jbarnett

First post here but after trying to gather as much info as possible and finding so many different responses it's now time to try and get some more concise answers.

I have a '74 block and #8 heads torn down and ready for a re-build and along came an opportunity to supercharge it. Of course I'm pretty jazzed about the prospect!

However, in trying to figure out what rods, pistons. cranks and just some overall knowledge around such a build I've come up short. The searching on SBO builds in general has overloaded my brain with info and left wondering what is pertinent and what isn't.

I'm using a stock crank, block, mains, and the #8 heads at the moment.

Rods - I have read that 403 rods with work with the stock crank but all I can discern is that they'll fit the rod journals but that doesn't say anything about what that means for pistons. I have also read a lot of of folks turn down the journals to 6.100 and use Chevy rods. With a standard crank would you use 6.200 to keep it a 350? What rod length equals what in regards to CI?

Valves - I am assuming that bigger valves will be a must. Any suggestions?

Cams - No clue other than a bigger on the exhaust I would guess?

How limited would I be by the stock crank?

Car is a '74 Cutlass. Will run 3.73 gears w/posi, 200-4R trans, not sure on converter. 1 5/8th's Hooker Super Comp headers and 2.5" exhaust. It has 275/50/15's in the rear which are 28" tall I believe.

I've read through lot's of stuff on here but I had to reach out for help.

Any help is appreciated.

J

cutlassefi

With all due respect before you tackle putting a blower on your ride, you may want to take a little more time to learn about engines in general.
Rods have nothing to do with stroke, and the 6.100 would be the rod length, not the journal size.
And just an fyi, ditch the idea of using 403 rods if you're going to make any power at all, they're junk too.

Mr Nick

Do you already have the intake base and blower assembly?

The big question, how much power do you want to make?

captjim

Exactly. If you want a cool cruiser where the blower is mostly for looks and street fun, you will be OK with the 350 block/crank and low boost. If you are serious, better to go with a diesel block.

wr1970

I agree with this statement. Low boost no problem.

edzolz

Who made you find a blower intake for small block??

jbarnett

Sorry, that was a typo. I meant 2.100.

As for using 403 rods it was a matter of using aftermarket 403 sized rods with the idea that I wouldn't have to turn the rod journals down at all.

J

jbarnett

Dyers lists one and I believe so does Supercharger USA and Hampton.

J

jbarnett

I don't but it's being provided. Not that much power to be honest. Under 500 and not running a high amount of boost.

This is cool street car set up, not a race car.

J

jbarnett

What about using the #8 heads with some larger valves? I want the car to run on 91 octane.

J

captjim

Those heads are OK, but will need a lot of porting. You might be better off using a big block head and a flat top forged piston to keep the compression ratio right, you will have a LOT more flow and won't have to worry about losing anything on the bottom end. BTW, nobody makes SBO aftermarket rods.

cutlassefi

If you're only looking for 500hp then don't worry too much about head flow.
Just do an I beam SBC Rod and a custom piston. That'll enable you to push it a little more if you ever want to.

jbarnett

I see where you're going with that logic of using the BB head. That actually may be pretty easy to accomplish.

I came across these rods for a 403 Olds which is why I asked about using 403 sized rods so, potentially, I wouldn't have to have the crank turned down:

http://www.summitracing.com/parts/es...ake/oldsmobile

However, it seems going to Chevy rod and piston route is just too easy and cost effective to pass up.

Thank you so far for all the input.

J

jbarnett

Thanks. I have seen yours and CaptJim's posts quite a bit on here in terms of providing info for folks. I appreciate it.

J

cutlassefi

Dude those are for a big block.
Again with all due respect it seems you may be in over your head. Quit before you cost yourself a bunch of money, and get nothing in return.

jbarnett

Now, with all the drudging of info I have come across is it not so that it is said you can use 403 rods in a 350? If that's not the case I wouldn't be entirely surprised because as I have said, there's an inundation of info but it's hard to separate the good from the bad at times. I'm very new to Oldsmobiles.

