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Hello,
I am finally getting to dig into my first Volvo, a 75 242DL with a B20F motor. Its a very clean body, so I'm restoring it into a daily driver. The first thing to get done is sort the drivetrain out. The CIS is shot, after sitting for the past ten years. Rather than fix it, I'm taking an unusual route. I'm adapting a Honda DPFI tbi setup to a Weber downdraft manifold. The whole thing is going to be run by MegaSquirt. It won't make much power (120-130hp is all the Hondas can pull with them), but it should get 30+mpg in the city with an onboard wideband and a really good tune on the MS.
I've figured out that much, but the motor needs rebuilding as soon as the fuel system gets installed and rough tuned (I don't want to break in the new block while I'm starting from scratch on the fuel tables...). I don't know much about the B20 in terms of what work should be done while the motor is apart. This is obviously going to be a low output motor, but I'm going to be beating the holy hell out of it and I want it to last at least 100K miles. This car will be driven all over the country, and at 130hp, will be at WOT alot. I don't mind spending the money now to build an engine that will go another 30 years.
I don't need to replace the cam for power, but should I be looking into aftermarket anyway? I understand these cams can wear really badly due to only being case-hardened, do I need to address that? Obviously steel cam gear is a good idea, what about the valvetrain? Is NOS good enough or should I be looking at high performance lifers and roller rockers?
As for the head, how much porting should be done considering the restrictive intake? Any beyond basic cleanup? I want to up the C/R by shaving the head, how high can I go and still burn 87 octane?
Any other B20 weakpoints I should take care of now? I see new front covers and valve covers that promise to stop the motor from leaking, are they worth it or is new stock equipment good enough?
Thanks in advance,
-Aaron
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Uniberp has a D-jet manifold on ebay now for a fairly reasonable price.
That would give you better perf with megasquirt than the downdraft manifold.
Far as that goes the CIS manifold would also be better than the downdraft
manifold if you can get a way to measure throttle opening.
It is not so much that the cam isn't hard but there is a cam/lifter interface
problem with many of them. My conclusion is that there were quality problems
with the case hardened lifters and when the hard skin is broken through the
lifter presents a hard knife edge to the cam lobe. You definitely want to
check valve lift on all cylinders. If it is equal at about 0.375" or more
on all valves your cam and lifters are OK and I would not mess with them.
Volvo blocks are fairly hard and cylinder wear like (pardon the expression)
iron. I've seen them go 200,000 miles with less than 0.005" cylinder wear
and no measurable wear on the crank or bearings. So if you are going to pull
the engine I would check compression first and if it is over about 150 psi
on all cylinders and the bearings plastigage good AND the valve lift is good
you might go ahead and run it like it is. It probably has a D or K cam, either
of which is pretty good for street use and has good power.
--
George Downs Bartlesville, Heart of the USA!
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I know a multi-point FI setup and a plenum based manifold would be more powerful, but my main goal is fuel economy. I used to be a Honda guy, and these DPFI units are well known for delivering 40+mpg on the little 1.5L motors. A common swap is to put the MPFI off of the VTEC civics, and miliage falls to the 28-32 range depending on the ECU. It's a restriction to power to be sure, but it has its own benefits. IMHO, this car is nearly fast enough for what it is right now, with maybe 85hp and a BW35. An M41 swap and a better running motor, even a 100hp one is fine. Personally, I think the slow is part of the charm. I have zero performance asperations for this particular car, its just the daily. Besides, the DPFI and weber mani can be had for <$200. The MegaSquirt can be used to run anything, so if I don't like it later, I'll tear it out the DPFI and start over. I think I'll like it fine if 30mpg in the city can be extracted out of a 242.
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I'd still vote for using a D-Jet mani and D-jet parts. They all fit right on, no mechnical madifications necessary. Megasquirt works well with it. If you feel that the Honda setup will increase MPG just by strangling the intake side, then just use the D-Jet parts and put a stop on the gas pedal about 3/4 of the way down - same end result. Then later on, if you want more power your modifications will be restricted to removing the stop and allowing the throttle to open all the way.
I'd guess you could get a D-Jet mani, injectors, and fuel rail for $200, fairly easily.
As for the valve train, with a stock cam, and stock valve springs, and using a 'stock' redline (i.e. not revving over 6000 rpm, not that a D grind cam will encourage you to go much higher anyhow) you really won't need a steel timing gear or roller rockers, those are primarily needed on engines that see valvetrain stresses higher than normal, from high lift cams and/or high ratio rockers and/or high revs. As for performance lifters, I think the SBC lifters you see touted as high perf really weigh as much (if not more) than the stock units, not sure what makes them high perf. They would be viewed as 'high perf' on an SBC when replacing a set of hydraulic lifters for use on a more aggressive cam, but stock Volvo lifters are solid already. Tubular pushrods are nice, but again, make little to no difference on a stock motor used in reasonable RPM ranges.
As for the head, the bottleneck is the exhaust port. But if you aren't aiming for more power than stock, don't bother spending any money on porting. It has no issues making 130 HP with the stock head.
--
I'm JohnMc, and I approved this message.
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