clamshell mount placement - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sammywells · 11-21-2019, 07:33 PM

Working on a 68 1/2 ton with 350 and Hei and a 700r4. Using the later clamshell mount. Brackets are from a c20. My question is where do i mount the brackets to the frame so the i have enough clearance with the hei and firewall. There are different holes in the frame but not sure which ones to use. Right now I just have a rolling chassis and want to mount the engine and want to make sure the engine doesn't hit the firewall when i put cab on. Transmission mount is already loose and can be moved.

GASoline71 · 11-21-2019, 09:40 PM

Are you referring to engine stands as the "C20 brackets"?

Gary

sammywells · 11-21-2019, 10:14 PM

Yes, engine stands from a c20

**HO455** · 11-21-2019, 10:39 PM

Here is how my 67 is mounted. The front holes pictured and not the best photo showing the distributor in relation to the firewall.

sammywells · 11-21-2019, 11:50 PM

HO455, is that a clamshell mount. Looks like the older style.

**Grumpy old man** · 11-22-2019, 12:22 AM

This picture might help , small block with a turbo 350 trans .

**MikeB** · 11-24-2019, 01:59 PM

SammyWells -- I suggest you create a new thread asking if there are HEI clearance issues with a small block mounted in the rear set of frame holes on a 67-68. I can't recall any issues on the this forum, and I'd bet at least half the 67-68 trucks have been upgraded to large cap HEIs.

**HO455** · 11-24-2019, 02:30 PM

Quote:

Originally Posted by MikeB

SammyWells -- I suggest you create a new thread asking if there are HEI clearance issues with a small block mounted in the rear set of frame holes on a 67-68. I can't recall any issues on the this forum, and I'd bet at least half the 67-68 trucks have been upgraded to large cap HEIs.

I am not completely sure but I believe the back set of holes were used on K models and HEI clearance is tight on those with some trucks OK and others touching the firewall.
If SammyWells still needs a measurement I can get one from the core support to a cylinder head (on my 2wd Burban) which would be the same no matter which style of motor mounts you made use of.

**MikeB** · 11-23-2019, 06:02 PM

On my 69, the rear set of holes on the frame are for 4WD trucks, the front set for 2WD. I have seen 67-68 2WD trucks use the rear set of holes, but I'm not sure they were all like that. I don't know what to tell you when using clam shells, because even my 69 C10 didn't use them.

Any movement fore or aft from the original location will require driveshaft lengthening or shortening, and may affect gear shift linkage and clutch linkage, if applicable. So make sure you keep it where it belongs. As for HEI clearance, my 69 had tons of clearance behind the HEI, but, again its 350 engine was mounted in the forward holes.

Also, it's important to make sure the engine has the correct driveline angle, and that your engine mounts put the radiator fan in the center of the fan shroud. Even when using an electric fan, I like to have the intake manifold carb pad level with the ground. Nothing looks sillier than an engine that's leaning forward. And even level is not ideal.

BTW, what was the original engine?

69 C10 small block mounts. 67-68 are probably the same.

11-21-2019, 07:33 PM	#1
sammywells Registered User Join Date: Jun 2018 Location: Lucasville,oh Posts: 61	clamshell mount placement Working on a 68 1/2 ton with 350 and Hei and a 700r4. Using the later clamshell mount. Brackets are from a c20. My question is where do i mount the brackets to the frame so the i have enough clearance with the hei and firewall. There are different holes in the frame but not sure which ones to use. Right now I just have a rolling chassis and want to mount the engine and want to make sure the engine doesn't hit the firewall when i put cab on. Transmission mount is already loose and can be moved.

11-21-2019, 10:14 PM	#3
sammywells Registered User Join Date: Jun 2018 Location: Lucasville,oh Posts: 61	Re: clamshell mount placement Yes, engine stands from a c20

11-21-2019, 10:39 PM	#4
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 11,393	Re: clamshell mount placement Here is how my 67 is mounted. The front holes pictured and not the best photo showing the distributor in relation to the firewall. Attached Images __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377

11-21-2019, 11:50 PM	#5
sammywells Registered User Join Date: Jun 2018 Location: Lucasville,oh Posts: 61	Re: clamshell mount placement HO455, is that a clamshell mount. Looks like the older style.

11-22-2019, 12:22 AM	#6
Grumpy old man Senior Member Join Date: Dec 2013 Location: Gods country East,Tn Posts: 8,545	Re: clamshell mount placement This picture might help , small block with a turbo 350 trans . Attached Images __________________ 1967 Factory short bed - Old school '71 - 350 / 4bolt / 487 heads / Edelbrock C3BX Muncie M-22 4 speed / Hurst Comp plus Factory 12 bolt posi 3.73 / 255-70-15 Smoothed firewall / Factory cowl induction Power disc brakes / power steering / 3.5-5" drop

11-24-2019, 01:59 PM	#7
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,599	Re: clamshell mount placement SammyWells -- I suggest you create a new thread asking if there are HEI clearance issues with a small block mounted in the rear set of frame holes on a 67-68. I can't recall any issues on the this forum, and I'd bet at least half the 67-68 trucks have been upgraded to large cap HEIs. __________________ Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

11-23-2019, 06:02 PM	#9
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,599	Re: clamshell mount placement On my 69, the rear set of holes on the frame are for 4WD trucks, the front set for 2WD. I have seen 67-68 2WD trucks use the rear set of holes, but I'm not sure they were all like that. I don't know what to tell you when using clam shells, because even my 69 C10 didn't use them. Any movement fore or aft from the original location will require driveshaft lengthening or shortening, and may affect gear shift linkage and clutch linkage, if applicable. So make sure you keep it where it belongs. As for HEI clearance, my 69 had tons of clearance behind the HEI, but, again its 350 engine was mounted in the forward holes. Also, it's important to make sure the engine has the correct driveline angle, and that your engine mounts put the radiator fan in the center of the fan shroud. Even when using an electric fan, I like to have the intake manifold carb pad level with the ground. Nothing looks sillier than an engine that's leaning forward. And even level is not ideal. BTW, what was the original engine? 69 C10 small block mounts. 67-68 are probably the same. __________________ Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

Thread Tools
Show Printable Version Email this Page
Display Modes
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.