I'll try to crawl under the car this weekend or next to see what I really have. All this engine stuff is burning a hole in my head...

 

big guy won't offer a cam to suit your gear? adios!

Contact these folk;

Charles Reichard & his mom&pop company have making cams most of his long life. Can personally attest to best personable service ever & big power in several race motors. Surprisingly affordable.
https://www.camcraftcams.com/

 

Well a stock L48 '77 auto would have come with 3.08s. And that is a big problem for a performance engine and/or cam. If you are note sure check the rpm, is it about 2350 at 60 mph? Yep 3.08s.

It is critically important for the cam/torque convertor/rear gear to match each other for the car to run well. It is the total combo that counts, not just one thing.
That rear gear needs either a real mild cam, or lots of cubes & TQ, or both.

So how do you drive it? hard/easy//city/highway etc.
Answer that first, then plan the whole build out, even if you have to tackle it one piece at a time.

 

I think at this point, I should just get it all to match up... even if I have to buy a new diff.... I will look into that also... thanks..

 

Upgrade to the GM Crate 383 or if the budget allows a Dart SHP block for ~ 400 cubic inches with a 4.125 bore & 3.76 stroke.

Ported aluminum cylinder heads & a nice roller cam package should round it out.

Best wishes with project.

 

Just got a parts list to build this thing... going with this setup.. will start ordering parts this weekend... hit my 5k budget

400hp +/-
L31 Vortec crate replacement long block
Hydraulic roller camshaft
Vortec-spec Squarebore intake manifold
plus all the other parts that go with it.

going to use my 650 holly DP and possibly replace my water pump/dist while I'm at it. Starter is newish so should be fine I hope. Might just pull the diff too once I dig into this project.

 

L31 is a great choice!

There's a diff rebuild pro here on CF ... GTR1999 ... Gary Ramadei.
He blueprints Your diff to Better than OE. He can strengthen it also. Of course, he can set it up with virtually any ratio desired.

Suggest a New Modern light PMGR starter (e.g. PG260) as found in all GM motors for more than 20 years (and like what came OE on an L31). About $70 will get one from DB Electrical in Tennessee. Likely your old bolts won't work properly and you'd need a pair of correct bolts for the PMGR starter.

read Remy tech bulletin twice, front & back; then read it again. Pay close attention to seemingly mundane subject of bolts; lotsa guys don't & then whine about problems.
https://autoprollc.com/wp-content/up...eb2016_web.pdf

Black oLives Matter !

 

Getting ready to make this happen.
Engine hoist - check
engine stand - about to purchase
block/engine stuff... ordering this week..
ramps - check

Is it a pain to pull the engine without the trans or should I pull them both at once? At this point, I should just pull both and have the trans looked at/etc..... not sure how much of a problem it will be getting it all out at once.

 

Dunno if your Xmember (under trans tailshaft) unbolts from chassis or not ? ... if Xmember does unbolt, that makes it so much easier to pull motor & trans together.

 

A lot of advice floating around - but let me see if I can help out a bit.

Cylinder heads are probably the most critical part of the build. The cylinder head flow is normally the limiting factor in making HP. A set of heads that flows well is going to make or break your build !!!

The camshaft sets the torque peak of the motor. If this is a street car - you want some low - mid RPM torque. Race engines almost always operate in the top third of the rev range - and that's all well and good - as having a no real low RPM torque is inconsequential for a drag race motor, but on the street - torque is king. One way to make torque is through displacement, and another is by selecting the right camshaft for the application, and the way the car will be driven.

Aftermarket (Dart / World Products) blocks are great - but there is nothing wrong with a factory block IF the HP level isn't going to get out of hand. GM used to use 4 bolt main blocks for "Heavy Duty" applications (truck use - where there would be prolonged periods of WOT operation, and high performance cars - where it was expected that the engine would operate at high RPM for a higher percentage of the time than a normal passenger car. If you can get your hands on a 4 bolt block - that would be a good choice to start your build with. Also - in the mid - late 1970's GM started removing metal from their block castings. Engines were making less than 200 HP at that time, and fuel mileage was all the rage - so that extra metal in the block casting was not needed. Again - an earlier block would be preferred if possible. I'd suggest talking to your machine shop -they may have some used blocks available....

IMHO - aim for around a 10.0:1 Compression ratio. If you're using aluminum heads - you could go a bit more... I would do a 383 over a 350, but in order to use the longer stroke 383 crank - a machine shop needs to notch a few lower cylinder walls for rod bolt clearance. If they screw up, and remove too much metal - they hit the Water Jacket, and the block is a boat anchor (so don't do this yourself)

I would use forged 4340 Connecting Rods. Either I Beam or H beam will work just fine in your application. You want good ARP connecting rod bolts - something like their 8000 series bolts would be the minimum I would consider. If you are buying a crank - a cast crank will work at the power levels you are planning, but a forged 4340 crank is not that that much more money. It's worth considering, and it's WAY WAY stronger than the forged 105* (alloy) Cranks GM sells. As for pistons - forged pistons are the most durable, but there are millions and millions of GM engines driving around every day on Hypereutectic pistons. Your call on the pistons. Whatever you do - the crank, connecting rods and pistons need t be balanced. This can be done by the machine shop - or you can buy a Rotating Assembly from places and it will come pre-balanced.

