Minor correction on net and gross HP. 1970 and earlier numbers are gross, 1972 and later are net. However both net and gross were advertised in 1971. I have the numbers only for Camaros, and since Nova is it's close cousin there should not be much difference:
1967 -155hp -8.5:1 -non-int -2"ex -points -3.08 3/4spd 2.73pglide&econo-3/4spd 3.55perf-all
1968 -155hp -8.5:1 -non-int -2"ex -points -3.08 3/4spd 2.73pglide&econo3/4spd 2.56econ-pglide 3.55perf-all
1969 -155hp -8.5:1 -non-int -2"ex -points -3.08 3/4spd 2.73pglide&econo3/4spd 2.56econ-pglide&TH350 3.08perf-pglide 3.36perf-3/4spd
1970 -155hp -8.5:1 -non-int -2"ex -points -3.08 3spd 2.73pglide
1971 -145hp -8.5:1 -non-int -2"ex -points -3.08 3spd&pglide
1971 -110hp -8.5:1 -non-int -2"ex -points -3.08 3spd&pglide
1972 -110hp -8.5:1 -non-int -2"ex -points -3.08 3spd&pglide
1973 -100hp -8.25:1 -non-int -2"ex -points -3.08 3spd&TH350
1974 -100hp -8.25:1 -non-int -2"ex -points -3.08 3spd&TH350
1975 -105hp -8.25:1 -1st-int -2.25"ex -HEI -3.08 3spd 2.73TH350 3.08perf-TH350
1976 -105hp -8.25:1 -1st-int -2.25"ex -HEI -2.73 3spd&TH350 3.08perf-both
1977 -110hp -8.3:1 -2nd-int -2.25"ex -HEI -2.73 3spd&TH350 3.08perf-TH350
1978 -110hp -8.1:1 -2nd-int -2.25"ex -HEI -2.73 3spd&TH350
1979 -115hp -8.0:1 -non-int -2.25"ex -HEI -2.56 3spd&TH350
Sorry if the axle ratios are a bit messy on there. Your '74 auto Nova with posi should be 8.25:1 CR with TH350 and a 3.08 posi rear. I'm not sure what year they went to the 8.5" rear, but IntegratedJ's and my '78s are 8.5", so I assume the '75 to '77 must have been as well. The only advantage the '66 engine has over the '74 is 0.25:1 extra CR. Hardly worth it.
Your '74 has hardened exhaust seats for unleaded, which is a plus. And it has a non-integrated cylinder head which is great for upgrading. Your wheezy 210cfm Monojet and 2" exhaust manifold can be swapped for a Holley 390cfm, Offy intake, and a pair of Langdon cast headers. Tubular headers won't fit on car engines, only trucks have the clearance. An alternative is getting a 2.5" HD 292 exhaust manifold or reproduction of it for tractor/generator inlines. HEI was the year after yours, but definitely upgrade to an HEI distributor with a quality cap/rotor/wires. Upgrade it with a Crane adjustable vacuum advance and springs kit. And while you're at it, swap the fixed 4 blade fan for the 3 blade truck clutch fan, or electric fans.
To figure out power upgrade numbers, best consult DueceCoupe and his Gonkulator.
But to take full advantage of the bolt ons, the stock non-integrated head is the weak point. That needs lumps and 1.84"/1.6" valve upgrades, and decking the head to reduce CCs too. And upgrading from the stock cam at least a step up to a hydraulic 240 or more.
Thank you for the extensive answer!!!
Yes mine is a 10 bolt 8.5 rear. I dont like the 308's in the rear, but they'll have to do for now. I am not racing or anything. Just a daily driver but would like some different size gears later on.
I didn't know my 74 had hardened exhaust seats for unleaded, since I didn't have a cat converter. I keep adding lucas ethanol treatment with every tank full.
The combination you just named is pretty much what I wanted to do. I figure start buying the parts, and once I have everything, then do the work.
My head was replaced right before I bought the car. He had blown the rad, and ended up cracking the head. He bought a used head, and had broughers speed shop check the used head he bought, and had it pressure tested also. Car runs perfect, besides me wanting more hp for hills...etc.
I did have the valve cover off to replace the gasket, he over tightened it...., and the numbers I found were as follows:
J69 towards the front of the engine on the head.
Towards the middle, looked like 1828000
I looked everywhere, but someone on a Nova forum said it appeared to be a 292 head from 69? I dunno. I can't find those numbers anywhere on the net.
I don't see those 390 holleys online anywhere, unless I am just being stupid and getting older. I found a local Offy intake on the craiglist, but he wants 500 bucks. Bit steep for me on a used one.
