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Guidence restoring 69 Cuda Modtop
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Author:  dratsum [ Thu Aug 24, 2023 11:19 am ]
Post subject:  Guidence restoring 69 Cuda Modtop
Hi Slant Sixers!

My wife has a 69 Barracuda Mod Top - it was her first car bought at auction 25 years ago (her dad has good taste). Patula is a bit rough around the edges (Patula is the car, not my wife), but she runs, and we take her out every now and again for local rides around town. We've finally got some money saved to begin a much needed restoration. We have never had much experience working on cars, but we want to learn and want to take on some stuff in our driveway. We also have a mechanic with a small shop and a body shop that we've known for decades who can take on bigger jobs if we need.

Patula is almost stock. At some point she had her motor replaced. If I decided the stamp correctly, it's a slant six out of a 66 Valiant. Tho, it's blue, which if I did my research correctly, it should be red. ANYWAY - Its a 255 with a carter 1bbl carb. An electronic ignition was added sometime before we bought it, but, its a weird flat thing screwed into the space under the hood above the passenger side tire with 4 wires running across to the distributor and black glue leaking from underneath. At some point the car was repainted, but, its the same Sunfire Yellow color.

I want to start with some simplish bolt-ons. She is in desperate need for more power. Not trying to go crazy, just wanna feel more confident that when I hit the gas, it will go. I have read a ton of articles and watched yt vids and read the forms, so, I think I'm informed, but, I;m not experienced, so not totally confident I understand everything.

I started a parts list, with some options, but, had some questions too for some concepts I didn't totally understand.

If you have a moment, take a look at my spreadsheet - its got my list with my options and links to the parts.
https://docs.google.com/spreadsheets/d/ ... sp=sharing

Just looking for a "Yes, yr going in the right direction / these will work" or a "no - don't ever do that."

Also - couple of questions, or somethings that were ambiguous to me...
- I read that you need a 'standard v8 throttle cable' with the 2bbl carb - Is the one I have in there correct?
- Is using my stock exhaust a good option if it has no cracks? I believe its cast iron. Should it polish it with going to a bigger exhaust?
- If I go Durta Duals, do I need to make a custom exhaust using pipe segments? I was able to find complete single systems, but no dual systems.

Thanks for your time, in advance. I'm sure I will have more questions as times goes on.

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Author:  DadTruck [ Thu Aug 24, 2023 11:52 am ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
Good luck with your project. I have a ‘68 Barracuda and really enjoy it. Slant six powered.
Looking at your engine build spread sheet.
1) unless you are going turbo or other power booster, stock style pistons and rods will serve you well and save you some money. On stock pistons, go at least .040 over bore, .060 is even better to move the cylinders out to allow better breathing. Silvolite stock pistons are fine.
2) over sized valves will help. A good machine shop will be able to fit in Chevy or other low cost valves in the 1.7 intake and 1.4 exhaust. The slant in the 68B has Ford 289 valves and springs.
3) no recommendation on a cam, as I don’t know enough about what your goal is. But I do recommend that you buy a copy of Desk Top Dyno. Goggle that. Will cost about $50.00 and with that you can try out cams, compression ratios, valve sizes and see the effect. A very useful learning and shopping tool.
4) you will certainly want to change out the timing gears and chain. Go through the oil pump. Look around on e bay and get a copy of a 1969 Plymouth Factory Service Manual. That will have the specifications for the motor and the rest of the car.

Good Luck.
Author:  dratsum [ Thu Aug 24, 2023 12:25 pm ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
Thanks so much for the help!

Did you think the phase one parts list looked good for carb, intake and exhaust? Wasn't sure about the Kickdown kit and throttle cables.

Also, with this set up, do you think the stock exhaust manifold with a single 2.5" pipe is enough?

