Intake/carb selection for 318 Chrysler

Thomas,
This may be a long posting: Mainly you must proceed with considerable caution on this upgrade as this vintage Chrysler engine is more "marine" particular than almost all other marine conversions. We found this out thru experience, aka mistakes, and numerous conversations with vintage Chrysler experts. Several items to keep in mind up front. You will need a reverse rot cam and I don't know of a roller version available, but a standard RR cam upgrade is available. Next, and the biggest anomaly, is the plumbing system which directly affects or is affected by the intake manifold, which is the most unique issue to this engine. As you will or have already noticed on your existing intake, it's stamped "MARINE", and is for a reason. Like some early pre '66+/- Interceptor Fords, there is no circulating water pump, only a two impeller raw pump in this case. Water flows into the front housing/cover- then into the starboard block then head and into the intake- then BACK into the front cover and then into the port block and head and then finally out of the intake and out of the engine. The water path isn't open straight thru or across the front of the intake/engine like most do prohibiting the use of an automotive intake, UNLESS you modify it to operate like Marshall did to control the flow as required. (see Marshall Morgan's hot 273 Chrysler 1970 Mustang in the diaries with an Edelbrock) You must block the flow and direct it back out of the intake with a new nipple. You'll see the hose on the left front leading from the intake back into the front cover. So study the way the water flows thru the somewhat confusing diagram in the Chrysler owner's manual in the REFERENCE SECTION. A standard auto intake will not flow adequate water to the port side of the engine. BUT, I do recommend having the modification made and going with the aftermarket intake as it made a considerable difference in performance, and your original T-stat housing and hoses will then hook up correctly.

Your factory marine intake has a "wedge" built into it, (Chrysler was serious with the marine stuff) and you may want to install a wedge with the new intake, but it will run fine without it with a newer modern carb. I'd want to stay with the original Carter or a Holley (won't bolt on orig marine intake) or Edelbrock marine carb (back barrels won't open on orig intake as ports too small). Many of the newer Edelbrock intakes are of the spread bore design, but many standard square bores, like Marshall's, are out there on Ebay and at good prices, and if you're gonna buy something used, an intake is a safe bet. Hope this answers some questions. If you want to discuss this at any time, feel free to give us a call.
Reid      

reidp wrote: Thomas, This may be a long posting: Mainly you must proceed with considerable caution on this upgrade as this vintage Chrysler engine is more "marine" particular than almost all other marine conversions. We found this out thru experience, aka mistakes, and numerous conversations with vintage Chrysler experts. Several items to keep in mind up front. You will need a reverse rot cam and I don't know of a roller version available, but a standard RR cam upgrade is available. Next, and the biggest anomaly, is the plumbing system which directly affects or is affected by the intake manifold, which is the most unique issue to this engine. As you will or have already noticed on your existing intake, it's stamped "MARINE", and is for a reason. Like some early pre '66+/- Interceptor Fords, there is no circulating water pump, only a two impeller raw pump in this case. Water flows into the front housing/cover- then into the starboard block then head and into the intake- then BACK into the front cover and then into the port block and head and then finally out of the intake and out of the engine. The water path isn't open straight thru or across the front of the intake/engine like most do prohibiting the use of an automotive intake, UNLESS you modify it to operate like Marshall did to control the flow as required. (see Marshall Morgan's hot 273 Chrysler 1970 Mustang in the diaries with an Edelbrock) You must block the flow and direct it back out of the intake with a new nipple. You'll see the hose on the left front leading from the intake back into the front cover. So study the way the water flows thru the somewhat confusing diagram in the Chrysler owner's manual in the REFERENCE SECTION. A standard auto intake will not flow adequate water to the port side of the engine. BUT, I do recommend having the modification made and going with the aftermarket intake as it made a considerable difference in performance, and your original T-stat housing and hoses will then hook up correctly. Your factory marine intake has a "wedge" built into it, (Chrysler was serious with the marine stuff) and you may want to install a wedge with the new intake, but it will run fine without it with a newer modern carb. I'd want to stay with the original Carter or a Holley (won't bolt on orig marine intake) or Edelbrock marine carb (back barrels won't open on orig intake as ports too small). Many of the newer Edelbrock intakes are of the spread bore design, but many standard square bores, like Marshall's, are out there on Ebay and at good prices, and if you're gonna buy something used, an intake is a safe bet. Hope this answers some questions. If you want to discuss this at any time, feel free to give us a call. Reid

Thomas,
Come on down. We'll have a boat hangin in the boathouse for a few more weeks.

Like 79Nautique clarified, the intake I referenced as Marshall's is indeed an older Edelbrock, and simply a predecessor to the excellent Performer intake.

I do feel the intake is a worthwhile performance investment, esp if you have some interest in doing the head work as well.

