307 Olds H/O stiffer valve springs necessary?

[kustomkyle]

I plan on getting the 1986 VIN Y (140HP) Olds 307 rebuilt to VIN 9 H/O (180+HP) specs. and have purchased a NOS GM cam. The H/O engines were supposed to use stiffer valve springs, but what was it that made them necessary? At first I thought it was only because of the cam, but it seems it may also be because of the 3.73 rear gearing in the 442/Hurst Cutlasses (higher sustained RPM's). Which case, or are both true?

I have 2.56 gears in my car and do not plan on changing them. Would the standard VIN Y 307 valvesprings be sufficient (new)? I can find the standard springs just about anywhere, whereas the ones specific to the H/O engines do not appear to be made anymore (auto parts store wise) and there are only 5 still available from GM through Vintage Parts.

I know no one really bothers to work on 307's but any help would be appreciated.

 

[Minion1186]

if your keeping the 2.56 and the rpms relatively low (like under 6200) then it should be ok. I dont believe they used different valve springs, mainly because it wasnt too much bigger of a camshaft than a stock 307's. Someone correct me if i'm wrong.

 

[jrm81bu]

If it is going from a non-roller to a roller, then you will prolly want to upgrade the springs due to the increase in weight.

 

[kustomkyle]

It is a roller to a roller cam. The H/O cam has higher lift and or duration (???) than the standard VIN Y cam. It is supposed to help generate an extra 40hp (but a slight loss of torque, which should be regained with a good dual exhaust).

As far as I've ever seen or read the valvesprings are different. Minion, did you rebuild the 307 that used to be in your car? If I remember right it had some work done to it. Did you know anything about what springs were in it?

 

[83hurst-olds]

I can only imagine if the springs are truly different, that the parts would be expensive as people like myself would want originals in our original '83 H/O. If so, then the parts would likely be more than going with an aftermarket (if exist) or other beefy springs.

 

[DoubleV]

I'd 'spring' for the better springs. You don't need 'VIN 9' springs per se, just ones that match the cam you're using.

In the end though, and I know this is going to sting, but the roller 307 HO motor is a dog. I don't think you will be at all happy with it, as there was alot more to the whole set-up than just a bigger cam and those 442's still were slow. The 442's had way better gearing gearing, higher stall converter, tuned carb and lots of other stuff that isn't worth mentioning, and you'll already be addressing the exhaust which is good.

Seriously though, you will be very unhappy with a roller 307 HO long block...especially with 2.56 gears. You will probably be running mid 16's if you're lucky. You'd get more performance with just a gear swap and a tuned VIN Y engine with good exhaust.

If you insist on building a roller 307, you should at least address the pathetic compression ratio and get a good valve job on the heads ( not that head work on the 7A's will get you huge gains though ).

 

[kustomkyle]

Seriously, the car as it is now has 2 dead/dying cylinders and smokes. It originally had 140Hp, supposedly. It still performs pretty good too me, and pulls like a freight train over 55MPH. It gets 20-25MPG. Yes, I will be more than satisfied with the car after the rebuild, as I will be driving it everyday, just like I am now, rather than drag racing it. I have accumulated almost everything needed for the rebuild except the valve springs and have less than $500 in parts, which includes 2 sets of pistons depending on what I may need as compared to a $700 rebuild kit for a standard 1986 VIN Y 307. Yes more can be done with more cubes, I don't care.

 

[DoubleV]

It still performs pretty good too me, and pulls like a freight train over 55MPH.

Your idea of a freight train differs from most I guess, but if you think you'll be happy then that's all that matters. The thing is, after you get used to the new level of power, you're gonna want more.

Either way, remember to measure everything so you know your exact compression ratio and make sure you degree your cam. Don't just guess or make assumptions here or it can bite you in the @ss. Be prepared for extra costs too. Good luck.

P.S. Roller VIN 9 motors were rated at 170 HP. The non rollers were 180.

 

[olds307 and 403]

I would 0 deck with those pistons and mill the heads to reach true 9 to 1. My 3.42 gears are the best of both worlds. I actually lug much less and run the same rpm at 60 mph. My converter only locked sometimes and caused higher rpm. I cruise at 2000 rpm at 60mph and is more responsive everywhere.

 

[kustomkyle]

Your idea of a freight train differs from most I guess, but if you think you'll be happy then that's all that matters. The thing is, after you get used to the new level of power, you're gonna want more.

I actually drove a 1993 Cadillac Fleetwood for a couple years previously before I got the Regal. It was supposedly rated at 180HP and 300ft.lb. That is what I want my car to be like. That car had more than enough power in all situations. I don't know what gears are in it, but they only came with either a 2.93 or 3.08 (I am leaning more towards 2.93 as it is a non-tow package). Power really isn't a big interest to me, I am more concerned with having a smooth running and more reliable car.