5 liter MOPAR

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2 Darts

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I know there are mostly ¼ mile junkies here. There was a time when MOPAR was interested in lap times, too. I am thinking of something that might be raced today. Kind of stops thoughts of the NASCAR attempt that was so owned by hyper-pack Valiants in 1960 & 1961 that the series was dropped.
Back in 65 and 66 there was Team Starfish running Barracudas and Group 44 running Darts in the A/Sedan class of the SCCA on the amateur level, called TransAm for the pros. I am interested in running a MOPAR in the SRVA. Unfortunately the only engine available back in 65 & 66 was the trusty rusty 273. The cars are allowed a 5 liter engine without penalty. The 318 block can be used, but it carries a weight penalty. I might be able to make a case for running a 340 block, however coming up with a Keith Black crank to bring it down to 305 CID is going to be cost prohibitive if not impossible. *
I have read the rules for the class. I have posted a link so you can too. Barracuda / Valiant / Dodge Dart (64-66)
However, a 273 cut .030 over and fitted with a 360 small journal crankshaft yields 301.xx cubic inches. Very much allowed by the rules. I have a few ideas about how to outfit the engine beyond just getting to the 301 CID mark. To be competitive, the engine needs at least 450 hp at the crank, on a single 4 barrel carburetor. I will assume an operating range of 3000-8000 rpm **. Cylinder heads can be any year and roller cams are possible, as is dry sump lubrication piggy-backed on a wet sump.
I'd like to see what the collected wisdom of FABO has to offer as suggestions on building a MOPAR to specs.
Questions I have are:
Has anyone established a go-to person for finding solid 273 blocks?
Are high compression pistons available in the after market? Forded or cast?
Is the piston speed going to be a limiting factor on how tight the engine can be run?
Can 1.88/1.60 valves be installed on 308 heads with some machine work, of course?
Is there enough meat on the cylinder heads to let the seats for the 1.88/1.60 valves be installed on the engine?
Can the RHS/Indy heads be used without notching the block?
Magnum cylinder heads?
Intake can be aluminum, so should it be dual or single plane? Recommendations?
Thinking of using an an Accusump along with a Windage tray (for the 360) and a road race oil pan?
DUI or Mopar electronic distribiutor?
What kind of headers would you install and route through the left side notch in the cross member into a NASCAR type of outlet?

Notes:
* Keith Black was the prime contractor for the factory AAR and TransAM cars MOPAR teams fielded in the 1970 season. I read somewhere that depleted uranium was used in the crankshaft counterweights.
** Boss 302 Mustangs will turn up to 9000 rpm routinely. I don't think piston speed will let that happen with a 3.58 crank stroke.

It is kind of late. But I will leave with a few visions dancing in my head.
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The fellow with his back to the camera was the driver of this car. Do you know who he is?
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upload_2020-11-25_3-11-41.jpeg
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Recognize this fellow?

upload_2020-11-25_3-13-18.jpeg
 
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Neato idea. If you go .040" over, you'll be even closer.
 
I don’t see how you can be even close to competitive giving up that much bore size. What are the cylinder head rules?

That small bore is a power killer for several reasons.
 
Just spitballing here, but what about a 360 block with a 3" stroke? In essence you would have a Mopar 302 and the larger bore. I don't know how expensive the crank or pistons would be, but it might be worth it to check and see.
 
For that application, you're going to want the faster spin-up offered by less stroke, not the increased bottom-end torque offered by more stroke.
 
