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Re: 283 Exhaust Manifolds
Lugnutz #1422128 Sat Aug 28 2021 03:21 AM
Joined: Feb 2004
Posts: 23,180
H
'Bolter
A heat riser has a spring, a flap valve, and a counterweight to route exhaust gas under the carburetor during engine warmup. On a V8, there are passageways through both cylinder heads and the intake manifold to facilitate the gas flow to the carburetor until the bimetal spring relaxes and the gas flow and the counterweight pushes the valve open. That open hole has none of those things, and is used by people who don't think the engine designers who went to a great deal of effort to build the system knew what they were doing. The standard excuse that "I'm in a warm climate" doesn't take into account that exhaust gas is somewhere in the 1,000 degree F. range or more.

This is the correct heat riser for a 2" pipe manifold- - - -ignore the "Corvette" designation. There are others on Ebay for lots more money that just say "2 inch".

https://www.ebay.com/itm/224312028645?hash=item343a09ede5:g:aUMAAOSw7Ilf-49p

Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: 283 Exhaust Manifolds
Lugnutz #1422221 Sun Aug 29 2021 12:38 AM
Joined: Feb 2016
Posts: 546
7
'Bolter
Depending on the application some 283's did not have the heat riser, I was surprised to find mine did not have it from the factory. 1957 2 ton Low Cab Forward, 283, single exhaust.


1957 Chevrolet 5700 LCF 283 SM420 single speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto
Re: 283 Exhaust Manifolds
Lugnutz #1422223 Sun Aug 29 2021 12:42 AM
Joined: Sep 2011
Posts: 2,338
L
Lugnutz Offline OP
'Bolter
Anyone ever come up with a manually operated heat riser? The inline 230 heat riser flap is notorious for failing, and of course the owner doesn’t know because it’s one of those items that gets neglected.

Re: 283 Exhaust Manifolds
Lugnutz #1422224 Sun Aug 29 2021 12:49 AM
Joined: Feb 2004
Posts: 23,180
H
'Bolter
The 1931 Buick straight 8 I worked on in the mid-1970's had a manual heat riser. It also had an updraft carburetor, I believe. Buckshot, since the big rigs with the 283 ran more or less full throttle against the governor all the time, the exhaust generated plenty of heat under the intake withuot a restriction on one side.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: 283 Exhaust Manifolds
Lugnutz #1422228 Sun Aug 29 2021 02:13 AM
Joined: Dec 2002
Posts: 4,256
Moderator - The Electrical Bay and Rocky Mountain Bolters
I'm a bit late to the conversation. But I just picked up a set of chinese ramhorns. they are very light! compared to the original set that I have.


Another quality post.


Real Trucks Rattle

HELP! The Paranoids are after me!
Re: 283 Exhaust Manifolds
Rusty Rod #1422230 Sun Aug 29 2021 02:18 AM
Joined: Sep 2011
Posts: 2,338
L
Lugnutz Offline OP
'Bolter
Originally Posted by Rusty Rod
I'm a bit late to the conversation. But I just picked up a set of chinese ramhorns. they are very light! compared to the original set that I have.
I’m returning mine to Summit Racing. I thought they were decent for the money, but these original GM manifolds are 2” whereas the Dorman manifolds (China) I bought from Summit Racing are 2.5”.

Re: 283 Exhaust Manifolds
Lugnutz #1422231 Sun Aug 29 2021 02:25 AM
Joined: Feb 2004
Posts: 23,180
H
'Bolter
On a hard pull at high RPM on the dyno, I've seen original equipment rams' horn manifolds glow cherry red all the way from the heads to the exhausat pipe flanges. Headers get so translucent you can see the flames dancing around inside the tubing. I wonder what those Chinese repops would look like during a full throttle run up sometning like the Grapevine hill in California? That's 6 miles of 6% grade. or at least it used to be when I was trucking there back in the late 1970's.

Big block Chevy motorhome engines had a bad habit of cracking exhaust manifolds (and heads) from the stress of pulling those big shoeboxes uphill. I've done some road testing with the engine cover off at times, and the orange glow from the exhausts is pretty impressive on a long upgrade.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: 283 Exhaust Manifolds
Hotrod Lincoln #1422297 Sun Aug 29 2021 05:20 PM
Joined: Mar 2007
Posts: 4,977
Leo Offline
'Bolter
Originally Posted by Hotrod Lincoln
On a hard pull at high RPM on the dyno, I've seen original equipment rams' horn manifolds glow cherry red all the way from the heads to the exhausat pipe flanges. Headers get so translucent you can see the flames dancing around inside the tubing.
Jerry

Yep, used to see that all the time at the short track stock car races. Brings back good memories.

Re: 283 Exhaust Manifolds
Lugnutz #1422307 Sun Aug 29 2021 06:16 PM
Joined: Feb 2004
Posts: 23,180
H
'Bolter
I've measured exhaust port temps on small block round track engines approaching 2,000 degrees F. No wonder headers burn up spark plug wires!
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: 283 Exhaust Manifolds
Lugnutz #1422336 Sun Aug 29 2021 10:48 PM
Joined: Feb 2016
Posts: 546
7
'Bolter
Back in my beer delivery days we had 366's, 427's in medium duty trucks and 454's in a couple of one tons, manifolds would glow red when we would pull into the barn, the medium duty engines were bullet proof.


1957 Chevrolet 5700 LCF 283 SM420 single speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto
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