Thinking about a 454.. 1978 GMC C15 1/2 Ton

[HunterRotten]

A topic I posted in the 73-87 section has had a lot of feedback and I am seriously considering a 454. In fact I told the guy I'd take the 1981 454 with 115,000 miles for $500 and the 094 heads for $300 ontop of that.

If you want to read up on that, here is the link to the thread.

Someone suggested I come here and ask what this would do to my truck. My truck as of right now has mcgaughy's 2" lowering coils and 2.5" drop spindles. I plan on replacing the coils with 1" drop coils from Belltech if I find out what the spring rate is. If not, then stock equivalent coils. To accompany this, I also have CPP tubular control arms on the top and bottom.

On the rear end I now have brand new 1950 lb springs (4+1 leafs) and a set of caltracs. This has been flipped with a mcgaughy's flip kit.

Here's an image of how the truck sits with the 2.5" drop spindles, 2" drop coils, and 1250 lb rated leafs on a flip kit that are sagging.

There's a lot of unknowns here and thats why I've come to this forum to see what other opinions are. I think the 1950 lb springs lifted the rear up but not much more than .25"

[andrewmp6]

Something else to think of do you have a 10 bolt or 12 bolt rear end ?

[HunterRotten]

Originally Posted by andrewmp6

Something else to think of do you have a 10 bolt or 12 bolt rear end ?

I have a tremec TKO 500 manual 5 speed, a heavy duty driveshaft made locally and a GM 12 bolt with a factory 3.42 ratio.

My truck is in pieces so I can't really test it out with dumbbells. I don't have the cab in my possession at this moment.

[James the III]

sbc is 575 lb
bbc is 685 lb

this is both all iron including the intake..
so 100 lb different..
get 100 lb's of dumb bell weights and put them in the engine compartment..
and look at how it sits..