cdrod

I’m ready to start building the engine for my 442 convertible project. This car will be a daily driver, so no track time, or racing just spirited driving to and from work and all of the chauffeuring that goes along with having 2 active kids. After talking with Mark (CutlassEFI) I was 90% sure I would stroke my sbo simply because the Chevy parts are cheaper and stronger than reconditioning the 40-year old Olds parts; but I recently scored a good deal on some Mondello-built ProComp heads so stroking the small block is now a given. I’m not looking for a monster motor, and this engine will seldom see more than 4500 rpm. Here are my goals and some questions too:

Goals:
1. Peppy daily driver with good throttle response and reasonable gas mileage
2. I’d like close to 20 mpg hwy with light-footed overdrive
3. Updated roller cam and roller rockers to survive with modern low-zinc oils
4. I want a broad torque curve, CR = 10:1-10.5:1, 400HP needs to run on premium pump gas
5. ProComp heads w/big valves, milled to 70cc
6. Performer 7111 manifold with rebuilt Q-Jet 750cfm
7. 200-4r trans, 3.42:1 rear gears with Torsen TrueTrac differential
8. 17” aluminum wheels with 10.5” wide 265/18R40 tires on the rear 26.5” tall rear tire

Questions:
1. Pistons choice: looking at Keith Black #9907HC-STD, good choice?

2. Rod choice: looking at Scat eBay - SCAT#SCA 2-ICR6000, What rod bolt hardware do I need, ARP-8340, ARP-8740 or ARP-2000

3. The ProComp heads were built by Bernard Mondello in 2013, for a guy in San Marcos, TX but he never built his motor so they’ve been sitting on the shelf for 2 years. They are fitted with ProComp valves and springs as well. Anything to be concerned about here? I’ve read some accounts of valve seats falling out or pitting badly. I’d rather do this right the first time and don’t want to take a risk and have to tear down the motor at a later date.

4. Is there a big difference between long tube and shorty style headers? I’m considering the Sanderson 0351-P headers for easier installation and ground clearance. Am I leaving HP on the table by not running long-tube headers?

5. Cam suggestions?

Eagerly awaiting your replies.

The Stickman

Do you need a crank? BTW a 265/40-17 is 25.4 inches tall. A 275/40-18 like I have is 26.7 inches tall. Here is a good wheel tire guide to use.


http://www.rimsntires.com/specspro.jsp

cdrod

Stickman:
I don't think I'll need a crank. I have a '76 long block that should be a good build-able core and just in case, I have a spare small block crank of unknown date if the '76 crank is no good. Thanks for the info on the tire size and the for calculator link. I've just been looking up tire info from the tirerack.com website which showed a 265/40R18 as 26.5" - I rounded up to 27". I'd really like to run a 285/40R18 in the rear, but the wheels I want to use only come in a 9" width which is probably too narrow for the 285 tire. Still working out wheels and tires.

The Stickman

OK well if you need it I have a 330 forged crank that is already offset ground for a 3.5 stroke that was done by J&S Machine. I also have the flexplate to go with it.

cdrod

Stickman:
Interesting, how much do you want for the 330 crank and what do you think it would cost to ship to Houston, TX?

captjim

cdrod, here is my advice. While it might be fun to discuss your build on a forum like this, personally, I would do one of two things. 1) Choose a builder to work with who has a proven track record with Oldsmobile engines, sit down and come up with a budget and plan. Follow all of the recommendations, (not some of them, don't pick and choose). Or 2) copy an existing build that matches your budget and goals. Do NOT use a forum like this to make important decisions, you will end up with a lot of varying suggestions. "Too many chefs ruin the stew" Good luck!

The Stickman

PM sent

olds 307 and 403

Those pistons are Okay but have the old school thick rings. I am sure the base rod bolts will be fine. Follow Mark's advice, he has built a few.

cdrod

Captjim:
I appreciate the words of caution, and I understand the “too many cooks” metaphor; but I’m not expecting this thread to tell me how to build my motor. I’m hoping to get some education about building this motor from people who have more experience than I. For example, I would never have even considered a small block stroker build until I learned about it here on ClassicOlds; and I would not have considered using aluminum heads either until I learned of their advantages over stock iron heads. The goal of this thread is to glean some useful tips on how to build an Olds motor in a Chevy world – lol. I’m not about to let someone build my motor without understanding the details necessary to make it last and making sure they know what they are doing.

