Wednesday, December 22, 2010

Chevy Starter Tech Guide


The Inside Scoop On Chevy Starters & Accessories
STORY Wayne Scraba

Starters for Chevy cars are simple, or so it seems. But get the mix of flexplate or flywheel diameter and starter nose combinations wrong, and you’ll be met with plenty of frustration. Another sizeable issue is absent hardware.

If you miss a piece or two (case in point is the oft-missing nose brace), then your starting woes will increase manifold. The end result will never prove warm and fuzzy.

Before we examine the starters and ancillary hardware, there are some things you should know about Chevy flywheel/flexplate combinations. As most of you are aware, some starters don’t fit certain flywheels and vice versa. The following chart depicts the various flywheel/flexplate combinations (and vintage GM part numbers) used in pre-’86 Chevrolets:

Chevrolet Flexplates & Flywheels
Description Vintage Part No.
•14-in., neutral balance, 168-tooth, SB 471598
• 14-in., neutral balance, 168-tooth, BB 471597
• 14-in., counterweighted for 400,168-tooth 471578
• 14-in., counterweighted for 454, 168-tooth 14001992
• 123/4-in., neutral balance, 153-tooth, SB 471529
• 123/4-in. nodular iron, 10.4-in. clutch, neutral balance 14085720
• 123/4-in. nodular iron, 10.4-in. clutch, counterweighted for 454 3963537
• 14-in. iron, 11-in. clutch, counterweighted for 400 3986394
• 14-in. iron, 11-in. clutch, counterweighted for 454 3993827
• 14-in. iron, 10.4- & 11-in. clutch, neutral balance 3991469

As you likely gathered, there are some critical differences in the above combinations, particularly when it comes to flywheel (and flexplate) size and balance. Two different systems of balance were used on Chevrolet V-8 engines: Internal balance and external balance. Aside from 400ci small-blocks and 454ci big-blocks, all pre-1986 Chevy V-8 engines were internally balanced. The others were manufactured with externally balanced or “counter-weighted” flywheels and harmonic dampers. The correct flywheel/flexplate combination must be used for these engines. If the right mix of hardware isn’t used, expect some serious vibration issues which will eventually lead to considerable engine grief.

Two different flywheel diameters were used: 14-inch and 12 3/4-inch. The large diameter flywheels incorporate a 168-tooth ring gear while the 12 3/4-inch versions maintain 153 teeth on the ring gear.
The 1986 and newer flywheels and flexplates have a 3.00-inch crank flange bolt circle, while earlier units use a 3.58-inch pattern. The 14-inch ring gears require a starter with offset bolt holes in the nosepiece. On the other hand, 123/4-inch examples use a starter with bolt holes that are parallel. Almost all Chevrolet blocks are drilled for both types of starters.

Vintage part numbers for Chevrolet heavy-duty starter offerings:
Description Vintage Part No.
• HD starter, 123/4-in. flywheelor flexplate 1108789
• HD starter, 14-in. flywheel or flexplate 1108400

Way back when, if you had (for example) a good 12 3/4-inch flywheel starter and your car was fitted with a 14-inch flywheel, there was a relatively easy fix: change the nosepiece. Chevy offered the starter nosepieces separately, and you’d disassemble the starter and replace the nosepiece. A couple of other pieces that made up the starter puzzle were heavy-duty starter braces along with unique shouldered mounting bolts. If you don’t use the appropriate bolts along with a starter nose brace, you’ll be sure to encounter cranking woes. The following chart shows vintage part numbers for these pieces (keeping in mind most, if not all, of these old part numbers are likely long discontinued):

Description Vintage Part No.
Starter nose piece - for use with 123/4-in. flywheels 1968122
Starter nose piece - for use with 14-in. flywheels 1984098
Starter brace – small-block 354353
Starter brace – big-block 3965588
Starter bolt, long 14057099
Starter bolt, short 14057098
Starter bolt, special for use with 1966-’68 Corvette starters 3733289

Starter Identification
Like other musclecar components, the starters feature an identification number along with a date code. Prior to 1956, all Delco starters used an identification tag that was riveted to the starter motor housing. After the 1956 model year, the tag was eliminated. The starter ID number and date code was stamped directly into the body of the starter housing. Given the massive number of starters used over the years, it is impossible to list every combination. However, the stamped starter ID number happens to coincide with the unit part number.
What about date codes? These codes consist of a number that represents the final digit of the calendar year. In other words, a number “9” indicates 1969. Following the year code is a character that indicates the month of production. This character is a letter. Following the month code character will be a number or pair of numbers, which designate the day of the month (from “1” through “31”).

