The Stay At Home Dad 273 Build.

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seabee

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Here's my 273 build for anyone who is interested. The goal was for it to be streetable enough to drop the lil' one off at school, ballet etc., but fun enough to keep Daddy happy on the weekends. A big thanks to FABO members and especially Justin, (1Wildand CrazyGuy), for all of the help and guidance along the way.

Solid Lifter Cam, lifters, and Springs by Schneider Racing Cams:
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( http://schneidercams.com/lasmallblockv-8.aspx)

I reused the #315 closed chambered heads. Justin ported the heads to flow:
INT/EXH PORT NO.6
---- int--------exh
.100- 61------na
.200- 128-----94
.300- 174-----114
.400- 196-----133
.450- 204-----148
.500- 199-----153

chambers measured 66.5-67 cc (64cc original)


The heads were taken to Mesa Machine in Escondido, decked .040, new valves and springs and I used the Fel-Pro Q8553PT head gaskets. Added Comp Cams 7822-16 7.5" Pushrods.
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I rebuilt my Eddy 1406, running everything through the ultrasonic cleaner:
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My original pan was dented up prettey bad so I got this zinc plated replacement off of Ebay and used a "crush-proof" gasket and new pan bolts:
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I re-used the perfomer intake and had to have the surfaces milled a bit to line up with the heads with a Fel-Pro Q1213S3 performance intake gasket.
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I added an Edelbrock 2696 Square bore to spread bore adapter/spacer after the break in. The outside of the carb measured 11 degrees cooler than before.
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I replaced the oil pump with Mopar Performance P4286589 and the harder shaft P3690715
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Compression test (plugs out but without throttle open) was 150 +/- 3lbs across the board.

So far, so good......Will do one more "Dialing in" tomorrow at Justin's before Mopar Night on Grande then I can really evaluate how much was gained. So far, I can feel a really big difference in low end power and a "snappier" feel on the throttle.

Some Videos:

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Surprised you feel more low-end torque since your cam has much more lift than even the factory HiPo engine. The adapter might have helped since that gives you 4 holes and I have read that 4-hole manifolds are better on the low-end.

I put a hydraulic cam (0.422/0.444) in my 1965 273 w/ Rhoads leak-down lifters. They claim to give more low-end torque, smoother idle, and better mileage, but I have no basis to compare. I got several sets on ebay, for as little as $25 I recall. I may try on my other cars.
 
What pistons are in there? How far in the hole? Did you measure the compression ratio?
 
Nothing against anyone's choice of engine but it's cool to see love for the 273. I know yours sounds awesome too.
 
What a cute helper you have. Enjoy your time with her. Oh and Thanks for sharing your build.
 
Great build, nice car, and your daughter is cute as a bug!!! I am an original fan of 273's and I'm glad to see you build one. You two will have lots of fun with that little engine. I watched all your videos. I am surprised at the sound of that Schneider. I really was thinking serious about that cam but I used the Isky E-4 instead because it was closer to the Charger 273 cam. No regrets but I may take mine apart over the winter and back the valve timing back to zero and sneak a bigger bump stick in there. Just for more rpm and attitude at idle. I have the heads and the compression to back it up. I see you used manifolds instead of headers. Me too. Headers make a world of difference over the stock manifolds but not this time around for me. Maybe my next project. The aluminum intake and carb spacer are a plus too. The original cast 273 intakes get so hot and although they are open plenum intakes, they are short. If they were a high rise design they would run cooler and better. Congrats on you good sounding, good looking, and good running 273! toolmanmike
 
Very nice build, impressive. Also, your daughter's reaction is adorable! My son loves my old Mopars.
 
Thanks everyone for the feedback.

What pistons are in there? How far in the hole? Did you measure the compression ratio?

Sorry, I didn't run the measurements. Stock 4-valve relief pistons that came flush with the top of the cylinder.
I should have mentioned that this was a short block-up rebuild and was the result of leaking head gaskets. The PO had said it was low miles on a rebuild which at first was hard to believe given the mess he had made using barrs leaks and what seemed to be tap water damage. But once I had the block out the bores measured/looked really good and still had crosshatching so I decided since it didn't smoke before I would drive it for another couple years (hopefully).
 
Sounds real good!

Your daughter is priceless, love the reaction. Great that she likes it!

I heard it runs pretty good.
 
Nice cam choice.Always liked small solid cams for bumping mid range torque.
 
Surprised you feel more low-end torque since your cam has much more lift than even the factory HiPo engine.

More lift doesnt mean less torque. Lift picks up hp...which is torque.
With the amount of air flow gained over stock...if there was any rpm shift of power, its more than made up for by the extra 40 cfm of intake port flow.

The cam was choosen to access the peak flow @.450 lift 'minus lash' yet keep the torque at a useable rpm with stock convertor and gears
This car pulls hard off the line and when passing on the freeway, it would be nice if you all who may question this could take a ride.

273 That feels more like a warmed 318....and sounds like a 340 with those flowmasters. Air flow and the right cam, simple as that :D

btw the compression ratio 'if i remember right' was dialed to 9.4 and the chambers are about 57cc's, then figure the head gasket.
 
btw the compression ratio 'if i remember right' was dialed to 9.4 and the chambers are about 57cc's, then figure the head gasket.

I'm planning my own 273 build and I'm curious how you got to 9.4:1 with flat pistons. Were the pistons actually flush with the deck, or just close? I can't find any off the shelf 273 flat tops that would give a zero deck.

Was the chamber volume 57cc's before or after milling?

What's the cylinder bore size?

That head gasket is like .050" compressed and I think the bore is like 4.12".

Does anyone know the volume of the valve relief cuts? I can't find anything definitive, but sounds like around 5cc.
 
The heads were 66.5 cc's when pulled off and measured. Heads were milled to remove about 8 cc's. The gasket is .045 crushed, not .050..and the gasket bore is 4.180 with the 8553 felpro.
Ran the nunbers through KB'S calculator and got 9.4 without figuring valve reliefs.
figuring the valve reliefs '5cc'?? would be around 8.9
Still, 42* overlap & 150 psi cranking , its just fine and doesnt turn over with more than 18* initial fully warmed up.
 
The heads were 66.5 cc's when pulled off and measured. Heads were milled to remove about 8 cc's. The gasket is .045 crushed, not .050..and the gasket bore is 4.180 with the 8553 felpro.
Ran the nunbers through KB'S calculator and got 9.4 without figuring valve reliefs.
figuring the valve reliefs '5cc'?? would be around 8.9
Still, 42* overlap & 150 psi cranking , its just fine and doesnt turn over with more than 18* initial fully warmed up.

OK, I can get into that range with the CR calculator if I assume zero deck clearance, or close to zero depending on what the cylinder bore is. Did this engine have custom pistons, or maybe they milled the deck when they rebuilt the short block?

The reason, I'm not letting go of the bone is I'm wondering if there is a source somewhere for zero deck 273 pistons.
 
In my Mopar Enigines book it state that 68-69 273 are 0.001" below deck if the deck height is 9.599" so basically zero decked, since there's a lot of misinformation out there who knows though.
 
I remember when taking the carbon off the piston tops at TDC it was pretty much flush with the deck. Definitely not above the deck though.I know that's not he best scientific analysis.

I do know the block is a 66' (B273) but since I have only had it 3 years who knows if it was decked in the past. I really wish I would have done more checks before tearing into it and reassembling.
 
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