In a few weeks i will be rebuilding my L-48, I have purchased a set of '70 300hp heads & shorty headers. I plan on putting a 2101 intake on it.
I want to drive the car on some out of state cruises and need a reliable motor, buuut also want to bump up from the anemic 190hp.
I plan on running a mild cam w/ stock stall converter.
My question is do I stroke the motor(383)? It is only ~ $300 more and i should get more hp/tq than i could from 350.(?)
Does stoking it hurt reliability?
Do I just build back what i got?

 

You can't beat the torque these 383s put out. For the price it takes to build you will never regret. I can't count how many times I've been asked if I have a big block. It's the power these cars were supposed to have from the factory.

Good luck

 

Never heard anyone with a 383ci say they wish they hadda built a 355ci

 

Just make sure you use good quality components whatever you decide. I'd go with forged everything and ARP studs in the lower end..

 

I agree we use all forged rotators the Scat 6 inch rods with the 7/16 bolts or the Callies compstar rods, Compstar crank and the Maule pistons and we have been getting some good results with the AFR 195 Eliminators.

Here is a link to one we just dynoed Friday and I wish the customer had gone with a HYD roller cam as I think we left some torque and hp on the table.

http://www.chevelles.com/forums/showthread.php?t=236517

 

Is the stock dual snorkel air cleaner( '80 L-48), Rochester Quad and Edelbrock 2101 intake too low flow for the 383?
The heads are 370 casting w/ dates of A270 & A280. Should I go with 194/150 valves or go 202/160?
The machine shop is recommending Eagle crank, 5.7 rods w/ offset Hyper pistons

 

You really should think about using better heads. GM Vortec heads are good and inexpensive.

 

It's only money If you have to grind/replace the crank, then there's no reason (other than $) not to go with a 383.

Overall, the cost is going to be a little more than $300 as the crank is a bit more expensive, you'll pay around $200 for clearancing and you need decent heads for that many cubes.

Unless you're going to be turning beyond 6K, using spray or forced induction or trying to make more than 450 HP, I don't see any reason to use an all-forged assembly. Not disagreeing with prior posters - just a different perspective/experience.

Go for one of the cast crank/hypereutectic balanced rotating assemblies from Scat (my preference) or Eagle and call it good. I agree that those 'auld skool' heads aren't going to cut it - a good aftermarket 180-195cc runner head is minimum for a strong 383 IMHO. The stock iron Vortec heads are a great pick, but right at the bottom of the range IMHO at 170cc runners. Car Craft and others have some great builds based on the Vortecs for comparison - so the combo definitely works!

One question you need to ask is if you're replacing the rotating assy and heads...that it might make more sense to look at a crate or building up from a bare roller-cam block. There's a huge difference in the power available from a roller cam.

"Shorty" headers are also a poor investment; a set of long-tubes is a far better choice.

The Q-jet is fine with a rebuild and tune, and the Edelbrock Performer is fine. Set aside $300 in your budget for a good dyno tune when you're all done. IMHO I'd invest in an open element cleaner with a K&N filter.

Bottom line is budget - figure on about $2700 for a relatively stock rebuild, and about $3200 for a relatively mild 383.

 

Yes do go 383.

I agree on using a cast/hyper setup for this ... stock convertor & mild cam.

Also suggest freshening the stock 76cc heads ... they will make a very streetable compression ratio in a 383 with the flattop pistons that're most inexpensive ... gas quality has gotten pretty crappy & ain't likely to improve ... suggest build with that in mind. OE 76cc heads will flow plenty enough for a mild-cammed street 383 ... plenty flow for one that's mild enough for a stock convertor.

You do not need the expense of a roller cam if you're building with a mild cam; hydraulic flat tappet OK for this.

Shorty headers don't do much ... probably not worth the hassle & maintenance ... iron manifolds with a good true dual exhaust also OK for stock convertor & mild cam.

In addition to balancing the rotating assembly ... keep it in mind to put together a reasonably matched, balanced system.

volume corrected for typical piston chamfer:
76cc heads & most flattops in a thirty-over bore ... with a thin shim felpro 1094 head gasket and a 383 (3.75") crank will make about 9.6:1 static compression ratio with a good 0.040" quench height.

if you have original numbers-matching motor ... do not let machine shop mill away block's numbers during any decking ... discuss this w/ machineshop OWNER / Manager BEFORE any machinework begins.

 

IMHO, the OE "smog" heads are marginal for even a 350 and just not enough for a 383. They're usable with a little bowl cleanup and new springs - but definitely will limit power output.

