888 / 302 intake manifold

[Haut Medoc]

Re: 888 / 302 intake manifold

Agreed. However, I don't think they use a different y-pipe. The 1/2" of extra deck height won't affect much on the y-pipe. I'm sure the difference is covered up by the rubber exhaust connections from the y-pipe to the riser.

There is a difference in the measurement.....
There are 302 Y's & 351 Y's.....

 

[89cruisers]

Re: 888 / 302 intake manifold

Alright, well like I said the engine checks out, I have timing at about 6* at idle, and it does advance to about 30* at 3k rpms. Doing a engine swap isnt much in the plans as a 351 is a bit hard to come by. Although it might not help, I dont see anything "bad" that can happen by adding the 4 barrel, afterall, if it doesn't help and I sawp out the drive, the 4 barrel has small primarys which will help with fuel efficiency. I dont see much of a selection for anything smaller than a 15" dia? It does currenly have a 4 blade 15x16, Might possibly try the 15.5x13, or a 15x15 3 blade, seems 3 plades are moving less water, so less stress on the engine?

 

[haulnazz15]

Re: 888 / 302 intake manifold

Should be more than 6-degrees BTDC at idle.

 

[Aloysius]

Re: 888 / 302 intake manifold

The 4bbl. certainly won't hurt you, just don't expect miracles. Personally, I run 36 degrees total advance, but my mixture is ok and I don't run flat out for long.

Bump it up 2-4 degrees..it will really wake it up.

 

[JasonB]

Re: 888 / 302 intake manifold

If I remember correctly, standard timing on a Mercruiser 302 is 10deg BTDC. Also, make sure you are timing off the correct cylinder, #1 on a Ford is the opposite side as a Chevy. #1 is on the left facing the front of the engine. A Chevy guy timed my 302 for me once and did it off the wrong cylinder. It ran lumpy at idle and had horrible power.

Also, just for discussion, be careful with the firing order. The factory cam in many (all?) 888's was a 351 order.

302 order: 1-5-4-2-6-3-7-8 with 1-2-3-4 on the left and 5-6-7-8 on the right. The dist turns counterclockwise

351 order: 1-3-7-2-6-5-4-8

http://www.offroaders.com/tech/V8-engine-firing-order.htm

 

[Aloysius]

Re: 888 / 302 intake manifold

Most marine cams use the 351 firing order..seems like ALL the reverse rotation cams are the same 351 pattern, just reversed.

 

[89cruisers]

Re: 888 / 302 intake manifold

Well I lowered it to 6*, when I took it for the run that day it was at 10*, I put it at 6* so that it wouldnt be so fussy with the octance being a bit on the low side since when I actually use this, the gas will sit 2-3 weeks at a time. And thanks for that info on the firing order, which I however do have it correct

 

[haulnazz15]

Re: 888 / 302 intake manifold

Put the timing back at 10. The octane of the fuel isn't going to decrease significantly over 2-3 weeks. It isn't a high compression engine anyway unless the previous owner built it that way.

 

[JasonB]

Re: 888 / 302 intake manifold

Is the dizzy advancing ok? I believe the max advance is 24-26 degrees by 4k.

 

[Aloysius]

Re: 888 / 302 intake manifold

It should be all in at cruise..3000 rpms. The question is..what is REALLY in the distributor? I've seen 0 to 40 degrees advance in distributors. Only if you know what YOUR distributor does can you rely on initial timing.

 

[89cruisers]

Re: 888 / 302 intake manifold

Well I put the rpms at 3k and timing at that point was at about 30*, I will put the timing up to 10 at idle then.

 

[haulnazz15]

Re: 888 / 302 intake manifold

I want to say that the total ignition advance can go up to 36-degrees for the 302/351w. So 10 degrees base plus 24-26 total advance would get you there. It will vary based on what springs you have in the dizzy, but it's usually best in my experience to have all of the advance in by 4000rpm like you were using. However the ignition timing chart for the 888/233 shows that 34 should be max timing at 3200rpms. with 36 being right at 4000. You can experiment, but I think having it at least at 34 degrees will help you out a bit.

 

[Aloysius]

Re: 888 / 302 intake manifold

I agree with haul. Mine actually loves 38 degrees, but I back up a couple for safety. It's all about flame front spread and turbulence. That 4.0" bore takes a while to spread across, and the heads don't induce much turbulence.

 

[89cruisers]

Re: 888 / 302 intake manifold

alright thanks, looks like I will set it to about 10-12 at 650rpms then. I did notice the exhaust bellow is missing so it does release the exhaust thru the drive, just right outside the bellhousing, not sure if that effects performance though. Im hoping my axle for the trailer comes in soon, its getting cold and I want to see if the tune up and removing the hydro-foil helped out any before it gets to late to launch

 

[Aloysius]

Re: 888 / 302 intake manifold

It's gonna make more power if the air is cold!

 

[89cruisers]

Re: 888 / 302 intake manifold

haha true

 

[CLAYAROBINSON]

Re: 888 / 302 intake manifold

Just tagging post to show-up in my repies

 

[89cruisers]

Re: 888 / 302 intake manifold

Just an update since this thread seemed to get a lot of attention, I ordered the 3 blade 15.5x13 prop today and should be in Thursday, The axle for my trailer should be in by thursday as well so I should be able to get it launched next week, winter gear and all lol. I also removed the hydrofoil. I hopefully will change the oil and add some engine restore to help repair any compression concerns...even though it showed okay. Any other suggestions?

 

[89cruisers]

Re: 888 / 302 intake manifold

Took it out yesterday, with the hyrofoil off, a 15.5x13 prop, and timing set to about 12* at idle, it only went up to 3200 rpms, and a max of about 32mph

 

[haulnazz15]

Re: 888 / 302 intake manifold

Definitely should be turning more RPM's than that. Did it bog down at all or was it just a "wall" you hit at 3200 rpms?