122power
dude
- Joined
- Feb 20, 2009
Get help before the Volvo game consumers you, you have cars parked at every living relatives house and your spending your food budget in the TB for sale section
Truer words never spoken. I to am guilty lol
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Get help before the Volvo game consumers you, you have cars parked at every living relatives house and your spending your food budget in the TB for sale section
So really, unfortunately, it's a bit of a jump past just swapping a cam into a stock motor (D cam or IPD/Isky VV71/street perf cam) and getting 130-ish hp and moving on up from there.
This.
I tried to do a 'rally' build on a B20 for a rusty pile of a 144, which totally derailed the whole project.
If you want to step up to any kind of performance cam to break the 130 hp mark, you'll probably have to shave the head, get it ported, do valve work, etc before you see any power benefit. By the time you've spent all the time and money to accomplish that, you have a 145 hp motor that only runs on 93, and makes zero power below 3,000 rpm.
Manual swap, K/D cam and maybe a lighter flywheel will do a lot to liven up the feel of the car. I would just stick with that.
The most often recommended swap for a cam is a K or D cam. These cams were recommended as the go to upgrade cam for carb'd B18/20 motors. They came stock in the fuel injected motors. They are about the same but the K has three degrees less duration. Slightly better down low torque and slightly better idle with the SU carbs. I doubt you'll notice a difference though.
They will both pull to the 6k redline on these cars.
Also I thought the '68 140s came with a B18? Was your car swapped at some point?
First thing you should do is get rid of the auto and put in a manual gearbox.
We've been over this already, B20 swapped hopefully alternator and all.
Stock fuel injected 'D' cams work very nicely on otherwise stock pushrod motors. But they won't do too much for you while you are still using the automatic trans - that trans doesn't like higher revs.
And past that there's no real cheap single mod you can do. Volvo did a great job on the motor and didn't inadvertently gimp it by under-carbing it, or putting a restrictive exhaust on it. There's really no HP just waiting to be unlocked.
The stock exhaust is really quite nice - 4 into 2 into 1 (looking at the cast exhaust manifold and the dual tube downpipe). No gains to be had by swapping that until you've done a lot of other mods.
The stock carbs are also a bit overspecced on the motor, they're certainly feed a stock B20 as much as it needs, even at higher RPM's, and they can keep up for a fair amount with other mods, possibly with different needles.
Adding HP on a normally aspirated motor is mostly a case of either adding torque, or adding revs. Adding torque is not easy unless the manufacturer strangled the engine somehow, that's not the case here. So it would mostly involve adding more displacement, to that end it's possible to overbore a B20 block and use B21 pistons. That certainly adds more low end torque that you can rally feel. And accompanied by other mods, raises peak HP as well.
And the other part of the equation is raising revs, which means changing the cam to one that is suited to higher revs, and then modifying the intake/head/exhaust to support flow at those higher RPM's as well. Putting too much cam on a stock motor is pointless, it just raises the power band to a range that the rest of the setup can't support. And hurts power down low. Tradeoff with no advantage.
And unfortunately, Volvo heads are somewhat intrinsically bad at lowing air, mostly in the exhaust ports. Due to both intake and exhaust manifolds being on one side of the engine, they pushed the exhaust ports down lower in the head. So the port has to do a very sharp turn past the valve. And stock heads are somewhat restrictive in that area, so to really uncork much extra HP some very skillful and knowledgeable porting work needs to be done. And that's pretty pricey stuff. And since Volvo heads are a bit weird in the exhaust ports, a 'regular' domestic head guy might not know how to work with it properly.
Only once you have an expertly modified head can you move on to needing other supporting mods - more carb (like DCOE's), a proper 4:2:1 header with bigger tubes, etc. And that just means making torque at higher RPMs which at some point means forged pistons, h-beams, double valve springs.
So really, unfortunately, it's a bit of a jump past just swapping a cam into a stock motor (D cam or IPD/Isky VV71/street perf cam) and getting 130-ish hp and moving on up from there.
Almost forgot, when you swap to a manual, try to get your flywheel lightened, knocking off 4 or 5 lbs from the outside edge will certainly make the engine feel far peppier.
You won't lose torque, that's created by the motor. You'll have to be a bit more skillful in starting from a dead stop, but unless you spend a bunch and get something super duper light, it won't be an issue. If you just have a machine shop knock of a chunk around the rim, it will make it feel peppier (like matching revs on shifts, accelerating in lower gears), but won't make that much of a difference.
Isn’t all toilet paper sliced?
If I ask, will I laugh or roll my eyes?
Swap in the M40 and see where you're at.
At a minimum a Pertronix would help that weak stock ignition. Plus it's nice to get rid of the points.