easytobedead

I have recently picked up a 1979 hurst olds with the olds 350. I would like to beef up this engine with out having to tear down the hole engine.Lead me in the right direction

455man

You concerned about leaving it stock? or stock appearing? Are you tested for emissions?

easytobedead

well any thing i take off im keeping just so if i want it stock again i can put it back on but it will not have to be emission so thats a good start.

69442C

I restored a 79 HO for someone about 8 years ago and we did just as you are asking. I used to own the car back in 80's so I knew how it ran and that a little more power would be nice. The engine as it came from the factory was 170 HP I think..maybe 180. After the engine was rebuilt and upgraded a little, we figure we were able to achieve 250hp and maybe a little more.

The car I owned was featured in the Jan 1980 issue of Super Stock magazine and when the article was done, the car was run at Atco Dragway and ran 16.7 in the 1/4 mile. No race car but not a total slug. I installed a test pipe, rejetted the carb, changed the advance in the HEI and I was able to achieve 15.7 @ 89 mph at the same track. Not aweful considering the car had 2:73 gears. Photo attached of one of those passes taken in 1982. And yes, I did beat the 403 T/A whose driver was not too pleased. But to be fair, his car wasn't tuned correctly.

One of the drawbacks to your engine is the 8.5 compression ratio. We bumped that to 9.25 but I realize you don't want to tear into the engine. If you want to keep it stock looking, you would be limited to a cam change, a quality valve job, having the HEI set up to give a little better advance, try to improve the exhaust by using a "Test Pipe" in place of the catalytic converter and tune the carb a little. Maybe install an 83 or 84 HO exhaust system to help flow. When we built the engine, it was done with low end torque in mind since the car would only be street driven. I don't have the info on the cam but can get it if you would like to know. I also believe the ports down inside the manifold, under the carb, were plugged as they are there for emissions.

If you change the cam, carefully measure all of your lifter bores. The engine in my old car had one lifter bore that was .010 oversize and nothing was stamped on the motor to designate that. So make sure you know if you would have that too.

Brian

455man

I had a friend that had one with about a 3.55 posi under it. Seemed stock but maybe someone put that in there. Tranny already had a shift kit. Again not sure if this was factory. Put in a 180 degree thermostat, tuned carb, curve in the HEI, cold air intake, headers if you want to go that far. If not free up the exhaust best you can. Not gonna make lots of power without unbolting something but you could see 15's. I think my friends car did 16.1 consistently with nothing done to it.

easytobedead

well here is what im thinking, I have no problem unbolting anything that i can put back on so i wanted better breathing head a flotech exhaust with at least a 2.25-2.75 true dual mufflers with not cats also was thinking about either a flame thrower ignition upgrade or the msd.now i know i cant get heads of an older 350 i just don't know which one would be best.

Intragration

2.5" true duals would help. You'd need to alter your trans crossmember to avoid interference on the driver's side. Headers are always a nice addition, I put them on all my cars that I'm trying to get power from. You CAN make power with manifolds, but if you're not going to be doing much else to the engine, you'd get some benefit from headers. IMO the aftermarket ignition is a waste of money. Recurving your factory HEI is easy and you'll notice the difference. Someone else would need to chime in on the best heads. I think the problem is, if you have a factory head gasket, it's thinner than what's available now, so if you swapped and did nothing else, you'd be gaining in the flow department, but losing a little bit of compression.

captjim

IMO, the easiest way to boost the performance is to get some older 350 heads. #5, #6, #7, or #7a have smaller chambers and flow better, so you get the benefit of both better compression and flow. You will have to have the head bolt holes drilled. Spend a few $ on a GOOD valve job, a little bowl work, weld the dividers and fill the crossovers. Cr should be around 8.6 +/- with a .028 gasket. Decent cam in the 210 @ .050 on the intake, Performer, decent carb, headers w/duals, a 3.42 gear and it should run low 14s all day. Those year G-bodies are pretty light.

Intragration

I get it now, disregard what I was saying about swapping heads. I was aware of the dished pistons, but the later low-compression motors got dished pistons AND bigger combustion chambers. The 7A heads you're talking about Jim would have a smaller sized "A", versus the later smog 7A heads, right? And for my curiosity, how much difference would JUST filling the crossover and welding the dividers make, all other things being equal?

captjim

Yes, it would be the "small a". 7A heads are for a 307. This 350 should have 3A heads, which are awful. 14cc dish down .025 with a 68 chamber and a .028 gasket will yield mid-upper 8.xx to 1. Mill the heads down to 64 and you are right at 9 to 1, perfect for a mild street engine.

The thing with the crossovers and center divider is that without those it really negates a lot of the benefit of headers, IMO. So it is really hard to quantify, but once the heads are off it isn't that expensive and IMO is a cost effective upgrade.

easytobedead

well 7a heads off a 307 ?i have a set of them laying around looks like they do come in handy after all.thank you for the info guys

455man

I dont think he's advising 7a heads off a 307. I think he means 7a off a 72 350. Basically look for pre73 heads off a 350.

Intragration

That's my impression. 7 small "A" would be older, higher compression and better ports. 7 big "A" would be 307s and would be junk.

easytobedead

Ah well ty for the clarification bud that could of been a doozy haha,well time to shop for the heads