Exhaust limits/Carb choice

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maw

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Good evening folks, and first post.

I'm trying to keep my youngest son from making many of the same mistakes I made 30 years ago on hist first car.

He recently picked up a '67 Dart with a blown 318, but the body is fairly straight and the car has an 8-3/4 Posi with 3.55 gear set and a 904 AT. I've donated a spare 360 to the project which was intended for my '37 Dodge PU. The motor is bored +.030 and is filled with KB107s yielding 9.4:1. The cam is a Crane H278-2 (222/234, .467/.494). The manifold is a Wieand Stealth which is a dual plane similar to an Edelbrock Performer RPM, but with a spread-bore flange.

I have two questions concerning the package:

1) At what point do I saturate a cast iron exhaust manifold set and have to go to tube headers? (The car came with a set of Hooker Comps which have a couple of flattened primaries which could be fixed. I also have a set of 360 A-body cast iron manifolds.)

2) We have both a 750 Thermoquad and a Holley 650 spreadbore double pumper. Which would be the better choice.

Thanks in advance for any opinions offered.

Cheers, Mark
 
maw,
Is this going to be a street car or street and strip car? To save money for now I would use the manifolds and then later when he's ready go to hedders. The carbs will work better with hedders but being his first car and inexperience it may be better with manifolds.
 
maw said:
The manifold is a Wieand Stealth which is a dual plane similar to an Edelbrock Performer RPM, but with a spread-bore flange.

I have two questions concerning the package:

1) At what point do I saturate a cast iron exhaust manifold set and have to go to tube headers? (The car came with a set of Hooker Comps which have a couple of flattened primaries which could be fixed. I also have a set of 360 A-body cast iron manifolds.)

2) We have both a 750 Thermoquad and a Holley 650 spreadbore double pumper. Which would be the better choice.

Cheers, Mark
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Mark, the Weiand Stealth has a square flange and the Action plus has the spreadbore flange, though through pictures, thats the only difference I can see.
You can keep the exhaust manifolds though the power difference will be noticeable between them when you do swap them over. Search headers here for opinions and been there done that fitting of Super Comps and tti's.

To get more from the manifolds, a longer exhaust timing duration will be needed. I would talk to a cam manufacture and tell him of the manifold useage. The cars that race in the F.A.S.T class run real well with manifolds and use a different cam timing set up unlike I would with headers.
(They also stroke there engines .)

On the carb, the T-Q has certain advantages over the Holley. Smaller primarys for the street for better throttle response and mileage. (Or at least should. Good mileage should be obtainable no matter the carb primary size.) The double booster design is key there. The secondarys are huge @ 2-1/4 for a real powerful kick.
BUT, the tuning parts are a little harder to come by and it can be a trickier carb to set up and set straight than the Holley if your not use to them.

The added CFM of the T-Q may be helpful, but not needed. 650 cfm is enuff to really move a powerful 318. A T-Q though larger has adjustable air door opening size and it's adjustable on when it opens making this carb fine for the 318 as well though it's 100 cfm (or so) larger, it will not be to much.

The bottom line is what ever carb you feel comfortable with is the one for you.
 
rumblefish360 said:
The added CFM of the T-Q may be helpful, but not needed. 650 cfm is enuff to really move a powerful 318. A T-Q though larger has adjustable air door opening size and it's adjustable on when it opens making this carb fine for the 318 as well though it's 100 cfm (or so) larger, it will not be to much.

The bottom line is what ever carb you feel comfortable with is the one for you.
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He recently picked up a '67 Dart with a blown 318, but the body is fairly straight and the car has an 8-3/4 Posi with 3.55 gear set and a 904 AT. I've donated a spare 360 to the project which was intended for my '37 Dodge PU. The motor is bored +.030 and is filled with KB107s yielding 9.4:1. The cam is a Crane H278-2 (222/234, .467/.494). The manifold is a Wieand Stealth which is a dual plane similar to an Edelbrock Performer RPM, but with a spread-bore flange.
Click to expand...

Depending on the use for the car. Toy/Street/Strip/Daily, that would vary my decision. The TQ will be a much more humble daily driver. The Holley will get it done better at the track, but be more finicky.

-Mike
 
Sounds like it will be a fun combination! Repair the headers and use them, since you've already gotten them with the car. Either carb would work good, once tuned correctly to the combination. I run a 600 Holley DP on a 318 with a 904 trans and a small converter, so I can say from personal experience that a DP and a auto trans can work well together.
 
Thanks guys,

This is his first car, and as far as driving experience he has only what he accumulated during Drivers Ed. He does have experience with dirt bikes, quads, waverunners, etc, so reaction and response should be OK when given a spirited ride.

The car will be his daily, nothing more. Back and forth to school, work, movies, etc. No "official" strip time is anticipated.

The Stealth is a spread bore manifold, I just went out and checked. I have always used Holleys on my toy's and have no experience tuning the ThermoQuad. My guess is it would be slightly better on mileage and may have a softer power delivery than the DP Holley, but this is just a guess. The ThermQuad was on the original 318 when we got the car.

The headers could be pounded out and patched, maybe even a "skid plate" welded across the bottom of the lower tubes to protect them against close encounters with speed bumps. They only offer around 2" of ground clearance and fixing them looks like a perpetual problem. I just don't know at what horsepower level their benefit begins to outweigh the drawbacks. We're hoping to see 300hp or so at the crank from this package. These headers were a royal PITA to get off.

The cam is a split pattern with around 10 degrees more exhaust duration than intake. I'm not sure that will overcome the restrictions in the manifold, at least as far as the 300hp target.

Thanks again.

