470 mercruiser rebuilt engine install questions

[aarons 470]

Hi all. I checked the adults only section under Mercruiser and I am not finding any information on the 3.7 liter/ 470 engine; in the engine manual.
I had my engine completely rebuilt, and the head. (Found out It's a cobra jet.)

Was not a cheap build, I want to make sure I get my torque correct on the head, and I read there is a procedure for the head install that needs to be followed. I cant seem to find the procedures to do this. Engine is from an 83

 

[alldodge]

Guess I'll try another

 

[stonyloam]

The Dodge man is becoming quite the 470 guy If you did not get an OEM Mercruiser head gasket, toss the one you have and get one. The headbolt threads need to be coated with Perfect seal (Permitex or NAPA aviation sealant will do). Make sure that there is no oil or water in the bolt holes. The retorque is very important, there is some debate as to whether you do it when the he engine is still hot or let it cool. I did mime hot, worked fine. You will need to remove the rocker arms to retorque head bolts (yeah it is a pain). BTW the rocker arms need to be torqued in a specific order too. They must be torqued with the valve closed: @ TDC #1 I & E, 2 I, #3 E, #4 I Rotate 360 degrees, one full turn, then #2 E, #3 I, #4 E. when the valves are closed the proper rocker arm will be pretty loose. Good luck!

 

[achris]

The retorque is very important, there is some debate as to whether you do it when the he engine is still hot or let it cool. I did mime hot, worked fine.

The Merc manual says "...Also, cylinder head bolts must be retorqued after engine has been bought to normal operating temperature. Failure to do this can result in head gasket failure."

I read that as retorque while hot.... But its importance cannot be overstated.

Just my 0.02

Chris...

 

[aarons 470]

Awesome, Thanks guys.
My complete gasket set that came from the machinist are Victor Reinz, already paid for. Are these ok?

Curious how come a sealant on head bolts as opposed to antiseize?

Do I put any rtv silicone etc on head gasket?

Thanks again

 

[GA_Boater]

Don't know about the Victor head gasket. Got a number?

Anti-seize isn't sealant, it's basically doped grease. Perfect Seal or the equivalent is used to seal the head bolts. One of our members posted this as a substitute. :wink:

Ayuh,........

Permatex #2 is a Good replacement for the Mercruiser stuff...........

Yamabond or Kawibond are also substitutes.

As far as using RTV on the head gasket, you run the risk of blocking passages.

From the manual;

 

[achris]

Do I put any rtv silicone etc on head gasket?

Not ever....

Head gaskets on all engine always go on as they come out of the packet...

Chris.......

 

[aarons 470]

Ok thanks. So nothing on head gasket. Yes I realize anti seize is more of a lubricant was just curious why not anti seize on head bolts as opposed to the sealants recommended?

So to clarify on head bolts, perfect seal, napa aviation seal, yamabond, and permafex #2 will all work?

Thanks

 

[Scott Danforth]

Get a factory Mercruiser head gasket

 

[alldodge]

Ok thanks. So nothing on head gasket.

Yes absolutely nothing on the head gasket, and the head and block surfaces need to be clean and dry

Yes I realize anti seize is more of a lubricant was just curious why not anti seize on head bolts as opposed to the sealants recommended?

Antisieze is not a lubricant its a chemical which is used to keep surfaces from rusting or otherwise bonding together.

So to clarify on head bolts, perfect seal, napa aviation seal, yamabond, and permafex #2 will all work?

Thanks

Yes, it needs to lube the threads to get a correct torque. Torque is the amount a bolt is stretched. The sealing part is needed because water passes by the bolts

 

[stonyloam]

Aftermarket head gaskets are designed for use with the 460 Ford V8, which is iron head on iron block, the 470 Mercruiser is iron head on ALUMINUM block, so the OEM Mercruiser head gasket http://www.mercruiserparts.com/13709-gasket is designed specifically for that application, and has some extra sealing features that are not found in the auto gasket. The auto gasket might work fine, but for the extra $80 I personally would not chance it, as you say it is an expensive rebuild. All of the other gaskets in the kit should be just fine.

 

[stonyloam]

Yeah I think some of the bolts might penetrate into the water jacket, and (as I understand the theory) you need to make sure that there is no water or oil in the blind holes because if there is you could developed enough hydraulic pressure when you torque the bolt down that it could crack the aluminum block.

 

[Faztbullet]

These motors are lil powerhouses if built. I sold several to a fellow that ran them in dirt track cars up north as the engines was light and they could add weight to car. With internals balanced,head worked,reground cam, hi comp pistons,sheet metal intake and 1050 Holley was told they get around 550hp at 7500rpm.

 

[aarons 470]

Ok, this gasket set does specify it's for a 470. But you guys have the experience, I don't want to risk it.

I just bought a thermostat that attaches under the exhaust manifold. Shop said it is the stock one recommended. It says 160 deg on it. Is this the right one? I am running a red dot heater and....

Reason I ask is mine is an 82 engine with the smaller exchanger. but I'm using the 4" exchanger from an 88 engine I have. Maybe this changes the thermostat temp requirement?

The guy who built my engine has 40 years experience and mostly builds race engines.

He told me about how these engines stock and even more so when rebuilt have to high of compression and can cause problems. So he built it to run on lower quality gas etc. bored 30 over if I remember right.

He also used different pieces around the main bearings from a regular 460, he had to file them slightly but he said it was a part mercruiser messed up on and the regular 460 ones are much better. Moon shaped pieces around bearing. I'm probably explaining it wrong but I was glad he knew what he was doing lol.

I'll prob have more questions, plan is it's going in Tomm, or at least the lower end. And the local boat shop had permatex aviation sealant.

 

[aarons 470]

No Title

 

[aarons 470]

I have a cast exhaust manifold but it's even worse. On the aluminum one in pic there rhebworst spot is just over an 1/8th" wide about 5/32nd. The other side is all about 5/8ths wide

 

[Scott Danforth]

Need replacing

 

[alldodge]

Agree need replacing, or if it can be put on a lathe and flattened so long as not to much is taken off

 

[wrestling coach]

"I just bought a thermostat that attaches under the exhaust manifold. Shop said it is the stock one recommended. It says 160 deg on it. Is this the right one? I am running a red dot heater and....

Reason I ask is mine is an 82 engine with the smaller exchanger. but I'm using the 4" exchanger from an 88 engine I have. Maybe this changes the thermostat temp requirement?"




​I have the same '82 engine. I swapped the 3" exchanger for a 4" exchanger and continue to run the 160* Tstat. No need to change that.

Dennis

 

[alldodge]

Manual list 160 thermostat so your good with that. There is no issue with having a larger HE, the cooling will work easier. Same as putting a larger radiator on a car/truck