'67-9 BB closed chamber Aluminum heads exhaust valve dia.

[Wayne M.]

I always thought that the exhaust valve size for #3904392 ('67 L88 and L89) and #3919842 ('68 and '69 L89; '68 to mid-'69 L88) was nominally 1.84" dia., and this seems to be backed by the P&A30 period catalogs which show a different part # for aluminum head exhausts, although they don't specify diameter. Square port INTAKE valves were 2.19" for both iron and aluminum heads.

But A.Colvin's Chev-by-the-Numbers '65-69 says should be 1.72" (like the iron heads), and the description for one set on eBay can't make up their mind whether it's 1.72" or 1.88" [like the open chamber L88 heads #3946074]

Checked mine (off mid-year '67 '842' castings) and seems to confirm the 1.84".

Can I assume that Colvin & the eBay poster are in error ?

[Clem Z.]

Re: '67-9 BB closed chamber Aluminum heads exhaust valve dia.

I always thought that the exhaust valve size for #3904392 ('67 L88 and L89) and #3919842 ('68 and '69 L89; '68 to mid-'69 L88) was nominally 1.84" dia., and this seems to be backed by the P&A30 period catalogs which show a different part # for aluminum head exhausts, although they don't specify diameter. Square port INTAKE valves were 2.19" for both iron and aluminum heads.

But A.Colvin's Chev-by-the-Numbers '65-69 says should be 1.72" (like the iron heads), and the description for one set on eBay can't make up their mind whether it's 1.72" or 1.88" [like the open chamber L88 heads #3946074]

Checked mine (off mid-year '67 '842' castings) and seems to confirm the 1.84".

Can I assume that Colvin & the eBay poster are in error ?

all closed chambered aluminum BBC heads i ever saw had the i.840 ext. valve.

[Patrick B.]

Re: '67-9 BB closed chamber Aluminum heads exhaust valve dia.

The TRW part number for the 1.84 exhaust valves is S2614, but I have not been able to locate any. Any ideas on a source?
Do you have to modify 1.88 valves to get them?

[Dick W.]

Re: '67-9 BB closed chamber Aluminum heads exhaust valve dia.

The TRW part number for the 1.84 exhaust valves is S2614, but I have not been able to locate any. Any ideas on a source?
Do you have to modify 1.88 valves to get them?

Good engine machinist can cut the seats to fit. For maximum benefit the ports right under the seats need to be pocket ported.

[Clem Z.]

Re: '67-9 BB closed chamber Aluminum heads exhaust valve dia.

if you change to a larger exhaust valve in the aluminum head i would get a new seat installed because the seat used with the 1.880 valves are "venturi" shaped seats for better exhaust flow.

[Patrick B.]

Re: '67-9 BB closed chamber Aluminum heads exhaust valve dia.

Clem and Dick--- I don't want to change the heads. I just want to get 1.84 valves to fit the stock seats on 67 aluminum heads. Any sources or does one have to machine 1.88 valves down to make a 1.84 valve these days?

[Clem Z.]

Re: '67-9 BB closed chamber Aluminum heads exhaust valve dia.

Clem and Dick--- I don't want to change the heads. I just want to get 1.84 valves to fit the stock seats on 67 aluminum heads. Any sources or does one have to machine 1.88 valves down to make a 1.84 valve these days?

looks like you will have to machine down some 1.880 valves. no one lists a 1.840 valve as i bet there is very little call for them