Firewall clearance with a 292 straight 6 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Dagobah · 10-06-2021, 09:53 PM

I was wondering if any of you good looking intelligent people could take a quick measurement between the back of the valve cover and the firewall if you've got a 292 in your truck with stock motor mounts.

We are looking at modifying our motor mounts (or frame mounts) to move the engine as far back as we can. Talladega here we come.

old51sedan · 10-09-2021, 09:17 AM

Quote:

Originally Posted by Dagobah

I was wondering if any of you good looking intelligent people could take a quick measurement between the back of the valve cover and the firewall if you've got a 292 in your truck with stock motor mounts.

We are looking at modifying our motor mounts (or frame mounts) to move the engine as far back as we can. Talladega here we come.

I see that no one has gave you a measurement, I can get that for you today, it will be the same as a 250 six. I'm curious as to why you want to do this as it will throw everything else off, nothing will fit right. Sounds like a lot of work to me.

RichardJ · 10-09-2021, 03:09 PM

Before I ask, why the hell, the 250 will have a different measurement, because the 292 head sits 1.75" higher.

My '67 with original 292, with manual trans and bellhousing mounts is sitting on really old rubber mounts.

The back of the valve cover is approximately 2 5/8" from the wall. The head extends farther back and measures about 1 7/8". These measurements are taken blind with old style, inside spring calipers.

If you are really serious, cut the firewall out, locate the engine and then build a new firewall.

Keep in mind, with the stock firewall. removing /installing a 292 head can be a chore. The #6 pushrods can't be removed without shifting the head forward.

**'68OrangeSunshine** · 10-09-2021, 05:37 PM

The 292 has a block that's 1-3/4'' taller than the 250, so it is much closer to the firewall.

If trying to remove push rods from #6, you can disconnect from motor mounts and rotate the whole engine to the right [Passenger Side] by 15 or 20*. [PIA]
I've been frustrated enough to think of boring a couple of 1'' holes in the top of the firewall ''alcove'' but didn't do it.

May70 · 10-11-2021, 01:14 PM

Concur with previous two posts. There is hardly any clearance back there as it is. You wont be moving the mounts back farther without modifying the firewall. If you did, you would probably have to pull the motor even to remove the valve cover. Not sure what it would gain you either but if you moved the motor back you would probably have to shorten the fwd drive shaft (right??).

I'm also one of the guys who found out the last one (or two) pushrods wont come out without contorting/pulling the engine.

IDK what you're doing but it sounds like a royal pain for ?? Good luck

54blackhornet · 10-11-2021, 01:37 PM

I swapped out a 250 for a 292 in a 68 C10. Tons of torque ripped out numerous set of motor mounts. It’s a great engine in a 3/4 or 1 ton truck used for pulling, certainly overkill for a daily driver...IMO

**LockDoc** · 10-11-2021, 01:46 PM

-
I don't know what you are going to use for a transmission but if you are going to use a manual with the bell housing mounts you will have to move the bell housing cross member back also. If you do need to do this it is a pain in the butt to get the rivets out of it with the cab in place.....

Just a heads up.

LockDoc

Justin Jones · 11-08-2021, 12:40 AM

Cab is off the frame currently, that's why we needed the measurement. We're not reusing the transmission/bellhousing crossmember. I know the 292 is longer than a V8 (of course), we were just looking to try to move it rearward as much as possible and not have to modify the firewall.

Dagobah · 06-25-2023, 10:25 PM

did anyone get a measurement between the firewall and a 292 valve cover?

**'68OrangeSunshine** · 06-26-2023, 12:37 AM

Maybe I can look later. It was 110*F today. Should drop to 75* tonight.
Did you want the height or the depth [from rear of valve cover to firewall]?

**67 twins** · 06-26-2023, 12:50 AM

Quote:

Originally Posted by Dagobah

did anyone get a measurement between the firewall and a 292 valve cover?

Your answer is in post 3. That's about the same as mine.

