Y or 9?....pics

[techg8]

Olds 307
Y or 9?

"supposed" to have come out of a 442........
7A heads means 86 or 87 engine
cast ex manifolds both sides, no tube manifolds.
"large" looking harmonic balancer
Oil sending unit has multiple wires - for gage pack?
carb was a replacement unit - no help there

Pulled the heads today - anyone whos been inside an 86 or 87 Vin9 roller cam motor recognize the pistons?

thanks for any help as for what to look for additional.

 

[ERIC87442]

Looks like my 87 vin 9 pistons

 

[DoubleV]

Pistons should be the same whether it's a Y or 9. The only way I can know you can find out for sure is to measure the lift of the cam.

 

[techg8]

Pistons should be the same whether it's a Y or 9. The only way I can know you can find out for sure is to measure the lift of the cam.

I was under the impression that the Y and 9 had different compression ratios.....I had assumed that was achieved via piston dish, no? Maybe it was head combustion chamber?

I do plan to measure the cam when I get that far.

 

[DoubleV]

I was under the impression that the Y and 9 had different compression ratios.....I had assumed that was achieved via piston dish, no? Maybe it was head combustion chamber?

No, the CR was a pathetic ( advertised ) 8:1 for both. Olds put no real effort/money into making the 307 any good for performance. Hell, the roller cam versions like yours were/are actually worse than the earlier 307's for performance.

 

[88hurstolds]

Balancer and manifolds are correct for a VIN9 motor.
Oil sender only has one wire.

 

[techg8]

Hell, the roller cam versions like yours were/are actually worse than the earlier 307's for performance.

because of the heads? 5a vs 7a?

 

[olds307 and 403]

Heads and slightly less compression. Olds were planning TBI by looks of the experimental manifolds. A big bore TBI and 9+ to 1 compression would have massively improved performance. Is there an O2 sensor in those manifolds? Cam, valve springs, balancer and manifolds 😛, were the only differences.

 

[techg8]

Is there an O2 sensor in those manifolds? Cam, valve springs, balancer and manifolds 😛, were the only differences.

Yes I pulled a broken-off O2sensor out of the passenger exhaust manifold.

 

[olds307 and 403]

Unless someone bothered to add those parts on, it should be the vin 9. The carb, if original is calibrated richer than the vin Y. Post the numbers on the carb, one of the experts will know.