2 Darts said:
I know there are mostly ¼ mile junkies here. There was a time when MOPAR was interested in lap times, too. I am thinking of something that might be raced today. Kind of stops thoughts of the NASCAR attempt that was so owned by hyper-pack Valiants in 1960 & 1961 that the series was dropped.
Back in 65 and 66 there was Team Starfish running Barracudas and Group 44 running Darts in the A/Sedan class of the SCCA on the amateur level, called TransAm for the pros. I am interested in running a MOPAR in the SRVA. Unfortunately the only engine available back in 65 & 66 was the trusty rusty 273. The cars are allowed a 5 liter engine without penalty. The 318 block can be used, but it carries a weight penalty. I might be able to make a case for running a 340 block, however coming up with a Keith Black crank to bring it down to 305 CID is going to be cost prohibitive if not impossible. *
I have read the rules for the class. I have posted a link so you can too. Barracuda / Valiant / Dodge Dart (64-66)
However, a 273 cut .030 over and fitted with a 360 small journal crankshaft yields 301.xx cubic inches. Very much allowed by the rules. I have a few ideas about how to outfit the engine beyond just getting to the 301 CID mark. To be competitive, the engine needs at least 450 hp at the crank, on a single 4 barrel carburetor. I will assume an operating range of 3000-8000 rpm **. Cylinder heads can be any year and roller cams are possible, as is dry sump lubrication piggy-backed on a wet sump.
I'd like to see what the collected wisdom of FABO has to offer as suggestions on building a MOPAR to specs.
Questions I have are:
Has anyone established a go-to person for finding solid 273 blocks?
Are high compression pistons available in the after market? Forded or cast?
Is the piston speed going to be a limiting factor on how tight the engine can be run?
Can 1.88/1.60 valves be installed on 308 heads with some machine work, of course?
Is there enough meat on the cylinder heads to let the seats for the 1.88/1.60 valves be installed on the engine?
Can the RHS/Indy heads be used without notching the block?
Magnum cylinder heads?
Intake can be aluminum, so should it be dual or single plane? Recommendations?
Thinking of using an an Accusump along with a Windage tray (for the 360) and a road race oil pan?
DUI or Mopar electronic distribiutor?
What kind of headers would you install and route through the left side notch in the cross member into a NASCAR type of outlet?

Notes:
* Keith Black was the prime contractor for the factory AAR and TransAM cars MOPAR teams fielded in the 1970 season. I read somewhere that depleted uranium was used in the crankshaft counterweights.
** Boss 302 Mustangs will turn up to 9000 rpm routinely. I don't think piston speed will let that happen with a 3.58 crank stroke.

It is kind of late. But I will leave with a few visions dancing in my head.
View attachment 1715636635View attachment 1715636634 The fellow with his back to the camera was the driver of this car. Do you know who he is?
View attachment 1715636642View attachment 1715636636View attachment 1715636638View attachment 1715636639View attachment 1715636640View attachment 1715636641
Recognize this fellow?

View attachment 1715636637
Click to expand...
From what I understand, the gentleman with his back to the camera is David Pearson.
 
RammerJammer75 said:
Just spitballing here, but what about a 360 block with a 3" stroke? In essence you would have a Mopar 302 and the larger bore. I don't know how expensive the crank or pistons would be, but it might be worth it to check and see.
Click to expand...


The problem is getting the crank. They are out there but the price is crazy.

Piston prices have come WAY dow in the last 20 years or so. The crank is a much bigger deal for sure.

One problem was the killing of Modified Eliminator by NHRA. Those classes were the feeders into Pro Stock. Many legendary engine builders cut their teeth in Modified.

They were small displacement, big RPM mostly clutch cars. From the time I was 8 or 10 I was going to build a Modified car. Had a buddy in high school that felt the same way. We were going to do a team together with me in a Chrysler and him in a Chevy.

Even after NHRA killed Modified we were collecting engine building tools to open a machine shop and build engines that we liked.

His untimely death in 1986 killed that off (no pun intended) and at that point it took 8 more years before I had any inkling to build engines for a living.


I said all that to say that a lot of people have never seen Modified car make a pass. What it sounds like. How they leave. What RPM and gear ratio do.

To that end, the market for cranks of even an OE stroke length have virtually no market.

I think NHRA should go back to the 1977 or 1978 rule book and bring back Modified with those exact rules.

That would be a blast. That would motivate me to go back to the track.
 
yellow rose said:
The problem is getting the crank. They are out there but the price is crazy.

Piston prices have come WAY dow in the last 20 years or so. The crank is a much bigger deal for sure.
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I'd say the crank would be expensive, and custom pistons aren't too much more than shelf ones. But it would be badass to build it and make it competitive.
 
Not a unlimited budget but it is a race engine and it will cost to build. It's not like a 350 Chevy for a stocker dirt car.
 
