[Ronj1969]

Does the flywheel determine the clutch disc size ? Is it supposed to be 10.5 or 11 switching from a Saginaw to a Muncie and want to make sure I have everything for a smooth transition

[PAUL K]

With a Pontiac the bolt pattern on the flywheel determines the clutch diameter. A lot of aftermarket flywheels accept both clutches.

[Ronj1969]

I think it’s the factory flywheel

[STEELCITYFIREBIRD]

The outer diameter of wear pattern from the previous clutch disc will be very telling. ✌🏼

[Ronj1969]

Tourqe Master is the only clutch and pressure plate I can find locally at Oriellys anybody have luck with either of them

[tom s]

Look up McLeod.Internet is your friend.Tom

[78w72]

I use the Zoom brand clutch in my 78 400 4spd, summit carries them and some others, been 15+ years in use & works great on the street and some test & tune drag use. Pretty sure it was a 10.5" but a stock flywheel should only use 1 size so just confirm that size with the oreilys part. I used a Hays brand billet steel flywheel that I think accepts 10.5 & 11".

[72projectbird]

Originally Posted by Ronj1969

Tourqe Master is the only clutch and pressure plate I can find locally at Oriellys anybody have luck with either of them

I've never used that brand, but if the car is mostly stock, they're not super picky about clutches.

[John Milner]

If your flywheel is on a 1977 400, it probably has the small 2.5" center register and as far as I know, all of those flywheels accepted an 11 inch clutch. Probably best to just measure your existing clutch and get a clutch after you have verified. Some clutch kits do not come with the right pilot bushing for a Pontiac crankshaft. I have used National 7109 pilot bearing in a lot of Pontiacs.

[Ronj1969]

This is what I purchased hoping it fits

[track73]

My 79 WS6 came with an 11" clutch.

[Ronj1969]

My block is from a 76 Catalina I remember there were 2 sizes of flywheels when I got mine 20 yrs ago I bribe there was a 2.49 and a larger 2.75 ? Now I’m in the hunt for some Muncie shifter rods

['ol Pinion head]

Def measure the pilot on the crank, many 400 cranks have been replaced in the late '557 shortblocks over the years. Thinking back, I believe Pontiac went to the smaller pilot size in mid '76 model. In the Pontiac 400 core program I had going for over a dozen years, one of the main reasons I shut it down was my hitting a long streak of pulling '76-78 400 shortblocks with cranks that had spun rod bearings. Got to a point that pulling a '557 400 long block core just to get 6X heads, a dexent valley pan, hardware, & occasionally a good timing cover, wasn't worth the time. At the time, I would not pull to stock a standard bore '557 400 blocks unless it was really clean and/or had a 4 speed TransAm 2 letter code.

['ol Pinion head]

Attempting to aource the shifter rods, the first thing I'd do is see if the stamped steel shifter bracket you have will bolt up to the tail housing of your early Muncie. The '71-74 1/2 Muncie tailhousings have a wider triangular pattern than the tight mtg pattern which is used when mounting to the bosses on the 5 bolt boss "W" pattern early Muncie tail housings. Later today, I'll do a comparison out in the shop & take some pics.

[78w72]

Originally Posted by 'ol Pinion head

Thinking back, I believe Pontiac went to the smaller pilot size in mid '76 model.

1976 sounds about right for the change to smaller pilot size... but an FYI is that the 78-79 & possible 77 W72 engines used the larger pilot crank of earlier years, they used the 481988 blocks for W72s & apparently the older cranks too.

I found that out when rebuilding the 78 W72 engine in my 78 TA, the original flywheel had some issues & the machine shop suggested replacement vs surfacing & reusing, I bought 2 or 3 OEM type flywheels and found out they had the smaller pilot, none of the auto parts stores or even summit had the right one for my 78 W72 4 speed... the only aftermarket flywheel I could find with the larger size pilot (at the time ~2008) was the hays billet from summit, has been in use & working great since.

[Ronj1969]

Here is what I have I also will have the rods and shifter from the Saginaw

[unruhjonny]

With the clutch you have two factors:
1) od size of clutch disc
2) transmission input shaft style (eg: coarse or fine spline; typically 71+ Muncie is fine - some 70 Muncies were fine, but if the trans was rebuilt, you will have to confirm.

With the shifter, and rods you have three factors at play:
1) shifter mount
2) gear levers
3) shift rods

71-74 Muncie shifter mount is the same part used for 74+ BW-ST10.

the 1-2 & 3-4 roads are interchangeable between both styles (there is another thread that I believe I shared side by side images);
The hardest to find shifter rod is the correct 70-74 Muncie reverse rod;
The BW transmission has the reverse gear in a different spot, so these are very different.
I have found that if you are willing to invest the time, you can find a suitable replacement for the OE reverse rod.

If you use the aftermarket hurst rods, you have to use the corresponding hurst gear levers;
I personally prefer the OE rods, as they are beefier, but many others prefer the aftermarket rods.

Good luck!

[John Milner]

It appears that your shifter bracket is bolted upside down. Flip the bracket to where the threaded hole is pointing up. The bracket should look like the one pictured when bolted up.

As far as the Saginaw 1-2 3-4 rods/arms working for the Muncie, you are just going to have to bolt your shifter up to your Muncie, line the shifter up and try them.

['ol Pinion head]

Originally Posted by 78w72

1976 sounds about right for the change to smaller pilot size... but an FYI is that the 78-79 & possible 77 W72 engines used the larger pilot crank of earlier years, they used the 481988 blocks for W72s & apparently the older cranks too.

I found that out when rebuilding the 78 W72 engine in my 78 TA, the original flywheel had some issues & the machine shop suggested replacement vs surfacing & reusing, I bought 2 or 3 OEM type flywheels and found out they had the smaller pilot, none of the auto parts stores or even summit had the right one for my 78 W72 4 speed... the only aftermarket flywheel I could find with the larger size pilot (at the time ~2008) was the hays billet from summit, has been in use & working great since.

In the last 40 years, have personally owned over a dozen original '77-79 factory 400 4speed engines. 5 of them in #'s matching project cars, over a half dozen just as WA-WC-Pwh coded shortblocks or intact original engines. Though quick inspections, every one of them had its original small pilot "late" 400 cranks, not an early 2.75" pilot 400 crank. Further, for many years, I pulled nothing special 6X-8 headed '557 casting 400's out of '76-78 model Pontiacs as part of a whls engine program I had going with my Pontiac engine builder. After several years of putting together 400 6X-4 combo's, I was always running short on decent oil pans, timing covers, late valley pans, & oil filter hsgs. As my Pontiac crate engine builder buyer did not desire the '557 casting 400 blocks, I typically parted out the more generic '557's & set aside the few '77 W72 blocks that i came with. Eventually I supplied numerous small pilot std/std 400 cranks to locals who were determined to stick with the small pilot matching factory 11" flywheel in their '77-79 4speed TransAms.

In the mid 00's, I ran into a streak of tearing down three '557 casting shortblocks in a row which had bad crank journal/spun rod bearings. For well over a decade, all of these longblocks were bought at a deep wholesale price (way less that what you, 78w72 or I would sell a decent used valleypan for over the last dozen years). At that point in time, I began to question the effort I was putting into pulling these low value 400 cores. Continued to buy, but was much more selective.

[PAUL K]

Fwiw..... When Pontiac switched over to the light weight 75-79 small register crankshafts, some of the early versions had the larger 2.75 hub.

I've never seen a 76 or later 400 block use the heavier large hub crankshaft from the factory.