Component Advice for a Vintage Racing Engine

[Vintagewrench]

I'm rebuilding my own 1967 Volvo 1.8 L four for use in vintage road races and hill climbs and will be asking some of you for help and guidance along the way. My background is I’ve been an automotive machinist for over forty years, and operate my own machine shop that concentrates on rebuilding pre-war racing engines and cars.

SBC lifters are the same diameter as those used in Volvos and Isky has been supplying them with their cam kits for decades and they work well in this application.

Know a cam grinder that can grind the taper off of a cam so it can be used with roller lifters and am wondering what the center-to-center distance is for Chevy lifter bores. If it is really close to the Volvo dimension hopefully the link bars that come with the lifters can be used.

If not, if anyone knows the type of steel and heat treatment used for link bars we can machine suitable ones here in the shop.

Thanks in advance for any assistance.

[Walter R. Malik]

I'm rebuilding my own 1967 Volvo 1.8 L four for use in vintage road races and hill climbs and will be asking some of you for help and guidance along the way. My background is I’ve been an automotive machinist for over forty years, and operate my own machine shop that concentrates on rebuilding pre-war racing engines and cars.

SBC lifters are the same diameter as those used in Volvos and Isky has been supplying them with their cam kits for decades and they work well in this application.

Know a cam grinder that can grind the taper off of a cam so it can be used with roller lifters and am wondering what the center-to-center distance is for Chevy lifter bores. If it is really close to the Volvo dimension hopefully the link bars that come with the lifters can be used.

If not, if anyone knows the type of steel and heat treatment used for link bars we can machine suitable ones here in the shop.

Thanks in advance for any assistance.

What is the center to center span for the lifter bores on the Volvo block...?
You say the Chevy lifters can be used so, there are several different length tie-bars for different engines which can also be used; they don't have to be the CHEVY tie-bars.

[rebelrouser]

Why not use the retaining method the newer SBC used from the factory. If you have to machine stuff, I think these would be much easier to make, and while not familiar with you type of block, should be someplace to drill and tap to put a spider retainer in the valley. Not sure how much rpm you plan to run, but I think it would take 7,000 rpm OK.

https://www.summitracing.com/parts/cca- ... gJQdfD_BwE

[Vintagewrench]

What is the center to center span for the lifter bores on the Volvo block...?
You say the Chevy lifters can be used so, there are several different length tie-bars for different engines which can also be used; they don't have to be the CHEVY tie-bars.
[/quote]

Thanks for the quick reply and the informative information.

The center-to-center distance is: 2.032

[Walter R. Malik]

What is the center to center span for the lifter bores on the Volvo block...?
You say the Chevy lifters can be used so, there are several different length tie-bars for different engines which can also be used; they don't have to be the CHEVY tie-bars.

Thanks for the quick reply and the informative information.

The center-to-center distance is: 2.032
[/quote]

Big Block Ford lifter center to center is very near that spacing.
Chevy lifters with big block Ford tie-bars would fit your dimensions.

Many lifter companies would make those special order, (I have had lifter pairs made for a Plymouth "Poly" engine which used Big block Mopar lifters with Small block Ford tie-bars), or, use a CompCams lifter which has a removable tie-bar and you could simply buy the Big Block Ford tie bars.

[jred]

your not thinking of using the stock type flat tappet cam and trying to use roller lifters are you ????

you did say regrinding cam to take the taper out I don't think that any roller cams that I know of have taper on the lobes??

[PackardV8]

Know a cam grinder that can grind the taper off of a cam so it can be used with roller lifters and am wondering what the center-to-center distance is for Chevy lifter bores. If it is really close to the Volvo dimension hopefully the link bars that come with the lifters can be used.

It's a bit more complicated than just taking out the lobe taper. The lobe profile to follow a roller lifter is completely different than that to follow a flat tappet. Usually, there's not enough meat on a flat profile to be ground to a roller profile.

Nearly fifty years ago I worked on a Volvo rally car for which we made a custom billet roller cam. Yes, we did use SBC roller lifters. Start with a custom aluminum gear, as the fiber gear won't stand the strain. Then, the diameter of the two front camshaft bearing journals have to be bored larger than stock. This is necessary to be able to fit higher lift cam lobes, but it also makes the camshaft diameter larger and hence stiffer.

[Vintagewrench]

Why not use the retaining method the newer SBC used from the factory. If you have to machine stuff, I think these would be much easier to make, and while not familiar with you type of block, should be someplace to drill and tap to put a spider retainer in the valley. Not sure how much rpm you plan to run, but I think it would take 7,000 rpm OK.

Thanks, that's an interesting modern way of locating them. I have seen this method used on a few of the early engines I have worked on.

Big Block Ford lifter center to center is very near that spacing.
Chevy lifters with big block Ford tie-bars would fit your dimensions.

Many lifter companies would make those special order, (I have had lifter pairs made for a Plymouth "Poly" engine which used Big block Mopar lifters with Small block Ford tie-bars), or, use a CompCams lifter which has a removable tie-bar and you could simply buy the Big Block Ford tie bars.

Excellent info, Thanks!!

your not thinking of using the stock type flat tappet cam and trying to use roller lifters are you ????

you did say regrinding cam to take the taper out I don't think that any roller cams that I know of have taper on the lobes??

Yes, that was what I thinking as a way to use one of the flat tappet racing cams that is readily available but haven't really investigated it yet.

It's a bit more complicated than just taking out the lobe taper. The lobe profile to follow a roller lifter is completely different than that to follow a flat tappet. Usually, there's not enough meat on a flat profile to be ground to a roller profile.