Thanks / b
Author:  Charrlie_S [ Thu Aug 24, 2023 3:36 pm ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
can you post the numbers on the engine behind the alternator? A slant six out of a 1966 Valiant should not fit, unless the trans was also changed to a 1966 trans (or using a special torque converter). The size of the pilot hole in the crank got larger in 1968 as did the pilot on the torque converter. A 66 engine will not fit up to a 79 transmission.
PS: Is the trans an automatic or a stick?
Author:  Rick Covalt [ Thu Aug 24, 2023 6:00 pm ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
For a mild build or even a high performance build the stock rods and pistons are plenty good. Save money there. My personal opinion is that buying a $550 2 barrel is not as good of a choice as it would be to buy a $400 Edelbrock 500 cfm 4 barrel. You are already buying the manifold why not use the 4 barrel. It is easier to tune and works fine on our small engines. Plus you are only running on the 2 barrel 99% of the time. Check Ebay and Amazon you will find a $30 or $40 kick down cable for a 904 transmission. I have been using them for years without any problems. Have the head planed to bump the compression some and if you are not going to install bigger valves, you can at least clean up the bowls under the valve seats to improve flow with stock size valves. If you use anything other than a stock exhaust manifold you will need to have the pipes custom made. There are no bolt in exhaust pipes for headers or Dutras. I would not buy an expensive cam kit from Clifford. You can get a new cam from other good vendors for less money. Oregon cams will grind you a new cam for under $200 and they are great to work with. The #819 cam ran well in my mild truck engine and would probably work good in you car too. The #818 would be a step down but also a nice step up above any stock cam. A set of 340 valve springs would be on the list also. Others will chime in with more definite cam info for you.
Author:  ProCycle [ Thu Aug 24, 2023 7:20 pm ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
Before you do anything get Doug Dutra's book and read through the whole thing.
--> https://www.amazon.com/Chrysler-Slant-S ... oks&sr=1-1
Author:  DadTruck [ Thu Aug 24, 2023 7:32 pm ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
Quote:
Thanks so much for the help!

Did you think the phase one parts list looked good for carb, intake and exhaust? Wasn't sure about the Kickdown kit and throttle cables.

Also, with this set up, do you think the stock exhaust manifold with a single 2.5" pipe is enough?

Thanks / b
I run MPFI on the slant in the 68B so I really don’t want to comment on a carb, Rick C is on track recommending a 4 BBL.
The 68B has a 904 with a Locar kick down, no issues there.
And Charlie brought up a good point concerning the crank flange.

Concerning the Dual Dutra’s, I have a set of those on the slant I in the 83 D150. They fit and work well, but they are very heavy and along with the cost of buying the Dutra’s you still need to make or have made custom down pipes. I don’t mind the heavy Dutra’s on the D150, it’s a heavy truck anyway.
On a light A body to me it makes sense to go with headers. They will be lighter than the set of Dutra’s and depending upon if you go with shorties or long tube, headers get you closer to the exhaust pipe hook up. Just my opinion.
Author:  dratsum [ Thu Aug 24, 2023 8:19 pm ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
Quote:
can you post the numbers on the engine behind the alternator? A slant six out of a 1966 Valiant should not fit, unless the trans was also changed to a 1966 trans (or using a special torque converter). The size of the pilot hole in the crank got larger in 1968 as did the pilot on the torque converter. A 66 engine will not fit up to a 79 transmission.
PS: Is the trans an automatic or a stick?
Admittedly, I looked up the numbers on the motor many years ago, but I just rechecked the numbers using another thread on this form and I think I was mistaken. If I’m reading them correctly, this motor was made in dec 1968.

Block stamp is 2806830 225 1968-1970 also 198(RG-series)

9 428878 Is the stamp on the passenger side of the motor near the back. (Doesn’t match vin
)

The stamp on the line of the oil pan is PT 225 T 2709
Which if I did this right = Dec 27th 1968 build date in the 10000 year calendar.

/b
Author:  dratsum [ Thu Aug 24, 2023 8:35 pm ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
Quote:
My personal opinion is that buying a $550 2 barrel is not as good of a choice as it would be to buy a $400 Edelbrock 500 cfm 4 barrel. You are already buying the manifold why not use the 4 barrel. It is easier to tune and works fine on our small engines. Plus you are only running on the 2 barrel 99% of the time.
Thanks for the recommendation for the 4bbl. I got the 2bbl idea from the Motor Trend “Making Slant Six Sense” article where they said
Quote:
Our theory is the six-in-a-row will go better with a two-barrel than a small four-barrel Holley 390 or Edelbrock 500 cfm. There's no waiting for the secondaries to kick in.
I was on the fence and was swayed because they seemed pretty happy with their results. But if I go the 4bbl route - The Offy 4bbl intake is a little cheaper than the aussiespeed, so, going that way will save a couple hundred as well. I assume I would want to go with a 500cfm carb with electric choke as the best direct replacement? I don’t have a choke lever. Also, I live in NY where it gets cold.