I thought my mobile number was out there somewhere but my mistake. It's 704-451-5080, and it stays on just about all the time, for boat talk anyway.
Thanks.   

I have to apologize for bringing this thread back from the dead!

Although the last thing I need is another project, I inadvertantly stumbled across a few nice candidates recently. Both of these boats are of the 1969-1972 vintage, and both have been equipped with Chrysler 273 motors. The only thing I know about these motors is what Ive read in this post and others like it on this forum. Im curious how favorably these motors compare to the Ford 289/302 that seem to be more common. Are parts still available for these motors? How well do they compare performancewise? I a$$ume they are just as reliable?

Hopefully ReidP will chime in as I know he has a few Chryslers. Maybe his return to the forum is a sign that I should snatch one of these projects up?

Brad, glad to hear you had good luck with your Barracuda. Ive got no room or time for a project, but if the parts are available Im not sure I can pa$$ this one up. Ill let you know how I make out.

Tim, sorry I missed this the other day, but it's another of my favorite subjects, AND engines. Some may be aware that I'm a somewhat hard core Ford guy, but the Mopars are close second when it comes to marine stuff.. And after running my green Mustang and Marshall Morgan's 273s for the last two years I'm hooked. They only rated this engine at 200HP compared to 210 for the earliest '65-70 Ford 4Vs. As to a power comparison between a 273 and the earliest 289-302 Ford, from what I've seen the Fords by
virtue of 16-29 more cubes, have a little more low-end on average, but on the top-end, my money's on the Chrysler. I've yet to run one in a '71 up hull which is typically a little faster than the earlier hulls. But on the early hull, the fastest stock boats I've seen had the Chrysler. I've actually got a vintage Chrysler Marine sales flyer that specifically touts the high rpm power of the 273. I don't want to offend the more plentiful Ford brethren however, as that's still an easier engine to get even more HP out of, and even easier than any sub-308 c.i. BowTie. So snatch up those projects, Tim. I've got you a new HI-PO RevRot marine cam on the shelf in the garage, you can make those heads flow just like 340's, and a factory domed 10:1 piston is available from Egge Machine for that rebuild. This is Marshall's 1970 273.
    

alot of nice touches

TRBenj wrote: Reid, thanks for the input. Do you think those 273's have better top end than even the H-M 302's? It looks like the project I was eyeing was snatched up before I moved on it- its probably just as well. It was a '70 Mustang that was a little rough- but appeared solid and all original. There will definitely be an older CC in my future- Ill be keeping an eye out.

I had to chuckle... in doing a little bit of reading on my newly-acquired '70 Stang (273 Chrysler), I stumbled across a gold mine of a post from (who else but) Reid. And at the very end, a few questions from myself, circa 2006- inquiring about a 273 that I hadnt purchased (yet). Well, it took me 6 years and 4 owners to finally come to terms on the boat, but it finally made its way home! So Im glad I found this thread (again).




Back to reading!

Ha, I was gonna wait for a tuneup before I posted any water test results. Lots of parts ordered this week- Im thinking the ignition parts should make a noticeable difference, as the points were in pretty lousy shape. No idea what the timing is either.

Big little engine is a great way to put it- the thing is huge! Hard to believe theres only 273ci in there, ha.

Last I remember on Greg's Skier is that it was pretty far along. I forgot it had a Chrysler in it!

The boat sounds great. Is it redwith a white deck, a twin to Sage's?

Bruce, a near twin- its a year or so newer so minor trim differences... And it's red where Sage's is mahogany.

It does sound good!

TRBenj wrote:

Great video, sounds great. I'd stand behind a Chrysler over a Ford anyday..I've got a 75 Chrysler 360, never rebuilt, that I trust far more than the 74 Ford 351 I've got in the other....

skicat wrote: And the yellow ski nautique?

You'll have to ask Jerry about that.   Did you by chance mention it to him at Nashville? He still says he's gonna work on it soon, but "soon" in this case could mean sometime in the next 10 years.

TRBenj wrote: I had to look up your old thread to remember what color the deck was on your Skier... all red- love it. skicat's '71 Skier

Man, that is what it looks like? I couldn't remember myself!

Maybe I do need to get it out and throw some chairs in it and see what it will do.

And yes, I did ask Jerry about the yellr one. I think he has been trained by the master!

74Wind wrote: TRBenj wrote: Great video, sounds great. I'd stand behind a Chrysler over a Ford anyday..I've got a 75 Chrysler 360, never rebuilt, that I trust far more than the 74 Ford 351 I've got in the other....

Hey i know Chrysler makes a nice motor but whats so bad about the 351 Windsor? Its a very simple and reliable motor with good low end torque. One of Fords best (surprisingly). The only better series that i can think of is their FE series motors. But any way. Could you take a full shot of your boat? Also that motor sounds real nice for how old she is! How many rpm's was that pushing?