79 Blazer with 396 big block

[Bhovseth]

I just got a 79 Blazer that has a 396 big block in it instead of your standard 350 or 400 small block. The engine is pretty much brand new and has had alot of upgrades on it. When I orginally got the truck it had a HUGE cam in it that required a stall converter. I had a new cam put in it that is good for low and mid range power. The truck also has Hedman headers and a 3 inch flowmaster exhaust. Since I got the truck it has eaten up 3 starters and a drive shaft. I had to get a high torque starter installed as it kept eating NAPA starters left and right. My question is this. Have any of you put a Big Block V8 in an older blazer and if so what kind of problems have you encountered? Or do any of you anticipate any other problems I am going to run into with the extra horsepower of the big block engine. It does have a Turbo 350 tranny in it which I am kind of worried about.

Basically I have had my Blazer 3 weeks and it has been in the shop 2 of those weeks. I hope this is not a trend that is going to continue. Thanks for any advice in advance.

 

[RingMaster4x4]

You will prolbey have problems with the TH350, But what about tires, susp, Gearing? what are they like what do you use it for? A little more info would help us help you.

 

[RingMaster4x4]

there is also a lot of people from AZ on this board.

 

[PhoenixZorn]

I once came home with a grin on my face and told my dad I found a 66 Impala with a 396... he told be it had way too much power for me, being only 16 at the time, and it had a powerglide tranny.... I would have probably killed myself in it. =)


Anyway... your switch to a high torque starter will probably fix your starter problems, as big headers on a big block produce un-real amounts of heat for a standard NAPA starter. I blew my own starter the day after I brought my truck home after my 350 install with headers. I put a standard starter back on, and I'm going to buy a high torque starter to replace it with, but will still run the standard one until I blow it up.

As for your driveshaft problems, did you replace it with a stock shaft or did you get a performance or offroad aftermarket one? I'm pretty sure the torque a 396 produces even in stock form is unbelieveable when up against a stock driveshaft. You will probably continue ripping them apart unless you build it up or change something. With the Turbo 350 tranny, you should be ok with the 396, since they came stock behind the 396 for a few years if memory serves... If you want to upgrade, I don't have any suggestions for you, but if you initially had a bigass cam in it for high end power, and now have a low end power cam, you may have thrown off the balance between your motor and tranny. It may now have too much low end power for a T350 to handle... but again, I'm not an expert in that field.

I would however say if that 396 is anything but stock, you are pushing near 350-380hp and 400-450ft/lbs of torque. The stock one was big enough, running between 280-320hp, depending on the car it came in.

 

[Bhovseth]

You will prolbey have problems with the TH350, But what about tires, susp, Gearing? what are they like what do you use it for? A little more info would help us help you.

It has 35 inch BFG mudders on it. As far as I know about the drive train it is all stock. The suspension appears to have cheap but new shocks and a 4 inch lift. I just had the front and rear end diff serviced. I also had the wheel bearings repacked all the way around.

Also after the shop replaced the camshaft in it(it is a comp cam model 11-205-3 I think) 2 days later it was making alot of noise from the engine. The engine only has about 400 miles on it as it was just built by a motorhead who ported and polished the heads and built the motor orginally for a race car but later put it in his blazer which explains why it had such a huge cam in it. Anyway 2 days later the engine made loud banging noises so I took it back to the shop and they found the camshaft to have chunks out of it and very worn on the 7th cylinder I think they said. They beleived it to be a defective camshaft and got a new one from comp cams and now it is running great and hast ALOT of power. Thanks for the replies to my post.

 

[RingMaster4x4]

your TH350 should last OK as long as you don't hot rod it too much, but don't be too suprized if you don't have a little trouble in a year or two. I when through 4 TH350's (each lasting about a year execpt the last on that made it two) in my blazer in my sig. line, but I was hard on it and I am running bigger tires.