Flywheel
 

Im going to change flywheel and starter in my 81 auto Im wondering if the flywheel is internally or externally balanced?

Orig engine? 350 or 355? 2-piece seal? Internal. Flywheel neutral.

original engine 350 was bored and balanced may have a 400 crank did not get build sheet from engine builder not sure on seal

You cannot put a 400 crank in a 350 without a lot of work......work that is not cost effective anymore. If you think it has an aftermarket 383 crank......look for a "bite" or "notch" out of the harmonic balancer. This will be external.......
I would pull the flywheel and post a pic here.......easily identifiable.

Jebby

Thanks for all your help harmonic balancer was smooth all the way around

like jebbysan said

OP
Motor's been into ... too many possibilities ... guessing game ... pull flywheel ... count teeth (168T or 153T) ... post clear pics of both front & back of FW.

With flywheel off, post a clear pic of crankshaft flange-boltcircle.

make note if there is ANYTHING sandwiched between back of FW & crank flange-boltcircle.

Why are you changing the flywheel. Starter gear on flywheel beat? Replace the ring gear. 20 bucks. Little bit of heating and beating. But at any rate, removal is first step in replacement. Don' order anything until you get old one off and know what you have.

Ive been having starter trouble and now teeth are a little worn so i want to change both. I thought I had 168 tooth flywheel due to staggered mount starter but it was 153,

Nope. If you have old style staggered bolt starter, it only works with 168 tooth flywheel. This guy? https://www.ebay.com/itm/BBB-Industr...EAAOSw241YlO61. Will miss 153 tooth wheel by a half an inch. NO 81 came stock with 153 tooth flywheel. Here is what you need. See YouTube for install instructions. Man trans only. Auto trans welded on. https://www.ebay.com/p/Clutch-Flywhe...94916fffea06f4

Thanks for the info. Im really hoping to use small mini starter due to hooker headers not a lot of room,

This is what I run:

PRW 1628300 SFI-Rated 21 lbs. 168 Teeth Billet Steel Flywheel for Chevy SB V6/V8 1955-85 265-454

https://cimg6.ibsrv.net/gimg/www.cor...c57e24ef39.jpg




and this starter:
https://www.jegs.com/i/MSD-Ignition/121/5095/10002/-1

MSD Ignition Red DynaForce Starter Chevy V8

starter Permanant Magnet Gear Reduction (PMGR has a planetary gear; fits closer than ministarter w/ spur gear) $50 delivered
https://www.dbelectrical.com/product...sdr0019-l.html


flywheel perfection 168T internal balance 2-pc RMS 30 pounds $70
https://www.summitracing.com/parts/p...et?prefilter=1

Pull your flywheel. Post pics and casting number. Inspect teeth and post pics of the worst ones. Chech auto machine shops near you to see if they can change the ring gear and how much. Can be done at home though. Ring gear in 400 degree oven. Flywheel in freezer overnight. And unless high compression big block and 7000 rpm use, the 50 buck starter and 69 buck flywheel will do the job.