350 Olds Build, What converter?

80Grand_LeMans

Dragway Regular
Jun 4, 2008
1,249
0
0
Peabody MA
I'm building a mild Olds 350 and just realized I don't want to waste it all if my converter is no good. Here is what I got so far.

Olds 350 stock bottom end.
Edelbrock cam: 204/214 Duration 448/472 Lift
Stock ratio roller rockers
Edelbrock performer intake
Double roller timing chain
Holley 750
Flowtech 1 5/8 to 3" full length headers
1970 Cutlass 350 heads, with larger 1.992 Intake Valves/1.624 Exhaust Valves

The heads will also raise the compression a tiny bit. The trans and converter are stock, not sure what the stall is and not sure what the compression is but hopefully I can get some help with that.

I will be doing my own research as well aside from this but I figured if someone felt like chiming in it would obviously be helpful. thanks.
 

80Grand_LeMans

Dragway Regular
Thread starter
Jun 4, 2008
1,249
0
0
Peabody MA
Forgot about tires and gears.

Its a non posi 7.5 that came stock in my 80 grand lemans with a 229ci chevy motor. No idea what the gearing is. And the tires I plan to use are 255/60r15's or something close. I know thats not much of an accurate statement but its the best I can do at the moment.
 

malzer

Amateur Racer
Aug 31, 2010
212
0
0
Gettysburg Pennsylvania
With the camshaft You have selected you could get away with a stock torque converter or one that is slightly "looser", say a 2000-2500 rpm stall converter, but from what you have written I believe you will see the biggest performance gain from a lower geared rear differential.

The stock ratio in your rearend is probably 2.29:1 or 2.41:1.

Look at what you intend to do with this car, as in do you want to get in it and drive 200 miles at freeway speeds or is it just going to be a local weekend cruiser.

This will help you decide what gear ratio is best suited for your application, however I believe that even a mid 3 series gear ratio (say 3.42)will really wake that packege up.

Just my thoughts.

later.
 

SSedan64

Dragway Regular
Oct 5, 2009
948
0
0
MACON, GA.
X2^^ on Gears.
Will a Chevy TC work with an Olds Crank?
The Pilot Dia. is the same but, the length looks even with the mounting points/pads?.
The Pilot Snout on the Chevy TC looks longer to me>> http://www.transparts.ru/pdf/tc_gm_03_web.pdf
 

malzer

Amateur Racer
Aug 31, 2010
212
0
0
Gettysburg Pennsylvania
TH350, should be able to use either Olds/Chevy converter or an aftermarket unit with no issues.

Most flexplates have two sets of boltholes in them from the factory.
 

Bar50

Pro Stocker
Jan 31, 2009
1,870
2
38
Tulsa, OK
joel6011 said:
use a chevrolet bolt/nut converter, those are stronger than the bop converters


How do you figure?

Bolts and nuts versus threaded tabs with larger diameter bolts that are fine thread?




Something else to look out for is that Olds motors do not have adjustable valve train. They do not even allow for the changes in valve height from a valve job.

Buy the Comp Cams kit, or at least the conversion rocker arm studs, use SBC rocker arms, and for most of the small block Olds you run a 429 Ford push rod (I think thats what it was). If not it will have a valve train noise and bend push rods.


Small stall ill work, think motor home, 1-ton or in the old days a Z-28 converter. They are identified by the six mounting lugs instead of three (you don't have to use them all). They are about 800 RPM over stock.


S10s and Camaro/Firebird are you friend for the rear gears you want. Most Z-28s have a 3.23.
 
SSedan64 said:
X2^^ on Gears.
Will a Chevy TC work with an Olds Crank?
The Pilot Dia. is the same but, the length looks even with the mounting points/pads?.
The Pilot Snout on the Chevy TC looks longer to me>> http://www.transparts.ru/pdf/tc_gm_03_web.pdf

GM calls for 6.125" - 6.187" for torque converter height for all V8 torque converters. The problem with interchanging a Chevrolet torque converter into a B-O-P application is that some Chevrolet converter cores utilize a front cover that does not have the correct shape/contours to fit properly with a B-O-P flexplate. If memory serves correctly, most Chevrolet passenger car TH400 converters will fit properly, where as the Chevrolet TH350 converter will not.

To answer the original post, a Hughes GM20-BPO would be a good choice over a stock torque converter. This is our Street Rod series 12" converter, and features an advertised stall speed rating of 2,000 RPM. This converter will provide an improvement in low-RPM acceleration and drivability, and will not have a high percentage of slippage or efficiency loss.

You would also do well to change the gearing in your rear axle, even if you only swap in a junkyard set of 3.08 or 3.23 gears.
 

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