'77 mopar 400 cam swap

[casey henson]

Thinking I might do a cam swap when I do my timing chain. Would Lunati's version of the 375HP 440 cam be too much cam for the low compression 400? Lunati #

10211005​

Vehicle Make	BB Chrysler, Chrysler
Camshaft Type	Hydraulic Flat Tappet
RPM Range	1800 to 5500
Intake Lift	0.455
Exhaust Lift	0.470
Intake Duration at 50	216
Exhaust Duration at 50	226
Advertised Intake Duration	278
Advertised Exhaust Duration	288
Camshaft Series	Factory Performance
Valve Setting	Hydraulic
Lobe Separation Angle	112

 

[Don Frelier]

I think that one would do pretty well.
Short duration on the intake and a wide lobe separation angle.
The Summit 6421 is similar with a little less lift and inexpensive

 

[DodgeBoy5150]

Thinking I might do a cam swap when I do my timing chain. Would Lunati's version of the 375HP 440 cam be too much cam for the low compression 400? Lunati #

10211005​

Vehicle Make	BB Chrysler, Chrysler
Camshaft Type	Hydraulic Flat Tappet
RPM Range	1800 to 5500
Intake Lift	0.455
Exhaust Lift	0.470
Intake Duration at 50	216
Exhaust Duration at 50	226
Advertised Intake Duration	278
Advertised Exhaust Duration	288
Camshaft Series	Factory Performance
Valve Setting	Hydraulic
Lobe Separation Angle	112

That's a great looking cam!
I decided to buy the Summit 6400 -- partially based on this thread from a few years ago - The slug 400 on the dyno.
Whatever you decide to buy I would recommend some NOS lifters-- the new production lifters seem to be junk

 

[rumblefish360]

LMAO on finding NOS lifters.
That cam will be OK because it has the wide LSA of 112. IMO, look for one a lot lower, A LOT. This makes low end torque. Something a low compression engine doesn’t have & needs all the help it can get with making some.

 

[Geoff 2]

I like David Vizard's comments about cams: the right one costs the same as the wrong one.....
That cam will 'work' but I think you could do a lot better. I would use the Isky 264 Mega.
As for lifters, have your factory lifters re-faced & they will be good as new...& not wipe lobes like today's junk.

 

[casey henson]

All these look real good ! That summit 6400 is about as close as you can get to a generic 375 horse cam. I had saved that article"400 slug" awhile back but had forgotten about it. . The 6421 is interesting also. 365 horse cam . what about that less lift on the exhaust side. what is the deal there ?

And man, do you guys ever have me scared to buy a set of lifters now !

 

[gtxrt]

6421 is smaller than a stock hp cam. the 6400 is real close to a stock hp but even better it's on a 112 LSA and not 115 LSA like a stock one.

 

[RemCharger]

I like David Vizard's comments about cams: the right one costs the same as the wrong one.....
That cam will 'work' but I think you could do a lot better. I would use the Isky 264 Mega.
As for lifters, have your factory lifters re-faced & they will be good as new...& not wipe lobes like today's junk.

Basically the same cam, but you're saying the reduced lsa will increase the torque

 

[gtxrt]

Basically the same cam, but you're saying the reduced lsa will increase the torque

yes more bottom end and peekier torque. i think the factory went with a 115 LSA for a little smoother idle and a little better gas mileage. a 214-222 for a factory car is pretty big, when most were 188-209

 

[Geoff 2]

Yes,
Rem.
A quote from DVs BBC book, p. 97: ' If maximising HP & TQ are the goal, spreading the LSA to improve the idle & low speed drivability is a very counterproductive move. The correct answer here is not to spread the LSA, but to go for less duration'. [ Italics in original ].

That is why I recommend Isky cams: single pattern & most grinds are on 108 LSA.

 

[gtxrt]

Yes,
Rem.
A quote from DVs BBC book, p. 97: ' If maximising HP & TQ are the goal, spreading the LSA to improve the idle & low speed drivability is a very counterproductive move. The correct answer here is not to spread the LSA, but to go for less duration'. [ Italics in original ].

That is why I recommend Isky cams: single pattern & most grinds are on 108 LSA

yes, Isky said if you need extra exhaust duration your intake duration is to small. 4*-6* extra exhaust duration shouldn't hurt much. there is a balancing act for the street, tight LSA with small duration could cause detonation. i would run 109 LSA in my buick nail head because of the restrictive heads like DV say's. i think 110 LSA is a nice compromise for the street unless you want every HP then 108 LSA is the one. That's why i like the faster ramp cams your have your nice smoother idle and bottom end and still make power in upper end. just my opinion.

 

[casey henson]

This make a lot of sense. I have noticed this through the years of looking at different cams and manufacturers. Lunati and Iski has always stuck with that 108 and Comp at 110. I mean on their standard run of the mill cams.

 

[casey henson]

That being the case a Comp 260h looks good also...

212/212 @ .050
440/440 lift on a 110 lobe sep.

 

[rumblefish360]

Basically the same cam, but you're saying the reduced lsa will increase the torque

Side will!

6421 is smaller than a stock hp cam. the 6400 is real close to a stock hp but even better it's on a 112 LSA and not 115 LSA like a stock one.

That move helps, I’d go further… ummm, narrower.

Yes,
Rem.
A quote from DVs BBC book, p. 97: ' If maximising HP & TQ are the goal, spreading the LSA to improve the idle & low speed drivability is a very counterproductive move. The correct answer here is not to spread the LSA, but to go for less duration'. [ Italics in original ].

That is why I recommend Isky cams: single pattern & most grinds are on 108 LSA.