**67 twins** · 06-26-2023, 12:52 AM

Quote:

Originally Posted by '68OrangeSunshine

The 292 has a block that's 4'' taller than the 250, so it is much closer to the firewall.

If trying to remove push rods from #6, you can disconnect from motor mounts and rotate the whole engine to the right [Passenger Side] by 15 or 20*. [PIA]
I've been frustrated enough to think of boring a couple of 1'' holes in the top of the firewall ''alcove'' but didn't do it.

It's 1.76 inches taller, not 4 inches.

**'68OrangeSunshine** · 06-26-2023, 01:20 AM

Quote:

Originally Posted by 67 twins

It's 1.76 inches taller, not 4 inches.

You're right. I stand corrected.
Maybe I should've had 1.76 beers instead of 4 beers two-and-a-half years ago, when I answered that post offhand.
I really don't remember.

Dagobah · 06-27-2023, 07:58 PM

i appreciate it fellas!

**'68OrangeSunshine** · 06-27-2023, 08:46 PM

Quote:

Originally Posted by Dagobah

i appreciate it fellas!

OK. I'll put on my asbestos suit and go EVA in Direct Sunlight. It's only 104.
Gotta check the mailbox anyway.
Get back to you, if I don't vaporize...

Vertical Clearance .........4-1/2''
Horizontal Clearance......2-1/2''

'68 C/10 is a Factory 292, Original* engine on original mounts.
[* After a rebuild following 250,000 miles running with a '67 292 block. But we always put it on its OEM marks.]

Dagobah · 06-28-2023, 12:09 AM

that is awesome, thanks so much Orange

**'68OrangeSunshine** · 06-28-2023, 01:21 AM

Quote:

Originally Posted by Dagobah

that is awesome, thanks so much Orange

Yeah. No problem.
So if you're on Dagobah, I must be on Tatooine, where high-High Noon is when the twin suns Tatoo I and Tatoo II are both at their zenith, and humanoid lifeforms unlucky to be caught on the surface, get fried.

Dagobah · 06-28-2023, 01:35 PM

all I know is it's mighty humid here and I am definitely underwater on my project

**'68OrangeSunshine** · 06-28-2023, 11:57 PM

Quote:

Originally Posted by Dagobah

all I know is it's mighty humid here and I am definitely underwater on my project

I have an old fridge on the back deck for beers and sodapop. I went to grab a cold one this afternoon and it was 90* inside. The door had opened itself.
Also the electric motor on my swamp cooler is burned out. A room A/C an 4 fans are not cutting it.

Justin Jones · 10-28-2023, 01:20 PM

Quote:

Originally Posted by '68OrangeSunshine

OK. I'll put on my asbestos suit and go EVA in Direct Sunlight. It's only 104.
Gotta check the mailbox anyway.
Get back to you, if I don't vaporize...

Vertical Clearance .........4-1/2''
Horizontal Clearance......2-1/2''

'68 C/10 is a Factory 292, Original* engine on original mounts.
[* After a rebuild following 250,000 miles running with a '67 292 block. But we always put it on its OEM marks.]

It looks like the 2 1/2" is to the valve cover but the head is closer to the firewall. Is that correct? It's hard to tell from the picture. I didn't want to bug you to re-measure, just asking.

**MikeB** · 10-28-2023, 03:26 PM

I just have to ask why you want to move the engine back a couple inches, when it will cause all kinds of headaches for virtually zero benefit. Inquiring minds want to know.

Justin Jones · 10-29-2023, 09:13 PM

Less weight hanging out over the nose of the truck and more towards the center. Better weight distribution.

54blackhornet · 10-30-2023, 12:55 PM

Unless you’re autocrossing it no way moving it back a few inches will accomplish much. A built 250 would be a better choice. I replaced a shot 250 with a 292 and was very disappointed in the decision.

