Max rpm 2800

wowzer52 · Post by **wowzer52** » Sat Mar 05, 2011 10:54 am

I need a driver to get 140 yards

I'm interested in this as mine used to get 4000rpm loaded but have fallen off to 3600.

kallen · Post by **kallen** » Sat Mar 05, 2011 6:24 pm

OK, on my 1981 318 cid. engines the timing can be set by the timing marks on the flywheel ring gear ( stamped).You can compare the intial timing setting to the harmonic balancer. Move the rubber cover at the top of the bell housing. I have seen the balancer ring move to give a false timing mark. Under the plastic cover covering the distributor the firing order is on a label. Had a similar problem with rpm and traced it to the float level. Reset and it was good.

plansea · Post by **plansea** » Sat Mar 05, 2011 6:30 pm

No Production today. 80 degrees here today and the Admiral had other ideas. Larry

Captain Blast Off · Post by **Captain Blast Off** » Sat Mar 05, 2011 10:18 pm

I have to agree with Kallen; your first thought was that you had a fuel problem. Look at your float level and fuel filter then check pressure and volume of your fuel pump. Since you've been running this thing for some time and it runs great at low rpm it will be fuel delivery (float level, filters or low volume / pressure from the pump), air restriction or mechanical advance stuck (which is unlikely because the engine would run real sour).

If you're not getting any rough running or backfiring I would really check your float level, fuel filters and fuel pump output before you go too far.

Steve

rossjo · Post by **rossjo** » Wed Mar 09, 2011 9:06 am

Well Larry - did you get out of the Salt Mine and get her running? Cruised by Monday on my way fishing (will this wind ever stop?) but didn't see anyone on board.

I'm happy to help, but my reputation as a mechanic must be well known

on the docks.

plansea · Post by **plansea** » Mon Mar 21, 2011 5:57 pm

For all you guys that have taken so much interest in my problem, i have good news and not so good news. I was able to get the "extra" plug out of the gas tank top, assembled a new fitting and pick-up tube and lengthened the manual shut off valve lever. Good to go, simply sealed off the broken one with epoxy . With help from my new engine tach i determined that lower helm tachs pretty well stopped working at about 1600 rpm. After that they increasede at maybe 10% and that was not consistant. Therefor what i thought was 2800rpm, was actually closer to 4000 !! In neutral no less !! Many many thanx to those of who said check the tachs first. I changed resisters,coils,plugs, and finally plug wires. I reset timing at 5 degrees and then at 7, remember these engines were designed to run on 86 +- octane. I get 91 at the marina. That said, i get 25 degrees advance at 2500rpm,32d at 3000, and 35 at 3500. Both engines. A short run in the harbor,wot resulted in only 2800 rpm @ 19 mph with the tide and small tail wind. Into the sea wot only 12 to 13 mph. Bottom cleaned and trim tab repaired the day before. I have not checked the float levels or fuel pressure,I need to get someone to do that for me. I am beginning to wonder if mebby someone has repitched the wheels and did't change the numbers or something like that? I apologize again for such long posts, just don't know how to say it any differently. Larry

plansea · Post by **plansea** » Mon Mar 21, 2011 6:03 pm

For all you guys that have taken so much interest in my problem, i have good news and not so good news. I was able to get the "extra" plug out of the gas tank top, assembled a new fitting and pick-up tube and lengthened the manal shut off valve lever. Good to go, simply sealed off the broken one with epoxy . With help from my new engine tach i determined that lower helm tachs pretty well stoped working at about 1600 rpm. After that they increasede at maybe 10% and that was not consistant. Therefor what i thought was 2800rpm, was actually closer to 4000 !! In neutral no less !! Many many thanx to those of who said check the tachs first. I changed resisters,coils,plugs, and finally plug wires. I reset timing at 5 degrees and then at 7, remember these engines were designed to run on 86 +- octane. I get 91 at the marina. That said, i get 25 degrees advance at 2500rpm,32d at 3000, and 35 at 3500. Both engines. A short run in the harbor,wot resulted in only 2800 rpm @ 19 mph with the tide and small tail wind. Into the sea wot only 12 to 13 mph. Bottom cleaned and trim tab repaired the day before. I have not checked the float levels or fuel pressure,I need to get someone to do that for me. I am beginning to wonder if mebby someone has repitched the wheels and did't change the numbers or something like that? I apologize again for such long posts, just don't know how to say it any differently. Larry

alexander38 · Post by **alexander38** » Mon Mar 21, 2011 6:10 pm

Keep chasing it you'll catch it. Get the fuel system checked before you haul it and pull the props.

rossjo · Post by **rossjo** » Mon Mar 21, 2011 6:11 pm

If you're only getting 4,000 RPM in neutral @ WOT, there are still motor problems. Did you check it with a strobe tach?

As for props, Sean can pull them in the water on your next bottom cleaning and Skips (on Cross County road) can check them out for you. But I think this is premature if the engines won;t pull more than 4k in neutral.

When did you rebulid the carbs? Are they Carter AFBs or what?

plansea · Post by **plansea** » Mon Mar 21, 2011 6:24 pm

I have not checked it with a strobe tach. The carbs were replaced just before i purchased the boat. They are Elderbrock (Carter afbs I think). After all the fine tuning and replacements the engines do run much better, but still NO CIGAR. Larry

prowlersfish · Post by **prowlersfish** » Mon Mar 21, 2011 7:03 pm

Are you carbs opening all the way ? and a photo or laser tach is what you need

kallen · Post by **kallen** » Mon Mar 21, 2011 10:09 pm

Are the carbs right for the engines (cfm). maybe the after market carbs need to re-jetted.

Captain Blast Off · Post by **Captain Blast Off** » Mon Mar 21, 2011 11:22 pm

You may want to check that you have a big enough CFM carb. I don't recall your engine size; I've had a big block Chevy that would not pull over 5k rpm (in a car) but with a 750 it came alive and would pull hard to 6500 rpm. Also ran a 460 Ford in a smaller jet boat and it needed a 750 cfm carb. My "other" boat has a 454; it's a marine power factory set up with the big Q-Jet which is over 700 cfm.

If you have the right size carb then make sure your throttle is adjusted correctly and check that your secondary's move freely. Don't pass up float level and fuel pressure / volume.

You'll get it.

Steve

plansea · Post by **plansea** » Tue Mar 22, 2011 8:41 am

Very good points by all. I had not considered the possibility of the carbs being too small. This is only a guess but i think they are 650cfm. My engines are 400ci,280 hp. I will ck carbs this afternoon. Larry

rossjo · Post by **rossjo** » Tue Mar 22, 2011 9:01 am

Gentlemen -

Unless both of the carbs have serious issues, the engines (one of them anyway) should run at 4,000 RPM in neutral. I would think you can get over 4,000 RPM without even opening the secondaries in Neutral.

Thoughts?

Larry - are the coils old?