Author Topic: I want to replace cracked log manifold with 4" center risers on CVZ (Read 11062 times)

Scott in nh · « **on:** February 01, 2016, 03:21:07 PM »

I see a kit available:

http://www.ebay.com/itm/161727206100?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Will this fit under the hood on my CVZ?

How about a typical aluminum dual-plane 4 bbl manifold and carb?

CVX Fever · « **Reply #1 on:** February 01, 2016, 03:34:21 PM »

Centerrise manifolds should fit just fine. Same with the aluminum intake manifold & 4bbl carb.

california special · « **Reply #2 on:** February 02, 2016, 07:43:14 AM »

i put that kit on my 1980 cvx. the risers are very close to the engine cover but it does clear. dont just buy the exhaust spend the extra money on the full conversion kit. it comes with water seperating fuel filter adapter bracket, alternator adapter bracket, and a low profile exhaust elbow to clear the oil cooler. not to mention all the necessary hoses to plum it and a new t stat housing. everything u need to bring the motor into this century.

Scott in nh · « **Reply #3 on:** February 02, 2016, 08:00:49 AM »

Quote from: california special on February 02, 2016, 07:43:14 AM

i put that kit on my 1980 cvx. the risers are very close to the engine cover but it does clear. dont just buy the exhaust spend the extra money on the full conversion kit. it comes with water seperating fuel filter adapter bracket, alternator adapter bracket, and a low profile exhaust elbow to clear the oil cooler. not to mention all the necessary hoses to plum it and a new t stat housing. everything u need to bring the motor into this century.

Thanks for the recommendation - do you have a link for this kit?

Plugcheck · « **Reply #4 on:** February 02, 2016, 02:37:16 PM »

I have a 79 CVZ, Vortec SBC, qject on performer manifold and GLM center rise manifolds that clear my stock height engine cover, but I doubt they would if I added 4" risers to them. I can locate a pic or video if you want to see it.

Scott in nh · « **Reply #5 on:** February 02, 2016, 02:46:13 PM »

Quote from: Plugcheck on February 02, 2016, 02:37:16 PM

I have a 79 CVZ, Vortec SBC, qject on performer manifold and GLM center rise manifolds that clear my stock height engine cover, but I doubt they would if I added 4" risers to them. I can locate a pic or video if you want to see it.

That would be very useful.

I want to fix it right and don't want to spend almost as much replacing with stock log manifolds, but don't want a headache because accessories and the motor hatch don't fit.

Are you happy with the Qjet?

I ask because a rebuilt one from JET seems to be the cheapest way to go (a new Edelbrock car is about $100 more and a Holley $100 more than that)

CVX Fever · « **Reply #6 on:** February 02, 2016, 05:12:40 PM »

Here's a ink for conversion kit. Just "google" mercruiser center rise conversion" and you'll get plenty of options.

http://www.marineparts.com/partspages/merc/merc28.htm

FYI the newer 5.7 going into my CVX18 has center rise manifolds and I'll bet Jeff R's paycheck I won't have ay fit issues with the engine cover!

CVX Fever · « **Reply #7 on:** February 02, 2016, 05:20:57 PM »

Quote

I have a 79 CVZ, Vortec SBC, qject on performer manifold and GLM center rise manifolds that clear my stock height engine cover, but I doubt they would if I added 4" risers to them.

Just for clarification, a 4" riser will work just fine. The 4" refers to the exhaust diameter. If your talking about the spacer between the riser and manifold which typically raises the riser 3" then yes that won't fit. But those are not needed for his application

carlsoncvx18 · « **Reply #8 on:** February 02, 2016, 06:03:11 PM »

I do not have mine home in storage, but if i remember correctly the stock center rise exhaust is the same height as the the carb with the spark arrestor on.

Maybe just a tad lower, Should fit .

Look under cvx18 floor rebuild there are several pictures there.

Maybe our good friend Gregg will move them into the thred.

california special · « **Reply #9 on:** February 03, 2016, 07:47:30 AM »

ill try to upload some pics later. i got the kit off of ebay it was about $600 cheaper than i could get it thru my job.

Scott in nh · « **Reply #10 on:** February 03, 2016, 08:16:04 AM »

Thanks guys,

I'm hoping pictures will show/explain issues with the brackets and thermostat housing.

Honestly I just wanted to fix an existing problem with an upgrade, but if that means spending more than the kit I posted above then I think I will just stay with the logs, throw a 4 bbl on it and call it good.

Scott

Plugcheck · « **Reply #11 on:** February 03, 2016, 09:22:00 AM »

Not the best pictures, but what I had on hand at work. The red boat is my project Timi and shows the center rise manifolds, 3" I believe, with 3" spacers. Not certain if this was the stock exhaust or not, but they do clear the engine cover in this application. The Timi engine sits higher, and the cover is taller. The second picture was taken when I had the interior out and was cleaning up and repainting for the season. My risers are fairly tall, but no spacers. Just about the same height as the air cleaner/spark arrestor. They are aftermarket GLM set up, cost about $500.00 from my machinist new for the pair. I made the "Z" tubes by TIG welding four 90"s together.

As for the Qjet, I would not likely have any other carb on a SBC/BBC. The spread bore design, exceptional fuel metering, fuel economy when your being nice, and incredible rush and sound when you open them up, nothing else like it. One drawback, if they are not set up correctly, they can be a drain on your soul. Many have warped horns and worn out throttle bushings which contribute to soggy performance. Granted I'm kinda old, but I grew up working on Qjets and Thermoquads, so I have a certain comfort level with them. Not that Holley, Carter, and Edelbrock don't make fine carbs, they are great for bolt on and go performance, I just like to tinker, optimize, and play with engines a bit more than some, and the Qjet has a lot of potential in that regard.

