High compression in 1 cylinder - 7.4 carb

[snowbrd84]

And here is a video of it turning over.

 

[snowbrd84]

OK I think I found the problem. Very loose.

 

[tpenfield]

yup, . . . in the previous video the #8 rocker did not seem to be moving as much as the others.

You will have to determine if it is the rocker arm or the valve lifter that is at fault.

 

[snowbrd84]

yup, . . . in the previous video the #8 rocker did not seem to be moving as much as the others.

You will have to determine if it is the rocker arm or the valve lifter that is at fault.

The bolt is tight. Can't tighten it more to remove that slack. That mean it's a stuck lifter?

 

[jimmbo]

Collapsed Lifter, could also be a bent Push Rod. Remove the Rocker Arm and exam the Pivot point, and check the Push Rod for Straightness. Next step would be to remove the Intake, and pull the Lifter to check it out.

 

[Lou C]

Yep that #8 intake valve seemed like it was hardly moving relative to the others. Unlike the earlier small blocks this engine has the non adjustable valve train. So at this point you have to decide how far you want to go with it. You can remove the pushrod & see if it’s bent. If so you can replace it but keep in mind they don’t bend for no reason. If it’s not next is the valve lifter. Not sure how easy they are to remove on the Big Block Chevrolet. Most likely you’ll have to remove the carb & distributor & then the intake. Is the boat in the water? I saw water in the exhaust Y pipe…hopefully it’s the lifter not the cam lobe.

 

[jimmbo]

I thought it was odd that it doesn't have the usual Adjustable Rocker Nuts, but I supposed GM/Mercury made the change for a Reason. I used to consider adjusting the Valvetrain a relaxing task on a Hot day. I wasn't impressed with my Olds/Buick Engines.

 

[snowbrd84]

Removed rocker arm from #8 and put #6 rocker arm on - same gap so rocker arm is fine.

Push rod dead straight and identical to #6 pushrod.

Spring heights are same for 6 and 8. So Def push rod side is low. Stuck the bore scope down the push rod hole. I can't tell anything from the pic, but based on responses it sounds like either lifter is collapsed or cam lobe is wiped out. Sprayed some Deep Creep down onto the lifter and put everything back together.

Will have to research what to do next to uncollapse or replace lifter.

Feasible to replace cam with engine in the boat? This boat does live in the water in a slip.

 

[jimmbo]

Pull the Lifter out and examine it. 999 out of a Thousand you can determine if the a Cam Lobe is wiped just by looking the Lifter.
.
If the Lifter is collapsed, I would try taking it apart, freeing it up, cleaning it and reassembling it and putting it back, as putting a new Lifter onto a used Camshaft, often wipes the associated Lobe in Short Order.

 

[snowbrd84]

Pull the Lifter out and examine it. 999 out of a Thousand you can determine if the a Cam Lobe is wiped just by looking the Lifter.
.
If the Lifter is collapsed, I would try taking it apart, freeing it up, cleaning it and reassembling it and putting it back, as putting a new Lifter onto a used Camshaft, often wipes the associated Lobe in Short Order.

Does the intake have to come off to remove lifter?

 

[jimmbo]

Yup

 

[snowbrd84]

Bummer. Can the intake manifold gaskets be reused or should I be ordering replacements?

 

[ScottinAZ]

Bummer. Can the intake manifold gaskets be reused or should I be ordering replacements?

you will need new gaskets.....

Honestly, I wouldnt worry about purchasing gaskets until you find out the full scope of work. if you need a cam, you are a lot deeper in the parts bin than just intake gaskets.

 

[nola mike]

you will need new gaskets.....

Honestly, I wouldnt worry about purchasing gaskets until you find out the full scope of work. if you need a cam, you are a lot deeper in the parts bin than just intake gaskets.

$10 in gaskets and you may get back on the water, otherwise you're waiting on them and cursing USPS.

 

[snowbrd84]

$10 in gaskets and you may get back on the water, otherwise you're waiting on them and cursing USPS.

Looks more like $80-90 for gaskets running the part number 8M0050225. Will go ahead and order so I have them on hand. Fingers crossed its just the lifter.

 

[ScottinAZ]

$10 in gaskets and you may get back on the water, otherwise you're waiting on them and cursing USPS.

True, I wasnt thinking that you need marine intake gaskets.... most any NAPA should have a set of gaskets for a Chevy Rat motor..... marine not so much though

 

[Lou C]

The head gaskets have to be marine grade & I see that Fel Pro also sells marine intake gaskets separately from the full set. You want the marine gaskets because one thing you don’t want to have happen is for the water passage in the intake to leak into the cam valley. Marine engine gaskets are more corrosion resistant.
Make sure to get intake gaskets that match the port design you have; there were oval & round port designs…

 

[nola mike]

The head gaskets have to be marine grade & I see that Fel Pro also sells marine intake gaskets separately from the full set. You want the marine gaskets because one thing you don’t want to have happen is for the water passage in the intake to leak into the cam valley. Marine engine gaskets are more corrosion resistant.
Make sure to get intake gaskets that match the port design you have; there were oval & round port designs…

I don't think there's a difference between marine and auto intake gasket. both composite IIRC.

1998 CHEVROLET C2500 SUBURBAN 7.4L V8 Intake Manifold Gasket | Shop Now at RockAuto

Engine Parts and More for Your 1998 CHEVROLET C2500 SUBURBAN at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

 

[ScottinAZ]

I don't think there's a difference between marine and auto intake gasket. both composite IIRC.

1998 CHEVROLET C2500 SUBURBAN 7.4L V8 Intake Manifold Gasket | Shop Now at RockAuto

Engine Parts and More for Your 1998 CHEVROLET C2500 SUBURBAN at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

if thats the case, I would just source them locally if it were me. Rock Auto has good prices on the parts, but you eat it up in shipping..... unless you have a sizeable order, and even then sometimes its not worth it. Same with the lifters, and possibly the cam, depending on spec and availability.

 

[snowbrd84]

Sierra part was basically same price shipped to West Marine so ordered the intake gasket. If I need Cam, I can just order cam shaft kit from auto parts store, right? Nothing "marine" about the cam or internal parts?