I'd be REAL careful with any general CR guideance...there are just too many variables - deck height, etc. Definitely agree shooting for ~.040 quench one way or another.

Good catch and comment regarding the stamping!!!

 

Lots of good info. I know if you ask 10 ppl about this you will get 10 diff answers. I want to keep the OEM dual snorkel air cleaner and associated plumbing, i chose the heads to keep stock look while improving from my stock heads and only $500 for the set complete. I want more hp than 190, about 350fwhp would be good. I don't need a 450-500 hp motor. I was going with a 350 but thought a 383 would give me more tq for a few buck more. Like most ppl i am trying to get the most bang for my buck, money is limited to 2K for rebuild, plus i still have to get rad done, new water pump, hoses, etc..

 

At $2K, I'd buy a good rebuild kit from Northern Auto Parts including new Scat I-beam rods (you can't get yours reszed for the price), a ground stock crank (exchange) and then have the stock heads overhauled including new springs. There are a few upgrades for the kit that I'd recommend if you decide to go this direction - including the CompCams Xtreme Energy XE262H cam.

Going this route with stock intake and exhaust manifolds/shortys will get you to about 250HP and 325TQ, long-tube headers to about 275HP and 340TQ and finally long tubes + the Edelbrock Performer to almost 300HP and 360TQ. You can't hit your HP goal with this budget, but all of these TQ numbers will give a huge SOTP boost.

To make this happen, you'll need to be cheap Make sure the machine shop throws your tin in the tank with the block, etc. The only big-ticket item I'd suggest is balancing if you can afford it, figure about $300. If they have to take a cleanup cut on the block and heads I'd suggest asking for a very smooth finish to allow running a steel shim gasket - this will give just about perfect quench (.025 deck height + .015 gasket = .040 quench).

I'd be happy to help with a specific parts list, but sit down with your machine shop before doing anything else.

BOTTOM LINE is that at that budget you're going to get caught short if you don't stick to a pretty basic performance overhaul. An engine you can afford that's done and back in the car is way better than too much engine that sits on the stand because you can't afford to finish it.

 

I want to keep the OEM air cleaner & plumbing, stock Rochester carb, the 370 heads, shorty headers coated inside & out w 2.5 dual exh. and will rebuild my #'s matching block. I can replace the intake w/ Performer 2101 and can go w/ 194/150 or 202/160 valves if it will help. Question...Do i stroke it or will the OEM stuff cut hp/tq down so much i might as well build the 350, and which intake valve size combo to use and do i rebuild stock radiator, add a row or go alum.???
Thanks, Jeff

 

Two comments regarding a 383:

* Unless your budget goes to 3K, you'll fall short.

* Will it bolt together and run? Yes. Will it perform? No.

A 383 just requires more airflow than what your combo will deliver IMHO.

'nuff said from me - shuttin' up to leave room for other opinions

 

Stroke it, and if that's all the money you want to spend now leave the heads alone. Sure, you aren't going to see massive gains, and you won't be using the 383 as effectively as you could... but you're never going to see huge numbers with those heads. You'll still have a bit more grunt than the same setup with 350ci.

I can't think of a time when I thought more displacement was a bad thing... so if its only $300 more for the 383, do it! Then, save up and buy a real nice top end down the line.

*shrug*... my $.02

edit: Just saw that you are keeping everything else. So again, you aren't going to see huge numbers, but if you want the most out of everything else you have, stroke it. (Then in a few years you're going to say "I'm glad I did that" as you put your AFRs on there...)

 

Heres a site you can look over for complete rotating kits www.flatlanderracing.com. Go with an internal balanced rotating kit. Its a better way to balance something plus it will allow you to keep your 350 balancer and flexplate. Either go for underchassis headers or keep your stock exhaust manifolds.

 

Any input on the valves or radiator? BILLLA and YEL76LOW, you seem to be on the same wavelength as me, as i tweak this, your input is very useful. Please keep it coming, that goes for everybody, the more info, the better decision i can make.
Thanks,Jeff

 

Don't waste any money on your heads you don't have to. put the money in the shortblock later on down the road you decide you want more power then change heads.

 

Hah! That's the first time someone thought I knew what I was talking about...

Does your cooling system work now? If it ain't broke don't fix it!

 

It does get too warm on hot days or if you use a/c and in traffic. The radiator was not taken well care of by previous owner. It needs fixed, i just didn't know how far to go, clean & rod the 2 row, add a row or go alum.?