/b
Author:  Rick Covalt [ Fri Aug 25, 2023 4:09 am ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
Yes the Offy will be perfectly fine and the Edelbrock 500 with electric choke would be my pick. The 500 is what I am running on my truck right now and it works great. Starts easily all winter long (I am in PA) and is easily adjustable from the top.
Author:  Dart270 [ Fri Aug 25, 2023 1:06 pm ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
I'll have engine mod recommendations when I have more time...

When do we get to see the mod top pics??

Lou
Author:  SlantSixDan [ Fri Aug 25, 2023 1:57 pm ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
Read this post.
Author:  dratsum [ Fri Aug 25, 2023 5:27 pm ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
Quote:
Read this post.
Read. And thank you.

Petula still has the drums. I’ve had front discs on the list for a while, but, my wife is into the 14” hubcaps And for the longest time i couldn’t find discs that worked with the stock wheels. The drums work pretty well, except that the brake pedal is like, 6” too high. (I have a discussion around this active on the brakes thread of abodiesonly and here) at some point 2 point shoulder straps were installed. They are funny things. They button snap to the headliner is you dont feel like wearing them I guess. They attach to the top of the lap belt buckle where it attaches to the side of the seat near the center console.

I dunno how much butt feel matters. I’m pretty comfortable with the drums for how we drive this baby. Brake pedal height aside. The scariest thing is lack of power when needed.

That said - I added 14” whee compatible discs and new lines to the list.
Author:  dratsum [ Sun Sep 08, 2024 5:46 am ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
Bringing is post back from the dead! I posted this as a new topic last night then remembered this thread. So I moved it here.

Trying to diagnose issue with slant six. This motor has been modified with an Aussie speed intake manifold, Four barrel Edelbrock, 1905 carb, performance distributors Tri-power, HEI distributor and inferno coil with a new set of live wires, durta duels with a custom y pipe going into a single 2.5" exhaust. We also installed a Tuff Stuff Performance Gear Reduction Starter. 6084A

Had my mechanic do the install for me, but he was never able to dial in the tune properly. He's doesn't specialize in these old cars. I am not experienced working on motors, But before I take it to someone else, I would like to try to diagnose what the issue is. To start, I wanna make sure I had the right words to describe the problem. I think this might be sputtering, when I give the car the gas it feels like the engine is almost cutting on and off. Like, it's not getting consistent fuel, or fire. I don't think it's a misfire - - it’s not rhythmic, kind of inconsistent like/

It will get up to speed, but the acceleration is not at all smooth. I gets there slowly.

She fires up right away and idles well. No fuel smell.

I made a video. you can hear when I open it up, it doesn't hold the revs. https://youtu.be/BcmiLJzTi3c

I thought it might have been an ignition issue. In doing some YouTube video diagnostic stuff I realize that the ballast resistor was still connected so the new coil wasn’t getting the 12V it needed - so I bypassed it by jumping the cables together. I also tried replacing the voltage resistor with a new one, just in case it had gone bad. When I attached a multimeter to the resistor FLD side, it was bouncing around 6-8 V. I tried an inline spark tester and the light flashing kinda matched the hesitation in the motor. The bulb didn't flash with consistent brightness or rhythm. Not sure if that's normal, or an indicator of something.

Any tips on where I should try next? Does this sound like a rich / lean issue? Ignition system? Timing?

Thanks! Drat
Author:  Rick Covalt [ Sun Sep 08, 2024 10:12 am ]
Post subject:  Re: Guidence restoring 69 Cuda Modtop
Quote:
I also tried replacing the voltage resistor with a new one,
What is this resistor? Not talking about the ballast I assume? No, That spark does not look right. You should have a steady consistent spark. Is that inconsistent spark on all the plugs or just one? Did you put new plugs in it? Did you adjust the valves recently? What is the timing set at? Check for air leaks along the manifolds at the head. At the carb...etc
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