so im buying a engine off a member and was wondering if i will need to upgrade my convertor im guessing it may be stock the cam specs are specs are 236-236 -520-520 lift with stock rockers,power from 2500rpm or so ,all the way to 6000 rpm and since the only thing i know about convertors is how to remove and install and i really dont know anything about cams so thats why im asking thanks
What are your intentions for the car and rear end gear ratio/cruise rpm? I'm not the expert, but that is what they will need to know to help you out.
im guessing the gears are around 2.93 it going to be a cruising car wit the a stop at the local drags one a month
2.93 gear + 27" tire + 60mph = 2180 rpm For a 99% street car you want to stay 4 or 5 hundred rpm under cruise on the converter so it looks like stock is your best bet. Cam is a little healthy for a stock converter but should run and drive just fine. You will just be leaving a little on the table at the strip. We'll see how my analysis compares with the guys in the know.
Steve's advice is good. It sounds like that camshaft is not too large. Some camshafts trade off low RPM torque for more high RPM HP, when this is the case a higher stall converter will help get the car moving quickly off the line. What happens when the car is leaving from a stop is that the torque converter is actually slipping and when this happens the engine is spinning quicker than the transmission. This causes a multiplication of torque which get the car off the line quicker and it come in handy with engines that have aggressive camshafts. If you use a high stall converter then there will be a loss in fuel mileage when driving under the stall RPM compared to the stock converter. On my turbo Skylark I am using a high stall converter so that I can floor the gas off the line and the RPM will immediately come up to about 2800 RPM where my turbos will be creating boost. I will give up a bit of fuel mileage with this setup though I will increase my smiles per gallon! To find out your rear end ratio just have a friend drive beside you on the highway at let just say 65 MPH and then see that your RPM is at that speed. The reason for the second vehicle is to ensure your speedometer is correct. Then just tell us your RPM your tire size and we can calculate your rear end ratio.
Just because a converter is marketed as xxxx stall does not mean that it will stall there in your car. If you buy an off the shelf converter, you may get lucky with something that you will find meets your needs. You could also get something that is too loose, and then it will feel like the transmission is slipping during normal driving. With the current state of converter technology, you can have your cake and eat it too, but that costs more than the commonly available converters that you can order from Jegs or Summit. It is possible to build a converter tight for the street, that will also stall where you need it when you romp on it. The torque converter is a really important piece of your combination, and you should not scrimp on it. Call a converter manufacturer and give them as much information about your engine build and car. They can build a converter that will do what you want. Jim Weise has a really good converter guy that can build a quality converter. You can also call Coan, ATI, and several others and see what they can do for you. You are going to be cruising this car, you don't want a converter that is too loose. Have a look here, http://www.v8buick.com/showthread.php?147066-TSP-9-5-quot-Street-Strip-converters-Lifetime-warrantee!
IMHO that is too much cam for a stock converter especially. It will feel like a dog until over 2000. If you have a TA catalog look at some of the converter recommendations for their converters. That should give you some idea what you need. Bob H.
You are doing an awful lot of guessing about this engine and car. Are you sure about the cam, and which member are you buying this engine from?
Wouldn't you rather have a converter that's a little too low for the cam vs a little too high for your cruise rpm? Specifically for a mostly street driven vehicle. Not arguing, just learning.
Sean i will use my gps to get speed and rpm @ 65 for my rear end. i think that i will use the stock converter and see how it acts and if not good ill change it not to hard. and larry i know those are the cam specs i was guessing on my rear end gears and i have no clue if it is still the stock converter in my car there is no guess about the cam.
236/236 is a cam you will need a converter for. Kind of unusual in that it is a straight pattern cam. A 1971 Skylark 350 probably came stock with a 2.56 gear. Look for about 2000 RPM at 60 MPH.
I got out on the highway and @ 65 my tack was between the 2400 and 2600 mark mor towds the 2600 so now what convertor should i have for that cam with 235/60/14 so 25 in
The biggest mistake new guys make is to over cam a car. That is exactly what you are doing IMHO. Buick engines like a split duration cam. More exhaust duration (about 10*) than intake duration. That helps out the weaker flowing exhaust port, and makes more power. Also, you are leaving out part of the cam specs. The Lobe Separation Angle (LSA). That will determine how much overlap the cam has (intake and exhaust valves open at the same time). On paper, a 236/236 cam is going to have a lot of overlap, and lower vacuum, unless the LSA is pretty wide, like 118*. That cam might work really well in a 455, but would be pretty big in a 350. I'd re think my cam choice if I was you. Also, your tires are too short. About 1 1/2 to 2" short. I'm thinking that doesn't really look very good. The 70-72 Skylark/GS has very big wheel wells. There is a lot of room for some bigger tires that look much better.
Josh, I'm not a very smart man when it comes to guts of a Buick engine, but I'm learning, so when Larry speaks, I tend to listen. Take his advice under great consideration. That's my 2-cents.
well i like the way my car looks with those tires for now and thos are the tir i will use untill i do more performance and need bigger wheels what cam would you suggest
For a 350, it's hard to beat the TA212 http://www.taperformance.com/proddetail.asp?prod=TA_212-350 Can you post a picture of the car, side view?
Too small. This is my car with P255/60R-15's all around. Your tires are a full 2" shorter, although they don't look that short in the avitar, but it's a small picture. Are you sure of the tire size?
Dumb converter questions coming ... what's the stock stall speed of a th350 converter off a sbb 350? And when someone says, "... a stall speed of 2500." Are they referring to the low or high end of the stall speed? i.e., stall speed 2200-2800. My combination is TA90-94H cam, TA valve springs, home ported heads, polished TA stage 1 intake, current 2:93 gears (eventual upgrade to a 3:23 posi), 255/60-15 tires. TA says a small stall converter recommended. Is the stock OK or is a tad bigger needed? what would you suggest? Thanks. Jeff
Jeff, Stock stall speed is generally 1400-1600 RPM. Stall speed will depend on engine torque, car weight, and gearing. Take a stock converter that was behind a small block, and put it behind a big block, and that same converter will stall higher. Put the same converter in a heavier car, it will stall higher. Put it in a car with a lower numerical gear, it will stall higher. When someone talks about a 2500 stall converter, it is really misleading. There is no such thing as a converter that will stall at the same RPM in any application. That is why you shouldn't buy one out of a catalog. A good converter manufacturer will want to know everything about your car, and will custom build one for you. They will usually adjust it also if it is not right the first time. In general, you want the converter to stall about 500 RPM higher than the beginning of your power range. In your case, about 2000 RPM. There is also converter efficiency to consider. You want a converter to feel tight during normal driving, but stall higher when needed. That is the difference between a cheaper converter, and one that is custom built for you. It really can make or break your driving experience.
