14 replies to this topic

[grande_guerre]

Here's the deal: 84 bronco, just swapped the dying 302 with a 351W long block. almost done, i just need a 4 bbl carb and need to run the vacuum(what a bear...) my first question is: i found a part off the back of my 302 that is a pipe that runs between the back of both heads and has a vacuum or valve switch in the middle. It looks like it runs to my air pump. When i fit it to the 351w, it doesn't seem long enough... am i just not fitting it right, or do i need a new part? second question: the long block i bought, did it come timed, or do i need to do all that? any other tips on replacing a 351 would help tremondously! thanks for all the help!

[Seabronc]

The pipe you are talking about is the air inject pipe for the heads. Since the distance is greater on a 351, you will need one from a 351. It does not hook directly to the air pump. The air pump is hooked to the ACV which is mounted on top of the air pipe to the catalitic converter. From the ACV air is directred either to the heads or to the CAT depending on what is going on with vacuum.. Attached is a calibration for an85 351, which I use for my engine vacuum system controls.

Good luck,

[Seabronc]

Here is a picture of the air pump / air inject system. The airpump is on the front left with the Air Bypass Valve mounted on top, from there the large hose goes to the Air control Valve, (note vacuum line hooked to top of ACV). Then a large hose runs to the head Air Inject pipe which has a check valve on it ( to only let air flow in). The ACV is mounted on top of the CAT Air Inject pipe with a check valve also ( air in but no exhaust back). Hope this helps.

[Seabronc]

Another angle showing the ACV hookup.

[grande_guerre]

that's perfect. thanks! and i'm curious, does one need this, or can i just block the ports in the head off if i'm not worried about smog testing? also, my long block, does it need to be timed?

[STLKIKN]

If you are really not worried about smog...
lose the air pump, cats, egr manifold (if thats what you have) and anything else related to emissions...
you will end up having one vac line from the carb to the dist. and a pcv...
Engine compartment can't get much cleaner than that.

Ford sells screw in plugs for the air tube ports on the 5.0, don't recall the part number, but I've used them on F.I and carbed engines with no problems. (should be the same part for the 5.8)

As for the long block... If you REALLY trust the builder then I wouldn't worry about it initially, but it never hurts to double check someone elses work before you twist the key.

[Seabronc]

Ditto on STLKIKN's comment. If you do that, go to a manual choke or you will most likely have run problems untill the engine gets warmed up, especially when it is cold out, then again maybe it doesn't get cold where you live.

[Seabronc]

PS. I would expect the block to come timed, but it wouldn't hurt to check it.

[grande_guerre]

how would i check it if it's not running? i only recall timing it with it running...

[Seabronc]

I think you are asking how to make sure the distributor is in the correct position. That get's you in the ball park so it will start and run. Then after you have it all togetner, you need to do the time it while running.

Did it come with a distributor installed? If not, there is a peoceedure to make sure the new one is installed prtoperly.

Good luck,

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[grande_guerre]

Would you happen to know what the proper procedure is?

[Seabronc]

OK, this proceedure assumes you have rotated the engine without the distributor installed and applies to a Duraspark II system.

A.

1. Rotate engine untill number 1 piston is on compression stroke.

2. Align timing marks for correct initial timing.

3. Install distributor with rotor pointing at number one terminal position in cap, and armeture and stator poles are aligned.

(The armature is the 8 pointed star wheel on the shaft, the stator is the part with the coil. Looking down on it, you will see a smallpole sticking out. Align so they are pointing at each other.)

4. Make sure oil pump intermediate shaft properly engages distributor shaft. It may be necessary to crank engine after distributor gear is partially engaged in order to engage oil pump intermediate shaft and fully seat distributor in block.

5. If it is necessary to crank engine, again rotate engine until number 1 piston is on compression stroke and align timing marks for correct initial timing.

6. Rotate distributor in block to align armature and stator assembly poles and verify rotor is pointing at number 1 cap terminal.

7. install distributor holddown bolt and clamp; do not tighten.

B. If in the above proceedure, the armature stator assembly poles can not be aligned by rotating the distributor in block, pull the distributor out of the block enough todisengage distributor gear and rotate distributor shaft to engage a different distributor tooth and re-install distributor, repeat the above steps as necessary.

C. Connect distributor wiring harness.

D. Install distributor cap and ignition wires. Check that ignition wires are securely connected to cap and plugs.

E. Set initial timing per specification on Vehicles Emission Control Information Decale.

F. Tighten distributor holddown bolt to 17-25 in. lb.

G. Recheck initial timing and adjust if necessary.

H. Connec diaphram assembly hose.

Since this is a replacement engine, I'm attaching the Emissions calibration decale that I use for my 351. My truck originally had a 302 so I had to find a decale that matched my engine configuration.

Good luck,

[grande_guerre]

all right man! this is going to make my life a lot easier... not that the carb isn't going to be tough enough as it is... anything i should look out for when putting the new carb on?

[Seabronc]

As far as the carb, if this is an old intake manafold, check that the surface the carb is mountecd on is flat. Mine had a few erosion spots from the EGR and had to mill it down just slightly. If you don't you probably will have a vacuum leak at the base of the carb. Also, make sure you have the right gaskets and properly snugged carb. Torque carb attaching nuts to 12 - 15 ft. lb. If you under torque, you may have a vacuum leak and if you over torque you may break the mounting tabs on the base of the carb .

God luck,

[grande_guerre]

sweet. Thanks seabronc!