489 build sheet?
05-05-2026 | 11:02 AM
#11
Registered
Joined: Jul 2024
Posts: 194
Likes: 86
The 781 and 049 heads are grear performers for sure.
290 alum heads with 2.250" valves are way too big for most marine perf engines...but they flow well to male up for it. Some epoxy on the port floor would really wake them up. One ofntheblarger issues is that you can't really put a 2.19 valve in them.
The AFR 265s are an amazing option.
Great numbers on the 496 and iron ovals. What RPM did you turn?
Have you seen Vortec Pro's 781 and PP head results?
The 088 head exh port is worse than the oval heads.
Oddly...the L29 Vortec exh port may be the best factory BBC port ever cast. Small and fast..with a D port short side setup.
290 alum heads with 2.250" valves are way too big for most marine perf engines...but they flow well to male up for it. Some epoxy on the port floor would really wake them up. One ofntheblarger issues is that you can't really put a 2.19 valve in them.
The AFR 265s are an amazing option.
Great numbers on the 496 and iron ovals. What RPM did you turn?
Have you seen Vortec Pro's 781 and PP head results?
The 088 head exh port is worse than the oval heads.
Oddly...the L29 Vortec exh port may be the best factory BBC port ever cast. Small and fast..with a D port short side setup.
05-05-2026 | 11:12 AM
#12
Registered
Joined: Jul 2024
Posts: 194
Likes: 86
Here is the 2nd set of 781 heads i ever ported. I have the on the bench waiting to go on another 496 for my truck.
these flowed 311 on intake at 600.
Exhaust flow was 232 at 600 lift
I like looking at 400 lift numbers. These heads flowed 272 at 400 in intake and 187 on exhaust. This is very stout 400 numbers for a production iron head. Years ago I did a ported set of peanut port heads with a 2.25 intake. Never flowed them but the 489 inch truck motor put out over 650 torque and still did 511hp at 5200. Torque peak was at 3900. Stroub hydro roller.
these flowed 311 on intake at 600.
Exhaust flow was 232 at 600 lift
I like looking at 400 lift numbers. These heads flowed 272 at 400 in intake and 187 on exhaust. This is very stout 400 numbers for a production iron head. Years ago I did a ported set of peanut port heads with a 2.25 intake. Never flowed them but the 489 inch truck motor put out over 650 torque and still did 511hp at 5200. Torque peak was at 3900. Stroub hydro roller.
Last edited by hpmaniac; 05-05-2026 at 02:13 PM.
05-06-2026 | 07:03 AM
#14
Thread Starter
Registered
Joined: Feb 2026
Posts: 8
Likes: 2
I've ported about 10 sets of 049 oval ports and the exhaust really responds with some mild porting, raise the roof about 100ths and clean up the short turn radius and they will gain 50 cfm, takes 15 minutes per port. I use oval ports on anything less than 500ci. Last 496 I did made 680 hp on pump gas with ported 049 781 heads. Hydro roller 256 267 at 50 630 lift. If budget allowed a set of afr 265 heads would be awesome.
05-06-2026 | 10:14 AM
#15
Registered
Joined: Jul 2024
Posts: 194
Likes: 86
05-06-2026 | 01:35 PM
#16
Registered
Joined: Jul 2024
Posts: 194
Likes: 86
They just are way to big of head, yes its a big cubic inch engine but many people forget that we are trying to accelerate a engine from idle to 52-5800 rpm for most builds and that large head will slow the rate of engine acceleration down compared to a properly sized head. I believe that 088 head has a 325 intake runner, great for 65-7k rpm but not great in a marine engine. For Na 502 a head runner between 265-300 is much better. Boosted you can get away running a bigger head in some cases.
05-06-2026 | 04:38 PM
#18
Registered
Joined: Aug 2019
Posts: 1,247
Likes: 420
From: BC
Here is the 2nd set of 781 heads i ever ported. I have the on the bench waiting to go on another 496 for my truck.
these flowed 311 on intake at 600.
Exhaust flow was 232 at 600 lift
I like looking at 400 lift numbers. These heads flowed 272 at 400 in intake and 187 on exhaust. This is very stout 400 numbers for a production iron head. Years ago I did a ported set of peanut port heads with a 2.25 intake. Never flowed them but the 489 inch truck motor put out over 650 torque and still did 511hp at 5200. Torque peak was at 3900. Stroub hydro roller.
these flowed 311 on intake at 600.
Exhaust flow was 232 at 600 lift
I like looking at 400 lift numbers. These heads flowed 272 at 400 in intake and 187 on exhaust. This is very stout 400 numbers for a production iron head. Years ago I did a ported set of peanut port heads with a 2.25 intake. Never flowed them but the 489 inch truck motor put out over 650 torque and still did 511hp at 5200. Torque peak was at 3900. Stroub hydro roller.
PP heads are the ultimate sleepers. When you thonk about it...they are just super SBC heads sized ports with way better int/exh valve sizes...and look at the kind of power a SBC makes with limited displacement.
Nice porting work. Have you got access to the flow bench? Or take it in to the local machine shop and get them to flow it?
05-06-2026 | 04:47 PM
#19
Registered
Joined: Aug 2019
Posts: 1,247
Likes: 420
From: BC
Getting a set of old iron heads reworked is expensive these days. Guides, seat work, valve job, mild porting etc...adds up.
Bare Alum quality castings can be very economical when viewed from that perspective. Depends on your setup and if you have closed cooling etc.
If the 088s are in good shape..run them..and get on the water. Nothing wrong with them...but it just wouldn't be my first choice.
Bare Alum quality castings can be very economical when viewed from that perspective. Depends on your setup and if you have closed cooling etc.
If the 088s are in good shape..run them..and get on the water. Nothing wrong with them...but it just wouldn't be my first choice.
