383 rebuild

[Matt B.]

I have been reading and trying to research how to build this motor. 1st, the car is a 71’ roadrunner, 4spd, and has 3.23 gears in it now. I am planning on putting 3.55 gears in. Motor is getting bored .030 over. Have the 346 heads along with a set of 452. The motor had a tick, full of oil and grime. Which is why I am rebuilding. I know I jumped ahead of myself and bought a cam already. Cam is a Lunati grind # is vdbcr-265. I’m not looking for major power, but want a good strong running engine that runs on pump 91-93 gas. Just wanting help.
Thanks Matt

 

[Don Frelier]

With iron heads I would shoot for about 9 - 9.5:1 compression. You need the deck height, measure the chamber volume and have some help with piston selection to get there. You also need to factor in the head gasket thickness when doing the calculation. A good engine builder can help you with all these decisions.
I suggest you get a couple mopar big block books and study them.
There are some really knowledgable people here when you get specific questions.

 

[F4R/T]

I don’t know your specs for the cam you chose, but just remember they have certain numbers that must go with it, I like squeeze so I always target 10-10.5.. just follow the cam requirements in my book.. It doesn’t take a lot to make a 383 run hard, I would run the 452 heads with a good 3 angle valve job and tidy up the castings with a little at home port work . Stock rods and crank are fine, good oil pump and timing set, degree the cam in and top it off with a good intake and carb. Make sure you get your dist and carb dialed in, talk to Halifaxhops about the dizzy if you have questions or need one. Also what do you want for a oil pan set up?Don is absolutely correct measure all numbers , record and set your goals ! Best of luck.. don’t skimp on pistons either just buy quality and stay away from Chinese parts .. lots of smart folks here with a million ideas take your pick just put the package together per the cam you bought.

 

[Nate S]

That's a pretty big cam, here's what I found:
"
Grind # VDBCR-280
lobe separation 110,106centreline ,251/259@050,566/586 gross lift,014 lash"

Maybe pause a moment and tell us what you want to get out of this? How do you intend to drive it? What other parts you are looking to buy or reuse. 3.55 isn't very deep of a gear for this cam, I'd be in for something more like 3.91 or 4.10. Anyway, before you ride into battle behind that cam maybe define the specifics of what you want.

 

[diesel_lv]

As Nate S said, decide what you really want before committing to a build around that cam. It might be cheaper in the long run to buy a cam suited to what you want. That includes keeping that cam you already have as a souvenir on the wall as a reminder.

 

[Don Frelier]

FYI Nate's number doesn't seem to match the original post?
vdbcr-265
VDBCR-280
I couldn't find the part on the Lunati webpage.

 

[Nate S]

FYI Nate's number doesn't seem to match the original post?
vdbcr-265
VDBCR-280
I couldn't find the part on the Lunati webpage.

Good catch! found that in a search. No sign of the number on the Lunati website.

 

[Nate S]

Found a Lunati VDBCR-262, seems likely. 220 / 226 @ .050, .475/.494
That seems a whole lot more reasonable! Nice little bump over a magnum cam and certainly appropriate for 3.55s. I'd go for 9.25:1 and no higher. Just built a 426 with similar cam and heads at 9.25. Knocks on 89, doesn't (except in some oddball situations) with 93. Calculate actual compression ratio, don't just go with "these are 9.5:1 pistons". If you need help post numbers:
Current deck (before disassembly) scrape carbon off.
Distance from bottom of old piston pin to top of piston (this allows us to calc the real deck height instead of assumed factory).
Amount block will be decked
We'll guess at 88cc for 542 heads, probably quite close.
From there we can calculate piston compression heights and head gasket thicknesses to give you the CR you want.

 

[Matt B.]

Cam specs are lift .475 in. And .494 ex, duration at .050- 220 in. And 226 ex. The intake is an edelbrock performer with a Holley 750 on top. If I need to get a different cam I need to.

 

[Nate S]

Seems like you have a nice combo. Headers would probably help a bit too. It’ll make for a nice ride, comfy to drive but nice “go” when you stomp it. Happy to help with the compression ratio stuff. I made up a nice spreadsheet where you just plug in what you’ve got.