So I'm also dads car. I think there is a valve swap here as well that will help me when porting. Also is there and reason I can't put 73 heads on a 77 engine? I want to get a extra set I have done rather than pulling his car apart and have it down.
Pretty positive the 350 heads all interchange the 77 will be open chambers....so you get a decent bump in compression
i open chambers? im pretty sure you have some mods on 72 back heads for a 350 to make them work. Seems like I ran into that with my old lesabre. I have 2 sets of 73 heads want to get one of them done. I dont want a huge cr bump either. Want the thing to run on regular 87 octane. So am i safe doing that? Just building highway cars we can drive to shows not racers.
All 350 heads are open chamber. IIRC ‘73 and up have the water ports/holes above the center two chambers, which will need to be blocked if using on an earlier (72 and down) block. On the left in the pic is a ‘78 350 head On the right is my original ‘71 350 head
so they are basically the same head after 73 thats all that matters. What about a larger valve or valves? is that worth the trouble. Not trying to go crazy just want to make the car enough that it gets up when needs too. The 77 pretty gutless in stock form. Im going to a fitech, mild cam, e fans, headers and have the heads opened up some dads and similar on my 455. Still staying on 87 octane. overdrive trans. Basically building them so we can drive them as highway cars. Not going to race them ever.
If you’re going for a stock type rebuild I’d stay with the standard size valves, and a standard (3 angle) valve job. What I would do is have the exhaust guides cut down and machined for seals as Buick didn’t use seals on the exhaust side, and the guides are a mile high.
well im wanting to up the performance closer to the 30o hp (flywheel) mark. I didnt know if its something i need to get close to that.
Order custom pistons from Auto Tec, get the compression ratio at LEAST 10 to 1 Regular rebuilder pistons you’ll be lucky to get 8 to 1 Don’t be afraid to stuff some compression in it from the factory 7.9 to 1 Compression does good things! You WILL have to run it on pump premium probably, but you could try mid grade gas and be conservative with your ignition timing.
def dont want to do that. Id rather go less power than have to run a upgraded gas if that makes sense. Im not rebuilding the engine itself. just having the heads worked a bit and the mild cam. bottom end wont be touched on either car as they are low mile cars.
What lift is the cam your considering to use? One good reason for going to a bigger intake is seen in this photo showing the flow killing casting lip on the short turn of this intake port. if your staying with stock size valves then fill it in with two part liquid epoxy and when it gets just to the state of not flowing any more blend it in with your finger wet water soaped up well with dish washing detergent. do not grind that lip back to get rid of it, fill it in. even with running a bigger valve many times you still need to fill it in. It’s a vital part of a 3 angle valve job in that area.
TA_284-88H-350 so im looking at basically stock parts for most part but hes going to port them for next to nothing if i want so i figured go ahead with that.
So your cam is kicking the valves open to .475” as I have found out. what’s most important when running less then .500” lift is this, and I hope the fellow working on your heads knows and keeps this info in mind. Even with the stock valve sizes used the amount of valve area the head has is underutilized with the factory valve job. The OD of the seat falls short of the OD of the valve itself by .040” or more in some cases. This then means that the first thing that needs to be done before a grinding burr is working on a port wall is to apply a 3 angle valve job. In terms of the exh valve if you are staying with a stock size valve you can only get a good 2 angle job in place . This would then be a 30 degree top cut and the 45 degree seat. The valve itself should also be back cut with a 30 degree . Back to the the reason for maximizing the valve job. With the size intake valve used in these heads all the air flow that gets into the cylinders up to .300” lift is controlled by the valve job and the area / shape that there is for about 1/2” on either side of the valve job. .300” lift is 58% of your total .475” lift that you have to work with. This also means that up to .300” lift or so the air mass is not yet following the actual contours and area available in the main runner of the port but for the afore mentioned area before and after the valve job. This effect is called the change over point, and if flow test are done in .050” lift steps can clearly be seen as turbulence taking place and will be reflected on the flow benches Manometer reading. Above .350” lift in terms of the intake port that big ugly blob of a valve guide support is the biggest restriction, but it also induces much needed swirl / mixture motion to the incoming air and fuel charge. Getting increased high lift air flow numbers out of the port means giving up some of this mixture motion, but you do not want to give up too much of it.
Ta performance valves with some clean up Porting will help perform better. Get the inexpensive 1734 flat top pistons from a 3.0 v6. With the 284-88 cam and a decent tube/carb jetting you should be close to 280-290 hp and 360-370 torque. It will be about 9.6 compression. That cam will like a bit of converter also.
wont be pulling engine apart. just heads off. so pistons are staying stock. i have a fitech. Is there a cheaper valve i can run vs ta ones? just asking.
Not that I’m aware of. You can try AM&P if it’s still in business, I know Mike Phillips retired . If you mill heads a bit the 288 does like more compression. Advance the cam 4 degrees with the lower compression.
