Okay so I have a 1970's truck longblock... It's going into my firebird this spring break. I was wondering about any extra parts that will be needed. I'm 95% sure that it will bolt to my 700r4, is that true? Any special tools I need? I should probably get a timing light, eh?

Any input at all is appreciated, considering ive never done this before.

 

Yes your trans will bolt to it.

You will need a different oil pan. Get one for a 2nd gen Camaro 70½-79, with a driver's side dipstick tube. The truck pan will not fit your car.

You will need a flex plate of the same sixe you have now, probably 12¾" (153-tooth), except for a 55-85 motor instead of a 86-up one. The one for a 83-85 Camaro/Firebird 305 is the correct one.

The driver's side dipstick will not clear your car's exhaust manifolds. You need headers anyway; get a set for a TPI 350, NOT FOR L03, and the cat and cat-back to match. Good excuse for headers.

 

I've got Hooker 2055s already on the car.
I was wondering about that damn flywheel though, guess I gotta get a new one.
83-85 will work? whats the avg cost for one of them? I'll look now...

 

When I bought my IROC (a 1986), it had a really sick 305 tuned port motor. I had an extra truck 350 that I was running in my Corvette temporarily. I had rebuilt it for 10:1 compression, stuck an Iskendarian 270 cam in it, ported the stock iron heads as much as I could, and left the truck oil pan in it. And it fit just fine in my F-body. The truck motor I have is also from the 70's.

The block is desireable, because it's a 4-bolt main block. I have it overbored 0.030" over. I would like to stroke it to make a 388, but it's still running perfectly after about 50,000 miles.
It's also extremely strong. I have been able to beat up on LS1-powered F-bodies with about a 3 to 4 car length lead on them. Totally pisses them off too.

All I did to the tuned port was to bolt it on. Went from a carb to tuned port, not even a prom change. I always intended to play around with the prom, but never got around to it. It does have a true dual exhaust system with Hooker headers. But otherwise, it's just a simple engine swap that worked very well.

My dipstick is on the passenger side, by the way. The # of teeth on the flexplate, I don't really recall. I think it is probably the smaller 153 tooth set up.

350's are internally balanced, so you might end up with a very slight imbalance if you swap from the truck's larger flywheel to the smaller F-body one. OR you could keep the larger one and swap bell housings. Lakewood makes a bellhousing that'll work. I had to do that when I had the 355 in my Vette.
Or you could just try the smaller stock flywheel and get a Fluidamper harmonic balancer. If you feel anything, it would be a slight throbbing at steady rpm's. It's more important to use a manual tranny engine with a manual tranny. Or else you'll have to have a machine shop rebalance if it wasn't.

T5 manual transmissions are very limited in how much torque they can take. Your 350 will make enough to shorten the lifespan of that transmission. So budget some money for repair or eventual replacement.

 

Rockin - He has an automatic transmission. And you're wrong about the size affecting balance. The only thing it would affect is the starter type. (You're really using a carb PROM to run a TPI???)

Token - For an automatic, it's commonly called a "flexplate", rather than flywheel. I don't know how much they cost, but the typical Summit/Jegs type is 168 tooth. Boneyard might be a better choice, but you could probably order one through a parts store or dealer.

70's truck heads are pretty poor choices for performance. Porting them is pearls on swine - a waste of time & money. I'd seriously consider doing something in that area before going ahead with this swap.

 

Vortec 906 heads

 

You said "1970's truck longblock". That means block, rotating assembly, & heads. You never mentioned Vortec heads.

Add Vortec-specific intake manifold to the list of needed parts.

 

What I meant by the "size affecting balance" was that the engine is internally balanced using a particular component. It wouldn't necessarily affect balance, but it potentially could. I have been told by my machinist that if my friend using the 283 I built for him and had balanced for his Turbo 200 flexplate, decided to switch to a 700R4 with its larger flexplate, that I really should have the assembly rebalanced. Because it was spin balanced to that particular combination. I agree with you that any effect would be minimal at best, but it doesn't hurt to have a perfectionist machinist. I'm not going to worry about it, and you're probably right, he shouldn't either.

Another clarification, my IROC had the 5.0 liter TPI engine. The prom is a tuned port injection prom, but it is still the original California spec OEM chip. For that matter, I'm also still using the 19 lb/hr 305 injectors. I realize a few tenths in the quarter could be gained by upgrading injectors and prom, but shoot, pulling away from an LS1 F-body by at least 3 carlengths isn't bad. I know my 355 tuned port motor can't breathe like the LS1, but it's all in the torque.

I also agree that with the Vortec heads out, it doesn't make since to port a stock 70's iron head. But when I built this engine, the Vortec wasn't even developed yet. So my choices were $400 spent porting and shaving the stock heads to flow well, or a grand for the cheapest aftermarket head.

Like I said, 3 carlengths ahead of an LS1 is simply performance that works. Better heads, stroking to a 383, upgraded prom, bigger injectors...these are all in the future.
But it is possible to build fairly serious performance into these cars without spending a small fortune.

 

The flexplate/flywheel should never be part of the internal balancing. It should be balanced separately if required. a machinist that balances the rotating assembly with the damper/flexplate/flywheel is doing his customer a disservice.

But, like you said, this shouldn't be something Token worries himself over.

 

Five7kid, I wish I could agree with you, but unfortunately I don't. I've called a few machinists in our area, known for their performance engines, and they are in agreement.

Anytime you change an internal component, rods, pistons, crank, etc., you have to check the balance. The harmonic balancer needs to be a part of the spin balancing procedure. Likewise, either flywheel or flexplate has to be part of it on the other end of the crank as well.

I've experienced this in practice. The truck motor in my IROC I originally built for an earlier IROC, but I couldn't get the title paperwork straightened out, so I got rid of it. This motor was balanced for a flexplate. The 327 went bad in my 68 Corvette, so having a spare motor, I swapped it into my Corvette temporarily until a permanent engine could be built for it. Only problem was, the Corvette had a Muncie, and therefore, a flywheel instead of a flexplate. The engine ran well, but always had an out of balance throb at certain rpm's. Later, when I got another IROC with a clear title (the one I have now), I swapped it again, and this time, there was a flexplate for the IROC's 700R4. The throbbing is gone and the engine runs MUCH smoother now.

Please correct me if I'm misunderstanding you. I agree that different flexplate sizes shouldn't really matter, but I disagree that the flexplate/flywheel is not part of the balancing procedure.

Regards

 

You should not balance an engine with the damper or flexplate/flywheel because you may need to change or replace one of those items. Do that, and then you have to rebalance the engine.

You had an out-of-balance flywheel and/or clutch. Being "balanced for a flexplate" had nothing to do with it.

The damper/flexplate/flywheel are only part of the total balancing process in that they should be balanced - not that they are balanced with/to the engine.

 

My block is from a 78 Fullsize truck. Mine already had the smaller pan on it, So I didnt need a new pan. I also used the flexplate that was on the truck motor. It might be different for you, I already had a built Th-350 in mine. Right now I have some decent older 1.94 heads on it, But my next step is a nice Vortec 906 with some port work, or some Sportsman IIs!