jclausen

Greeting all!!

I have a stock "Y" 1989 307 with 7A heads. I would like to swap the heads with the 5A heads. Since the engine has a roller cam, what else would have to be changed? Pushrods, rocker arms, springs, etc? I planned on replacing the cam anyhow but would I now go with hydraulic?

Any other suggestions are greatly appreciated!!

Thanks,
John

joe_padavano

Rocker arms and pushrods are the same on 5A and 7A heads. Your roller cam block uses 0.921" lifters. The flat tappet cams typically use 0.842" lifters. I don't know if you can use the 0.921" flat tappet lifters from the mid-60s motors, but they will be expensive.

The other problem you will have is with the intake and exhaust manifolds. The 7A heads have tiny ports and the manifolds are designed to match. The A5 intake and stainless tubular exhaust manifolds will bolt to your 5A heads, but the flow disruption from the port mismatch will probably more than negate any performance gain. At a minimum you need an A4 intake from a 1981-85 motor and the matching cast iron exhaust manifolds.

jclausen

Thank you Joe, that's really great info. I would have thought at least the push rods would be different.

Here is the cam kit i'm looking at: https://www.summitracing.com/parts/cca-cl42-229-4

I was also going to use an Edlebrock Performer intake.

The only last concern is the exhaust. I don't mind buying headers but I don't know what will actually fit the car.

The car is a Chevy Caprice Estate wagon. I know....chevy, please don't kick me out of the forum for that one!! HAHAHA!!!!

Any ideas on the headers?

Thanks again,
John

olds 307 and 403

Aren't the push rods shorter due to the taller roller lifters? I would get a Vin 9 roller replacement cam. Either find used early manifolds, Thornton manifolds or try Sanderson or Hedman shorty or A body full length headers.

joe_padavano

That kit will come with 0.842" diameter lifters.

I have an 86 Caprice wagon with Olds 307 myself.
I'm now parting it out. It does have a factory gauge pack.

I believe the 77-90 B-body cars can use the G-body headers, but the problem is that there is a pair of bolt-on frame braces that run from the suspension crossmember to the frame rails that get in the way of these headers. Others have removed the braces to install headers. I question the wisdom of that, especially if you plan to use the car like a wagon and carry heavier loads. I think I'd just stick with cast iron manifolds. If you are retaining the CCC system, you'll need the 81-84 307 manifolds that have the O2 sensor boss.

joe_padavano

Yeah, I suspect that is correct. When I said the pushrods were the same, I was only thinking about swapping the heads. I didn't think about the lifters going from roller to flat tappet. To be honest, I don't really know.

jclausen

I picked up my wagon for $400 from an older guy who can't drive anymore. The interior is in pretty good shape, except for the headliner. Everything is original with only 22000 miles on it. Oh, except for the A/C which has been converted to 134 and blows pretty cold. That's a necessity here in Texas.

That's what I was thinking.
I thought all the Vin 9 cams were hydraulic......If not then any idea where I can pick one up online?

I think I'm going to go shopping at one of the local salvage yards and see if I can pick up a donor engine. That way I will have all the parts or at least some examples.

Is the VIN 9 and VIN Y block the same? Once the 5A heads are on it, I can just treat it like a earlier VIN 9 motor?

I didn't really plan on keeping the CCC. I know, that will add a distributor and a carb to the list. I think I saw something about modifying the carb to work without the computer.

Thanks again for the really great help!!

John

olds 307 and 403

See I almost forgot about the O2 sensor in the manifold, either use early manifolds or get a set of Sanderson shorty headers and custom duals with the O2 bung added into the pipe or collector.

joe_padavano

They are.

1983-85 VIN 9 motors are flat tappet hydraulic.
1986-1987 VIN 9 motors are ROLLER tappet hydraulic.

By 1986 model year, every single Olds 307 had roller lifters. They were hydraulic roller lifters.

Cutlass Fan

With today's oil you should stick with a roller cam.
If you're thinking of buying another engine why not get a 350 or 403 and build that. You would gain a lot more power than you would swapping heads and cam on a 307. Even a stock low comp 350 4 but with duals would probably out perform the modded 307.