As far as a cam - probably something in the 220 degree of duration (@0.050 lift) is going to be more than enough to get the job done. I would suggest calling Comp Cams and Howards cams and speaking to their tech people for a recommendation. Tell them it's a street engine build, you're looking to make around 400 HP and 425 - 450 ft Lb of torque with a 383 displacement, and that you are looking for a nice fat torque curve. You can run roller lifters in a pre-roller cam block - but you need lifters that are designed to do that (they have link bar between every two lifter to prevent the lifters from rotating).

IMHO - don't even consider going with stock iron heads. Something like the Edelbrock Performer RPM heads or if $$$ allows a set of AFR 180 cc heads would be great choices. There are plenty of other options as well.

Just to get an idea - below is a link to a 383 Rotating Assembly ad from a place called CNC motorsports - the cast crank balanced rotating assembly with forged pistons (crank, rods, pistons, rings etc), runs about $1,600.

https://www.cnc-motorsports.com/1-90...h-pistons.html

A forged crank version will run about another $300 or so...

One last "suggestion". After the engine is assembled - pay the $$ to have it run in and tuned on an engine dyno. It's not cheap - but the dyno is THE way to tune the carb and the ignition advance curve. With aftermarket parts - the factory tuning is worthless. The aluminum heads are probably going to need a lot less ignition timing. Carb jetting is anyone's guess. On a dyno - you're reading and logging Air/Fuel ratio in real time. That makes adjusting the carb a whole LOT easier....

GOOD LUCK with the build !!!

 

Looking for a distributor. Any suggestions?

I contacted DUI and they said based on my specs, this is what they make for their dealers so I can grab off the shelf.

I want a black/alum dist to match the theme of the engine so looking at this. Not sure if I need the vac/mech option or just one/other. Still learning here....

Will either of these work out, or another option?
https://www.summitracing.com/parts/pnx-d100700

https://www.summitracing.com/parts/dui-14000


static compression ratio = 9.4:1 (OE L31)
duration @ 0.050" = 218*/227*
total valve lift = .525"/.520"
lobe separation angle = 112*
Max rpm = 5500
vehicle weight = 3500 lb
Fuel = 89 octane pump gas
holley 650 DP carb

 

For a motor that's primarily street driven; I recommend a distributor that's known for reliability and one that you can easily & quickly get replacement parts for (e.g. module, coil, trigger aka pickup). CD boxes fail and no one nearby can fix it. Same goes for trick/custom distributors.

For a carbureted sbc/BBC, there's really just one type dist that is a robust, reliable, proven winner; the Delco Remy 4-pin HEI (and its copies).
DUI has a very good 4-pin HEI with several available options.
Same does for AC Delco / Chevrolet Performance / GM pn 93440806.

Both of the above 4-pin HEI have a nice performance curve AND you can get their replacement parts at virtually any local parts store. Both make Plenty HOT fire. They rarely need service but are easy as pie to work on.

I suspect both small cap distributors (dui & pertronix) linked in post 51 may have parts which may not be so readily attainable as are parts for 4-pin HEI.

 

For a carbed street motor; I recommend Both mechanical & vacuum advances; both working in concert.

 

YEP!!! Nearly impossible to find a distributor without mechanical advance (unless you want to go with a computer controlled distributor - NOT). Without vacuum advance - part throttle fuel mileage will suffer SIGNIFICANTLY !!!

 

ended up just buying this...
https://www.gmpartsdirect.com/oem-pa...butor-93440806

figured if I'm building a new engine, should just do it all new... need a good air cleaner now that fits under stock hood... theme is all black/polished alum

 

Do you have an OE dual snorkel assembly ?
All Star has several aluminum assemblies which could be polished; they look racy because that's what they are.~ $70,
https://allstarperformance.com/air-c...acer-all26094/
Also an offset stud available; lets you move assembly front to back
https://allstarperformance.com/offse...-6in-all26057/
As well as offset base
https://allstarperformance.com/air-c...fset-all26091/

I agree all new with all new. Pretty sure the Rock Auto piece is actually new as well; regardless of its misprinted description.

93440806 ...You've made a very good distributor choice!

Btw, I viewed your products. Very, very attractive but smidge out of my strata; given that, I 'spose a few bux on a this cam or that distributor is inconsequential.

 

Now you know why I'm trying to figure it all out (and get help)..... and keep that look per se'... polished and clean

 

Seems like this is on backorder (wasn't mentioned on the site). second order from this website in 2 days that they cancelled my orders.... might have to go with another site or DUI...

 

Call, phone RA & verify if 93440806 in stock and Not reman.

 

Finally got all my parts plus a few extras for this engine build. Going with a black/aluminum theme.
Hope to start building it soon. Looking to get a new trans next and just swap everything out at once.