Just bought a 1979 1/2 ton 4X4 short bed...

[57NAPCO]

I bought it a few months ago and just now had a chance to fly out to northern Calif to pick it up. Guy told me it had 82,000 original miles, one owner. Seems to be true but he also had told me it had a 350/350th in it.
I just pulled in to Eureka, CA and got a hotel, I popped the hood and I look at the emissions sticker and it says 6.6. I checked the glove box and sure enough it says 400ci engine. Is there an easy way to tell if it is a 400ci by just looking at it? Sure looks to be a 350. Either way it's a good truck.
Thanks

[Boosted1984Silverado]

Just get the casting number off the block in the back. If its hard to get to I just use a small collapseable mirror to view it.

[Bowed]

350's are internally balanced and 400's are externally balanced . For the 400 you can look for weights on the engine side of the flex-plate and a balanced / harmonic balancer , which is usually done in the form of a cut or notch on the backside of the balancer . 400 casting #'s are 330817, 3951509 and 3951511 . If it has 3 freeze plugs each side it is 4 bolt and 2 freeze plugs each side are 2 bolt on the 400 .

[57NAPCO]

Thanks for the info, I was hoping there was an easy way to visually see it


I'm heading up to gold beach Oregon this morning to do some commercial albacore tune fishing with a good buddy. Then back to Texas, 2700 miles in total for this trip...if it makes it,,, hah

I'd post pictures but this software does not allow it directly off an iPad or iPhone

[Bowed]

Originally Posted by 57NAPCO

I was hoping there was an easy way to visually see it

Well the balancer is easy to check out . Like I said there should be some type of cut or notch on the rear edge of the harmonic balancer , but I have seen 400's with a light scalloping on the front edge of the H-B or even a small weight tacked on the front side , after-market style . The 350 harmonic balancers are smooth edged . They also left a hair more material on the outside of the block at the cylinder bores on the 400 . you might be able to see or feel the irregularity . If it is in fact a 400 and you run in a hot climate , you should have a heavy duty radiator . . Good luck fishing .

[4x4k30]

here is a pic of a 400 balancer