generalmopars

Hey everyone, I'm new here so here goes. I'm building a 70' 350 4bbl to replace the 307 in my 1990 Buick estate wagon (box B body). The engine is an all stock rebuild except I'm using a jm 20 22 cam. The motor is all reassembled except I havnt gotten new rockers yet. My question is can I get away with the factory torque converter of my th350 I will be using or do I need something a little looser? I'm not sure what rear gears it has, it is not a possi. I'm not looking for a drag car but more less something that can be driven everyday and will pull great on the highway. I'm planning on using a tranny cooler but I'm afraid of the idea of a stall converter because I don't want to burn up the trans around town. Thanks, please reply somebody.

generalmopars

Hey everyone, I'm new here so here goes. I'm building a 70' 350 4bbl to replace the 307 in my 1990 Buick estate wagon (box B body). The engine is an all stock rebuild except I'm using a jm 20 22 cam. The motor is all reassembled except I havnt gotten new rockers yet. My question is can I get away with the factory torque converter of my th350 I will be using or do I need something a little looser? I'm not sure what rear gears it has, it is not a possi. I'm not looking for a drag car but more less something that can be driven everyday and will pull great on the highway. I'm planning on using a tranny cooler but I'm afraid of the idea of a stall converter because I don't want to burn up the trans around town. Thanks, please reply somebody.

generalmopars

Hey everyone, I'm new here so here goes. I'm building a 70' 350 4bbl to replace the 307 in my 1990 Buick estate wagon (box B body). The engine is an all stock rebuild except I'm using a jm 20 22 cam. The motor is all reassembled except I havnt gotten new rockers yet. My question is can I get away with the factory torque converter of my th350 I will be using or do I need something a little looser? I'm not sure what rear gears it has, it is not a possi. I'm not looking for a drag car but more less something that can be driven everyday and will pull great on the highway. I'm planning on using a tranny cooler but I'm afraid of the idea of a stall converter because I don't want to burn up the trans around town. Thanks, please reply somebody.

joe_padavano

You want the LOWEST stall speed converter that will work with your engine and gears. For what sounds like an essentially stock engine in a relatively heavy car that is primarily street driven, I wouldn't use a converter stall speed that was much higher than stock. You aren't launching on a drag strip, so any higher stall speed will cause slippage at freeway speeds.

By the way, I merged your identical threads. You'll get a better answer sooner if all responses are kept in a single thread so incorrect info can be identified and corrected.

generalmopars

thank you for merging them. this is the first fourm ive ever joined and I wasn't sure where I should make that post lol. that's what I was thinking, use the lowest stall possible. im not sure what the factory stall is and ive been told it can shut off at idle when put in gear. im thinking about trying the factory converter anyway but if I have to step it up, does a 2000 sound ideal or is that still asking for trouble on the street. thanks for the response btw.

joe_padavano

The only time I've ever heard of a converter causing an engine to stall out at idle is if the clutch on a lock-up converter sticks on. Also, keep in mind that rated stall speed of a converter is only at a single operating point. A larger engine with more torque will stall a given converter at a higher speed than a smaller engine. Stock converter would have been 1600-1800 stall speed. I wouldn't go any higher than 2000 RPM with this combo.

generalmopars

ok. that gives me piece of mind. im going to give the stock converter a wirl just like I wanted to do all along. I got all worried because lynn at mondello was all like "woah... wagon... your going to need a 2400 stall converter for that cam, I can get you one real cheep only 300 something..." bastard trying to upsell me stuff I not only don't need but something that is going to ruin my build in the end. im new to building engines, yes olds motors are my engine of choice however I have a 68 cutlass and I rebuilt that 350 to stock specs using the factory cam 5 years ago and have had no problem. he just put a bug in my ear and got me worried but I think ill be just fine. thanks. im going to be posting other threads on recommendations as to do I need to rejet my quad, timing advance and other tuning stuff. what fourm would you recommend I post those on. thanks a bunch by the way.

76olds

I have a basically stock 350 in a heavy 76 Olds Cutlass Supreme, I added bolt ons and that's it.
I bought a TCI Saturday Night Special T/C.
Stalls around 2000-2200. The car pulls a bit better.( Took a few weeks to loosen up and come alive it seemed)
I put 3:42 gears in along with headers, that made a huge difference.
I would say if you have cash to spend and not worried about how much you spend on the car, then I'd go with the TCI.. Saturday Night Special T/C .
Hope this helps
Eric

Fun71

My concern would be that 224º duration cam. The engine probably won't make much power down low so a higher than stock stall converter may be needed, especially in a relatively heavy vehicle.