As for costing myself a bunch of money that's not an issue. I am doing the research to prevent that so I have no problem even seeming foolish or asking a "stupid" question. I'd rather get flamed and learn than not. Most everything in this build will be provided as well. Most, but not all

J

cutlassefi

You need to take a step back.
307, 330, 350 and 403's all share the same Rod dimensionally.
400, 425 and 455's all share the same rod journal dimensionally with the only difference being length, so it's vastly different than a 403, 350 or any other small block Olds Rod.
You may want to go to more of an informational website first before you go any further. Might save us all a lot of back and forth.
By the way, what is your budget for this project?

jbarnett

Actually, this has all been very helpful.

I've poured over quite a few forum threads, The Olds Faq site, and more and the sheer abundance of info is part of why I came here to ask some questions. People will say "All Olds heads are interchangeable." but there's a lot of info left out such as what manifold you can run, if headers will match up, and others. I understood the idea behind CaptJim suggesting a BB head as with a boosted motor the larger ports could help, especially on the exhaust side.

That link to rods on Summit I posted is are listed as for a 403 Olds. I know that a BB rod is a different length as the stroke would be different. I asked using 403 rods in reference to reading people say they interchange with a 350 Olds crank and some suggest them using them as a cheap way to increase strength in the bottom end. Those rods listed as 403 rods are forged H-beam so that would be a definite increase in strength in the reciprocating system. If Summit has incorrect information then that's simply that.

Budget wise I'll likely spend around $2k but that's a bit of a misnomer since a good portion of parts will be donated. However, it's hard to ask for something if you don't know exactly what you need and Olds specialists aren't just around the corner. If I was building a Ford or Chevy though...I wouldn't even be here.

J

cutlassefi

The exhaust ports are all pretty much the same in all Olds heads. The only difference being valve sizes.
And don't assume the Rod has to change with the stroke, the two really have nothing to do with each other.
I still think you're in over your head, sorry.

wr1970

I think cutlassefi is right after reading this whole thread. You are in over your head. Just make sure you buy the right parts. The more questions the better off you will be.Make the list of your build. Then ask questions you can always cross parts off a list before you buy but not easy sometimes to get rid off parts you don't need.Hang in there be patient. Using after market small block chevy rods would be the way to go like Mark said and strong enough you can add more power down the road later after you sort this all out.Good luck on your build i will be watching this thread. Cool project I like your ideal.

olds 307 and 403

Unless the blower manifold has 455 sized ports, use your #8 heads, with a good bowl port and at least W31 sized valves, 2"/1.625". The exhaust port is good except a lip right under the exhaust valve. If you bother with BBO heads have 84CC chambers out of box, just have them by a decent shop and use Cpmetic head gaskets. Summit Racing has their Eagle rod info wrong, I am sure a few people bought those rods incorrectly. Mondello and Olds Rocket Parts sells SBO I beams but another member bought a set and the dimensions were all over the place. Olds Rocket Parts is sold out of the rods and don't deal with Mondello's. If you can find around a 10cc forged SBC 400 piston and match to the right length rod, that will require narrowing the rod or widening the crank and a .025" grind on the crank journal. If you go mild on the boost, use the factory rods with Speed Pro forged pistons with the 6cc dish and your #8 heads with the work I mentioned above. If want to take the risk dealing with Mondello's and buy their rods, those will be only aftermarket rods you will find.

1BOSS83

I'm going to ask the question I always ask, as IT is the most important question.

How much money do you want to spend?

oldcutlass

Imho, its going to cost considerably more unless you have the engine and all the parts.

Mrgadget

Take a look at my post from June, 2014 and see what I went through.
https://classicoldsmobile.com/forums...lock-done.html
It definitely was worth it, still runs great, manifold was key to keep it under the hood. If that is not a problem, then a "normal" SBO blower manifold would work if you could find one.

