Ive read different/conflicting statements. Also how can you tell the difference in the rod, (press fit vs floater)? ID of small end(with bushing) is 0.981" and OD of pin is 0.984". The pistons came with locks, plus they have grooves for them, so I assume floaters?
Oh recommendations for rear main seal?? Ive seen prices vary from $7 to $40... preferences?
Just doing some reading/research and getting confused.
Measured piston height(center of bore to top of piston) 1.851"
Measured eyebrows on pistons and come up with 8cc
Thanks in advance

 

[nm9stheham]

Yes they normally have the small end bushings, for the floating pins which you indeed have from the description of the pin lock grooves in the pistons' pin bores. Sounds like you also have the package of 16 pin locks somewhere with the pistons.

These are the heavier SBM rods which were used in the 360's also and later found their way into the 318's, under a variety of casting PN's. The weight you showed for the rods is spot on for data found in several sources. I looked at all of your other weights and such and they mostly look normal; the piston compression height should be 1.841", and the difference between the pin diameter and the small end hole (the pin to pin bore clearance) should be less than .001" (i.e., it will be reeeealy snug) so those numbers may be off due to measurement accuracy.

I'd go with a rubber formed rear seal; MUCH easier to succeed with than the old rope type seal. (At least for me....)

Thanks for the eyebrow check.... numbers are always appreciated.

 

[4spdragtop]

When using plastigauge for bearing clearances, can I do all the mains at same time? Or do I do one at a time?
Sorry for stupid question lol

 

[nm9stheham]

All at the same time is fine and efficient.

Do it with a dry crank and bearings. Place one strip on each journal with the engine flipped upside down. Make sure all bearing shells are properly and fully seated in caps and blocks (and they will crush into place anyway). Just torque all the main caps down (I like to do it in 2-3 steps of increasing torque, like 25, 50, then final ft-lbs), pull them back off, and read it. (Not stupid questions...)

 

[4spdragtop]

So plastigauge on the cap side only, or do both bottom and top?
Thanks again, doesn't seem like much progress yet, but getting to hopefully start bolting stuff in.
Spent more $$ today tho. Turns out the 2 pk of 3/32 drill bits were on sale. Less than a buck a 2pk, so I bought 8 in total. TASK brand so hopefully not junk. Bore gauges are house brand, I saw them and figgered for $30, why not.
Thanks!

All at the same time is fine and efficient.

Do it with a dry crank and bearings. Place one strip on each journal with the engine flipped upside down. Make sure all bearing shells are properly and fully seated in caps and blocks (and they will crush into place anyway). Just torque all the main caps down (I like to do it in 2-3 steps of increasing torque, like 25, 50, then final ft-lbs), pull them back off, and read it. (Not stupid questions...)

 

[nm9stheham]

Just between the cap and the crank; place it at the highest point on the crank with the engine upside down. That way, the plastigage will set to the total clearance between crank and bearings.

I have a set of bore gages just like that. Fair warning: They take a lot of patience and some skill to use and get accurate, consistent results. The handle has to be perfectly parallel to the bore axis; if not the readings will be large. And perfectly in the center; otherwise the readings will be small. It takes a touch and a good feel and practice to use them.

 

[Abodybomber]

Just between the cap and the crank; place it at the highest point on the crank with the engine upside down. That way, the plastigage will set to the total clearance between crank and bearings.

I have a set of bore gages just like that. Fair warning: They take a lot of patience and some skill to use and get accurate, consistent results. The handle has to be perfectly parallel to the bore axis; if not the readings will be large. And perfectly in the center; otherwise the readings will be small. It takes a touch and a good feel and practice to use them.

Great posts , that make definition. Thank You .

 

[krazykuda]

Swung by car store, they dont have the small plug. Dorman #555-008 crosses over to Papco #260-118 so thats ordered up.
Whats a good way to remove the plug? Im thinking center punch, then drill then thread a screw in?
Suggestions?
Main bearings are full groove, but rod bearings arent. Would grooved rods be a recommended upgrade?

Thanks
Steve

View attachment 1715109030

Center punch, then screw... I wouldn't drill to keep chips out of the oil galleys...

 

[4spdragtop]

Not any assembly progress, but hopefully soon. Got the rod holes drilled and chamfered. Still have to fine sand where I drilled thru the bushing.
Measured main crank journals and rod journals
Rods 1&2 2.1051"
3&4 2.10515"
5&6 2.10495
7&8 2.1049
Mains 1 2.480
2 2.485
3 2.480
4 2.480
5 2.480
So all is good. Crank was turned .020/.020
To chk bearings before I install and plastigage, should i use inside micrometer to measure bearing id?
Thanks all!

 

[nm9stheham]

Not necessary and can be off if you don't have properly calibrated equipment or of you are a bit off on setting the measuring equipment.

BTW #2 main is .005" different from the other 4. Typo?

 

[4spdragtop]

Good eye. I'll chk my notes after work to see what I scribbled down, and remeasure to be on safe side (more than likely human/me error)
Thanks again nm9!

Not necessary and can be off if you don't have properly calibrated equipment or of you are a bit off on setting the measuring equipment.

BTW #2 main is .005" different from the other 4. Typo?