small block build?

-
J

jacobw

New Member
Joined
Jun 25, 2015
Messages
4
Reaction score
0
Location
santa cruz
So i got my first mopar the few weeks ago for free, 66 valiant slant six auto running on 5.5 cyl. came with no back window, no front bumper, toast trunk and fender. After some help from friends i found a back window trunk fender and a bumper. yesterday i found a guy on craigslist selling mopar drivetrain for pennys on the dollar so i bought what i thought was an unassembled 318. funny enough the only thing not 318 about all the parts was the block, with 273 casting number stamped into the side. yet for 20 bucks i don't mind the mess up but i was wondering if i can still put it all together. the block says its a 66-69 with 2806030 casting number heads are 318 with only a 5 digit number that didnt cross reference and crank has a 2658898 casting number. guy said it was a 318 with a .030 over bore im not sure if he grabbed the wrong block when he gave it to me or just didn't know like myself before some research. question is can i still slap this all together to make a healthy mildly-hot motor?
 
Welcome to FABO!!


Here's how to id your engine block:

http://www.forabodiesonly.com/mopar/showthread.php?t=285021


You can still make a 273 run well, just get the right parts. check to see if the crank is cast or forged. The earlier 273's had forged cranks, the later ones got the 318 cast crank...


Here's a site to help you look up casting numbers and some info. You can also find free downloads for service manuals there:


Main Page:

http://mymopar.com/index.php


casting #'s:

http://www.mymopar.com/index.php?pid=20


Service manuals

http://www.mymopar.com/index.php?pid=109
 
Welcome also!!!

i to have a 66 A-body (barracuda) with a 273. Given what I know so far, I'll probably go with a 318 when it's time to rebuild. Pistons are cheaper and more plentiful. I can use lots of the 273 parts- forged crank, rods, and, ect. So far the big expense is headers if you choose to go that route. $20 great deal !! Start looking for a steering center link off a v8 car as I think this is something that you'll need for your swap.
Have fun !! (This is the fun part- building) and remember - ask questions twice and buy once :D
 
The head casting number is indeed 7 digits; check on the runner castings.

Are you sure about the crank number? Look again; perhaps it is 2658393.... a later 318 cast crank. That may not balance up with 273 pistons without the right pins and rods. But it is close enough to balance if you took it to a machine shop and had them balance that crank to the 273 rods/pins/pistons.

Do you have the rod casting numbers?

Kinda sounds like the wrong block, just based on the possible crank number. I would try for the 318 block. I like the 273 but it seems to be sought by mainly those who want an original numbers matching motor. My son and I have a complete 273 and still have decided to go the 318/340/360 route. If you go 273, there is just one current manufacturer of pistons for them, Egge, and they are around $400 for a set. I would go for the 4 bbl domed ones for the CR.

You'll need to change the k-member or modify your /6 one for a V8 mount. Good luck with it all!
 
The one cave eat is the small cylinder bore is unable to accept the 1.88 intake valve IF the head has it.
IF the 273's heads are of the first 2 years, '64-'65, the angle and size of the holes T&D attach the intake are at a different angle and a smaller size. Later year parts can be swapped on without issue. The heads and intake from a later year 273 or 318 will work perfect fine.
 
so the number is indeed 2658393 they looked like 8s but look more like s's but it is a cast crank without a doubt rod numbers are 2406782 (318 rod 1970 full floating) attached to 322np sealed power cast pistons. would all this work together? i'm trying to make a healthy workhorse with decent pickup for around town so i don't hold up traffic not some hotrod or some gutless stock slant 6. suspension is #1 for me for any of my previous builds so i'm starting with a 8.8 linked rear end and dealing with the torsion shenanigans up front. the body work fills up the gaps of time inbetween cash flows.
 
Perhaps check your rod number again.... maybe 2406785? Used in 273's and early 318 LA's.

It should all work together, just that the balance may not be right on with the 318 crank and any 273 pistons. I think I recall that the early 318 piston weight was 23 grams heavier than the 273 4 bbl, but the 318 pin was lighter to compensate.

Read up on some 318 threads here; the biggest challenge with the small 273 displacement is to keep a decent compression ratio. So you'll have to learn how to compute the CR with some online calculators and not get the pistons too far down and let the CR get too low. Smaller changes in piston height have large effects on smaller displacement engines.

Look at your heads and see if any of the exhaust valves are recessed.

Check the diameter of the hole of the rear of the crank. With that crank number, it should be for the later larger hole. (Pilot or torque converter snout.)

BTW, my local machinist is putting together a 273 for someone in this area and says he is using some Ford V6 pistons in the 273. He is bushing out the rod's small end to use the different Ford pin. If you want that as an option for 273 pistons, I'll ask him what they are from; not sure how/where the comp height is being set.

BTW, who said stock /6's are gutless? He's a liar LOL
 
nope rod number is definitely 2406782. odd. thinking of just test fitting everything. gonna need some bearings but that seems about it.
 
the 5 digit number on the head is the date code, what are they, month day last number of year. go for it
 
jacobw said:
nope rod number is definitely 2406782. odd.
Click to expand...
Not odd... Maybe I turned the 2 into a 5 in my notes....

BTW, I found in my notes that the early 318 and both 273 2bbl and 4 bbl piston/pin/rod assemblies will balance out to the same crank; the different piston weights are compensated by using different pin weights. This all assumes you use the lighter con rod. The 2406782 looks to be the lighter con rod (726 grams).

If you want to check, total stock piston+rid+pin weight without rings and locks should be around 1478 grams.
 
I'd look at the casting date on the block, because it sounds like all this could have come on this motor if it's a '68 or '69. That cast crank was used in many later 318s and that's a number I've seen for 340 cast cranks- sounds like that may be from another motor but everything else could've come on it.
 
Sounds like you have a bunch of mixed parts. If you put the wrong combo together, it will have vibration issues. Cast cranks require a different balancer and flex plate. I think you would be miles ahead by buying a complete engine with all the parts you are going to need, like all the brackets and pulleys. Not to mention the balancer, and flex plate. If you have to rebuild it, it should go together with minimal problems. Would be even better to locate a donor car . Then you'll have all the little parts that takes forever to find.
 
Infecteddog said:
I'd look at the casting date on the block, because it sounds like all this could have come on this motor if it's a '68 or '69. That cast crank was used in many later 318s and that's a number I've seen for 340 cast cranks- sounds like that may be from another motor but everything else could've come on it.
Click to expand...
Never thought of that bit it looks like you are probably right. I just looked up the PN's that we got in a '68 273 and the rod & crank & head PN's are the same as the OP's. Block PN is 2806030-273.
 
I believe that the 68 * 69 318 and 273 had the same cast cranks and heads those years...
 
And FWIW..... the Ford pistons the our local machinist is putting into a 273 are for the old 223 inline 6.
- Same standard bore as the 273.... 3.625".
- Pin is considerably smaller at .921" so rods have to be bushed out for this.
- Compression height is 1.858" so is around .040' taller than the 273 pistons. This is interesting because you could get them to pop up out of the block like 340 pistons for better CR, especially like with the open chamber heads like the 675's. May still need some machining off of the top, but the open chambers have enough headroom so you would have some decent quench space.
- I have not looked at eyebrow distances to the valves which would almost certainly require more machining; this issue would take some more work to flesh out so don't just buy these thinking they will just pop in.

Sealed Power has them with flat tops. KB/Silvolite has them in flat top. Both cast. I have no idea if there are any forged units around.

Use these and impress your friends by saying you have Edsel pistons in your 273 LOL!
 
You must log in or register to reply here.
-

Back
Top