400 SBC...EDIT: Rod Bolt Issue, Post 6

[toomany]

I'm rebuilding a 400 and was running the casting numbers. I got the block figured out (330817, 72-80, 2bolt, still looking for casting date), but when I did the heads ran into some confusion. The numbers are 458642...which show up on MorTec's website. But it's showing they only came on 350's. Now I know I have a 400 block (casting # proved that, and it has the "dimples" on the sides). The site is showing 333882, 468642, 3951598, 3973493, 3998997 comming on 400's. I am 100% possitive that my #'s are 458642...even had to other people read them.

The guy I bought the motor from said it had been rebuilt once and he was the original owner. I don't really think he would have swapped heads, especially from a 350...he knew his way around a motor.

My question is, would I be ok running these heads (assuming they check out ok)? If they were off a 350...I'm betting they've had the steam holes drilled already (haven't pulled them yet). The motor ran and made good power, but smoked allot (looked like you were pouring oil down the carb). It didn't smoke at start up or when idleing...just under load. So I'm thinking it's the rings, but I'm not gonna throw it together without going through the heads.

I was also looking for the chamber size and valve sizes, but couldn't find anything.


FWIW: This motor will be going into an 88 Camaro (I'm up to 4 now ) with a 700R4. I'd almost like the heads to come back cracked so I can get a set of aftermarkets...but the budget is a little tight for that.

 

[b454rat]

As long as they have the steam holes it will be fine. I ran a set of 350 heads on a bunch of 400s, had great results with all of them...

 

[82355]

They will work fine. I even know people who run them without the steam holes (I wouldn't personally). I would recommend just scrapping them instead and buying a set of Vortec's. By the time you get the machine work done to rebuild a set of heads, you end up at about the same price with an inferior head.

Martin

 

[4X4HIGH]

I just checked my books and the 458642 is definately a 327 or 350 head used between 1968-1986. Someone could have drilled the steam holes in those heads though.

 

[toomany]

I would recommend just scrapping them instead and buying a set of Vortec's. By the time you get the machine work done to rebuild a set of heads, you end up at about the same price with an inferior head.

That's what I want to do...but the budget might not allow it. I know that a set of aftermarkets is near the same cost as refurbishing a stock set.

I just checked my books and the 458642 is definately a 327 or 350 head used between 1968-1986. Someone could have drilled the steam holes in those heads though.

You wouldn't happen to know the camber size?

 

[toomany]

Found out that the heads were drilled for steam holes...so I'm good to go there. I ran into a possible issue with one of the rod bolts. All the rods appear to have the stock bolts in them. Untill I get to the #8 cylinder. One of the bolts looks like it's really streched, or it's been replaced. Has anyone ever seen this before? You can see how far the threads are sticking up above the nut compared to the other ones. I'll probably replace the bolts anyways, but I'm currious to see what other people think of it.

 

[royjones]

ok

while its apart replace them

 

[Hogback Fabrication]

For sure, the one with the threads sticking out was thrown in there by the previous owner. He probably lost one of the studs and had to replace it with one he could buy at the hardware store.

ARP studs are cheap insurance, that's what I would do.

 

[toomany]

I pulled the cap with the threads sticking out last night...the nut on the taller stud was finger tight! I put the socket on there and gave it a twist with my hand and it broke loose! On the plus side it is an actuall rod bolt that he replaced it with, just a longer one. Surprisingly the motor did not knock any (had low oil presure though). I had it running in my K5 a little over a year ago and in the Camaro friday night.

 

[cuervo]

I pulled the cap with the threads sticking out last night...the nut on the taller stud was finger tight! I put the socket on there and gave it a twist with my hand and it broke loose!

I would say that alone warrants a full going over of the entire engine.

 

[Captainfab]

SB400's have shorter connecting rods (5.565") as well as shorter rod bolts as compares to all other small blocks (283,327,350) This was done to provide adequate clearance with the 3.75 stroke. It sounds to me like someone replaced that one rod bolt with one for a 5.7" rod. You'd definitely want to replace all those rod bolts.