Carb

[87318]

I was looking on ebay and found a 670cfm carb off a 78 318. Will it be compatible with my 87 318?

[Dodgevanman]

The 670cfm carb. is most likely a Carter Thermoquad 4bbl. carburetor. I would venture to say that you're '87 is a Holley 6280 2bbl. carburetor with electronic feedback. Sorry but no, it would not be a direct replacement for you engine.

Are you looking to go to a 4bbl. carburetor?

[87318]

Yes, I would like to get a 4 bbl. The 78 carb is aftermarket. Its a holley street avenger.

[Dodgevanman]

You'll need to swap over to a 4bbl. intake manifold. If emissions testing is not a concern, you can get Edelbrock's Performer intake (P/N 2176 I think).

[87318]

I looked on summitracing.com and found a 750cfm carb. and manifold for like $460. Would this be a good setup? the carb is an edelbrock, I think.

[Dodgevanman]

750 is a bit too big a carb for a stock 318. You'd be better off with a 600cfm carb. Make sure you get the one with the electric choke.

[87318]

They also have a 600cfm. But its a manual choke. Would a manual choke not work on my van?

[DANVAN]

Ditto on what Dodgevanman said, no larger the 600cfm, and auto choke would be nice, u can use a manual one if u wish.

[Dodgevanman]

yeah..you can use a manual choke carb if you want. You'll just need to run a choke cable up to your dash. I just find them to be a pain in the butt. Just my .02.

[B-300]

Holley makes a kits to convert most of there manual choke carbs to automatic choke.

[87318]

So I have to change the intake manifold? Is there some kind of adapter I could get?

[B-300]

I have seen vans in the salvage yard on occasion using a square-bore holley carb with a square to spread-bore adapter on a stock 4 bbl manifold. (Don't try putting an adaptor to a 2 bbl manifold.) If you look at a 2176 Edelbrock manifold you will notice the divider between the is about 1/4" wide front to rear unlike a stock manifold.
This has a number of problems.
1. The fuel distribution is terrible.
2. The jetting is off considerably if the adaptor doesn't have a divider.
3. The linkages are off due to the height increase... This also causes problems when fitting a stock air filter housing. this assumes you have a 4bbl manifold, linkages and air filter housing. All of these are different than 2bbl setup.

[87318]

So I would have to change my linkage to get a 4bbl?

[Dodgevanman]

If you can find a 4bbl. equipped van in a junkyard and grab the linkage, that would be best.

[87318]

Is there any way to tell a 4bbl from a 2bbl other than looking at the motor?

[Dodgevanman]

Let's see..the last year for a factory 4bbl. was around '87 or so. '88 was first year for fuel injection.

I can post the VIN codes for 4bbl. engines (8th digit in VIN).

U=318/4bbl.

W=360/4bbl.

You can also find a factory 4bbl. pickup and use the kickdown linkage, but the throttle linkage will be different in the pickup. To be quite honest I don't know if the throttle linkage is different or not between the 2bbl. and 4bbl. setup on vans. Maybe "B-300" would know.

[B-300]

The linkage is different because the throttle shaft is over the center of the manifold on the 2bbl and in front of center on the 4bbl since it connects to primaries on the carb.... The kickdown link is longer.
The block is the same on both 2 and 4bbl, the heads have the larger intake ports on th 4bbl.. The manifold is the best clue since even engines have been replaced over the years, sometimes with one that doesn't match the VIN.
About a year ago someone did this swap and posted some pictures of linkages.. I don't recall the thread tittle though.

[87318]

Would I need to change my heads to that of a 4bbl or would mine still work?

[B-300]

The 2176 Edelebrock manifold will work on the smaller port heads used on a 2bbl, 318. The runners are large, up to the gasket area at the heads were the choke down to the smaller size... If the extra power is what your after, the larger port heads are needed along with porting (enlargement) of this choke point if using an Edelbrock manifold.
I just read a gasket catolog and it seems that 2bbl's on '76 up engines use the larger ports... I think the port size is an issue on earlier models only.
Not certian on the exact size, but if I recall correctly large ports are 2.19x1.1" and small ports are 1.89x0.89" wide. Also most small port intake gaskets are embosed steel and large gaskets are fibre.... The gasket material type should help you figure things out prior to disassembly.

[Dodgevanman]

Just wondering. Aren't the '87 318 heads of a swirl-port design or was that just in cars?

[87318]

The heads have the same port size on all '76 and newer 318's?

[B-300]

I couldn't say that all '76 up heads are the same, only that an old gasket catalog lists them as using the same large port gaskets... The catalog is old ~1990.

[87318]

So I could use the 4bbl without changing the heads for now? I will probably get to that later because they are not cheap. I looked on jegs.com and they were $600 a piece.

[Dodgevanman]

I think it was the factory 318/4bbl. engines that had the large port (i.e. 360) heads and the the factory 318/2bbl. engines had small port heads.

If you go with the Edelbrock Performer intake (p/n 2176) and the Edelbrock 600cfm carb, (p/n 1406) you should be okay. These are non-EGR pieces by the way.

[87318]

What does EGR stand for, I forgot? Will it make it run different without it?

[B-300]

EGR is Exhaust Gas Recirculation. Nate is probably correct on the port sizes... The catalog I was looking in was for cars.
The 2176 Edelbrock manifold is made to fit small and large port heads, you just need to open it for max power with large port heads.... I have one on my '71 that has a 360 in it and did so.
The EGR manifold costs more and is needed to pass a smog-check if you need EGR. It's the 3776

[87318]

I think my van is already EGR equipped. Would I need to get an EGR manifold? There are no smog tests around here. Does EGR have anything to do with the way it runs?

[B-300]

How does it run?... I know you had a problem with smoke in the exhaust from another thread. The EGR won't cause this but if the EGR valve sticks open the engine will tend to stall at idle.
The price on heads seems high. I used Edelbrock heads at a $1290 a pair a few years ago. I did have to modify the pushrod holes since the are on a '91 block with roller cam which has larger holes in the stock heads.

[87318]

Well it runs fine now, other than the smoke, I just don't want to make it run bad. I was thinking of going to the junkyard and getting heads and replacing everything. Could I use the heads off of a truck?

[Dodgevanman]

Yes you could, but in my opinion just stick with your stock heads and you'll be fine. As a matter of fact it would be a good time to have new valve guides and seals installed.

If emissions testing isn't a problem, you can also remove the emissions junk and catalytic converter (check local laws) and go with a true dual exhaust system.

[87318]

I already have a true dual setup. I have a Flowmaster Super 40 dual in- dual out. I had to have it put out in front of the tire because of the plastic tank. What othe emissions stuff is on it?

[Dodgevanman]

Ah okay.

Well you can remove the air pump, air tubes to the exhaust manifolds, etc.

[87318]

Will that add power? Would I have to take off and do any modifications to the exahust manifold? If I do take the exhaust manifolds off I will put headers on.

[Dodgevanman]

Headers would increase low-end torque. Personally I'm not a big fan of headers, but that's just me.

Where the air injection tubes go into your exhaust manifolds those ports would need to be plugged up.