I got a 454 BBC out of an 82 model motorhome for my early Chevy shop truck. Now, anyone who's ever driven one knows, 80s model big block Chevys are weak pigs. Why are they so weak, is it the cam, compression, heads, all of the above? What can I do to waken it up, short of changing heads or raising the compression. I have an Edelbrock dual plane intake to put on and a real carb. Do I need to change cams? or, am I just pissing money away if I don't redo the whole thing with better heads and some real compression? I just want a great running half ton truck. Someone with big block experience enlighten me here.
if it's just for running errands and hauling stuff it'll be fine with just your manifold swap (as long as it's not the tall deck) and a small carb like a 600 cfm edelbrock Or you could put some better breathing heads on it, like the 049's or 781's some cheapo headers a new cam, lifters and timing chain For a mild motor like that, I like the Schnieder 294/284 hyd Edelbrock dual quad and 1-3/4" tube headers. throw in a windage screen and flex fan and you're making an easy 325 hp with as much as 500 fp torque. all that stuff is relatively cheap and easy to find used. hell, I got most of that just laying around Paul
kind of along ways away for you but, here's an example of a good breathing head cheap http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33617&item=2443096864 there should be something like that in your area too. oh yeah, it might help to know what youre looking at too, like this ebay listing for instance, he is calling it a closed chamber head, the 781 is an open chamber design. open chambers do have less valve shrouding but I've made good power with closed chambers too, like the 215 casting.. damn, all this makes me want to build another one!
H.H. I have a pair of complete good used 781 heads $150 and a pair of bb headers for a pickup. $25 + ups. Lemme know, i'd like to sell em. Thanks
GM was fond of installing the cams in their smog-era motors a few degrees retarded...alot of times an older or aftermarket timing chain will really wake 'em up a bit. But...if you've got the cover off and planning an intake swap anyway...might as well slip a new cam in there, too! If you can find an older Holley Street Dominator intake for the oval port heads, it really works well with a 750cfm Holley vacuum secondaries carb, or a 700cfm double pumper. Headers, a little more spark advance, and some basic tuning will gain you some power without a head swap or compression increase...and you'll still be able to drink pump gas!
What I have is an Edelbrock Performer intake. I figured on using a 750 Edelbrock carb. I know people bag on them, but I've always been real happy with the Edelbrock carbs. Holleys require more maintenance than I like. Seems like I'm always having to fiddle with the mixture screws or replace busted accelerator pump diaphrams. The engine sat from 1990 till 2003 without ever turning over, so I'm sure that on the valves that were opened, the springs are weak. I figured a new cam and springs. I am open to cam recomendations. Half ton truck with 3.73 gears and a 2200 rpm converter. I want a little sound to it.
If you already have the Performer intake, then use it for sure! The 750 Edelbrock carb works okay on a driver and requires minimal fuss...so you'll be fine with that if you're not into tinkering with carb adjustments and tuning. Picking a cam with 'a little sound to it' usually requires sacrificing low-end power and living with a less than optimal set-up in a low compression street engine with moderate gearing, but I think you can get away with the following cam...it won't play "Hot For Teacher" for ya...but you'll notice a slight lope at a slow idle and it'll work well in a warmed-over 454... Crane grind # H-272-2 Duration @ .050" = 216 int/228 exh Advertised Duration = 272 int/284 exh Lobe separation = 112 Gross Lift = .515 int/.510 exh It's a Hydraulic Power-Max grind. Install it with a good double roller timing set and new lifters along with the new springs you mentioned.
I used one of Comp Cams extreme energy cams here, in my old grocery getter, this version also had the Edelbrock TBI heads with small combustion chambers to bring the compression up a point. 4.10 posi w/ 2500 stall..
This one has the 074 rectangle heads, and for the life of me, I don't remember which cam it has in it! but it's not too wild here it is in an earlier form with the iron oval 049 heads..
OK so what heads would be stock in an 83 1 ton Suburban? Timely thread as my bud wants to pick this low mile rust free "Texas Cadillac" and use it for some heavy towing. It also sat for 5 years but was recently driven up from FL with no problems. So what do you guys suggest to warm this thing up?
my 82 model 454 has #346236 heads on it. Listed as 120cc open chambers, 225 intake/ 116 exhaust port cc I figured they'd be the little peanut heads used on lots of truck 454s, but when I got the intake off, they're the same size as regular oval ports.
Cam, headers, vacuum advance from an early 70's bbc and use manifold vacuum to control it. The aftermarket intake and 750 cfm carby will fit right in. The lighter centrifugal advance springs help too. The original early 80's smogger motors retarded the timing as long and as far as posible to get the entire fuel mix burned in the combustion chambers. Really hurt performance and made 'em run hot. The distributor and cam mods will really wake up that smogger.
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