454 tall deck truck block

4SPEED427 · A Poncho Legend!

454 tall deck truck block

DonSSDD · Canadian Poncho Superstar!

454 tall deck truck block (new thread)

4SPEED427 · A Poncho Legend!

454 tall deck truck block

DonSSDD · Canadian Poncho Superstar!

454 tall deck truck block (new thread)

CdnGMfan · Canadian Poncho Superstar!

A 7.4 would only be in 70 series, as in C70 single axle, M70 tandem drive. Series 10 - 20 -30 are considered light duty (1/2 ton to 1 ton), and by the latter 1970s they were 2-tier light duty. Truck over 6000 GVW (better than 1/2 ton) were exempt from catalytic converters and Corporate Average fuel economy. 40s never used big blocks, and 50s (later called 60) used only 366 big blocks.

4SPEED427 · A Poncho Legend!

CdnGMfan wrote:
A 7.4 would only be in 70 series, as in C70 single axle, M70 tandem drive. Series 10 - 20 -30 are considered light duty (1/2 ton to 1 ton), and by the latter 1970s they were 2-tier light duty. Truck over 6000 GVW (better than 1/2 ton) were exempt from catalytic converters and Corporate Average fuel economy. 40s never used big blocks, and 50s (later called 60) used only 366 big blocks.

Yes, I posted wrong information above and I will correct that. While a 40 or 50 series was considered a medium duty truck, only the 60, 65 or 70 series medium duty trucks were available with 366 or 427 or 454.

LT1Caddy · Poncho Master!

Carl... for education purposes. Would that be single axle dump truck, 5 ton straight truck?

4SPEED427 · A Poncho Legend!

60, 65 or 70 could be single axle or tandem. The number remained the same but the letter designation for the truck changed between single and tandem axle. Kind of like pickups, a C truck or a K truck being 2 or 4 wheel drive.

CdnGMfan · Canadian Poncho Superstar!

CE is single axle V8, CS is single axle L6, ME is tandem axle V8.

Series 10, 20, 30 were light duty.
Series 40 was 1.5 ton with light duty styling through 1962. When they came back for '67
they used medium duty styling.

Series 50, 60, 80 were the mediums 1960 - 66.
Renamed 40, 50, 60 for 1967 through 72.
Renamed 50, 60, 65 for 1973, the 65 became 70 for 1978.

There was also a 70 & 80 series heavy duty conventional, the JV series. They ran from 1966 - 1988, ending up as a Brigadier / Bruin then Volvo-White-GMC.
Those ran GMC V6s through '73 for gas versions, replaced with tall deck 427 gas V8s for later versions. Typically they were Detroit Diesel powered though. A heavier 90 series came out for '70 & was what was still in production when GMC sold their heavy truck business to Volvo in the latter 1980s.

4SPEED427 · A Poncho Legend!

I am hoping someone knows of a 454 tall deck in a 1979 or 1980 C70 truck. I would love to get the casting number off the block.

On the site where I was being mocked for thinking they exist, it has gone completely silent since I posted the VIN and Service Parts Identification Decal that you see above.

I know they're still out there but SO hard to find. C'mon guys, help a brother out!!!

4SPEED427 · A Poncho Legend!

Still no luck finding a 454 C70 truck. I just watched this video. 4:00 mark, "new 7.4 litre"

Prefectca · Poncho Master!

I dont think the 454 truck block would be any different than the 427. Same bore size. All GM would need to do is manufacture four ring pistons to suite the longer stroke of the 454. GM already had a steel 454 crankshaft to use, I think it was probably a cheap way to increase cubic inches. It probably didnt work out in the sale department as trucking companies were more familiar with the 366 and 427 engines and usually just replaced the fleet with the same options as what was ordered previously.

Paul

4SPEED427 · A Poncho Legend!

454 tall deck truck block

ROSIES CAR · Addicted!

What makes those blocks different than others. Are they a desirable engine.

Prefectca · Poncho Master!

ROSIES CAR wrote:
What makes those blocks different than others. Are they a desirable engine.

To put a 454 crankshaft in a 427 the block needs to be notched for clearance due to the longer stroke. I had forgotten about that in my previous post. The big truck 454 was only available for two years, 1979 and 80 and other than in brochures no one has seen one. Carl found a truck serial plate and option list showing a 454 in a large truck and wants a block casting number to determine if it was a special casting or if it was a tall deck truck block or a standard 454 block.

