Help Please - re-jet 454 merc carb
 

Below is a pic of the carb that I removed from my 92 Sleek, with a 454 merc. I believe it is stock - can someone please confirm. My question is that I bought the boat from Pheonix (1124 ft altitude) and now live in Calgary (3438 ft altitude). Can someone please provide me some guidance on how to re-jet this thing? First, where are the primary and secondary jets? Second, do both need to be replaced? Third, how can I tell what type fo jets I have now, and what type would you suggest I need?

http://pic90.picturetrail.com/VOL216.../411480778.jpg

Thanks

Looks like a weber/edelbrock. What model, 1410?

You never said what the outcome of only 3900 rpm and 40 mph was, please update us.

Planning to update that thread after re-jetting. Though for a quick update I'm now at 4200rpm steady at 45 mph, after replacing my cap and rotor. Still not where I believe it should be. But been told that the jets are a big factor.

How can I tell - where would the model number normally be located?

Thanks

Call Jeff at Allstate Carburetor in Rochester, NY he will be able to get you the correct parts.

Stamped on the front. Go one size lean all around. May not make a huge difference in performance but maybe fuel economy.

Looked again fgor any stamped numbers or names. No names, but have 9772S 1152 stamped on the bottom frame. Is that a stock merc carb? By 'all around' I assume you mean both primary and secondary? Where are they? When I remove them, how do I tell what they are (so I can call the local shop and tell them what I need)?

Thanks

https://www.google.com/url?sa=t&sour...29Y3xAjkiJ-o9w

Check out the link to the pdf of the carb manual for edelbrocks. I believe they are the same carb. The secondary jets will have a number on them. The primary will be a combination of jets and rods. Take a look at the jetting charts, you want to go one lean on both cruise and power mode.

From some googl'ing, I believe the stock merc carb that I have is made by Weber. I live in Calgary (a city with 1.1 million people), and not one shop sells jets and rods for Weber carbs. I tried the 4 marine dealers and every national brand auto parts store. I guess you need to live in a city with 2+ million to get stores to supply Weber parts. I think some of them say they do for Holley and Edelbrock. Can someone confirm if the jets and rods of these 3 makes are the same? Otherwise I'm gonna have to order it on-line and wait a week or two for one.

T

Edelbrock is the same.

Well, opened up my carb to get at thge jets and weird enough all 4 were different. The two front primary's were close (.113 & .101) but still different, where the 2 secondary were very different in diameter (.098 & .077)

Took them to Mopak that carries Edelbrock jets and rods. Unfortunately I'm not sure of the knowledge of their "carb expert" or whether he steered me in the wrong direction. He wasn't able to confirm my carb (even though I gave him the 9772S number), so he went off a 1410 Edelbrock. I explained I bought the bought from Phoenix and needed it leaned out. In the end he gave me part #1431 for primary (.107) with part# 1445 rods, and 1429 (.101) for secondary. I'm questioning his knowledge cause for the longest time he kept ca;ling the 1431 primaries a secondary jet and spent 20 minutes finding me new primaries. It wasn't until I got home that I realized he was mixing up the secondary and primary jets - I called him and he said to ensure the 1431 go with the 1445 rods, so in the end I used the 1431 for primary and the 1429 for secondary (I think though he was expecting the diameters of the two to be opposite, so not sure if it is optimized). At least I have matching sets though now on each side.

Put it back together and it fired up nice on the hose. Revs nice. Haven't water tested it yet cause I think I first need it properly timed.

Will provide an update after timing is set and water tested.

Thanks

The jet charts were in the link I provided. I would use those. I have a 1410 carb and works great on a 375 horse small block.

The link was very useful. Only issue is that I really didn't have a good base, being that I had 4 different jets. The charts in the link show a 'base' and then explain how to adjust based on altitude change. Based on what I had, what do you think of the new jets and rods I got - do you think it will be an improvement? I guess one way to tell is from the plugs after I have been running them for a while.

Thanks

If serial number for your 1992 454 falls in this range - 0D805069-thru-0F304999. Below is an exploded view and parts list for the Weber carb. Model 9772S primary jets were .107 (#811541). Secondary jets were .98 (#811542).

http://www.marineengine.com/parts/me...rburetor-weber

Here's a great book on those carbs. You could find one on eBay or Amazon.
It will clear everything right up for you.

http://i205.photobucket.com/albums/b...pskn1mh6fq.jpg

Also, if you can find one of these rod/jet kits, you'll be able to really fine tune the carb.

http://i205.photobucket.com/albums/b...ps4ccjch5o.jpg
http://i205.photobucket.com/albums/b...psfvsjocjo.jpg

Are the primary bores 1 7/16 or 1 3/16"? If they are the bigger one it is a 750. According to the jetting chart "one step lean" would be:

Secondary jet: 1430, .104
Primary jet: 1433, .113
Rod: 1457. .073x.052

Here are the specs on the stock carb jetting/rods/etc as delivered by Mercruiser:

Page 2;

http://www.boatfix.com/merc/bullet/91/91_06.PDF