I've searched the archives and can't find any threads really informative on this subject.

Again, I'm going to look at a few camaros this weekend. The one I am definitely coming back with was described to me as a 85 IROC with a tpi 350 with rear discs and posi. I know the 350 is not original (what do you want for $400) but I am looking for a quick way to determine a 305 from a 350. External differences would be helpful, but the only things I know of is the exhaust manifold outlet is 2 1/4" for a 350 instead of 1 7/8" for a 305. Then again, if the motor was swapped in, these may be different anyway. I know to look at the casting number in the rear of the block, however, I don't have a complete list of 350 casting numbers, (I am assuming it is a roller block with the TPI on a 350, these weren't readily available until 87 so 87-92 casting numbers would be helpful)and it is difficult to see this with the engine installed in the vehicle. Anyone else know of any other distinct differences externally that are somewhat readily identifiable? I believe the crank pulley is the same size right? Measuring the diameter or counting teeth on a flywheel may prove to be difficult with this much snow on the ground (the cars are in a field). The cylinder heads may not be original either, but if they were, are there any determining characteristics between these besides casting numbers? I have also seen in a recent thread a comment about injectors for a 350 being purple color, however, this does not necessarily determine displacement on something for sure not original.
Anything else different on the block itself?

I have looked for enough 400's before, so I know that drill.
Basically I'm looking for tips to quickly determine a 305 from a 350. Any assistance would be greatly appreciated.

((Damn spelling errors ))



[This message has been edited by 89ragtop (edited January 24, 2001).]

 

the crank pulley is the same, the harmonic BALANCER is different.. there's somewhere to start.. the 350 will be slightly bigger.. they both use the same flywheel, both use same rotating assembly..

look at the VIN on the front of the block... that's another place to start..

look at the valve covers, that will tell you if the motor is a newer motor as it will have to have centerbolt valve covers, if not it's either an older 350 using the 85-86 TPI intake, or a roller 350 using pre-87 heads..

exhaust manifolds are the same
accessories are the same
distributor is the same

shine a flashlight behind the drivers side head and use one of those extendable mirrors that have an angle head and see if you can see the displacement... i have a 305 out of a 79 Camaro and it says the engine displacement..

that's about it... hope i gave you a few ideas..

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Webmaster: www.IROC-Z.org

 

you can't use the injectors as a guide..

you can't use the heads as a guide, either... the guy coulda put in a shortblock instead of a longblock..

harmonic balancer is the biggest clue

flywheel is the same, as they both use the same starter.. all SBCs use the same starter...

 

I know just about anything on the engine besides the block itself won't really help me positively determine one from the other.
I don't have any info that states what different sizes of balancers came on these. I've read 6 3/4" diameters were used on most all 305 and 350's after 1969. Is there a difference in the thickness perhaps?

 

i don't know the exact dimensions of the harmonic balancers but my best bet on the displacement would rest on that...

i can't think of anything else that right off the bat would clue you in... i know the knock sensor for a 305 is different than 350, bigger fuel injectors and also the computer chip..

the VIN is really the only way to tell, or the casting number on the rear-driverside of the block..

sorry man, i'd like to help you further...

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Webmaster: www.IROC-Z.org

 

I know I'm just gonna have to check in the rear of the block. It is just a PITA when it's still in the car. Oh well. Thanks anyway.

If anyone has anything else to say, spit it.
Thanks.

 

Balancers are the same, bothe 6¾". I have some of them.

Blocks are the same size.

The easiest way to tell is by the block casting number. That doesn't lie. Even the numbers stamped in the deck in front of the pass side head can be replaced. The # is on top of the bell housing flange, behind the driver's side head. Post the casting # or look it up at www.mortec.com . The factory was also kind enough to cast either a "5.0" or "5.7" there in digits about ¾" tall.

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"So many Mustangs, so little time..."
ICON Motorsports

 

The '87 Firebird I had 5 years ago had a 305. When I changed the timing chain, the balancer was 'hollowed out' on the back side. The '82 Z-28 of my friends' had a 305. It had a 'hollowed' out balancer (had to pull it off to go on the crate 305 I put in for them). The '88 GTA I had, with a 305 TPI, had a 'hollowed out' balancer. The '89 RS 305 Camaro I had had a 'hollowed out' balancer. My current toy, an '88 GTA with a 350, has the 'solid' balancer. None of the 350s I've seen since 1967 have had the 'hollowed out' balancer. However, I do seem to recall some early (mid to late 70s) 305s with a 'solid' type, albeit smaller, balancer. My suggestion would be to reach down and feel the backside of the balancer. If you can feel a 'hollowed out' area, the odds, in my opinion, is it would be a 305. If it is solid, most likely 350. Not always the case but it is a pretty good indicator.
jms

 

precisely... i was pretty sure that the harmonic balancers were different..

i thought they changed them to a larger size because of bigger displacement..

question: 400cid balancers are larger in diameter than 350cid?

 

No. Most 400 balancers are the same diameter as some 350s (some 350s used a smaller diameter-about 7"). About 8". However, the 400 is (for the lack of a better word) scalloped out around the outside of the balancer, about halfway around it.
jms

 

so the 400 is externally balanced both on the flywheel and harmonic balancer?

guess i learn something new everyday

thanks Jim

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Webmaster: www.IROC-Z.org

 

The 400 small block Chevy is externally balanced and uses a specific balancer and flywheel, both of which do not interchange with any other size small block.
jms