Stroker options

[Rebel426]

My 68 RR is getting close to finished at the body shop and it's time to plan out the drivetrain. My initial plan was to refresh and install a date correct 383 and 833. I have a lot of parts hanging around in the garage though. Here's something I'm kicking around and wanted to get some opinions on it. I have thought of saving the date correct engine/trans and running a 69 833 that I have in good shape and building up a 400 stroker that's currently on the stand. The 400 has a 4.15" crank but two cylinders with light scoring due to fuel wash so it'll need a hone/re-ring job. No biggie there. I also have a set of bowl ported 915 heads with oversized 2.14"/1.81" valves. Yes, I know all of the advantages with aftermarket aluminum heads, but we're talking stuff I have on the shelf already. I have a Lunati 703 Voodoo and the springs in the heads are a match for it. Intake will likely either be a Performer RPM or Mopar M1. The 400 with iron heads will appear like the stock engine to a casual observer with just the usual intake and headers (unless I get really crazy and run the exhaust manifolds too). Rear end with either drivetrain is a 3.55 sure grip 8 3/4. I will not be running slicks or regularly racing the car. I've owned this car since I was a teenager, over 30 years now. It will never be sold. The goal is a fun driver that looks pretty good and should win at some local shows. My questions are 1) would you just go with the correct engine/trans combo and not worry about it, and 2) how well do you think the combination of off the shelf parts I've outlined will work together? Detailed answers are always appreciated. I know which way I'm leaning on this one, but I'd like to hear what the other opinions are out there.

 

[4speed68rt]

Why save the original stuff? It's only original to that car, so why not rebuild it and put it in now and it will last for longer than you will be driving the car. If you put some other motor in, it will probably stay in there, and it wont be original any more. If you build it right and take care of it, it will last another 50 years or so, and the next "owner" will have the numbers matching stuff, like its supposed to be. Just my thought.

 

[BSB67]

A std stroke 383 or 400 with a 4 speed is more fun than a barrel of monkeys, IMO. Indestructable. But you leave a bunch of power on the table.

If it were me, and for no rational reason, I would build a 3.75 stroke 451 cu.in. motor. Still rpm like a 383/400, but better power potential. If the heads flow 270 cfm, fairly mild SFT cam and you'd have a 500 hp daily driver. Did I mention it'd be more fun than a barrel of monkeys?

Why did I sell my 383 4-speed car???????

 

[cdr]

If you already have the stroked 400, use it !!!!!!!

 

[Rebel426]

If you already have the stroked 400, use it !!!!!!!

 

[cdr]

looks like a small domed piston, you better calculate the compression

 

[qkcuda]

I was with you on the stroker until I saw those pistons. I think you will have way too much compression especially with that small cam

 

[BSB67]

View attachment 1370895

If you're this close, I know what I'd do.....

 

[BSB67]

I was with you on the stroker until I saw those pistons. I think you will have way too much compression especially with that small cam

Hmmmm. For pump gas, that's probably right.

 

[Rebel426]

I was with you on the stroker until I saw those pistons. I think you will have way too much compression especially with that small cam

If I go down that route I’m going to be checking clearances real close. I had already figured on a thicket gasket instead of steel shim. I do have a fatter Hughes but it’s solid that might help bleed off some cylinder pressure.

 

[BSB67]

Do the math. The 915s are probably 78-80 cc's. A zero deck std stroke 440 with flat-tops and 915's is about 11:1. Can only imagine what a domed 500 cu.in piston with 915s might be.

 

[Rebel426]

Do the math. The 915s are probably 78-80 cc's. A zero deck std stroke 440 with flat-tops and 915's is about 11:1. Can only imagine what a domed 500 cu.in piston with 915s might be.

These aren’t zero deck but the dome is positive deck. Like I said, I’ll have to do some measuring and triple checking. I may just put the heads and cam in the 383 and send it.

 

[gtx6970]

Ill be in a similar situation next year or so.

Mine uses a little oil and is 11.5 to 1 so High quality fuel is paramount. I knew what it was when I bought the car . And knew a rebuild was in its future at some point to lower the comp a bit.

Every builder I talk to starts the conversion with stroke it. Why?????/

I dont race the car hardly beat on it. Hell it could be a 318 for all I care . But its a hemi and everyone wants to make it a race car .

I say build it stock and enjoy it the rest of your days .


Just my 2 cents

 

[68 HEMI GTS]

I love strokers, those pistons are going to be an issue though, espically with closed chamber iron head. Either swap pistons or run the 383.

 

[33 IMP]

If those small dome pistons are on a 4.15 stroke crank, you can be sure the compression ratio is above 12 to 1, how much above depends on deck height.
You COULD run em...... with 906s with the chamber opened to bore size, and a mondo thick head gasket, and a medium to large flat tappet solid.
It just wouldn't be my first choice. And it won't be a "fun driver" with that combo. ( and I wouldn't even think about putting it together with 915s).

 

[Rebel426]

If those small dome pistons are on a 4.15 stroke crank, you can be sure the compression ratio is above 12 to 1, how much above depends on deck height.
You COULD run em...... with 906s with the chamber opened to bore size, and a mondo thick head gasket, and a medium to large flat tappet solid.
It just wouldn't be my first choice. And it won't be a "fun driver" with that combo. ( and I wouldn't even think about putting it together with 915s).

They don't come up to zero deck. They're actually about as far down in the hole as the dome is above deck. I do know it was ran with iron heads on it quite successfully. I don't know what iron head it was using though. If these things were zero deck plus the dome, there's no way I'd even consider it. I got the short block in a parts trade, and it's tempting to get a little sneaky with the RR but in all likelihood I will probably finish up the 383.

 

[33 IMP]

They don't come up to zero deck. They're actually about as far down in the hole as the dome is above deck. I do know it was ran with iron heads on it quite successfully. I don't know what iron head it was using though. If these things were zero deck plus the dome, there's no way I'd even consider it. I got the short block in a parts trade, and it's tempting to get a little sneaky with the RR but in all likelihood I will probably finish up the 383.

I have run Arias 12 1/2 to 1 pistons in a closed chamber, iron head 440 on pump 91..... but the pistons were something like .080 in the hole, the cam was a 270° at .050 solid roller, and actual cr was somewhere around 11 1/2. It was not a happy street motor, and I would have run a 50/50 mix of avgas/91 if I had access then, like I do now.
A fun-street motor, it wasnt.....