yankees

I need some help with rebuilding my 72 350 SBO. Right now it's completely stock with a 2 barrel and 69k miles. This is the 160hp motor that had approximately 8.9-1 compression with dished pistons and 7A heads.

I'm looking to get 290-310 plus hp out of this motor with keeping the bottom end stock, except for adding a camshaft, intake, carb and exhaust.

What would be a good street/strip cam to run with my existing combo? I want this thing to break in the 13 second range. I'm thinking about running 3.73 gears and a 4500 converter(that I already have) My 72 Cutlass will see some street time (less than 25 miles a month) since two 2 car shows are within 3 miles of my home and will see the strip 1-2 times a month in the Sportsman class.

I would like to run intake casting 410446 to keep the stock appearance if possible, but I need to find one first. What are your suggestions for achieving this power output with keeping the hard parts stock?


I figured this would be attainable since chevy gets 290hp out of their crate motor with the following specs below and 345hp with an intake & carb change.
Compression Ratio: 8.5:1
Heads: Cast Iron 76 cc Chamber - 1.94 Intake valve/1.5 Exhaust valve
Camshaft Lift: .450 Intake /.460 Exhaust
Flat Tappet Duration @ .050" (222°Int/222° Exh)
87 octane


Please give me your recommendations.



Thanks

captjim

4500 is WAAAAAAAAAAAAAAY too much converter, you will probably be shifting about then.

Your Cr is not 8.9 to 1. In fact, after using replacement head gaskets, it will probably be less that 8.0 to 1. The problem, is the huge dish, there just is no way to overcome them. Either replace the pistons with new or find some 14cc pistong on rods (very easy, they are plentiful) do a good valve job with a little porting. Here is my 13.9 build, just to give you an idea,
http://www.realoldspower.com/phpBB2/...ic.php?t=28012

import extermination

To keep a stock looking engine on some small block chebby, iv used the performer and carefully grinded out the words edelbrock. Then painted it along with the block.

507OLDS

Yes,that converter is way to loose,and will actually hurt your perfromance with your application.If you want to keep your shortblock stock,and do not want to replace pistons,you could get a set of mid-60's #4 330 heads.They have a slightly smaller combustion chamber,and you can also have them milled,to boost your compression even further.Having a 9:1 compression is achievable with the stock pistons,with proper head milling,and a thin head gasket.You will find that there are different thicknesses of head gaskets.
As for the converter,I wouldn't run anything looser than a 2200 stall.The 3:73 gear would be great,and you will see a notable difference with a gear swap,especially if you still have the stock 2:56/2:73 gears.
You could start with the gear swap,do nothing else,and tack it to the track to compare your pormance gains with the way it is now.Then move onto the engine & converter.

captjim

With stock dished pistons down .020, a .027 gasket and 60 cc chambers, I get 8.7 to 1 Cr. With the relatively short stroke, those big dishes are just hard to overcome. Factor in cost of milling heads and intake and you are pretty close to new slugs.

coppercutlass

x2 with captjim i tried this with my current engine there was no way around it i went with flat tops but i chose cast flat tops so i wouldnt have to balance my rotating assembly your best bet is to get a 73 -75 block with the 6cc dish pistons mill the heads and run a thin gasket., my last engine i did this it had 9 to 1 compression with a towing cam edelbrock intake carb 3.73 gear and 2200 stall ran 13.86 through the exhaust while it was all steel went to fiberglass front end went 13.71 i also do have 14cc pistons you can have just pay for shipping but two where broken when the machine shop changed them you will have to source 2

Redog

If you're going to swap a cam, you might as well rebuild the entire motor.

Top end packages like that are not really a good idea as a straight swap, esp in a motor that's 40 years old, even thought it only has 69K on it.

A 4 barrel mani and carb swap, and headers with exhaust is a good start and you can use that on your rebuild as well

captjim

Huh?? The only 350 that came with 6cc pistons was the high-comp 68-70, and those are pretty hard to find. 71-72 had 23cc, 73-80 had 14cc.

yankees

Maybe I'll just start with running a 650 Holley DP, Edelbrock RPM intake or a 410446 if someone has one for cheap and some headers.

Any cam recommendations?

I just got the car, so I would like to drive it around a little before overhauling the whole engine. Flat tops do seem ideal with the 64cc heads, but I want to run 87-89 octane gas and go 13.80's somehow.


Thanks for the replies and keep the info coming. This Oldsmobile stuff is all new to me.

cutlassefi

Copper, just because you got "like" cast pistons doesn't mean they were the same weight as what came out of it. I wish people would quit assuming things like that.

Yankees, ditch the idea of a double pumper, some think thats cool or something I guess. Thats not the right carb for a small block with 8.5:1 and an automatic, a 600+ vacuum secondary would be a nice addition.