If you get a quality converter, it won't slip any more than a factory converter at highway or cruising speeds. My car has a Hughes Performance 2500 RPM stall converter and I recorded the cruise / low RPM slippage at ~200 RPM, so nothing different than factory.

generalmopars

thanks eric & Kenneth. Ill look into both of those converters. what ill do is start calling a few converter companies and get a feel for whats going on.

HeavyOlds

That new cam won't be too wild. The 350 will have a bit more torque than the 307 too so it should be fine. If you want to drag race, the 2400 stall will give you better acceleration off the line.

generalmopars

im starting to see how this all works. well im not really looking to race, I just have a lead foot when im already cruzing. my goal is to have a car that can pull like a mad man on the highway with lower ISH rpms.

HeavyOlds

When you are already cruising then a higher stall converter won't help because the RPMs are up already. When you pass on the highway your transmission kicks down and your revs come up.

Also larger engines can handle larger cams. A cam on a 350 might sound rough but put the same cam in a 455 it will sound tame. I have a JM4-5 in my 455 with torker intake and ported Edelbrock RPM heads. It has 16" of vacuum at idle and idles smooth.

generalmopars

wow that's a lot of lift, I just looked up the specs hah but the duration isn't too much. ill bet it screams. is that a 67 you have, its a very pretty car. whats your overall opinion on the edelbrock heads.

HeavyOlds

It's a 66. That cam has a very aggressive race profile. Like Mondello says they make HP not promises. The Edelbrock head castings are pretty good but without porting they are similar to a C head. There is no water jacket above the intake port so lots of room to port. Those heads never did run right until I pulled them off again years later and found that two valves were cut out of round. My machinist thought they were bent but no evidence of piston contact and they looked more out of round to me. The valve springs aren't great either. I have my rev limiter set to 6000 and I think I was starting to get valve float. I put some comp cams bee hives on there now and set my rev limit to 6200. Pulls hard right up to the rev limit.

HeavyOlds

What is your compression ratio? With a bigger cam you can get away with more compression and it will help recover what you lose on the bottom end.

HeavyOlds

That Lynn is a salesman alright. I have found them helpful and gotten good service. Last year I bought some headers from him and somehow they sent the wrong ones. That's a big deal when shipping to Canada. They sent me a shipping label and exchanged for the right right headers. No cost or hassle for me. He gave me some advice on how to massage them a bit to make them fit which was helpful advice too.

generalmopars

well ive got factory #6 heads witch are advertised as 64cc but everybody says theyre more like 68cc, iv got the factory high compressions (basically flat tops) and I used the blue felpro gaskets. I was thinking high 10.1 but a guy on here told me I might be closer to 9.1

joe_padavano

With flattop pistons, OEM 0.017" head gaskets, and #6 heads blueprinted to the 64cc spec, you would have about 10.5:1. With uncut heads and 0.040" FelPro gaskets, expect to lose 1/2 to 3/4 point, so somewhere in the high nines.

Fun71

That was me.

You don't have flat top pistons as those were used in the W-31 engines only. The 310 horsepower 350-4bbl engines used 6cc dished pistons.

You can find one of the online compression ratio calculators and run the numbers to see what the compression ratio might be. It will be a fairly large range unless you actually measure the combustion chamber volume and piston-to-deck clearance to get exact values.


bore = 4.057"
stroke = 3.385"
heads = 64 to 70 cc
pistons = 6cc dish
piston to deck clearance = .015" to .025"
head gasket = .040" thick
head gasket = 4.2" bore

olds 307 and 403

With the usual .025" pistons in the hole and 68 cc chambers, you are right at 9 to 1. I am using Rocket Racing .028" head gaskets to help increase quench and compression.

golden rocket

Welcome, general mopars. my own personal thoughts is go with what used to be called a "RV" grind cam, about 1 to 1.5 steps above a stock grind. builds your power n about 1500 to 2800 R.P.M. range, smallish (600-650 cfm 4 barrel if hot injection, set of header with duals. pretty cheap build for a 350, make good power and torque for every day driving and towing, won't kill you at the gas pump either.

Have family up in the 'burg, and on the western side of Pa. Some good deer hunting up on the northern side by N.Y. state line.