Intake manifolds - carby type

[ToranaGuy]

Hey everyone,

Got an issue where I think my intake manifold on my F8b is cracked.What I'm trying to find out & couldn't by using the search function (yes some people actually use it), is if there is any differences in the F5a & F8b intake manifolds?

I know there are manifolds with no EGR & some with EGR, that's not what I need to know. I'm trying to be lazy & see if I can fit the intake from my F5a with EGR onto my F8b with EGR, as I can find a few non EGR f8b manifolds in my spare parts, but I can't find a spare EGR type, and I don't feel like changing the exhaust manifold as well, or trying to find something to plug the EGR hole up in the exhaust manifold.

Do the F5a & F8b EGR type manifolds interchange, if anyone knows?

Cheers

ToranaGuy

[Billie]

Ports are smaller on f5a. Fits but not good for performance

[ToranaGuy]

For now that wouldn't kill me, as long as it fits. Thanks dude, that's the answer I needed.

Remembering I have a few F8b non egr type manifolds here, I just wanna drop something on quicker to get it running & not have to piss fart around with the exhaust manifold too.

I need to get it running, I need to remove the dash from the EB Ghia & that might take a few days depending on what I find broken & what not under it, in a mission to change the heater core, I'm sick of driving in winter with no heater. The mighty boy has a heater lol, so I'll drive it to work & back....

Cheers

ToranaGuy

[Psi_Wagon]

before i made the extractors on mine, i cut the egr pipe off the exhaust manfild, welded the screwin bolt shut and screwed it back in. removing the rest of the egr gear.

[ToranaGuy]

Well guys, I thought I would update the thread a little.

Got around to pulling the intake manifold off today, nothing really out of the ordinary except the bypass was clogged up. I don't think that's a big deal tho, just makes it harder to bleed air out of the cooling system, not impossible tho.

Anyway, I pulled all my spare intake manifolds out. I noticed the F5a & F8b EGR type share something in common, that isn't the size of the fitting for the EGR pipe! So that scraps that idea, no easy swap. I can't swap the F5a exhaust manifold over due to the J pipe's being different, and mine is now customized to fit my exhaust system.

I had a look see at the cyl head on the F5a. Noticed it has a few little holes to mate up with holes in the intake manifold. Just like the F8b EGR type.


However, the cylinder head on the mighty boy doesn't have any holes that mate up to these extra coolant holes. The holes I'm talking about are in the bottom right corner's of the intake runners.

Intake from a pre EGR F8b - no holes. My cylinder head on the mighty boy, the lovely ported head that has cost a small fortune, has no holes for what look like extra coolant passages either!




So I'm thinking my manifold isn't cracked at all, I'm thinking I have a small coolant leak that is bleeding past the intake manifold gasket & into the intake runners. If there is coolant under pressure in those little holes and they smack up against a wall with a paper gasket, I'm thinking the coolant is bound to leak past & into the intake runners. IE, I'm using the wrong bloody manifold for my head!

I guess I need one of the "Elites" of the mighty boy world to tell me if I've been stupid or I'm just thinking stupid right now lol.

Cheers

ToranaGuy

[Brayden]

I think you'll find that the extra ports on the EGR manifold are to recirculate exhaust gas into the intake ports, not coolant into the manifold.

I've seen EGR manifolds used on non-EGR heads without coolant leaks before.

[ToranaGuy]

The EGR port sits in the base of the manifold under the carby, if you remove a carby & look down at the back of the bottom of the manifold you can see the EGR hole.

If they have been used without leaks before, I think I need to take the head off again & take it back for a re-test. Something might be wrong with it that wasn't fixed when it should have been. If that's the case, they will be fixing it for free this time, it cost me almost $300 last time, it hasn't been cooked & it has to be under warranty.

Cheers

ToranaGuy

[Brayden]

I know where the EGR port is on the back of the manifold, but from memory there is a secondary system on later model motors that recirculates air through those small ports. It might not be exhaust, could be fuel vapour from the carby (I'd have to check a carby/manifold to refresh my memory.

There is the chance that I'm completely wrong and those ports are used to plumb coolant somewhere.

[ToranaGuy]

Fuel vapor's, hrmm. I thought the canister was hooked to a port on the side of the carby. Never seen a F5 or F8 with a "smog pump" on it to require ports in the head like that, sort of like the holdens in the early 80's.

I might take another look at my F5a in the shed, see if I can see where the ports go to inside the head.

I also noticed the few manifolds I have all have different amounts of vac ports, one has none near the thermostat, one has 1 & the other has 2. The one with 2 I believe to be from an Auto gearbox car, other 2 I have NFI. I should take a pic of them all.

Cheers

ToranaGuy

[Brayden]

Correct, the manifold with two ports is from an auto. They're not vacuum ports though, they are water temp senders for switches on the vacuum assembly for the carby idle circuit. I started to draw a diagram that explains the system and really should finish it, as the info isn't covered in the SS40T auto supplement for some reason.

[ToranaGuy]

Thought as much. I had a look over your diagram you have posted up, and worked out that I also have 1 auto F8b carby in my pile of carbies(about 6 or so lol). I pulled it off because it would randomly idle too high, now I know that the vac hoses were messed up & that was causing the idle switch to make it idle high.

Cheers

ToranaGuy

[Brayden]

Oh, totally forgot I'd actually finished that diagram after all!

[ToranaGuy]

LOL! Yeah it looks good, and a good reference, thanks for putting that up there Brayden.

I'm no closer to having my boy running just yet tho. At least I know I should remove a lot of the vac hoses that were in my engine bay. lol. Being a manual, almost none are required, aside the dizzy advance.

Cheers

ToranaGuy

[Trav]

Mmm, interesting. The EFI manifold I have from a Jimny has the same ports and I was going to ask about them. On mine they match the F6A head but not the F8B of course. The F6A came from an auto I think.

My question is how much would they affect the flow?