4SPEED427 · A Poncho Legend!

Prefectca wrote:
ROSIES CAR wrote:
What makes those blocks different than others. Are they a desirable engine.
To put a 454 crankshaft in a 427 the block needs to be notched for clearance due to the longer stroke. I had forgotten about that in my previous post. The big truck 454 was only available for two years, 1979 and 80 and other than in brochures no one has seen one. Carl found a truck serial plate and option list showing a 454 in a large truck and wants a block casting number to determine if it was a special casting or if it was a tall deck truck block or a standard 454 block.

Thank you, perfect answer!

Prefectca · Poncho Master!

I was looking at farm trucks on Marketbook and found two with the S engine code. Unfortunately no pictures but they were both listed as having a 427!

4SPEED427 · A Poncho Legend!

Prefectca wrote:
I was looking at farm trucks on Marketbook and found two with the S engine code. Unfortunately no pictures but they were both listed as having a 427!

Can you PM me the links for those? Or post them here? I have been trying and couldn't find any.

Prefectca · Poncho Master!

https://www.marketbook.ca/listing/auction-results/217126417/1979-chevrolet-c70-farm-trucks-slash-grain-trucks

https://www.marketbook.ca/listing/auction-results/221522723/1979-chevrolet-c70-farm-trucks-slash-grain-trucks

4SPEED427 · A Poncho Legend!

Thanks, I'll have to create an account and check those out.

73SC · A Poncho Legend!

Something doesn't add up, both sale vehicles are Code S which Carl has undisputable evidence is the 454 V8 gasoline engine. One add says its a 427 even though VIN is code S, the other is silent on CID.

Perhaps the seller of the vehicle was so used to having 427's he just assumed the truck had it even when it was a 454. Regardless I believe Carl's evidence of the 454 truck engine and agree it would be nice to actually see one.

4SPEED427 · A Poncho Legend!

The smoking gun is there, just have to nail down a casting number. Gotta still be a few out there somewhere!

4SPEED427 · A Poncho Legend!

The guys over at Team Chevelle had a good laugh over my claims about a 454 tall deck last fall when I raised this topic. Anyone who knows me is well aware you can't hurt my feelings, so I really didn't care!

Anyway, I let the topic rest there after all kinds of GM details were posted showing evidence (brochure info, VIN breakdowns showing engine codes, part numbers from parts books etc) but I had no actual pictures of a block, piston, crank etc. Today a guy posted over there with pictures showing the block, crank, piston and rod etc from a 454 tall deck he took apart. The piston is unique because it has 4 rings. It's the same bore as a 427 but the pin is in a different place on the piston between 454 and 427.

I think the block is the same casting number as a 427 but it's notched for clearance for the connecting rod because of the longer stroke on the 454.

koolconvertible · Poncho Master!

You can make a monster stroker engine from the tall deck 427.....

GLHS60 · Poncho Master!

Appreciate you posting this Carl!!

That was my thread over at Team Chevelle that got updated.

I've had computer problems and haven't received many thread updates.

I'll have to find Clint's thread on here as I was unable to login for a longtime.

Thanks

Randy

4SPEED427 wrote:
I would like to continue the discussion on the 454 tall deck truck blocks here. Clint's thread about the tall deck he found in a wrecking yard has been somewhat derailed by me so to keep them separate I'll do this.
To begin, most people have never heard of tall deck 454's in the GM C70 trucks it seems. People on this forum have always been very courteous when I discussed the fact that the tall deck 454 exists, although it's super rare. People on other sites haven't always been as kind! The ones who have heard talk of them almost without fail vehemently deny such a thing ever existed. I've been mocked and ridiculed, recently I was told a tall deck 454 is a unicorn and that I was a ghost chaser. All fine, I've got thick skin and I really don't care if people didn't believe it.
Yesterday I found some evidence that is hard to argue with. A GM VIN for a 1980 GM C70 truck with the fifth digit of the VIN (the engine code location) being an S which decodes as option L42 7.4 litre (454).
Now, does anyone happen to know where one of these actually is? I'd love to get the casting number off the block as well as the stamped code on the front of the block, right side in front of the head (if they do the C70's the same as the cars and pickups.) If you are close to a 79-80 C70 and are able to look for an S in the fifth spot of the VIN that would be great. Thanks!