Hyperacme · « **Reply #12 on:** February 03, 2016, 09:39:30 AM »

Link to Jeff's floor rebuild thread ....

http://forum.cgoamn.com/index.php?topic=1847.msg19691#msg19691

Jason · « **Reply #13 on:** February 03, 2016, 09:42:44 AM »

Here is a picture of my 86 with center rise. These are 3" Outlets though. I know they don't sit any taller than the flame arrestor.

Scott in nh · « **Reply #14 on:** February 03, 2016, 09:50:35 AM »

Thanks, the pictures and your comments help a lot.

My concern with a QJet are the problems you mentioned.

On JEGS.com they have marine QJets rebuilt by JET - I like the price and would assume they are good quality coming from Jegs, but I have so much to do on this boat that "bolt on and go" performance is exactly what I am looking for!

So I would think they come off of Mercruiser 5.7's and should be good to go, but if they are going to take time and knowledge to tune, then $100 more to buy an Edelbrock (Carter) carb could be money well spent.

Also, I grew up with Mopars so am more familiar with the Edelbrock/Carter design.

Scott in nh · « **Reply #15 on:** February 03, 2016, 09:54:51 AM »

Also, my power steering and alternator are mounted like the blue boat above, so I don't see the need to change anything other than the manifolds - am I wrong?

Plugcheck · « **Reply #16 on:** February 04, 2016, 08:45:11 AM »

The blue boat is a 79 CVZ, and even with the rear half of interior, I don't think there is much difference between them and a CVX-18. My power steering pump and brackets came from the original 898 setup(SBC 305). I have two complete Merc 260's in storage with power steering set ups like Jason's, but in either the 898 or 260, I do not think any brackets tie into the exhaust manifolds. I can take a look tonight if you like.
I'm hoping I did not scare you out of buying a Qjet, if rebuilt properly, and I assume they would by JEGS or they would take it back. then they would be a bolt and go application no different than buying a used rebuilt other make of carb.

Scott in nh · « **Reply #17 on:** February 04, 2016, 02:15:52 PM »

Quote from: Plugcheck on February 04, 2016, 08:45:11 AM

The blue boat is a 79 CVZ, and even with the rear half of interior, I don't think there is much difference between them and a CVX-18. My power steering pump and brackets came from the original 898 setup(SBC 305). I have two complete Merc 260's in storage with power steering set ups like Jason's, but in either the 898 or 260, I do not think any brackets tie into the exhaust manifolds. I can take a look tonight if you like.
I'm hoping I did not scare you out of buying a Qjet, if rebuilt properly, and I assume they would by JEGS or they would take it back. then they would be a bolt and go application no different than buying a used rebuilt other make of carb.

The PO of my CVZ bought a used 5.7 long block and transferred everything from the 305 to it including the two barrel carb and manifold.

I did not know the 5.7 used different accessory mounts - this explains the discrepancy and my confusion, but is very good news!

You did not scare me away from QJet, the above convinced me to save some money and go that way.

Jegs has there own line of manifolds that are quite inexpensive too, so I will have basically all new center rise exhaust, carb and manifold for about $1200.

The plan is to have a reliable, reasonably fast, sturdy and pretty boat for <$5k all in

That price includes the purchase price, new floors, stringers and seat frames plus new upholstery and carpet and the above engine work (obviously doing all of the labor ourselves)

Plugcheck · « **Reply #18 on:** February 05, 2016, 08:12:58 AM »

Let me know if you have any further questions, my Z was really a basket case, and required everything. It got stripped down to nothing but a Fiberglas tub and built up from there. I spent approximately 12K so far, but more than half of that was engine and drive related. I may end up putting the stroker in the Timi and using the 260 in the Z, but who knows, I may end up trying the 305 again just to gain some perspective. I have pictures of nearly every step of the resto process, and many on here do as well. Sounds like you have a solid plan to get it together, hope to see pictures of your project progress.

Scott in nh · « **Reply #19 on:** February 05, 2016, 12:17:49 PM »

Quote from: Plugcheck on February 05, 2016, 08:12:58 AM

Let me know if you have any further questions, my Z was really a basket case, and required everything. It got stripped down to nothing but a Fiberglas tub and built up from there. I spent approximately 12K so far, but more than half of that was engine and drive related. I may end up putting the stroker in the Timi and using the 260 in the Z, but who knows, I may end up trying the 305 again just to gain some perspective. I have pictures of nearly every step of the resto process, and many on here do as well. Sounds like you have a solid plan to get it together, hope to see pictures of your project progress.

Thanks, I have followed many of the rebuild and general CVZ threads/posts here including yours.

My floor, stringers, interior and drivetrain are out, wood and glass have been bought, transom has been replaced - then I ran out of weather.

We were given a sewing machine and my girlfriend took a class (I've done some sewing in the past too).

We are ready to purchase marine vinyl, picked one out from the samples I got last year only to discover that Gary's Upholstery has gone out of business

so we are waiting for new samples to come in from a different vendor.

I'll be making new seats while she works on the covers.

Hoping for a nice spring starting in April so I can close up the floor.

I feel things will go faster after that!

We aren't experts in any of this, but have some experience in all of it, so I am confident it will look good to most eyes and hopefully run well too!