Hi, currently I have the stock 305 HO and 700-R4 in my 84 Trans Am. I've started building a 350 for it, but I have some questions. As far as a new balancer, I don't know which one to get. Summit has two versions. A 6.5" diameter one, and an 8" one. Which one do I use? Also, what is the correct number of teeth for the flexplate for my car, because I'm looking into getting a new one. I was told I need a new one because the rear mains were different between my 305 and the 77' 350 I'm building. Any suggestions on converters? Thanks.

 

Nothing is different between your engine and the one you're building other than the obvious (305/350)

The size of the balancer is whatever you want. Some people like bigger ones, some smaller. Larger ones are supposed to do a better job at higher RPMs, but that's speculation.

You can use the flexplate off your 305 if you want as long as it isn't cracked or warped.

As far as a converter, what is the rest of the 350 combo you're building? What rear gear do you have? What are your intentions for the car?

 

As long as your 305 is a two piece rear main seal, you are set. If it were me, I would just reuse the balancer that is on the engine now, as long as it is OK. Everything else will bolt up. I wouldnt bolt the stock exhaust back up though. It chokes a 305, it damn near kills the power from the 350.

 

I recommend having your crank, pistons, damper, rod, pistons and flex plate balanced. Also check and double check all clearance.

 

Use a balancer that matches the timing cover's tab location. A 305 has the tab at 12 o'clock, so a 305 balancer with the timing mark "up there" is needed. 350's and afterket setups place the timing tab atou roughly 1:30, so a balancer with the timing indicator "over there" is needed.

As far as re-using the balancer, inpsect it. Make sure the elastomer ring isn't slipping out. If you're really feeling exertive (don't think that's a word, but oh well), you can cross reference the timing mark with the piston location (TDC) to see if the outer hub has slipped any.

 

Why not just use the 305's timing cover too? That way you know they are good to go.

 

thanks for the replies. I will be using a crane powermax 2050, rebuilt ccqjet, s/r torquer heads, about 9.2 to 1 compression. I've got 3.73's outback, and it will be my daily driver, with trips to the strip every once in a while. So, i can just get a balancer for a 350 and a new timing cover and be set, right? (the marks will line up right?)

 

It depends on which balencer and timing cover you get. Why not just reuse the ones off the 305?

 

i guess i could, i would just like to use new parts is all. If it does check out ok though, i will use it

 

The thing is, this is my daily driver. I want to get the internals balanced, so it would take some time for me to get the old engine out and get off the old balancer/flexplate, take it to the shop, have them balance it, then put it all back together. So, which flexplate should i get? (as far as number of teeth, or any other suggestions.)

 

Be careful, I am not for sure about this but I thought that the 8 inch balancers were for externaly balanced motors (400) I could be wrong. Just make sure you use a balancer that matches the crank (internal/external balance).

Also, on your '77' 350, it may have had a 168 tooth flywheel/flexplate. If it did, and you are going to use the stock 153 tooth flywheel/flexplate off the HO, then make sure that your '77' block has the correct starter mounting bolt pattern for the 153 tooth starter. The 168 is differen't. I have heard that some blocks were drilled for both. My 74 block was not and I didn't find this info out about the starter bolts, untill I had the motor and tranny hanging halfway into the car. I had to pull it back out, take the tranny away from the motor and buy a new flexplate and starter then put it all back together.

That is what I get for not paying attention.

If the '77' block only has the bolt pattern for the 168 tooth starter, the shop you are taking the block to can drill and tap the new hole needed for the 153 tooth starter.

EDIT: The 168 tooth starter has a staggered bolt pattern, and the 153 tooth starter bolts are straight across from each other.