I replaced the HS6 on my '68 144 with HIF6s. Old HS6s had very worn shafts. It ran ok but was hard to keep in tune. I rebuilt and cleaned the HIF6s prior to installing them. I found a crack on my B18 combo manifold. I sourced a replacement. Put on new manifold studs and intake/exhaust gasket. I used the plastic spacer and all the gaskets for the HIF6s. I'm using the newer style one piece air filter as the elements are easy to source.

Its takes a lot of cranking to get it started. Many tries to keep it running. Need to leave the choke on to keep it going. I only have the front HIF6 carb enrichment. After a bit it will idle. I preset the jet adjustment level with the bridge and then two turns in. I can get it to idle a bit. Anything off idle it wants to stall. Nothing else was changed when the carbs were pulled and replaced with HIF6s.

I had checked the valves and compression prior. I checked points and timing. I had a suspect fuel pump. I replaced with a used Pierburg. No improvement. I pulled the plugs which are pretty new. Running very lean. Pulled carbs and checked the float settings. Fine there. No dirt.

The other day I had it running and happened to plug the PCV connection. RIght away I noticed an improvement. I have not had any time to work on it since. I started thinking about the way the B18 had the PCV and power brakes plumbed in. The PCV and power brake lines merged to one and connect to the imtake manifold. That was the only intake connection I had with the HS6. This is a large vacuum on one of the HIF6s. The other has a small connection. These are not the hot start connections.

I was wondering if the vacuum setup is my issue or at least needs addressed. I did check the valve at the power brake booster. All seems ok there. I was reviewing the B18 vs B20 PCV setup on the following page and wondered if I should move the the B20 setup. I need to see if my replacement manifold has the restricted intake nipple.

http://sw-em.com/pcv_diagrams.htm

The way the PCV and power brakes were plumbed seemed to work with the HS6s. Not sure how else it could have been setup with the one intake tap. Wondering where I can go from here to get it running right.

Craig

The small nipple on the bottom of the rear carb was intended to go to the vacuum retard on a B20B distributer. If you have a B18 dist. without the vacuum diaphram, plug off the nipple.

The larger nipple on top of the front carb was intended to go to the charcoal canister - again on a B20B equipped car. You can plug that off too as I doubt you have a charcoal canister on your '68.

What kind of intake manifold did you switch to?
The PCV nipple on a B18 is different from a B20. IIRC, the B18 nipple had a larger orifice and the B20 was smaller. Sometimes a B18 nipple would be installed into the B20 manifold and when combined with a weak brake booster, would let too much air in.

Check the mating surface of the manifold to head as well. If the new manifold was machined to true it up but the locating rings (in the intake ports) were not, it could be just enough to make for another leak. In other words, the manifold would be held just a hair away from the head making a proper seal impossible.

Are you sure your new one piece air filter holder has all the appropriate holes in it where it meets the carbs. There are a bunch of them and different filter housing have different holes and different carbs have different holes surrounding the main intake for balancing vacuum etc... . When I made this change I had to drill a few new holes and tape over some extra ones. Hope this helps, good luck.
--
Patrick ('68 220, '83 245).

Thanks for the input. The air filter housing came with the HIF6s. I studied all the holes and everything seems in order but will double check.

On the manifold it was checked by a machinist friend for trueness. It checked out and nothing else was done to it. I didn't have the head checked out. I used a new Volvo gasket and fresh studs and nuts. I checked manifold last night. Original and replacement both have the B18 orifice.

I have both ports on the carbs plugged.the manifold orifice goes to a T. From the T sit goes to brake booster and PCV. PCV was replaced both I have the one that was on there prior. Direction of PCV checked out.

As stated when line from orifice was capped it seemed to settle down and I could move the car around. Going to test with PCV connected. Then with brake booster.

Craig

You do have an in-line PCV valve installed right?
B18s used a "rattle" type PCV valve.
B20s did not.

You are correct in capping both of the fittings on the carb.
They normally start OK with only one enrichment device.
Do you have oil in the dashpots?
Have you done the piston-lift mixture adjustment?
Did you put new seals on the throttle shafts of the carbs?

I do have oil in the dashpots. I did a preset on the mixture adjustment. I adjusted after that as best I could based on how it was running. The PCV valve is present and of the rattle type. The HIF6s came off a Volvo B20 from what I know. The air box came with them. I went over the carbs all last winter cleaning and rebuilding them. I replaced the throttle shaft seals. New needle and seat. I put in new dashpot springs. All Volvo parts.

I should have some time this weekend to mess around with it. I'm going to focus on the PCV and brake booster since blocking that at the manifold seems to allow it to run much better.