Cheers, Mark
 
First car huh? Well I put the exhaust manifolds back on. 2 inchs isn't much and you know how kids are sometimes. Yes he has lots of motor bike ex. but out in taffic is not the same. He needs time to learn. Sounds like you are a great dad, some just get them a POS at first and get a new or very nice car for themselfs. A 360 with 3.55 gears in a lightweight 67 dart is going to be fast enough for the first year or two. Headers sometimes leak and make lots of noise--not that hes not going to want a pair of cherry bomb mufflers anyways-so I would just find a early set of 360 factory manifolds and make sure the heat raiser is open or better yet remove. With a dual exhaust it be fine. I also stay away from the DP carbs, yeah they are ok if you are in the right gear but again he needs to be watching the road not worrying about what gear the car is in. Sorry if I sound like a old fart but hes very young and has lots of time later on. That still will make a great first car for sure and if he takes care of it he can go all out later on. Just my 2 cents
 
stealth manifold, holley carb, manifolds with that cam will give a nice lmpy sound through 2 1/4" pipes - and no hassels with ground clearance.
with that cam, more like 340-350hp if the heads are decent. little bowl work and a little port blending will go a long way. stay with the 1.88 valve size.
 
If you're gonna use the manifolds, why don't you try to find some 68-71 340 abody manifolds. they'll work better than the ones you have. Sell the headers to someone who wants them more than you. Personally, I'd use the TQ, but you can't find jets or metering rods. You'd probably be better gas mileage wise with a 600 vacuum secondary Holley, or maybe an Edelbrock carb. Good luck. Sure wish I had a cool dad like you when I was 16.

don
 
I totaly agree with dodge freak and Im 28. My first car (that I drove with a license) was a 73 camaro with a balls to the wall 66 327 that had a holley DP and a set of headers. About 6 months later the carb was leaking and the headers were all bashed up.
Go with the manifolds and an Edelbrock carb.
 
Thanks for all the information folks.

We're going to run the Holley spreadbore DP and the cast iron 360 exhaust manifolds for the time being. Upon inspecting the ThermoQuad I found spiderweb cracks in the body casting. It looks like the material is beginning to fatigue with age.

Read every thread on this forum about the exhaust and just don't want to hassle the headers at the moment. We'll patch them up, add some 1/8" strip stock across the bottoms, and set them aside for a later time.

The heads were put together with a little clean-up in the bowls, then a set of Manley stainless Pro-Flows (1.88/1.6) installed. With the cam it should work good enough.

These decisions were mine - not his. He's listening to his friends who are telling him he needs nothing less than a stroked 440 with a tunnel ram and fenderwell headers. His opinion is I'm afraid his car will be faster than mine and I'm doing this on purpose. Well, maybe just a little ;)

Cheers, Mark
 
I would also recommend a replay tach..lol. then you can bust him later..lol.
 
lol thats just mean. you should be able to trust your kid to atleast know how to play. responsibly. I've done more than my share of 'playing' in the last two years i drove my 'cuda. i had a 87 12second 5.0 as well. No speeding tickets, no speeding/wreckless driving tickets. Just when you figure out the car can cross you over faster than you react is when you figure out what you can do. A good few 'lessons' with your kid in a big empty wet/dry lot can work wonders.
 
His two older brothers I trust, but this one is the "wild child". With two older siblings to always compete with he learned at an early age to push the envelope until it broke (or at least bent). Speed has no interest to him but acceleration does.

He's helped me on my present build and wants that level of performance for himself, but without earning it or gaining the experience to handle it. I'm currently building a twin turbo, EFI, 354 Hemi powered '37 Dodge PU and he has an idea of how quick it should be when done. The only thing left of the original truck is the tinwork.

I like the suggestion of adding a data logger to the car, maybe even tie it in with a GPS transponder :grin:

Cheers, Mark
 
Or you could do what I did to my buddies car. When he wasn't around I jacked up the rear and swapped out the pinion gear in the tranny so he thought he was going faster than he really was.
 
360scamp said:
Or you could do what I did to my buddies car. When he wasn't around I jacked up the rear and swapped out the pinion gear in the tranny so he thought he was going faster than he really was.
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thats a pretty darn good idea. just dont stick a 2.76 gear in when he has 3.91s lol. been there, done that
 
No Goody, that's reality for most parents. I know it was for mine. I didnt smoke, drink, never was unemployed from age 13 (had 2 paper routes, then after school jobs. Very responsible. But i also burnt off the RR tire of the station wagon I drove, pegged the 85mph speedo on a regular basis..etc. Kids will be kids. I'd rather have gotten bagged (like I did by the tell tale tire wear issue, and rubber in the wheel wells) then been "trusted". It's called parenting. It's your job to push the limits, and thier job to push you back to reality...lol.
 
GoodysGotaCuda said:
lol thats just mean. you should be able to trust your kid to atleast know how to play. responsibly. I've done more than my share of 'playing' in the last two years i drove my 'cuda. i had a 87 12second 5.0 as well. No speeding tickets, no speeding/wreckless driving tickets. Just when you figure out the car can cross you over faster than you react is when you figure out what you can do. A good few 'lessons' with your kid in a big empty wet/dry lot can work wonders.
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Mike, you'll understand when you have kids. Mine are only 3 and 1 but I already know, the more behaved they seam to be acting, the more trouble they are actyually getting in to. LOL
 
Goody, thanks for the bold hilights. I think the cid of 360 will still stand OK in there instead of the mistake of 318 cid.

A good few 'lessons' with your kid in a big empty wet/dry lot can work wonders.
Click to expand...
I did the very same thing with my wife when she first started to drive. Also in the snow. We went down to the railroads parkiing lot. It is about 200 feet by 1/2 mile boxed shape with just a few light poles. Snow in the lot is a wondeful teacher on how your car reacts without the penalty of traffic accidents.
Purposely do 40 - 60 and twist the wheel.
 
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