A sample starter date code might be as follows:
9 E 7

Broken down, the “9” indicates 1969 (1959 also applies). The “E” is the alpha code for May while the “7” indicates the seventh day of the month. Month codes are as follows:
NOTE: If you look at the above chart, you’ll notice that the letter “I” is missing from the above format. Why? Like many other GM date codes, the “I” could easily be mistaken for the number “1” and as a result, it was left out of the sequence.

While we’ve included the vintage part numbers, chances are you’ll have a very difficult time finding any of those pieces today. And if you do, there’s also a good chance the piece might cost you significantly. That’s the bad news. The good news is companies offer all sorts of starter hardware for Chevys. And aside from date codes, all of it is indistinguishable from vintage hardware.

Parts We Used
What follows is a short list of reproduction pieces we used in the article. Unlike the vintage part numbers, these pieces exist and are readily available.

Some pad-mounted starters, such as traditional Chevy jobs, incorporate shims to provide correct clearance between the starter drive gear (pinion) and the engine ring gear. At one time, a clearance figure of between 0.025-inch to 0.040-inch was recommended when the starter drive gear was engaged to the flywheel.
Typically, the baseline clearance figure used by many mechanics was 0.030-inch between the peak of the starter pinion gear tooth and the base of the flywheel teeth. In fact, many replacement Chevy starters of old included a set of shims that totaled 0.030-inches (thickness). But how do you know when to add or remove shims?
If the starter is making excessive noise, the folks from Delco provide the following troubleshooting info:

• If the starter has a high-pitched whine while cranking (before the engine starts), it usually indicates excessive starter-to-block clearance. Either remove the shims or reduce the number of shims to decrease the clearance.

• If the starter has a high-pitched whine after the engine fires (as the ignition key is being released), then there isn’t sufficient clearance between the block and the starter. In this case, increase the thickness of the shim pack or add shims.

• If the starter motor grinds and the engine does not start, then the gap between the starter drive gear and the ring gear is too tight. You have to shim the starter out (away from the block). In addition, take a close look at the ring gear. There’s a possibility it is damaged.

Code Month
A January
B February
C March
D April
E May
F June
Code Month
G July
H August
J September
K October
L November
M December

1 If you take a close look at a heavy-duty high-torque Delco starter, you’ll note the large (and unique) cast-iron nosepiece – most standard Chevy starters have aluminum nose pieces. Additionally, an offset bolt-hole pattern such as this example indicates that the starter will fit large (14-inch, 168-tooth) diameter ring gears.
2 Occasionally, you’ll have to shim a starter away from the cylinder block in order to obtain the correct gear clearance. There are plenty of shims out there, but we’ve found these 0.012-inch thick jobs used on some aftermarket mini-starters are perfect, even with the heavy-duty iron-nose Delco starter. FYI, you can also use thin fender shims, but this style of shim cannot fall out.
3 Believe it or not, these bolts are critical when installing a Delco starter. Note the special shoulders on the bolts. The shanks on the bolts are slightly oversize and serrated. They are designed so that the bolts will not back out once they are tightened. When installing these bolts, torque them to spec first (usually 25 to 35 lbs-ft), and then tighten the nose brace.
4 A key item that’s often missing is the starter nose brace. It should be considered mandatory on all HD applications. Chevrolet offers brace assemblies for big- and small-block models. They support the nose weight of the starter. Without it, the nose sags and can go out of sync with the ring gear. Even if you don’t use one of the HD starter assemblies, you should always include a starter brace.
5 Bolted to the oil pan rail (using the pan bolts) is a special clip that holds the battery cable in place. Most of them were thrown away over the years when the engine was serviced. With a couple of these clips in place, you don’t have to worry about using a zip tie (or worse) to affix the battery cable.
6 Clipped to the top of the Chevy starter solenoid in stock form is a special “S” clip. It holds the starter wiring harness in place (this is the harness that runs from the firewall, behind the passenger-side cylinder head, to the starter solenoid). If it’s MIA, then you can count on fried wires. Obviously, starting then becomes a big issue.


  1. After looking at the starter on my '02 Blazer and seeing it as a type of mini starter with the offset bolt pattern. I was wondering if it would fit the earlier offset pattern and have enough power to crank the 350 in in my Camaro? Primarily what I'm looking for is the sound.

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