**MikeB** · 10-30-2023, 01:33 PM

Quote:

Originally Posted by 54blackhornet

Unless you’re autocrossing it no way moving it back a few inches will accomplish much. A built 250 would be a better choice. I replaced a shot 250 with a 292 and was very disappointed in the decision.

Yeah, I doubt you'd see even 30-40 pounds less weight on the front tires. I'm sure an engineer could put an actual number on it.

Battery relocation and an aluminum radiator would probably save you more up-front weight than moving the engine back a couple inches. Also an aluminum water pump, if available, and a manual steering box.
All the above are located well forward of the engine center line; some ahead of the axle line.

Interesting advice form 54blackhornet about a 250. Less weight, less torque, but more horsepower potential with a variety of aftermarket parts available for them. Just don't use a 250 with integral head and manifold.

However, it sounds like your minds are made up on a set-back 292. I hope it works out for you.

Justin Jones · 10-30-2023, 01:44 PM

We don't always do what makes sense but sometimes do what we want to do. lol. It might not help much but we do intend to also incorporate the mods you listed as well aside from the steering box. We've installed a rack and pinion which is aluminum.

The 292 is original to the truck so we are keeping it and we're trying to make it as light as possible.

10-06-2021, 09:53 PM	#1
Dagobah Registered User Join Date: Nov 2014 Location: shreveport, louisiana Posts: 28	Firewall clearance with a 292 straight 6 I was wondering if any of you good looking intelligent people could take a quick measurement between the back of the valve cover and the firewall if you've got a 292 in your truck with stock motor mounts. We are looking at modifying our motor mounts (or frame mounts) to move the engine as far back as we can. Talladega here we come.

10-09-2021, 03:09 PM	#3
RichardJ Registered User Join Date: Apr 2010 Location: So Cal Posts: 1,460	Re: Firewall clearance with a 292 straight 6 Before I ask, why the hell, the 250 will have a different measurement, because the 292 head sits 1.75" higher. My '67 with original 292, with manual trans and bellhousing mounts is sitting on really old rubber mounts. The back of the valve cover is approximately 2 5/8" from the wall. The head extends farther back and measures about 1 7/8". These measurements are taken blind with old style, inside spring calipers. If you are really serious, cut the firewall out, locate the engine and then build a new firewall. Keep in mind, with the stock firewall. removing /installing a 292 head can be a chore. The #6 pushrods can't be removed without shifting the head forward. __________________ '67 GMC 2500, 292, 4spd, AC Last edited by RichardJ; 10-09-2021 at 06:19 PM.

10-09-2021, 05:37 PM	#4
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,451	Re: Firewall clearance with a 292 straight 6 The 292 has a block that's 1-3/4'' taller than the 250, so it is much closer to the firewall. If trying to remove push rods from #6, you can disconnect from motor mounts and rotate the whole engine to the right [Passenger Side] by 15 or 20. [PIA] I've been frustrated enough to think of boring a couple of 1'' holes in the top of the firewall ''alcove'' but didn't do it. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not. Last edited by '68OrangeSunshine; 06-26-2023 at 01:21 AM.*

10-11-2021, 01:14 PM	#5
May70 Registered User Join Date: Jan 2019 Location: Hampton Roads VA Posts: 643	Re: Firewall clearance with a 292 straight 6 Concur with previous two posts. There is hardly any clearance back there as it is. You wont be moving the mounts back farther without modifying the firewall. If you did, you would probably have to pull the motor even to remove the valve cover. Not sure what it would gain you either but if you moved the motor back you would probably have to shorten the fwd drive shaft (right??). I'm also one of the guys who found out the last one (or two) pushrods wont come out without contorting/pulling the engine. IDK what you're doing but it sounds like a royal pain for ?? Good luck __________________ 70 C20 Build link : Project Montezuma http://67-72chevytrucks.com/vboard/s...d.php?t=794479 How to repair that rusted out 67-72 c10-c30! Please subscribe! https://www.youtube.com/c/MaycoCustomRestorations

