BB machine work has begun. A few additional questions.
Thread Starter
Racer
Joined: Jan 2006
Posts: 265
Likes: 0
From: Bowie MD
BB machine work has begun. A few additional questions.
Well, I should have everything back in about a month. 454 is going 0.030" over, hypereutectic pistons, hydraulic rollers.
049 heads also going in for hot tanking and reconditioning. New springs, valves, etc. The exhaust will be taken to 1.88". The intakes are going to go out to 2.125", which seems odd to me. Will I have a problem finding valves that size if I ever have a problem?
I think I am going to go with the Centerforce Dual Friction clutch/pressure plate. 26 input spline, for the 74 M21 I've got. Is 11" diameter the size I am looking for?
I will pick up a steel flywheel, probably 30 lbs. Is 11" also what I am looking for?
Things are finally moving, and the wallet is draining!
049 heads also going in for hot tanking and reconditioning. New springs, valves, etc. The exhaust will be taken to 1.88". The intakes are going to go out to 2.125", which seems odd to me. Will I have a problem finding valves that size if I ever have a problem?
I think I am going to go with the Centerforce Dual Friction clutch/pressure plate. 26 input spline, for the 74 M21 I've got. Is 11" diameter the size I am looking for?
I will pick up a steel flywheel, probably 30 lbs. Is 11" also what I am looking for?
Things are finally moving, and the wallet is draining!
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Originally Posted by nihil
The exhaust will be taken to 1.88". The intakes are going to go out to 2.125", which seems odd to me. Will I have a problem finding valves that size if I ever have a problem?
Thinner stems do flow better ... It could be the machinist is installing new guides and thin-stem (sbc size) valves? ... dunno?
Thread Starter
Racer
Joined: Jan 2006
Posts: 265
Likes: 0
From: Bowie MD
Originally Posted by jackson
Exhaust no problem ... that intake is odd. SBC stems are .341" ... BBC stems are .371" . 2.125" x .341" is a common race size for sbc. Common sizes for BBC w/ .371" stems are: 2.065", 2.190", 2.250".
Thinner stems do flow better ... It could be the machinist is installing new guides and thin-stem (sbc size) valves? ... dunno?
Thinner stems do flow better ... It could be the machinist is installing new guides and thin-stem (sbc size) valves? ... dunno?
I'll ask about the thin-stem thing, maybe that is it. It's weird not having heard of this before.
Last edited by nihil; Jun 22, 2006 at 11:49 PM.
Pro
Joined: Jun 2005
Posts: 540
Likes: 4
St. Jude Donor '09, '24
Sounds like he is trying to sell you some BS. Tell him you want the 2.25 size intake valve which is readily available thru all the big speed warehouses. Doesn't make much sense to use a exhaust size valve of 1.88 with a 2.125 intake. Some stock GM heads had 2.19 intake size valves with the 1.88 size exhaust valve. Much better off bringing your own pieces to the machine shop and have them do the work for you to install them. Look thru the threads on here on BB motors and see what motor combinations will work for your application. What you don't know about engine work will surely cost you money with a less then reputable machine shop, houstonvett
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
Draining wallet,..welcome to the BB world.
He may be telling you the size of the intake port in the head's chamber,..not the valve size which will always be bigger,..usually about .090" in dia bigger.
Your flywheel will need to be a 14 incher and your clutch an 11 incher. Since your 454 is externally balanced, you'll need the externally balanced flywheel and ext. bal. harmonic balancer (I'm assuming you're using the stock crank (there are now some after-market 454 cranks that are neutrally balanced). Regardless, you need to have your rotating assy, flywheel and harmonic balanced all together. If you're engine man isn't requesting you bring the flywheel and balancer for the engine balancing, I'd be looking for another engine builder because he's an idiot,..especially since you're building an externally balanced engine.
And you'll need a starter with "off-set" mounting for the bolts,..not straigh across. You'll also need the larger "621" bellhousing and the correct flywheel cover for the bellhousing (I may have the GM part number somewhere,..it's still available).
Good luck!
He may be telling you the size of the intake port in the head's chamber,..not the valve size which will always be bigger,..usually about .090" in dia bigger.
Your flywheel will need to be a 14 incher and your clutch an 11 incher. Since your 454 is externally balanced, you'll need the externally balanced flywheel and ext. bal. harmonic balancer (I'm assuming you're using the stock crank (there are now some after-market 454 cranks that are neutrally balanced). Regardless, you need to have your rotating assy, flywheel and harmonic balanced all together. If you're engine man isn't requesting you bring the flywheel and balancer for the engine balancing, I'd be looking for another engine builder because he's an idiot,..especially since you're building an externally balanced engine.
And you'll need a starter with "off-set" mounting for the bolts,..not straigh across. You'll also need the larger "621" bellhousing and the correct flywheel cover for the bellhousing (I may have the GM part number somewhere,..it's still available).
Good luck!
Pro
Joined: Jun 2005
Posts: 540
Likes: 4
St. Jude Donor '09, '24
[snip] He may be telling you the size of the intake port in the head's chamber,..not the valve size which will always be bigger,..usually about .090" in dia bigger.
Might be the size of the combustion chamber which sounds too custom allready. If the shop tells you it's the size of the intake port grab your belongings and run, houstonvett
Might be the size of the combustion chamber which sounds too custom allready. If the shop tells you it's the size of the intake port grab your belongings and run, houstonvett
