Hello everyone,

First off, I apologize if this is covered in another thread- I did some searching and couldn't find what I was looking for.

I have a 1973 L-48, Mostly original (except for no radio and new exhaust). I absolutely love to drive it; somehow lots of torque and low center of gravity make up for the fact it only has 190 hp. But now I have the bug. I want to make the car even MORE fun, but keep the mostly stock appearance.

I would like to keep the cost lower than that of a new, more powerful crate engine. I've been reading up on stroker kits, obviously this is a popular thing to do in the performance world. I understand there is a general benefit in horsepower (estimated at +40) and torque. I also assume this will help "fix" the 8.5:1 compression ratio. I have some questions:

1) Is it possible to pull this off and still keep the carburetor/intake/headers/exhaust manifold I have currently?

2) Would I need to invest in one of those braces to shore up the 2 bolt mains?

3) what is the answer to life, the universe and everything?

Also, any sage words are encouraged/welcome.

Thanks guys,
Dan

 

1) Is it possible to pull this off and still keep the carburetor/intake/headers/exhaust manifold I have currently?

Yes

2) Would I need to invest in one of those braces to shore up the 2 bolt mains?

No. Use ARP fasteners.

3) what is the answer to life, the universe and everything?


42

 

 

rcread answered the questions, but let me add that after market heads, cam, intake, and exhaust are needed to take full advantage of a stroker motor. You might actually get better results with just a cam, the factory cam is smaller than the most mild aftermarket cam you can get.

 

These large journal SB's are an easy build as a stroker, we do them all the time and EVERY last one is 100% stock-appearing. Stock intakes, stock exhaust manifolds, and stock sheet metal, including a single-thick valve cover gasket! Some with the OEM Holley carbs and some with the Q-jets. Not a single issue/complaint so far with respect to power!

All are 100% full roller units and all use every factory component that came from the beginning. All are also independent balance for appearance!

These are somewhat difficult getting the roller rocker setup to fit under the factory covers, but it is doable. The specific chosen pieces determine the difficulty in the end.

The biggest factor chasing HP while keeping "the look" also comes down to the budget! The HP limits obviously would depend on all the pieces used. The C.R. also becomes a limiting factor. Most iron headed builds we do (we're talking pump-gas here) end up around 9.5/9.75:1. The increased stroke makes up for much of the torque "lost" from this lower final C.R.

(Add) I would trust the 2 B.M. setup but with studs at a minimum. Caps with the 4 B.M.'s could be installed but probably not mandatory here. The roller deal alone adds about 30 HP (nominal) to the numbers.

Thanks, Gary in N.Y.

P.S. The final HP numbers WILL vary by all the external components. The OEM Holley equipped builds will make more power over the Q-jets, but not by a whole bunch!

 

First off, thanks for all the responses. Man this forum is good.

Gary, you caught my attention.

First, I'm surprised that 9.5/9.75:1 is a "lower" final compression ratio. Currently I have a 8.5:1, so I'm delighted by those figures. I'm a sucker for efficiency.

Second, I didn't realize I had options with 'original'! I guess I'm considering this change a "rectification" for the sins of 1973 government oppression, so I'm not sure how much I care about things that no one knows about but me. Now that I think about it, I also have pertronix installed, so I suppose I wouldn't mind changing out anything like cams or rockers if horsepower is at stake.

Whats "the roller deal"?

When you say "we"... are you a company that does this kind of thing?

 

The 383 stroker kits are easy, reliable and best of all cheap if you are assembling yourself. All your original equipment will fit and perform as intended but you will leave a little horse power on the table. The good news is the torque will mostly be noticeable. Most machine shops don't even need your kit to clearance the block as most shops have done it so many times, they know exactly how to do it. You only need to make a few choices. Compression ratio, cam specs and internally balanced or externally balanced. Internally, you get to use your stock flywheel and hormonic balancer. Externally, you have to use the small block 400 flywheel and balancer.

 

That's incredibly helpful. I was literally JUST wondering what internally or externally balanced meant. Cams are a mystery to me, aside from what they do. So compression ratio is also a choice? basically it's do I want to buy premium or mid-grade, huh? haha

 

If you go the 383 route, you have to change pistons so you have options with the compression ratio there. Also, you can use your original connecting rods - just have them reconditioned and put ARP bolts in them.

 

I'm sure this would effect the moment of inertia for the rotational parts... any idea how the red-line would be affected by this change?

 

A good friend and I built a 383 with my L48. Nothing terribly expensive, scat stroker kit with the hypereutectic pistons and forged rods and cast crank. I didn't use studs for the mains though. It was a fun little build. Specs say CR is around 10.4:1 with 64 cc heads (no problems with pumps gas). I went with the ik200 brodix aluminum heads which are pretty basic. No roller setup here but I did install some roller rockers later on. Engine is almost 10 years old and still hanging in there. I've been pretty hard on this engine and it just keeps goings.

