1 pc rear main v 2 pc rear main
 

My latest project is building a 383 sbc for my 79 c10. I have built several sbc motors with 2 pc rear main seals (rms), but never a 1pc.

Anybody know what parts I would need specific to the 1pc rms if I am using aftermarket heads, intake, rotating assembly etc? From what I can tell the oil pan should be the only part not interchangeable in this scenario. What does everyone think?

Re: 1 pc rear main v 2 pc rear main
 

you will have to buy an aftermarket stroker crank specific for the 1 piece rear seal. other than that its business as usual

Re: 1 pc rear main v 2 pc rear main
 

1 piece factory roller block is the way to go! You'll have a great motor.

Re: 1 pc rear main v 2 pc rear main
 

Attachment 1498955

Sweet! I picked up the block today and the rotating assembly is on its way. I already have just about everything else. Check out the parts list below and let me know what you think!

factory roller block w/4 bolt mains
fully machined and .030 over
Eagle rotating assembly w/hypereutectic pistons 9.5:1 w/76cc heads, 3.75 stroke cast crank, forged 5.7in rods
EQ Torker heads w/2.02 in 1.6 ex, 76cc cnc'd chambers, and I believe 190cc runners, but may be wrong on that one
Stainless roller rockers 1.6
Holley Street Dominator dual plane intake
HEI distributor
th350 trans

Planning on a roller cam of course and waiting on Comps recommendation

What size carb should I go with 650, 670, or 700cfm?
I plan to keep it under 6,000 rpm with a rev limiter.
Anybody have experience with using a smaller carb on a 383?

Should I switch to a single plane intake? The truck will mainly see street use.

What about gear ratio for the rear end? I'd like to go fast and drive on the highway.

Any and all suggestions, tips, and comments welcome.

Thanks!



:metal:

Re: 1 pc rear main v 2 pc rear main
 

Sounds great! Although... I'm not a Comp Cams fan. Not gonna sling trash, they're just not my cup of tea.

I'm running a Street Demon 625cfm carb on my stock 402 big block. Electric choke, super easy to tune. Was very close right out of the box. I'd definitely stick with a dual plane intake. What about a 200-4R trans? .67 overdrive and a 3.73 gear would be killer! That's what I'm building now for my 402.

Re: 1 pc rear main v 2 pc rear main
 

Great point about the od trans! What rpm do you get out of the 402 and is it stock or modified? Carb sizing is one thing I'm not clear on. I always heard to go with 750 no matter what growing up, but over the years have learned that's complete non-sense. I know there is a bit that goes into, but not sure what. I run 600cfm carbs on 355's with great results, but would think a 625 is too small for much anything over this. On the other hand, I see 500cfm 2 barrels on race cars all the time and they run great.

What all would you take into consideration when choosing a carb?

Re: 1 pc rear main v 2 pc rear main
 

The 200-4r is still on the bench! So, I have the stock 3.08 and TH400 in there. Honestly, it's not bad with 235/75-15's, but run the numbers on a 3.73 and overdrive and it's much better at both ends. Where my 3.08/TH400 runs 2500 rpm, a 3.73/200-4r will be 2024 rpm... and have lower first/second/third gears!

As for carb size, ANY time you're not driving with your foot on the floor, you're not using the whole carb's airflow, right? So if you're building a drag car that's one carb requirement. On the street I hardly EVER put the foot on the floor. And, even though it's a 402, I'm using the truck as my freeway dirt bike hauler. 2 hours each way. So I'm going for as much air velocity, vacuum, and optimized ratios as I can. The truck drives amazingly well and really scoots. Your 383 will light the tires so bad it'll scare you.

Re: 1 pc rear main v 2 pc rear main
 

Well that makes complete sense. I really never thought about it that way, but you are absolutely right about the carb situation!
I've spent plenty of time going sideways so I'm not too worried about how well it hooks up. I'm also planning to raise the rear back up a bit for better weight transfer and a better stance so that might help some.

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Nice truck! Just my opinion, but are you sure you want to go with the O/D? Guess I'm a bit "old school", but your already setup with a TH400 (probably one of the strongest trans. GM ever made) and a 3:08 diff which is close to a perfect match. Running the 400 you will not have to install any electronics, TV cable & adjustments etc. I have had too many BAD experiences in the past with high performance engines and overdrives. (put 3 700R4's in my 82)
I'm not familiar with the 200.... maybe it's a better trans.... Guess it also depends on where you do most of your driving..... around town, the 400/3:08 would be perfect, on the highway the overdrive will shine....

