-
Hello Guest, welcome to the initial stages of our new platform!
You can find some additional information about where we are in the process of migrating the board and setting up our new software hereThank you for being a part of our community!
Pushrod engine intake Q's
- Thread starter AndrewNance
- Start date
AndrewNance
Amateur hour!
- Joined
- Oct 24, 2011
- Location
- Winston-Salem, NC
Yeah. Pretty much that top one.
For the record, I didn't know I even had a manifold that wasn't original to the motor. I just assumed I had the same one that every other B18 got. When my B20 is done it will have a ported F head with a Schneider 274 cam and stock F head valves. That motor is what all of this is for. So now I'm more curious as to which exhaust will flow better with that setup.
Last edited:
Redwood Chair
- Stock PSI Or Bust -
- Joined
- Mar 23, 2007
- Location
- Ocean Beach S.F.
This is as close as I have on the 140 intake routing.
An initial trumpet / venturi extending to the outer side of the header panel for 'ram air' and the other various parts to the box.
An initial trumpet / venturi extending to the outer side of the header panel for 'ram air' and the other various parts to the box.
- Joined
- Jun 2, 2007
- Location
- UK
The header won't give you more power with that camshaft, at least not in my experience. What you'll likely end up doing is move the power band up the rev range. A 274 degree duration cam is fairly mild. Personally I'd bolt on the cast iron manifold, fit the SUs and call the job a good 'un.
AndrewNance
Amateur hour!
- Joined
- Oct 24, 2011
- Location
- Winston-Salem, NC
Yeah its a 2k-6k cam. I wanted to remain streetable but still be fun. Well I'll look into just keeping the manifold I have and maybe ceramic coating it.
FattMatt805
juggalo
- Joined
- Sep 26, 2007
- Location
- Carmichael, CA.
I will check the shed when i go home for thanksgiving, i think i might have what you need
AndrewNance
Amateur hour!
- Joined
- Oct 24, 2011
- Location
- Winston-Salem, NC
I've got a spare set of SUs somewhere at my dad's that Matteson gave me on partial trade for an M46. I want to say they're on a manifold but I really can't remember.
Just have to check them for throttle shaft bore wear. I think perhaps they worked a little better with leaded gas (although the gas doesn't really go there, so maybe not) - but running a brass throttle shaft straight on a cast aly carb body wasn't a great idea in terms of wear.
The shaft wears the alu holes into ovals, then air leaks through. Mostly at idle, leaning the mixture, which is an issue because the vast majority of people will fine tune the mixture at idle, the leaks then make it run rich off idle.
And then they get bad enough for the throttle valves to start hanging up and not returning cleanly to idle...
There are places that can drill and bush them, though.
The shaft wears the alu holes into ovals, then air leaks through. Mostly at idle, leaning the mixture, which is an issue because the vast majority of people will fine tune the mixture at idle, the leaks then make it run rich off idle.
And then they get bad enough for the throttle valves to start hanging up and not returning cleanly to idle...
There are places that can drill and bush them, though.
AndrewNance
Amateur hour!
- Joined
- Oct 24, 2011
- Location
- Winston-Salem, NC
Yeah I already ran into that problem not long after I got the car. I had them rebuilt and rebushed though. So now I'm thinking I'll just stick with the iron manifold and sell my header to furnish some time with JetHot.
I think you'll be better off with the cast mani. Just hook it up to a nice open decently sized exhaust system. 2.25" is fine. 2.5" if you plan on making 200 hp (which isn't easy).
Not endorsing the seller (buyer beware), but here's a look at John Parker's (v-performance) new 4:2:1 header. He developed a new one, and says it's dyno proven to increase HP vs. his older one. The interesting part is that the newer one has a smaller section of pipe at the 2:1 collector, then opens up after that. Makes me think that even if the stock DP's 2:1 collector is a little smaller, it's still good to hook it to a larger exhaust. Exhaust gas velocity through the 2:1 collector area and then on into the more open tubing beyond.
I was trying to get one of those for the PV, but John said he was in short supply, and wanted to keep the ones on hand for replacements as needed for his racing car customers, but that he was having another batch made up. I didn't want to wait (took the old thing down to SE), so I got an el-cheapo 4:1 style header on Amazon. Someone must have been closing out their supply or something, $64, $73 shipped. I half expected to get a gasket or a flange in the mail, but no, it was a complete, solid, well made mild steel header. I chopped off the 3 bolt flange, welded on a v-band flange, bolted it up.
Not endorsing the seller (buyer beware), but here's a look at John Parker's (v-performance) new 4:2:1 header. He developed a new one, and says it's dyno proven to increase HP vs. his older one. The interesting part is that the newer one has a smaller section of pipe at the 2:1 collector, then opens up after that. Makes me think that even if the stock DP's 2:1 collector is a little smaller, it's still good to hook it to a larger exhaust. Exhaust gas velocity through the 2:1 collector area and then on into the more open tubing beyond.
I was trying to get one of those for the PV, but John said he was in short supply, and wanted to keep the ones on hand for replacements as needed for his racing car customers, but that he was having another batch made up. I didn't want to wait (took the old thing down to SE), so I got an el-cheapo 4:1 style header on Amazon. Someone must have been closing out their supply or something, $64, $73 shipped. I half expected to get a gasket or a flange in the mail, but no, it was a complete, solid, well made mild steel header. I chopped off the 3 bolt flange, welded on a v-band flange, bolted it up.
AndrewNance
Amateur hour!
- Joined
- Oct 24, 2011
- Location
- Winston-Salem, NC
That looks nice but John Parker won't see any of my money, just from what I've heard, although I was able to get him to exchange emails with me one time.
I figure with the 122 being so low, using the stock manifold will force me to have a custom downpipe built so they can tuck it as close to the car as possible. That would've been hard to shorten the pre-built header. My plan is to have the downpipe built with 2-2" tubes that collect into a 2.5" all the way back. I'll have it built with no muffler while I decide what I want to put in it eventually.
I figure with the 122 being so low, using the stock manifold will force me to have a custom downpipe built so they can tuck it as close to the car as possible. That would've been hard to shorten the pre-built header. My plan is to have the downpipe built with 2-2" tubes that collect into a 2.5" all the way back. I'll have it built with no muffler while I decide what I want to put in it eventually.