Cracked Quadrajet intake manifold

[AdamB]

Okay, while attempting to install an new thermostat in my 1984 Wellcraft with Chevy 350/ alpha one, I managed to crack the intake manifold right below the housing for the thermostat. Actually, I think it may have been cracked by pervious owner, given all the liquid gasket type material, and the fact that there wasn't a thermostat in there to provide back pressure.<br /><br />Anyway, I am now in the market for new intake, I jsut rebuilt the quadrajet on the boat, and it seems to run great. Would a standard rochester intake work the best, or would an after market work better, i.e more torque or whatever??<br /><br />Thanks. I see the quadrajet intakes on ebay pretty cheap...

 

[Don S]

Re: Cracked Quadrajet intake manifold

Depending on the room above your flame arrestor to the engine cover, see if you can get a bit of a high rise dual plane intake.

 

[AdamB]

Re: Cracked Quadrajet intake manifold

What would be the benefits of a high rise dual plane. I figured the high rise would be good for higher rpms correct? I am already having a problem with it wanting to over rev all the time. I was thinking over something for more torque, or do I have this wrong....<br /><br />Can you show me a link to a intake that would fit the quadrajet that is high rise and dual plane??? Thanks.

 

[rbezdon]

Re: Cracked Quadrajet intake manifold

Visit the Edelbrock web site. If you chose the 2104 dual plane you get a little more torque and the height is the same as the stock manifold. Mine bolted right in. Only thing to watch for is most after market manifolds are aluminum and if you run salt water this can be a problem if you dont flush every time you run.

 

[AdamB]

Re: Cracked Quadrajet intake manifold

Thaks Vatter41, I'll check it out. I run mostly fresh water lakes, but do occasionally run salt water and always flush afterwards.

 

[jimmbo]

Re: Cracked Quadrajet intake manifold

Benifits? usually better design and shape of the runners

 

[AdamB]

Re: Cracked Quadrajet intake manifold

So there isn't any low end torque loss with the high rise intakes??

 

[f_inscreenname]

Re: Cracked Quadrajet intake manifold

Edelbrock - Air Gap. I love them.

 

[AdamB]

Re: Cracked Quadrajet intake manifold

So how much more horsepower/torque would a Edelbrock 2101 (for my year) produce than a standard GM intake manifold like a GM 246250 with a Quadrajet. I need a intake for a spreadbore or I would have thought about the Edelbrock 2701... Would it be noticable??

 

[John_S]

Re: Cracked Quadrajet intake manifold

Adam,<br /><br />FWIW, Dennis Moore indicates in his SBC Marine Performanc book, that from idle to mid 3K rpms, there is no better intake manifold than the stock Q-jet. GM spent considerable time and money tuning the manifold with the Q-jet, to the small block. These manifolds should be relatively easy to find used, and in good condition. <br /><br />The GM cast iron high rise was found on Mercruiser LX and 350 mag engines. The Q-jet specs (jets/metering rods/hangers,etc) are slightly different for these engines as well. The timing curve is more agressive, too.<br /><br />The Edelbrock 2101 is between these two, and may not need any Q-jet carb tweaks, but the carb is known to be sensitive to engine changes/mods, at least more sensitive than the weber/edelbrock 4brls. It will produce more hp in the upper rpms than the stock manifold. I'd guess the increase would be between 10 and 20hp. <br /><br />Given your apprehension on loosing low rpm torque, I think, you will be better just staying with the cast iron manifold. No worrys about doing any additional tuning and it will perform the same as it did.

 

[AdamB]

Re: Cracked Quadrajet intake manifold

John S, thanks for the quotes from Dennis Moore, as I can't find that book anywhere.<br /><br />This is a 4,000 lbs stern drive that I have already put a torque-shift prop on to help get on plane. With the Torque Shift, it isn't too bad and could probably go to a higher rise intake. However, with a standard 19" prop, the motor would lug pulling skiiers, and then over rev to approx. 5200 rpms. So if the torque-shift ever goes, I would probably hate the high rise intakes. I am trying to get the best of both worlds in one boat, a deep V cuddy for bay/ocean fishing, plus pull tubers and skiiers in the lake.<br /><br />I just purchased for $10 plus $35 shipping:<br /> http://cgi.ebay.com/ebaymotors/ws/e...d=1,1&item=4559534585&sspagename=STRK:MEWN:IT <br /><br />My engine is a rebuilt 1979 350.

 

[Peter J Fraser]

Re: Cracked Quadrajet intake manifold

Adam,<br />That looks like a good deal to me.<br />About the same cost as we would expect here in NZ.<br />FWIW I paid approx US$30.00 for a factory aluminum intake manifold for my new engine.<br /><br />Regards<br />Peter

 

[AdamB]

Re: Cracked Quadrajet intake manifold

I decided to stick with the cast intakes as I do run in salt water... I may eventually switch to a GM high performance, but couldn't find any good deals and I want to get the boat running again. Hopefully, all works out. Went to local Napa and got gasket set and am just waiting to receive the intake.

 

[AdamB]

Re: Cracked Quadrajet intake manifold

I changed it all and all is well.... for now!! This intake didn't have provision for EGR hookup, would made it easier to put on.