Re: 1 pc rear main v 2 pc rear main
 

The 1 piece flexplate/flywheels are different bolt pattern as well. Since you are doing a 383 it might not matter but the later 350 engines use a externally weighted flexplate where the early ones are internally balanced.

Re: 1 pc rear main v 2 pc rear main
 

I would not even consider a single plane intake for a street engine in a truck. since you are using a 6000rpm limit you will be using a fairly mild camshaft for torque and the single plane wouldnt benefit you too much. I have seen them make more power than dual plane intakes at low rpm but I dont think you need to worry about it. A Performer RPM would be my choice.

I also would not use a 1.6 rocker arm unless you need it. and since you dont have a camshaft yet there is no need for it. They are not automatic power adders. They will also increase your valve lift which can cause problems with retainer to guide clearance, piston to valve clearance, pushrod clearance and require extra spring pressure. I would go with 1.5 unless you end up with a camshaft with low lift and need to bump it up to make sure of the heads air flow. since Im not familiar with those heads I dont know what they flow. A 190cc runner sounds good but tells me nothing about what they flow.

You can use a smaller carb but your fuel requirements will be different from say a stock 402. I would probably use the 670cfm carb from your list. I had a 670cfm street avenger years ago that was a decent carb. I was strictly Holley carbs when I was younger but I have been leaning towards qjets lately. They are great for economy and have great performance as well. Check out Sean Murphy Induction for more info on them. He is probably the best guy around for qjet performance.

Gears will depend on several things. What tire size do you have? What camshaft do you have? What transmission do you have? And is it up to the task of this new engine? Stall converter? What type of driving are you going to do most? is fuel economy important to you?

Dont forget you will want to upgrade the fuel pump to feed the new engine and possibly a ignition upgrade. A rev limiter isnt really needed unless you just want one.

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Freeway dirt bike hauler?

Pics of if didn't happen

Re: 1 pc rear main v 2 pc rear main
 

Oh Ya?? Take THAT:

Re: 1 pc rear main v 2 pc rear main
 

An O/D trans is certainly NOT a necessary change. But the truck didn't get its name for nothing: The BBDBH (Big Block Dirt Bike Hauler). 2 hours up, 2 hours back, as often as we can! The mechanical part of the swap and the functional tuning I'm fortunately very comfortable with. But, ya, it's tough to pull a working 400 out of an original build truck!

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This should point you in the right direction: How Big A Carb Do You Need http://www.hotrod.com/how-to/engine/...b-do-you-need/

Re: 1 pc rear main v 2 pc rear main
 

2004r and a 4l80E are worlds better than any POS 700r4/4l60E

Re: 1 pc rear main v 2 pc rear main
 

I have no problem with Comp other than that they'll likely suggest a thumpr cam which is mostly for sound, with power an afterthought.

I imagine any of those carb sizes will work well.

On a street truck I'd absolutely want OD but there aren't any great options for non electronic auto. A manual valve body in a 4L80e is a reasonable choice.

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This seems like a mis-match to me. Going for 76cc heads and pistons to make those work limits your ability to use any other performance head as they are all 64cc and for good reason which is chamber shape and efficiency. Even GM went to 64cc's stock after '95. If possible I'd go with 64cc heads and matching pistons to get 9.5:1.

Speaking of heads, you want to run 190cc ports with only 383cubes and a 6000rpm max? You want 180cc at best, or run the engine higher up.

Re: 1 pc rear main v 2 pc rear main
 

Not in stock form. The 2004r's are not strong in a OEM version. Costs a lot of money to build one right but they are good when you do it. 4L80E is strong but a power robber.


GM also kept the stroke at 3.48 in production sbc engines. When you add a 3.75 stroke it takes a large dish to get compression under 10:1 with a 64cc head. Nothing wrong with using the 76cc head here. Generally I would agree the 180 head would be better for low end power but the EQ heads are pretty decent and it will still make more torque than the tires will handle.

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Looks like a KTM 300 smoker. Very nice. I ride a Husqvarna TE310. Rekluse Autoclutch too.