BINGO!!!!! Nailed it! 100%
Next up in the power production enhancement, exhaust!
David Vizard has excellent books on this. Well worth the price and time to read. I suggest to the OP to pick up one or several of his books before making a cam choice.

This make a lot of sense. I have noticed this through the years of looking at different cams and manufacturers. Lunati and Iski has always stuck with that 108 and Comp at 110. I mean on their standard run of the mill cams.

Comp Cams uses the 110 LSA as a compromise as the 110 vs the 112 shows a good gain in low speed torque. As the LSA narrows or gets lower, the gain becomes less.
(Generally speaking as far as I have seen.)

As the LSA narrows, the idle becomes more and more choppy. This is often not so well liked by a lot of people. It makes driving a manual trans a little more difficult for some. This is also why Comp stays at the 110. It’s a decent balance between a decent idle and low speed torque is what they’ll tell you.

The move from a 110 to a 108 is IMO, a good move, one I have done and will continue to use. I have called Comp Cams up and requested a modification to one of there off the self cams to be moved from the 110 to a 108. There happy to do it for you. You can ask to talk to a tech and ask about moving the lobes or singular lobe to achieve this is the way to go.

It’s all about the valve timing, the results and the goal your looking to achieve. Be prepared to give them every last bit of detail you know of. It only helps them help you. The more they know, the better the result.

 

[gtxrt]

That being the case a Comp 260h looks good also...

212/212 @ .050
440/440 lift on a 110 lobe sep.

it's good you want to go small cam, one size bigger than the 260h would get you more closer to the 375HP cam or at least one with more lift. remember the 375HP had 450-458 lift. was talking with one of the upper guy at comp cams not the ones that answer the phone, said they put a 4* degrees built in advance just because most guys want too big of a cam and the 4* helps there bottom end cause of the bigger cam they order.

 

[gtxrt]

let me just throw in one thing lol. the reason for the more exhaust duration than intake is they say it helps get the exhaust out when not running headers or restrictive heads with small exhaust valves or low flow exhaust. I really can't find any proof either way. some guys run 12-14 degree spread like 216-230.

 

[casey henson]

it's good you want to go small cam, one size bigger than the 260h would get you more closer to the 375HP cam or at least one with more lift. remember the 375HP had 450-458 lift. was talking with one of the upper guy at comp cams not the ones that answer the phone, said they put a 4* degrees built in advance just because most guys want too big of a cam and the 4* helps there bottom end cause of the bigger cam they order.

I have over cammed a few over the years and gotten away with it. This motor will stay at the stock 400 compression ratio for awhile. I am installing the HP exhaust manifolds and 2.5 exhaust now. Next I was planning a performer RPM intake and cam swap. keeping in mind stock converter which is super tight in '77 and the 2.45 gears.

Later when and if I build a stroker motor things will be totally different.

 

[rumblefish360]

let me just throw in one thing lol. the reason for the more exhaust duration than intake is they say it helps get the exhaust out when not running headers or restrictive heads with small exhaust valves or low flow exhaust. I really can't find any proof either way. some guys run 12-14 degree spread like 216-230.

The reason you suggest is correct with what they call scavenging the cylinder for a better incoming intake charge. What was also found out is that the extra exhaust duration extends the rpm range of the cam. Add headers to this and better scavenging equaling more power is the result.

Comp Cams has there line of “Thumper” cams with a big wide split in duration. Other cam companies have also followed suite. Howard’s is one of them with there “Rattler” cams.
Hughes engines is another one. There cam is called the “Whiplash” cam. One of there small block Whiplash cams has durations of 213/226 @.050 = 13*’s difference.


I just purchased a Thumper cam for my Magnum 5.9, the durations are 227/241 @.050. The LSA is at 107. That’s a 14* split.

Off hand, I don’t know of any greater split difference cams.
I’m not sure if there are big block offerings from all of the listed companies above.

 

[gtxrt]

The reason you suggest is correct with what they call scavenging the cylinder for a better incoming intake charge. What was also found out is that the extra exhaust duration extends the rpm range of the cam. Add headers to this and better scavenging equaling more power is the result.

Comp Cams has there line of “Thumper” cams with a big wide split in duration. Other cam companies have also followed suite. Howard’s is one of them with there “Rattler” cams.
Hughes engines is another one. There cam is called the “Whiplash” cam. One of there small block Whiplash cams has durations of 213/226 @.050 = 13*’s difference.


I just purchased a Thumper cam for my Magnum 5.9, the durations are 227/241 @.050. The LSA is at 107. That’s a 14* split.

Off hand, I don’t know of any greater split difference cams.
I’m not sure if there are big block offerings from all of the listed companies above.

Buick has one for their 455 that kennebel make back in the seventies. Ta performance still makes it it has an 18° spread. As for Mopar I think you're right I've never seen one

 

[gtxrt]

The reason you suggest is correct with what they call scavenging the cylinder for a better incoming intake charge. What was also found out is that the extra exhaust duration extends the rpm range of the cam. Add headers to this and better scavenging equaling more power is the result.

Comp Cams has there line of “Thumper” cams with a big wide split in duration. Other cam companies have also followed suite. Howard’s is one of them with there “Rattler” cams.
Hughes engines is another one. There cam is called the “Whiplash” cam. One of there small block Whiplash cams has durations of 213/226 @.050 = 13*’s difference.


I just purchased a Thumper cam for my Magnum 5.9, the durations are 227/241 @.050. The LSA is at 107. That’s a 14* split.

Off hand, I don’t know of any greater split difference cams.
I’m not sure if there are big block offerings from all of the listed companies above.

But again that's what isky was talking about if you need more top end RPMs your intake duration is too small. But again you're right cuz he never mentioned about getting exhaust out with the higher exhaust duration which a lot of people agree on.