Nearly fifty years ago I worked on a Volvo rally car for which we made a custom billet roller cam. Yes, we did use SBC roller lifters. Start with a custom aluminum gear, as the fiber gear won't stand the strain. Then, the diameter of the two front camshaft bearing journals have to be bored larger than stock. This is necessary to be able to fit higher lift cam lobes, but it also makes the camshaft diameter larger and hence stiffer.

It's very interesting to find that you did all this 50-years ago (there is nothing new under the sun). Yes, it makes sense that a roller cam would use a different profile.

As to timing gears, I have a set of Cloye's gears with an aluminum cam gear already, but I am leaning towards using a set of steel gears that Volvo used in their 2.0 L marine engine.

The cam setup you describe is very similar to a roller cam that is made and offered today by a racer in Sweden with larger front bearing journals and bearings. Perhaps he heard about what you did in the past?

Thanks to all for your input!!

[Erland Cox]

What carburetors are you allowed to run?
What power do you want to make?

Erland

[Vintagewrench]

What carburetors are you allowed to run?
What power do you want to make?

Erland

Erland, Nice to have a high-performance Volvo expert from Sweden check-in!

I have a couple of sets of Volvo Competition Services intake manifolds and a sets of Weber 40 and 45 DCOE carbs, but I don't think the club will allow me to run them (I'm checking into this now). I probably will have to use modified SUs which will limit cam choice and power output.

Looking to end up somewhere in the 150-160 hp range, a little more may be possible but I don't want to end up with a highly-stressed engine that will take a lot of maintenance between races (don't have the time.) One of the keys to making power with one of these as you know is the cylinder head and I'll send you a private message to inquire about your porting and relieving services.

[Erland Cox]

Without Weber 45:s the best you can get is 150 hp with dual SU:s.
But I would not look at getting maximum power, I would build for a wide power band.
As the SU:s connect to 2 cylinders the overlap must be wider than with one throat per cylinder.
I would keep the rings in the head, this part of the head is big enough for 160 hp.
With a D cam on a B20 Amazon I have gotten 127 hp with Dual SU:s and the stock B20 exhaust manifold.
We put dual Webers with 36mm chokes on it and got 137hp.
I used the early B20 head with minor porting and 42.35 valves.
The B18 head is only 84mm wide, I don´t know how much you are allowed to bore the engine.
If you are allowed you should change from 11/32 stems to the B20:s 8mm.
42-35mm valves are classed and that is the absolute maximum you should use.
The B18 head has 1mm less cc between intake and exhaust and that is good with the small bore.

Erland

[Vintagewrench]

Erland, The top photo above and others below (click on the photos to enlarge) show a B18 head that I want to use on a spare race engine that is bored .030 over. The headwas ported, relieved, and shaved .140"/3.5mm back in the late-'60s or '70s by a professional shop, it has larger 1.655/42mm intake valves and standard sized 35mm exhausts that you mentioned earlier as being ideal. Need to CC it to figure out the compression ratio.



Stock B18 8:75 chamber for comparison. In the future this is going to be used on an engine with a period Judson supercharger.

The intake ports have been opened up to the size of the the locating rings but not much was done with the exhaust port openings and thankfully they did not lower the port floor. I can clean up the ports and take some photos of the shape in the future for you.

Based on what you see here how do up think this head might work even though the intake ports are larger than you prefer?





The center two guides in the photo below are conversion guides for B20 valves with the smaller .312 stems I machined from cast iron for a street engine, the outer assemblies are the originals. I would machine some bronze ones for the new engine to use the smaller stems.



Interestingly the photo below shows a 1960s Pontiac V-8 head that is very similar to the B18 & B20 heads.

[Erland Cox]

That head will probably work just fine.
The reason to keep the rings as long as possible are that the heads without rings often leak at the intake gasket.
Sharing bolts with the exhaust is not ideal.
Besides you probably don´t need the extra area with Weber 45:s or SU carbs.

Erland

[Vintagewrench]

That head will probably work just fine.
The reason to keep the rings as long as possible are that the heads without rings often leak at the intake gasket.
Sharing bolts with the exhaust is not ideal.
Besides you probably don´t need the extra area with Weber 45:s or SU carbs.

Erland

Erland, Thanks for looking it over the head and your thoughts about it and the manifolds.

Yes, I noticed earlier that locating the intake manifolds in the right spot and keeping them there would take some work without the rings. Planning on looking into installing a dowel pin or two on which ever set of intake manifolds end up getting used. Ran a set of anti-vibration stainless steel flex-top locknuts ( https://www.mcmaster.com/hex-locknuts ) all last season on the manifold studs which worked out great in use and heat didn't affect them and they stayed tight all year.

[Vintagewrench]

The cylinder head has one issue that needs to be taken care of before proceeding forward. At some time in the past when someone moved it the deck surface between two of the cylinders got scratched and there is also another mark below it as can be seen in the photo. At the widest point the scratch is about .030" and while it is hard to measure it the depth it appears to be no more than .005" to .010" deep.

The best way to get rid of it would be to mill the head to remove it, but since its all ready been milled .140" and the CR (will be checking it soon) is very high I'd rather not take anymore off of it or fill the area with a pin. A Cometic .030" thick gasket with 3-layers and a thin black coating will be crossing both of the marks.

The question is there any type of high-temp epoxy or another type of a compound that could be used to fill it and also seal against the pressure of combustion and stand up to racing use??