470 mercruiser rebuilt engine install questions

[aarons 470]

Ok thanks. So what fuel pump do you guys like better I have one where the bowl is below and one more points up.

The one that points below is a bit harder to change filter but it's easy enough to just take entire pump off for maintenance. It's from an 88 so I'm assuming it's better?

The upper bowl obviously easier maintenance and it comes off my 82 engine

 

[wrestling coach]

I have the carter pump. Filter above. But be aware here. I am not an expert yet on these engines but I have read elsewhere that the length of the arm on the pump that rides on the cam is an issue. You must have the correct pump/arm length or there will be problems with fuel delivery..

Dennis

 

[aarons 470]

Ok good to know coach, prob a good idea then to use the one that was on engine to begin with

 

[stonyloam]

The arm length was an issue with the new aftermarket (and apparently some OEM) pumps. Had to do with the thickness of the gaskets, and a too long arm that resulted in too much fuel pressure. The newer pump should be OK too.

 

[aarons 470]

I gently wire wheeled my head bolts to get the greese and old anti seize off.
Amd I am now soaking them in detergent. Would it do any good to spray on some good primer to help with corrosion or would it just come off.

 

[wrestling coach]

Your head bolts only need a non hardening sealer like Permatex Aviation sealer. The key is Non Hardening. Some of those head bolts will be in water jackets and some won't. No worry. A little Permatex Aviation on them all and you are OK. Chase and blowout all the threads for the best torque values.

 

[aarons 470]

No Title

Ok back to fuel pumps. Looking at
Arms they are way different. The silver one came with the engine that I rebuilt it's the 82. I assumed it was origional with that engine. I Was just going to use it to be on the safe side.

Thing is though,it was installed but may have never been used. The bowl looks bran new, I doubt they just replaced the bowl? And has a new filter inside (was out in wrong it's all bunched up) it has a way longer arm than the one from the 87.

The newer model mounts bowl toward bottom.

 

[wrestling coach]

I gently wire wheeled my head bolts to get the greese and old anti seize off.
Amd I am now soaking them in detergent. Would it do any good to spray on some good primer to help with corrosion or would it just come off.

​I doubt that was anti seize. Probably thread sealant like Permatex Aviation Sealer.

 

[wrestling coach]

Ok back to fuel pumps. Looking at
Arms they are way different. The silver one came with the engine that I rebuilt it's the 82. I assumed it was origional with that engine. I Was just going to use it to be on the safe side.

Thing is though,it was installed but may have never been used. The bowl looks bran new, I doubt they just replaced the bowl? And has a new filter inside (was out in wrong it's all bunched up) it has a way longer arm than the one from the 87.

The newer model mounts bowl toward bottom.

I just don't know about this one. Someone will however.

Dennis

 

[aarons 470]

No Title

Bowl is bran new, On the silver one that came with my 82 engine. So I'm assuming was installed but not used as the engine was being worked on. The fuel pump from the 87 (black one) did work when it was on my blue waters 470. I'm not sure if engines have same cam etc. the 82 engine is the 488 model I believe, it def has the cobra jet (larger) head.

 

[stonyloam]

Yeah that is a new fuel pump, and they are the ones that MAY have an overpressure problem. It is corrected by using a spacer with the gasket. Read this : http://forums.iboats.com/forum/engi...-outdrives/7449759-merc-470-fuel-pump-problem If you use it, it would be a really good idea to measure the fuel pressure. You can borrow the pressure tester from Autozone, should be about 3 psi. Are you sure you have a larger head? I thought that all of the stock 470 type heads were the same. They appear to have the same part number for all years and models, but I could be wrong, or someone could have modified a auto head.

 

[mickyryan]

I had just went through this problem with a 3.0 mercruiser if you use the other one that didn't come with it you will probably need a spacer gasket sold by mercruiser I don't know your part number but its about 6 timers thicker then a regular gasket, I went to electric myself because I just wasn't having that whole thing of a diaphragm going bad and filling the crankcase with fuel.

 

[aarons 470]

Yes it's def has the larger head. Machinist said it is the cobra jet head. They said it's a desirable head for power

I'm pretty sure it was Stock, I got boat from origional owner and he didn't mention changing the head out. I'll call him and ask.

I like the idea of going electric on the fuel pump, then I'm less likely of destroying my engine.

Any suggestions on which one to buy or pressure range?

 

[stonyloam]

I know someone here went with the airtex, I think you want a 3 psi pump. You will also need a oil reassure switch and a fuel pump relay to make it work safely. Read to the end of the above fuel pump thread, they finally went with an electric, and shows the one they got.

 

[aarons 470]

10-4, I will get that electric pump from that feed. Around 60 bucks not to bad. Then I don't have to stress over it.

What is an oil reassure switch?

And does the fuel pump relay need to be a specific model?

 

[alldodge]

For add on you need a three prong oil pressure switch with a Common, Normal Open and Normal Closed contacts. Remove the oil pressure sender, install a Tee fitting and reinstall the sender and new switch. Make the connections like this

 

[stonyloam]

You should use a fuel pump relay to turn the pump on and off. It can handle the current load better than the pressure switch. You use the oil pressure switch to control the relay.

 

[aarons 470]

Ok, I'm a little confused. I need pump relay and oil pressure switch? On this drawing would the relay be where the fuse is?

I know have another dilemma. I stumbled across some info about push rod lengths when checking out the merc head gaskets.

Said the rods can be different lengths. Well, I looked and one is longer than the rest and the some others seem to have very suttle length differences.

Im using rods from my parts 470 as the one I had built didn't have any when I bought it. Parts engine/head is from 1987. And like I said above my rebuilt head is a larger one.

1- so are the rods the same on the regular head as opposed to cobra jet head?

2- the rods must go in a certain orientation- if I can use the rods I have?

 

[alldodge]

Ok, I'm a little confused. I need pump relay and oil pressure switch? On this drawing would the relay be where the fuse is?

This is where the opinion comes in. I don't see the need for a relay but Stony does.

 

[aarons 470]

Do I need a 30 gph pump, or 19gph both are in psi range. 3-5 psi.