400 engine with small valves

[BozoWise]

I read my original 1979 manuel and it says that they put 4 barrels on many motors as an option and you can tell by the third number in the vin. I have the exact info at the shop if anyone wants it shoot me an email. The vin code can tell you lots about the original setup.

 

[mike reeh]

so you have a '77 which I see from your user info...

well I just tore apart my bone ass stock 77 400 last nite.. and guess what I found, the 1.72" intake valves in the original 458642 heads... if you search for these heads, you will find little to NO information about them.. what casting number are your heads? the casting picture looks like an upside down "T" right..

my engine block was a '509 casting with 2 freeze plugs.. supposedly a good heavy duty casting. (2-bolt)

anyways this was out of my 77 GMC K25 -- oh and it was definately without a doubt a factory 4bbl /forums/images/icons/smile.gif

id sure like to know a little more about what you found as far as casting #'s and what not, weisel.

man for being 100% stock and 25 years old that motor made some damn good low end torque. but it really ran out of breath at about 4000.. and now I know why!

exact measurement of the valves are 1.72 intake and 1.5 exhaust.. as for CC volume, no idea.. get a syringe, some plexiglass, and vaseline out and find out yourself /forums/images/icons/smile.gif that would be a cool little job, plus I guarantee you wont find out anything more than what has been posted on the net.. I already looked. but if you do come across anything, let us see it.. my pistons were dished with valve releifs and it made what, about 8.5-9:1 compression?

mike

 

[Hossbaby50]

I think you might have miss read the casting number in your heads. I got this off Mortec.com. Unfortunalely there was no description beyond the below.

"468642.....76-up...350/400"

 

[72THING]

Tim, (84_Chevy_K10)
Autozone and Advanced Auto's computers say there is no such thing as a 305 with a 4 bbl, and some of the morons there agree religiously with the computers. I was just using that as an example of never say never. I wasn't saying there WEREN'T 305s with 4 bbls. I know I wasn't perfectly clear on that, so I'll try to explain it better in the future. But, don' t tell me I'm nuts until you need read the post carefully.

Will

 

[mike reeh]

no they are 458642, without a doubt. that IS a legit casting number, there is just very very little info about it out there.

mike

 

[Hossbaby50]

Just though that you might have miss read it when I saw that number on Mortec. I have had problems telling 5's from 6's on GM casting number before.

 

[HuskerBlazer]

I don't know where you're getting this info...We've got 2 81-85 trucks at my dad's lot with 350's. Our '84 Suburban has a 350. The spec's on GM say there was a 350 available. (all 1/2 ton) And you are saying there were no 350's available from 81-85?

 

[89Blazin]

My 400 sb with double hump heads has 2.02s.

 

[weisel]

mike reeh, it is an upside down "T", I'll bring the casting numbers to school on friday, but I think they are 468642