Joesw31:
As to the “why not a 455” question. I don’t want the extra weight up front. I’m trying to better balance the front-to-rear bias and the small block combined with aluminum heads, intake, radiator, AC compressor is helping me achieve this goal. The small block should rev quicker and have less frictional losses for better mpg. The roller cam and rockers should help with this as well. I’m also planning to run headers (long-tube or shortys) and it seems like installation on a big block is much more difficult.

I picked up a running, ’76 350 long block w/#8 heads for $75 that should be a good buildable core. My initial plan, before I knew about the stroker approach, was to replace the #8 large chamber heads with some #7a heads with smaller chambers to boost the compression ratio. I haven’t fully disassembled this engine yet (I’ve only removed one head to inspect the cylinders) but I was pleased to find very little ridge and no scoring on the cylinder walls. The block is cast 395558-2 and has a VIN stamp of 36M so I’m sure it’s a ’76 block. From what I’ve read, I think the windowed main blocks were used in ’77 and later years.

I had a long conversation with Mark (CutlassEFI) about 2 years ago to discuss building this motor, but eventually decided that I wanted to be more hands-on with the build and I also wanted to be present for the dyno tuning. I know Mark wanted to build this motor for me, but understood my desire to be personally involved in the project. I have interviewed several local builders and had a good first talk with Dennis Faerman of Faerman Racing here in Houston. Dennis seems to be on top of his game and has built a few Olds motors. I don’t think he has built a stroked Olds motor, but he understood the concept of running the small journal Chevy rods on the offset Olds crank. I was very impressed that he has the capability to do the off-set crank grinding in his shop. All the other builders I met with wanted to out-source this component (most likely to Dennis).

I’ve been planning this build for 2 years, researching pistons, compression heights, head gaskets, finding the small journal Scat rods, etc. I even built a spreadsheet to calculate compression ratios and compute deck clearances so I could quickly test different parts combinations.

cdrod

Is it possible to get off-the-shelf pistons with the thinner ring pack without going to custom order pistons? I chose these KB pistons because they have coated skirts and the small 5cc valve reliefs.

olds 307 and 403

Another reason to consider the thin ring packs is less cylinder wear and parasitic drag. Thick rings robs power and reduces fuel economy. I have the Scat small journal rods with custom 403 stroker pistons waiting for me to get off my butt and build the motor. They are a nice looking rod and are supposed much stronger than the original. I picked up two nice 76 350's, one for $50 with a decent 76 Cutlass 2 door and the other for $120. Both had little wear on the cylinder and the cranks looked perfect with good to great oil pressure. I am sure 20 mpg is possible with the right combo. The roller cam, thin ring pack and efficient cylinder heads is a big part of the reason the LS series puts out the power and mileage it does. Your stroked 350 can have that with much better low end torque, the LS doesn't come alive till 4000 rpm.

cutlassefi

A little more expensive but a muuuch better piston.
http://www.cnc-motorsports.com/pisto...-125-bore.html

cdrod

I don't think the valve reliefs are even necessary on an Olds motor, but it's the closest thing to a flat-top Chevy piston I can find. I did interview Jeff at Westside based on your previous recommendation. I think the crank thing swayed me a little more into using Faerman knowing he had the capability in his own shop. The other think that impressed me about Faerman was Dennis figured out how to stroke the Olds using the small journal Chevy rods before I could even tell him about my motor plans. He's a sharp guy.

olds 307 and 403

Agree, much better.

cdrod

Mark:
What makes this piston so muuuch better the the Keith Black piston? One thing I liked about the KB piston is the coated skirt. Is this just marketing hype or is there anything to the claims of less friction?