I say run a bored 273, you might be missing a few cubes, than you have bragging rights that did with a smaller engine:lol:
 
Here's a crank that would allow 305.2 CI in a .020 over 318. I don't know what complications other than main bearing bore size would be involved with a small Ford block for bearing size, but you can find unrun old nascar team stock Chevy rods on ebay for cheap to offset some of the expense.
Crankshaft 340 Dodge 3.145 stroke - Clearance
 
RammerJammer75 said:
Just spitballing here, but what about a 360 block with a 3" stroke? In essence you would have a Mopar 302 and the larger bore. I don't know how expensive the crank or pistons would be, but it might be worth it to check and see.
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AFAIK, no one makes a 3.00 crank for the SBM. It could be made easy enough if you really wanted to have one. It will get expensive not to mention the custom pistons that need to be thought out a good bit before you take a step towards building anything.

It’s just money and lots of it.

Below is the Winberg web page for small MoPars. Most use a Ford 302 main bearing.
Dodge Small Block | Winberg Crankshafts
 
rumblefish360 said:
AFAIK, no one makes a 3.00 crank for the SBM. It could be made easy enough if you really wanted to have one. It will get expensive not to mention the custom pistons that need to be thought out a good bit before you take a step towards building anything.

It’s just money and lots of it.

Below is the Winberg web page for small MoPars. Most use a Ford 302 main bearing.
Dodge Small Block | Winberg Crankshafts
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You need any W5 intake gaskets? I have 2 sets I’ll never use. PM me if you are interested and I’ll make you a smoking deal.
 
LS pistons may come very close to a drop in with Chevy rods. The LS valve angle is 15 degrees, but the valve relief location may need adjustment. The LS1 came with a 3.898 (3.9 inch) bore size.
 
First thing to do is FORGET the 273 block. As YR allready mentioned, that tiny bore is a huge handicap. 340 block, destroked crank is the only combination that makes sense to me, largest bore possible, with the shorter stroke, that equals less piston speed, which will also be a issue with your 3.58 stroke idea
 
Coming from a design standpoint, what's the best combination for road racing? High rpm horsepower or loads of lower end torque? Would a stroker 273 be better than a destroked 340? (that doesn't even sound like a fair comparison does it) LOL
 
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I would start scouring the racing junk ads and so forth for a used short deck nascar type blocks. The 9.6 inch deck height that is so good for an increased stroke is a killer in the destroked engine.
 
Depends on the size, construction of the road course at hand. Short twisty tracks will like more lower end torque while longer straights will like a shorter stroke for high RPM.
 
toolmanmike said:
Coming from a design standpoint, what's the best combination for road racing? High rpm horsepower or leads of lower end torque? Would a stroker 273 be better than a destroked 340? (that doesn't even sound like a fair comparison does it) LOL
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IMO it’s almost always the biggest bore you can get and then make the stoke finalize the displacement.

The issue becomes (it haunted Chrysler for decades) is deck height and rod length. If you have a 9.560 deck and a 2.9xx stroke, you need one hell of a long rod, or a long compression distance on the piston or a compromise of both.

Chrysler finally started making shorter deck blocks to help with this. I’m all for relatively high rod to stroke ratios but once you are hitting the 1.9ish R/S ratio you are at the max unless you are incredibly induction limited. And I mean something like a 1 venturi carb on a tool box for an intake manifold.

So if you are interested in doing what the OP a is looking at, he really needs to sit down and write it all out. If he wants to be competitive he will need a short deck block with at least a 4.04 bore (depending on class rules for cylinder heads) and then he needs to see how he can get the R/S ratio livable with a piston that has a compression distance no more than probably 1.450ish.

Unless you want to be a back marker and a lapper.
 
This is for sale on Racing Junk
SS/COMP 300 cu in 340 R-3 block 8.900 deck,4.080 bore, roller bearings,exterior oil pump,vacuum pump,belt drive and front mounted distributor, meziere water pump,crank trigger,MSD 3,Winberg crank 2.90,W-8 heads,T&D rockers 1.65-1.70,Titanium valves,GRP Aluminum rods, 5.84 Gas ported pistons, stainless headers.One run since fresh.Photos on request.
 
The 9.6 deck height and high cam placement is great for big throw cranks.

Did they ever produce a short deck 59* block?
 
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