Worked on the problem this weekend with no progress. Actaully got worse and wouldn't start at all. Pulled plugs and they were wet and looked fouled. Odd as last I looked they were dry and it was acting like not getting fuel. I had capped all vacumn lines.

I put in spare plugs and switched out to 75 electronic dizzy which was on list of things to get done. I didn't want to change out the dizzy till this other issue was solved. With the plugs and dizzy it fired up and ran at idle ok for 10 minutes. I couldnrev it and it seemed better then it went south. Idle got rough. Starting spitting back via carbs. I did check timing when dizzy went in. It will start now and only run with choke on full. I did set the idle up a bit and that didn't help.

I pulled one carb and inspected the jet by removing it. Looked ok. I'm using a combo manifold with secondary butterflies still in tack. Does the HIF6 work with this combo manifold? I have the spaces under the carbs and all the proper gaskets. If I did use the spacer the carb linkage bottoms on manifold.

This is really a confusing issue. I thought the switch from HS6s to HIF6s would have gone without too much of an issue.

Could you be leaking massive amounts of air at the secondary butterflies? Those can be removed and plugged easily to provide a tight seal. Also, I don't think you can get secondaries actuating levers to work on the HIF throttle shafts. May be wrong on that though. If the levers won't work, then absolutely remove the secondaries.

How's the fuel pressure?
Ever do a compression check?
Ever had any head work? Or a valve job?

I looked at the secondary butterflies as I test fitted the HIF6s. A lever on then opened the butterflies smoothly. I will check for air leaks at the valves. I don't see any defects in the manifold. My old one I had noted a repair was performed and that is why I sourced a replacement. I changed the mixing chamber gasket and it appears to be a tight fit. I put in new throttle shaft seals on carbs as well.

I did a compression test when I got the '68 144 four years ago. Don't recall the readings but will do again. I did check valve clearance. Only one needed adjusted. Good movement on all valves. Paper work show a engine rebuild prior to me getting the car. Rings were done for sure but not sure who or what all was done.

Keeping an open mind on all possible causes till I narrow it down.

I just took a look at the spare combo manifolds I have and found they differed in that one had a single port for vacuum (B18-split vacuum to PCV valve and brake booster?) and the other had two ports-one in the center, one biased to the front cylinders (B20-fully open fitting for booster--restricted for crankcase ventilation?). Looks like you will need to stick with the B18 system but you need to be absolutely certain your PCV valve is correct for the Volvo--generic valves off the shelf for other motors may have the same size hose connections but the air passed is different. Beyond checking for vacuum leaks and being sure the ign timing/valve adj is where they should be--and adjusting the mixture when all vacuum issues are solved if you still have starting and running problems - I hope not-but-think you may have to dig deeper. -- Dave

Does the B20 combo manifold have secondary butterflies? I have all vacuum ports pulled and plugged currently to troubleshoot. That has not solved the issue as yet. So the PCV valve is out of the picture right now as is the booster.

Going to review valves, compression and timing then back to intake and carbs. Fuel pressured was just above 4 pounds. Put on spare pump and it's around 5 pounds now. Pulled pump output into container. There was good flow. I did pull float bowl covers. Checked float levels. Verified main jet pickup was clear. Can one bottom jet tube into float bowl cover? I have a spare set of Rover HIF6s. Its pickup tube was a 90 at bottom.

That fuel pressure is on the high side.
You don't need much more than 2 psi for your HIFs.

Also, I have only seen HIFs on cars without the "secondaries" intake manifold.
But HIFS will work with the secondaries manifold. That's what I have on my '70. No secondary butterflies though.

"Also, I have only seen HIFs on cars without the "secondaries" intake manifold."
Could it be that those B20's had the combo cast iron manifolds from '67 B18's? Those are the only combo manifolds I've ever seen that DIDN'T have the 2nd butterflies and central mixing chamber. Maybe those manifolds were used elsewhere around the world. As far as I've ever seen--'69 and '70 with Strombergs and '71 and '72 with HIFs had the extra throttles. With these cars decades old anything is possible. -- Dave

Besides checking all basic items. Maybe as a test I will wire secondaries open. If things improve I can pull the carbs and remove the butterflies and cap the holes.

sounds like my recent battle with a vacuum leak, if your biggest problems are at idle and low rpm, it a pretty good bet. disconnect a pvc hose that runs into the manifold and blow cigar smoke into it, any leaks will be pretty aparent. if most of it comes out the air cleaners then turn your idle screws all the way out so that the butterflys close off the carb throats.