888 / 302 intake manifold

[89cruisers]

Re: 888 / 302 intake manifold

Naw it was just like a wall. So over this winter will be doing the 4 barrel conversion and "see" what that does

 

[haulnazz15]

Re: 888 / 302 intake manifold

It sounds like the gearing is just too much to overcome.

 

[Aloysius]

Re: 888 / 302 intake manifold

Disconnecting the secondaries on my 450 cfm 4bbl's only drops the rpms 200-300 on my 302's. You simply won't find a thousand rpms by going to a 4 bbl. Something else is wrong.

 

[89cruisers]

Re: 888 / 302 intake manifold

Yes the gearing is off, but disconnecting the 2 barrels in a 4 barrel is not a good enough example because the primaries in a 4 barrel are small

 

[89cruisers]

Re: 888 / 302 intake manifold

As for the foam, I did consider that idea, but I did let the foam area around the gas tank sit and dry in the sun for about a month when I had parts of the floor removed

 

[Aloysius]

Re: 888 / 302 intake manifold

Yes the gearing is off, but disconnecting the 2 barrels in a 4 barrel is not a good enough example because the primaries in a 4 barrel are small

Primaries and secondaries are identical in size.

As such, your 2bbl. is way bigger than the primaries on the 4bbl., and certainly isn't "choking" the airflow at 3200 rpms. You are nowhere near airflow restricted now, so why add more airflow???

 

[89cruisers]

Re: 888 / 302 intake manifold

the reason for adding a 4 barrel is because next year I want a 4 barrel even if I get a new gearset for more power, so I might as well add the 4 barrel beforehand and see if it makes any difference before adding the new gearing

 

[choochooharley]

Re: 888 / 302 intake manifold

My opinion and take it for what its worth I wouldn bother with the 4bl carb but would just get a new se 106 outdrive you can buy a complete unit for 1195 or just the upper unit for 595 and sell the current drive and try to recoup the money....

 

[89cruisers]

Re: 888 / 302 intake manifold

Yes that is my plan next year, but I dont see why there is so much hatred for a 4 barrel, the Merc 225 is a 302 with a 4 barrel.

 

[choochooharley]

Re: 888 / 302 intake manifold

Im not sure the only difference between the 225 and 188 is the 4bbl carb. I think the compression reatio is different and it has a different cam. I am not positive on this im sure someone with more knowledge on the subject may know....As far as the 4bbl carb swap goes I dont beleive youll see any more top speed out of it than with a 2 bbl you will get up there faster. The secondaries are not open all the time only when needed.

 

[choochooharley]

Re: 888 / 302 intake manifold

Also after rereading this thread my book says that timing should be 8 degreees btdc and I think that 110 is a little low I think it should be 130 to 170.

 

[JasonB]

Re: 888 / 302 intake manifold

Good catch. 110 is a bit low looking. In automotive apps, I think it is 140-150. I've also read 120+ is good. Not sure what mine runs.

 

[89cruisers]

Re: 888 / 302 intake manifold

Well the 110 was with it dry and all the plugs in, it should be 150 with it wet and plugs removed

 

[choochooharley]

Re: 888 / 302 intake manifold

The compression is a toatlly different subject bottom line you need the correct gear ratio. That being said have you verifed yourself the compression or are ou just going by what the previous owener told you. What do you mean dry no oil? Also what should be and ought to be doesnt mean it is... Just my 2 cents

 

[haulnazz15]

Re: 888 / 302 intake manifold

The compression ratio didn't change other than small differences in the chamber volume in the heads. I don't think anyone is against you going to a 4bbl, they are a good addition and DO add a bit of HP. We just don't see it as being the answer to your problem of using the 233 outdrive with the 302. the 1.32 gearing just doesn't work that well with the 302, and it's questionable if it was the right unit for the 351w since the 350SBC's used a 1.50 gear ratio.

In any case, you can do the experiment for us and let us know how it goes. Maybe it will give a big enough boost to where you want to hold off on the outdrive swap.

 

[Aloysius]

Re: 888 / 302 intake manifold

The compression ratio didn't change other than small differences in the chamber volume in the heads. I don't think anyone is against you going to a 4bbl, they are a good addition and DO add a bit of HP. We just don't see it as being the answer to your problem of using the 233 outdrive with the 302. the 1.32 gearing just doesn't work that well with the 302, and it's questionable if it was the right unit for the 351w since the 350SBC's used a 1.50 gear ratio.

In any case, you can do the experiment for us and let us know how it goes. Maybe it will give a big enough boost to where you want to hold off on the outdrive swap.

Exactly. The 4bbl. won't give you 1200 rpms, but it won't hurt.

 

[89cruisers]

Re: 888 / 302 intake manifold

Somewhere on page one it will be seen that I did indeed check compression myself, and yes thank you lol, I agree that I wont get amazing results just from that...but it's not going to hurt, and if I get a mechanical secondary instead of a vacuum, then I will know that the secondaries will open with throttle position and not so much if it thinks the engine is ready for it

 

[89cruisers]

Re: 888 / 302 intake manifold

Ive thought about the foam, but so to offset it, my first run was with the rear floor, and seats and everything out (about 150 pounds lighter) no gear, and only 10 gallons in the tank, and with the 15x16 it stayed at 3k, so although the foam might be adding a bit of weight, there's not much I can do without ripping the whole floor out, but I think my unloading about 600 pounds of normal operating weight for the first test would have overcome any wet foam weight issues