Mr Nick

I have 285/40/18 on a 9" wide rim, there is some sidewall bulge but nothing unsafe. I would not go any wider on a 9" wide rim though.



https://classicoldsmobile.com/forums...18-wheels.html

cutlassefi

Stronger yet lighter. Better material (2618 alloy vs hypereutectic)
And better/thinner ring pack. I'd opt for this vs coated skirts in a heartbeat.
And yes the valve reliefs are a moot point. They won't come close to being an issue.

cdrod

Mark:
I know the forged ICON piston is stronger, but the 390 alloy of the KB piston expands less than the 2618 alloy of the ICON piston allowing a tighter clearance. I think a forged piston needs around .035"-.045" whereas the hypereutectic can run .020"-.025". So, what are the pros and cons of running tighter piston clearances? Also, I checked the weights on the CNC website and it looks like the KB piston is lighter by 144g; Icon=539g+132g pin, KB=425g+102g pin. Wouldn't the lighter piston be better, and do I really need the add'l strength of the forged ICON for my street build?

cdrod

Nick:
I have seen pics of your car with the Gasser rims while researching wheels for my project. I'm typically not a big fan of the 18" and larger rims on these cars, but it's a very good look for your car. Do you have any crowning issues with the 285 on a 9" rim? The Discount Tire guys were concerned that the 285 would not have a flat contact patch because of the narrow rim and said the "book" calls for a 9.5" minimum rim size.

I'm looking at the Bandit 109, cast rims from US Mags. It's an aluminum SSI look-a-like and I'm hoping I can mount a set of Olds SSI center caps to complete the retro look. The Bandit 18x9 rim has an 8mm offset or a BS=5.25. Do you think I would have any clearance issues running this rim and tire on the rear of my '72? Thanks.

cutlassefi

I'd be hard pressed to believe that piston only weighs 425 gr. That might be a misprint.
Yes the hyper runs tighter clearances but you won't find any builder that would pick the hyper before a 2618 piston.
Add to that the thinner rings. Unless the Icon turns out to weigh way more than the hyper I'd still use the Icon.

holiday88

I'm going to use these, and they're on sale today. I doubt I will notice any difference in my grocery getter, but my wallet sure will.

http://www.northernautoparts.com/part/sl-h400cp

cdrod

Mark:
I downloaded the Icon and KB catalogs to compare the piston weights: the IC759 lists as 539g/132g (piston/pin) whereas the KB9907 lists as 425g/102g. Do you think this is a misprint in the catalog? That's a 5oz. weight difference, seems pretty substantial.

cdrod

Mark:
I sent an email to UEM the maker of KB pistons, and they confirmed what you suspected; the 425g weight was a misprint in a previous catalog. The correct weight for the hyper KB9907HC piston is 595g w/107g pin. So the Icon piston & pin is lighter by 31g.

Fun71

The weight difference between a BBO and SBO is less than 100 pounds, and if you use aluminum intake and heads the BBO would weigh much less. For quick revving, 425 crank/rods in a 455 block would do the trick - oversquare bore:stroke and 7" rods, plus an additional 50 cubic inches over your stroker small block.

I know this isn't going to change your mind, but I thought I'd point it out.

cdrod

Fun71:
I considered using the aluminum parts on a big block, but the same parts on a small block will reduce the weight even further. I've been tracking all my weight reductions; with tubular sway bars, AL heads, AL intake, headers, AL radiator, AL AC compressor and AL drive shaft, I've trimmed 107 lbs. of sprung weight. I've shaved another 28 lbs. of un-sprung weight in the front with tubular control arms, C5 Vette disc brakes, and AL rims. They say that 100 lbs. of weight reduction=10HP. I don't know how much truth there is to the previous statement, but if so, I just gained 13.5HP with the weight savings.

Another thing that kept me in the small block camp is the '72 VIN plate on my car lists a 350 for the engine. I know I'm building a resto-mod so factory correctness is a moot point, but I'm not planning to change the interior or exterior color, so keeping the small block will be one more item that matches the car's original documentation.

captjim

I love small blocks, but the extra torque of the BB is going to FAR outweigh the benefits of the weight savings, IMHO. An SBO stroker is cool, but a 455 is really just a "factory stroker". They took the 455, same bore, added some arm, and a bunch of torque.