I posted on realoldspower.com and 2 other guys have different supercharger setups, more expensive than roots setup I have.
http://realoldspower.prophpbb.com/topic4039.html

Good luck, Frank

jbarnett

Saw your post on ROP and responded for some more info actually.

Was curious what you did for a cam and now that I think of it, did you change out your radiator? This 74 Cutlass has the stock radiator in it and while so far, cools great. But I can imagine that adding a blower could increase the need for cooling.

I actually want it to protrude from the hood. Black anodized blower, black Quick Fuel carbs, black scoop on a flat black car with gloss black trim pieces. So...the car's black is what I'm getting at.

J

jbarnett

I do and will. Like I mentioned before, parts are being donated so I'm quite lucky in that regard but I still need/want to know information to do things right.

Biggest cost will be heads but those may donated too.

J

cutlassefi

I wish I had friends like you have!

oldcutlass

Where are you located J?

jbarnett

After talking to you guys and doing more and more research here's where I'm at:

-Turning the rod journals down to 2.100 and running a forged I-beam 6.000 Chevy rod

-Having the block bored to accept 4.125 forged pistons

-Going with either the Procomp or Edelbrock heads. For the money it's more cost effective to go that route than to work over the #8's and with the blower it seems that the extra flow could be needed at least on the exhaust side. I don't mind switching to an electric fuel pump either. Harland Sharp seem to the choice for rockers yes?

-Thinking to go Hyd Roller for the cam but not sure sure on specs to run yet. I am sure one the people I'm dealing with can help there but curious what you guys think.

-Twin 450cfm carbs though hoping an electric choke wouldn't be an issue.

http://www.quickfueltechnology.com/c...r-450-cfm.html

I want this thing to run on 91, run cool enough to sit in traffic, and have the muscle to put your *** in the seat when needed.

jbarnett

I am a very fortunate person and I try to do all I can to help those who help me as well. This build isn't even for my car! Although I am the one who purchased it for the person who drives it so they would have a ride they wouldn't have to smog, was cheap enough, and I could work on it if something went bad, some really awesome folks have stepped up to the plate and I'm able to do something really, really cool for them.

J

jbarnett

SoCal

J

cutlassefi

220/230@.050ish on a 114LSA.

Mrgadget

My cam is a mild one.......268H 218/218 .456 lift on 110 LS.
My radiator is the stock one on the 1970, works great, never overheats, running 5psi boost when wide open which is not very often and 91 octane. with the a/c on and at 70-75 mph on a hot day it might get to 210-215ish.
By the way I'm in So Cal also, Fountain Valley.

jbarnett

That is a pretty mild cam. Comp right? I was considering that one for just rebuilding a 9 to 1 motor.

Are you running a 160 or 180 thermostat?

J

olds 307 and 403

If you have the blower manifold already, the tops of ports will need welded unless the rpm or victor was used as the base. The Procomps will be a good choice, bigger chambers, supposedly very good velocity for a 350 and cheaper.

Mrgadget

I believe it was a 185 thermostat, normal freeway driving w/o a/c on, it runs about 190-195.
Yes it is a Comp Cam.

captjim

Most blower kits use a dual quad intake, as that is the easiest to modify for a blower. In this case, I assume the Offy is preferred. Also, you want the compression low, like low-mid 8.xx to 1. You want big ports, velocity is not an issue with a huffer shoving the air in. And, you want a wide lobe sep like the cam Mark recommended, this keeps the charge in the cylinder.

Mrgadget

By the way, I have an extra Offenhauser dual quad manifold in excellent condition I might part with, #5587, I bought 2 when building my setup in case we screwed one up in the machining process or hell-arcing.

jbarnett

Cool. I'm not sure if I'll need it yet but I know that cutting and welding the base to it is par for the course. I think people usually use the high rise one though but not sure if that would really matter much.

Thanks.

I also learned that I may need to use a 6.200 rod to get the right piston compression height to make 8-8.5 to 1 with 77cc heads. Things you learn...

J

cutlassefi

What piston and stroke are you planning to use along with the 6.200 Rod?