If yor vette is an auto, think about getting a higher rpm stall to go well with new engine build.

A well balanced engine can spin up pretty good. Your rpms are typically based on the power rpm range of your cam and other engine parts to compliment each other.

 

If your thinking of doing this yourself...with a little help from the "forum".... I might suggest you run down to your local speed shop and buy yourself one of those books that explains what to do and what to consider when rebuilding and boosting the horsepower on a small block chev (sbc), lots of good info out there to help you learn.

 

You're surprised it's lasted 10 years? I've been reading about people concerned with engine wear and most folks say it's negligible, especially if built well.

I was looking at that same setup, but I also was thinking about going for the super light weight version- figuring if I keep the weight down it would help with throttle response. (but it's about $2.5 k)

Also, my car is manual, but good catch.

Yeah, I wouldn't be attempting this if I didn't have a guy with an engine crane and years of experience as a mechanic and general muscle car tinkerer. Is there a book that you had in mind? I am doing the research now before I actually go for it.

 

Haha yeah.....Fluids have been changed consistently, but my foot is always in it. Either way it's been a fun leaning project and a fairly cheap build. This was my 1st engine build, luckily I had the help/guidance of a friend who is a Mopar guy. The stroker kit was about $540 at the time so it was very hard to pass up. Looks like they run about $640 now. I think I had about 2500 total into the engine when we built it. We did everything but balancing and boring and it got all new internals.



This was about the 8 year mark when I put a new oil pan on and replaced rear main seal. Notice the clearancing on the rods

 

Great pics!

I am torn because I know once I go this route I can't go back. I'm thinking about investing in a used block and rebuilding the thing... especially after seeing these pictures I feel like I really want to tinker.

 

I understand. There's a good bit of things that I'm glad my buddy was there to help out and show me. Things like checking clearances on the crank journals (line bore I think it's called). Then there's the whole part of clearancing the block for the stroker crank and rods for cam clearance. Not to mention he had all the right tools and space too! If you've never been in an engine it'd help to have a friend who has help out.

I had my c3 for about 2 weeks and the engine began to knock so it was going to get rebuilt.

Here's a video from when we first cranked it to help get you some more motivation.

 

That sounds amazing. Tragically under-powered like mine- did you notice that the stroker gave it more nuts? Very exciting.

I also assume that the uneven idling sounds were because you guys still haven't dialed in the carb... yes? The guy in the miller highlife shirt looks like the kinda guy I'd trust with engine stuff.

 

I recently had my engine out and did a head/cam swap along with a roller cam conversion. I fought the urge to stroke it because someone had already punched it out to a 355 and installed forged pistons/rods/crank. I just couldn't bring myself to tamper with that setup.

Good luck with your build. I am glad that I have a '79 that someone else already took the stock stuff off of so I don't feel bad about whatever it is that I want to do. Engine looks nothing like stock and I prefer it that way.

https://i.imgur.com/LUKBARX.jpg

 

Thanks very much. Oh yeah, the old engine would barely spin over the tires. The stroker gave it a lot of torque and upper end rpms felt much stronger. No problem spinning the tires over afterwards even after I added the c5 z06 wheels that are 10.5" wide. Very fun and streetable engine. The choppy idle is mostly due to the cam choice. And yeah that's my friend right there. He's been into racing and building mopars since he was little. There's a few more videos in my signature with sidepipes on the car.

 

I chose to build an engine from the block up, because that way I could still drive my car while I saved for parts and waited on the machine shop(they seem to take forever). I would suggest if you want to buy a block to build, that you start with a 400 block. I did, and stroked it into a 421. Saved my money and month after month, bought parts as I could afford them. My total investment was just under $5K, but I did all the work, except machining, myself. Scat forged crank Scat 6" rods, Wiseco +.030" forged dished pistons. Howard's hyd roller cam,253 degrees at .050 and 620 lift w/ 1.6 roller rockers. Aluminum 220cc heads w/ dual valve springs. I calculate I'm getting a tick over 600 HP out of it, and with 11.6:1 compression, it runs on premium pump gas. Getting your quench right and using aluminum heads are key to running this high compression without problems. I started with a GM 509 block that I had Magged and Sonic checked. It has been my daily driver for the last two months now, without a lick of trouble. I LOVE this engine! I was not ready for the huge torque increase I got vs my built 350. I believe you will surprise yourself as well, if you decide to add 75 cubic inches to your small block. And, don't listen to all those who say you shouldn't use a stock block. As long as you're careful, a 2 bolt 400 block will easily handle 600 HP. Good luck with your build!