Fun71

Yeah, 13.5 more HP in weight savings but around 100 Ft-Lbs less torque than a BBO. Again, not trying to change your mind, just providing information for thought.

cutlassefi

Yep kinda thought so. Fwiw, I knew it couldn't weigh only 425. A Mahle 1.125 cd, 4.00" bore piston that's $600.00+ a set and has virtually no skirt on it only weighs a little over 400. The math just didn't jive.

So, with that said I stand by my original statement. For a few bucks more the Icon is a no brainer imo.

Thanks for the post.

cutlassefi

I understand your point but you forgot a few things.
The oversquare bore and stroke of the 425 won't necessarily make it rev quicker than a 455. Actually it has little to do with it. Rotating and reciprocating weight/mass has a lot more to do with it. And if you want to get technical, the shorter rod ratio of the 455 should actually rev quicker, albeit for the added stroke. The shorter stroke and longer rod on the 425 actually lends itself to be a bit lazier and most certainly make more power higher up in the curve, all things being equal on the two.

But keep in mind, the current mountain motors of today, 800+ cubic inches, run to almost 9000 and rev with the best of them. I've seen two now on my guys dyno built by Chris Nelson here in Florida. It never ceases to amaze me how they don't just fly apart.

cdrod

Mark:
Lunati recommended a #20420710 Voodoo roller cam with a duration of 211/219@.0505 & lift of .541/.549. Would you spec something different than this? How much HP and TQ can I expect from my stroked 350 given the info in my first post? Thanks.

Rodney

cutlassefi

My hp estimation is based off the cam you listed. Imo it's about 10 degrees too small. And I'd probably do a little different stagger and lobe combination.

Fullsizelover

Interesting I would like to know that also, I got the Lunati 20420710 cam as well, just bought the IC886 from CNC this weekend, only need the Procomps to finish off my build.
That combo gives 9.9 compression to run normal pump gas, but I have a 455

cutlassefi

Are you looking for a hp estimate? If so I'd guess 375-425, depending on intake, carb and exhaust.

Mr Nick

Excellent choice on those wheels, I've never seen them before.

I've done a burnout or two... and the patches are nice and even. Tire wear is even as well, but only about 4-5,000 miles on them so that would be hard to tell. The guys at the DT I used didn't mention anything about the rim width.

Your backspacing would be a touch less than mine, your rims will be 5mm closer to the quarter panel. I'm told the 68/69 cars have smaller openings than 70-72, so you should be fine. However I don't know if "more room" is on the inner wheel well housing, or outer quarter panel.

I'm also lowered a good 2" front and rear, if not more.

olds 307 and 403

He is also going for good fuel mileage, much harder with a 455. That cam should provide good fuel economy with a decent power boost but I am no expert. Remember he wants it to hit 20 mpg cruising. The Sanderson shorty headers are 10 pounds lighter per pair than the awful factory manifolds, I weighed them.

cdrod

I couldn't find that info on the web so I guessed about 15lbs. How much do the Sanderson header weigh?

olds 307 and 403

According to my bathroom scale, 5 pounds each vs 10 pounds each for the manifolds.

cdrod

Mark:
Why do you think the cam and carb are too small? Plugging numbers into a carb cfm calculator I come up with 600cfm at 5500 rpm and VE=100%, using VE=90% I calculate 535cfm. Is there something unique about the stroker combo that warrants a bigger carb? And common cam advice always cautions against running too big a cam, better to go smaller than larger, which seems to fit my application of a daily driver. I'm not saying your suggestions are wrong, I just want to understand why they differ from accepted practice. Thanks!

captjim

Those calculators always come up with unrealistically low numbers. You will do much better with something in the 750-800 cfm range.

olds 307 and 403

Qjet is either 750 or 800 cfm. The only other carb to consider for maximum mileage is the 750 Street Demon, an improved, all new castings version of the Carter Thermoquad in a 3 barrel for square and spread bore intakes. I was going to get the Street Demon but getting my 78 Olds 403 800 cfm Qjet custom built will actually be cheaper, since I am supplying the core.