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Volvo 144 Head Mods Questions

CRatcliff

Member
Joined
Nov 21, 2016
Location
Seattle, Washington
Hey All!

I'm doing some mods to the head for my 144 (F Head). Dropped it off at the machine shop yesterday and they had a couple questions.

First, the work they're doing:
Opening exhaust valves up to 38mm
Cleaning out bowls
Hardened valve seats
Unshrouding cylinders to the gasket lines
New valves
New springs 85lb/90lb rate
Possibly replacing valve guides
Milling the head to raise compression

The questions I have are:
-what should the Lifted rate be for the springs
-what is the desired compression for the head?

They're going to CC the cylinder and have me measure how far below deck the piston is, as well as the thickness of the head gasket, to calculate exactly. Advice on the best way to measure exactly how far below deck the piston is? I can snag a Harbor Freight tool, OR I have calipers if that's better.
 
Which cam are planning on using? The lift of the cam will determine which springs are suitable. They must have enough seat pressure at the desired installed height and not bind the coils at max lift.

The desired compression ratio will also depend on the cam and the type of fuel you have available. 10 - 10.5:1 is about the most you can run with today's fuel and a mild cam.

The best way to measure deck height is with a deck bridge and a dial indicator.

https://www.summitracing.com/search?PageSize=50&SortBy=DisplayPrice&SortOrder=Ascending&keyword=deck%20bridge

The next best way is with a magnetic base dial indicator.

https://www.harborfreight.com/multi-position-magnetic-base-with-fine-adjustment-63663.html

Obviously, you'll also need a gauge to go with your tool of choice.
 
Not sure which cam at this point - John V had recommended a custom cam from Sweden, but the company he was working with has had no luck getting the core for the cam. I would love to hunt one down, but if they're not available, I would also love any advice for an alternative cam.

Looking for something that will be fun to drive with a lower power band - not looking to go high-revving, more looking for something that has pickup at lower RPMs and more torque. I'm gonna throw on a T5 transmission as well, so hopefully won't be at 5k rpm at 60mph!
 
Which cam are planning on using? The lift of the cam will determine which springs are suitable. They must have enough seat pressure at the desired installed height and not bind the coils at max lift.

The desired compression ratio will also depend on the cam and the type of fuel you have available. 10 - 10.5:1 is about the most you can run with today's fuel and a mild cam.

The best way to measure deck height is with a deck bridge and a dial indicator.

The intention is to do "all the right things"---zero deck, thin gasket maybe, and carefully take into account intake valve closing after BDC ---dynamic compression...
The B20 having a cast iron head with a chamber very similar to other cast iron heads can very probably be perfectly happy with static comp edging towards 11.0 or so when combined with cams with somewhat more duration--or later intake valve closing---that is common in Merikuh.. Mayny Saab "ex-spurts" have claimed 10 to 10.5 "with todays gas" (30-35 years ago, but experience building ~~100 engines have shown with 92 octane and "middling" rally derived cams has shown that 10,8 to 11.3 comp working very well.
The cam we expect to source out of a shop in Sweden--if we find the right core ever--(which means if I go back and remember to note down which core they call for)

The guy does have a nice set of 2 x 45 DCOEs (same as works faultlessly on my widdle 1740cc V4)

The big issue I think overlooked is controlling ignition accurately...The dizzies are normal old Bosch JFUR4 fambly dizzies and thet DO wear in the V4s--so no reason to think they live any better in anything else, but ignition control is key to happiness.

The Oh Pea has lots of experience with carbs on high performance motorcycles and I have too with DCOEs--and making good linkage so the carbs is no worry.
And i did help do a B20 for a shop in Seattle "Apex Automotive" on the Carrerra PanAmerica open road rally Amazon.. worked gooooooood. (like 137mph shown on the super accurate rally odometer (with speed function) in an Amazon with 4,10 axle. But puttered around like a street car in town..
 
Would y'all advise having the machine shop zero deck my engine as well?

Also, if you have a distributer / electronic ignition that you would recommend, I'm absolutely in. All my bikes have moved to electronic ignitions (Hall effect, full on advance ignitions - not just points replacements) and it's great!
 
That's my plan. Plan to run a Yoshi cas adapter and ls coils. Of course I'd also like implementing a crank trigger as well.

Would y'all advise having the machine shop zero deck my engine as well?

Also, if you have a distributer / electronic ignition that you would recommend, I'm absolutely in. All my bikes have moved to electronic ignitions (Hall effect, full on advance ignitions - not just points replacements) and it's great!
 
Would y'all advise having the machine shop zero deck my engine as well?

Also, if you have a distributer / electronic ignition that you would recommend, I'm absolutely in. All my bikes have moved to electronic ignitions (Hall effect, full on advance ignitions - not just points replacements) and it's great!

Yes, have the block decked to 0.

123 ignition has a nice self contained distributor programmable via a USB and laptop for the B18/B20 engine.

http://123ignitionusa.com/volvo-b18-b20-naturally-aspirated-tune-4-r-v-v-usb-cable-sold-sepatate/

They also have one that's BlueTooth compatible.

http://123ignitionusa.com/blue-tooth-for-4-cylinder-volvos-fits-b18-b20-naturally-aspirated/
 
John, you saying the 123ignition is a POS? Either way the ignition is the next step after head/cam/carb :)


No! just bleed 'spensive but ignition control is vital...We didn't even pop the cap on your dizzy but I'll betcha its all worn to fawk...Lobes all janky and advance weights dodgy..and maybe gummed all to poo. Betcha a whole nickel.

If you can afford it good.
 
So we're on the same boat, are we thinkin to deck the block and get a thinner head gasket, and don't mill the head?


No you're jumping ahead..
if the pistons are down the bore say 008 that ain't much, decking is more about quench than raising comp--although there's a 1/10 of a point there maybe..But quench is a big deal especially with those 2 xzorst valve right next to each udder.

Quench to lower det threshold
 
Hahah, yeah, $$ is definitely going to be a bit of a problem right now. Probably a few months out for the ignition step. Just found out I need to replace the fork tubes on one of my motorcycles as well, so definitely just took a hit.

So for the compression, are we on hold for the cam?
If we can't get one out of Sweden, any advice on an alternative?
 
Any stockers around 036?
This particular motors on stock B20 rods which some people say hain't the strongest...

The F gasket is .039" compressed.

The B18 rods are notoriously weak. 6 bolt B20 rods are reinforced in the problem area and aren't a problem under 6500 rpm. 8 bolt B20 rods can be swapped for M rods if you don't think they're up to the task.

B20Rods2.jpg
 
OK, John, you've been 100% spot on thus far, so what would your next steps be:

Deck block or mill head? Start by measuring how far below deck pistons are?
Start with cam?
Thinner head gasket?
 
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