As far as a cam goes, you'll have to be careful there, too big and it will be a pig. I can grind you something if you like, let me know exactly which way you're headed and I'll help.

coppercutlass

i got cast pistons from a high compression 350 and they worked out great also i wouldn't just throw pistons on i did wheigh them . also cptjim sorry my mistake i was under the assumtion the 73 blocks had the 6cc pistons since the short block i had came from a 73 as the block stated but had the really small dish ., much smaller than the 14cc ones .

Jharken

Check this thread out.

Smogger 350

yankees

Jharken, Do you think your combo would work well with stock 7A heads? I'm just trying to hit the high 13's range. Also, how is it on the street with that camshaft and the 3.90 gears? Did you use your stock valve springs with that cam if not what did you use?

yankees

Also, let me know what you all think of this. I will picking up a 410446 intake and a buddy just gave me a Holley Spreadbore 650 List 7004-2 carb with a one inch phenolic spacer in very good condition, that he used on his Mopar 340. Looks like I just need a camshaft and exhaust, but is the Holley mentioned decent and is anyone using one.

Jharken

Jharken

Also, let me know what you all think of this. I will picking up a 410446 intake and a buddy just gave me a Holley Spreadbore 650 List 7004-2 carb with a one inch phenolic spacer in very good condition, that he used on his Mopar 340. Looks like I just need a camshaft and exhaust, but is the Holley mentioned decent and is anyone using one. Today 12:03 PM

That cam was nice on the street ran 87 octane and had 13" vac at 900rpms.
3.90 are fine on the street IMHO.
Valve springs were e brock take offs from new heads.
Never worked on a spread bore holley but love dp and vac sec.holleys.

My thoughts on motors are head gaskets up are were a lot of power is.Head gaskets down are insurance policy.

Have fun and ask ?'s, I and many others will help.
Jim

yankees

Mondello Perf this afternoon recommended this camshaft for a 350 with an Edelbrock RPM 7111 for a stock 350 with 8.5 -1 compression and stock 7A small valved heads

JM-18-20
0.488 0.496
260°/266°
216° 226°
112°
1000-5000


Which camshaft do you think is most comparable to Mondello's JM-18-20? See options below.


Also, if you have used something similar with good results with my type of application, please let me know.


Below are the 3 choices.



Cam StyleHydraulic flat tappet
Basic Operating RPM Range1,200-5,600
Intake Duration at 050 inch Lift218Exhaust Duration at 050 inch Lift224
Duration at 050 inch Lift218 int./224 exh.
Advertised Intake Duration262
Advertised Exhaust Duration274
Advertised Duration262 int./274 exh.
Intake Valve Lift with Factory Rocker Arm Ratio0.475 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio0.480 in.
Valve Lift with Factory Rocker Arm Ratio0.475 int./0.480 exh.
Lobe Separation (degrees)110



Cam Style Hydraulic flat tappet
Basic Operating RPM Range1,300-5,500
Intake Duration at 050 inch Lift 219
Exhaust Duration at 050 inch Lift 227
Duration at 050 inch Lift 219 int./227 exh.
Advertised Intake Duration262
Advertised Exhaust Duration268
Advertised Duration262 int./268 exh.
Intake Valve Lift with Factory Rocker Arm Ratio0.499 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio0.510 in.
Valve Lift with Factory Rocker Arm Ratio0.499 int./0.510 exh.


Cam Style Hydraulic flat tappet
Basic Operating RPM Range1,200-5,500
Intake Duration at 050 inch Lift211
Exhaust Duration at 050 inch Lift223
Duration at 050 inch Lift211 int./223 exh.
Advertised Intake Duration265
Advertised Exhaust Duration273
Advertised Duration265 int./273 exh.
Intake Valve Lift with Factory Rocker Arm Ratio0.472 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio0.486 in.
Valve Lift with Factory Rocker Arm Ratio0.472 int./0.486 exh.
Lobe Separation (degrees)110

Redog

The JM 18-20 cam is pretty decent, but the one that seems that everybod likes from Mondello, for a street car, is the JM 22-25-10. Nice lope, and produces around 14 inches of vacuum at idel. Necessary for power brakes

cutlassefi

Erson tq40 would be perfect, 220/228@.050, .504 lift.
I had that engle/mondello, didn't like it.
Your first 1 is a comp, the 2nd a voodoo, the 3rd is probably a lunati too. I wouldn't use the fast ramp stuff, I have backup on that.
Jmo

yankees

Is Erson still around or under a different name?

Looking for a good bracket cam for my combo that will rarely see the street. If on the street it will be very short distances 15 mins here and there for ice cream or to the gas sttn.

cutlassefi

www.pbm-erson.com

yankees

Has anyone tried running (carbureted) alcohol on their SBO 350 with 8.5-1 compression? If so, what pump did you use? The DRR guys say the stock 350 combo will make a ton more power with 8.5-1 and lower compression motors.

I just don't see many options for aftermarket fuel pumps.