10-11-2021, 01:46 PM	#7
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,656	Re: Firewall clearance with a 292 straight 6 - I don't know what you are going to use for a transmission but if you are going to use a manual with the bell housing mounts you will have to move the bell housing cross member back also. If you do need to do this it is a pain in the butt to get the rivets out of it with the cab in place..... Just a heads up. LockDoc __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -

10-11-2021, 01:37 PM	#6
54blackhornet Registered User Join Date: Jul 2008 Location: Eastern Oregon Posts: 2,386	Re: Firewall clearance with a 292 straight 6 I swapped out a 250 for a 292 in a 68 C10. Tons of torque ripped out numerous set of motor mounts. It’s a great engine in a 3/4 or 1 ton truck used for pulling, certainly overkill for a daily driver...IMO __________________ 71 C-20 07 Magnum RT AWD

11-08-2021, 12:40 AM	#8
Justin Jones Registered User Join Date: Aug 2015 Location: Shreveport, LA Posts: 39	Re: Firewall clearance with a 292 straight 6 Cab is off the frame currently, that's why we needed the measurement. We're not reusing the transmission/bellhousing crossmember. I know the 292 is longer than a V8 (of course), we were just looking to try to move it rearward as much as possible and not have to modify the firewall.

06-25-2023, 10:25 PM	#9
Dagobah Registered User Join Date: Nov 2014 Location: shreveport, louisiana Posts: 28	Re: Firewall clearance with a 292 straight 6 did anyone get a measurement between the firewall and a 292 valve cover?

06-26-2023, 12:37 AM	#10
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,451	Re: Firewall clearance with a 292 straight 6 Maybe I can look later. It was 110F today. Should drop to 75 tonight. Did you want the height or the depth [from rear of valve cover to firewall]? __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

06-27-2023, 07:58 PM	#14
Dagobah Registered User Join Date: Nov 2014 Location: shreveport, louisiana Posts: 28	Re: Firewall clearance with a 292 straight 6 i appreciate it fellas!

06-28-2023, 12:09 AM	#16
Dagobah Registered User Join Date: Nov 2014 Location: shreveport, louisiana Posts: 28	Re: Firewall clearance with a 292 straight 6 that is awesome, thanks so much Orange

06-28-2023, 01:35 PM	#18
Dagobah Registered User Join Date: Nov 2014 Location: shreveport, louisiana Posts: 28	Re: Firewall clearance with a 292 straight 6 all I know is it's mighty humid here and I am definitely underwater on my project

10-28-2023, 03:26 PM	#21
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,572	Re: Firewall clearance with a 292 straight 6 I just have to ask why you want to move the engine back a couple inches, when it will cause all kinds of headaches for virtually zero benefit. Inquiring minds want to know. __________________ Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, 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!

10-29-2023, 09:13 PM	#22
Justin Jones Registered User Join Date: Aug 2015 Location: Shreveport, LA Posts: 39	Re: Firewall clearance with a 292 straight 6 Less weight hanging out over the nose of the truck and more towards the center. Better weight distribution.

10-30-2023, 12:55 PM	#23
54blackhornet Registered User Join Date: Jul 2008 Location: Eastern Oregon Posts: 2,386	Re: Firewall clearance with a 292 straight 6 Unless you’re autocrossing it no way moving it back a few inches will accomplish much. A built 250 would be a better choice. I replaced a shot 250 with a 292 and was very disappointed in the decision. __________________ 71 C-20 07 Magnum RT AWD



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10-30-2023, 01:44 PM	#25
Justin Jones Registered User Join Date: Aug 2015 Location: Shreveport, LA Posts: 39	Re: Firewall clearance with a 292 straight 6 We don't always do what makes sense but sometimes do what we want to do. lol. It might not help much but we do intend to also incorporate the mods you listed as well aside from the steering box. We've installed a rack and pinion which is aluminum. The 292 is original to the truck so we are keeping it and we're trying to make it as light as possible.

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