I’m 75 years old and still have a little bushy but in my sistom. I like to stick up to myself.
A little more HP out of my 400
- Thread starter 41indian
- Start date
The car is totally stock, bumper to bumper
I don’t mind
Thank Bob, like I said, just a little more boost will be awesome. I had a 79 RV with the Lean Burn and dropped a valve doing 60 to 70 on the freeway and it was a big mess with about the same mileage. So it’s gitting a valve job no matter what. My Mopar guy suggested 906 heads
Wietse
Well-Known Member
Even with the 906 heads, those pistons are too far down the hole to get a decent compression and no quench.
Unless you add new(higher) pistons with all additional work that comes with it you won't be getting anywhere near 10.0 CR.
With a cam like i suggested, the static compression will remain original, but the dynamic compression will get a boost as the intake valve closing point is a lot earlier and will create more cylinder pressure.
Cheap and easy solution for more power compared to going full rebuild.
Unless you decide to go for a full rebuild anyway, then you can start from scratch and select the right pistons and have it zero decked. Add a good camshaft and you get both static and dynamic compression ratio's up.
Unless you add new(higher) pistons with all additional work that comes with it you won't be getting anywhere near 10.0 CR.
With a cam like i suggested, the static compression will remain original, but the dynamic compression will get a boost as the intake valve closing point is a lot earlier and will create more cylinder pressure.
Cheap and easy solution for more power compared to going full rebuild.
Unless you decide to go for a full rebuild anyway, then you can start from scratch and select the right pistons and have it zero decked. Add a good camshaft and you get both static and dynamic compression ratio's up.
Geoff 2
Well-Known Member
I could not find any specs on the Whiplash cam. Most of these cams with fancy names, Bootlegger, Whiplash etc have extended exh duration & tight LSA. That creates a lot of overlap & gives a raspy exh note to make the girls look..... Worst thing possible for a low compression engine. You need to retain as much cyl pressure as possible [ already reduced because of the low comp ratio ], rather than pushing it out of the cyl with a high overlap cam. The idle quality & vac will also be considerably worse. The cam I recommended earlier, single pattern & short duration, would be best to give [a] a modest hp boost retain low speed drivability.
Rv's did not run lean burn.
Lefty71
Well-Known Member
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It has been over 30 years but I could swear it was a lean burn
496 polara
Well-Known Member
If you are keeping the gears you have not much to do without hurting yourself IMO. I may suggest dual exhaust (2.25 probably fine).Lose the catalytic converter or at least gut it.
Maybe see if it likes a little more initial and total timing. Maybe a little quicker on the advance curve but not too fast with those tall gears. Plenty of airflow for the carb and cooler air is better.
Maybe see if it likes a little more initial and total timing. Maybe a little quicker on the advance curve but not too fast with those tall gears. Plenty of airflow for the carb and cooler air is better.
Wietse
Well-Known Member
If you had checked the link i send previously you would have come to know this cam is specifically made for low compression engines to overcome the low compression issues without the need to replace the heads, machine work, etc.
And you would have seen the cam card which shows all specifications of the cam...
https://www.hughesengines.com/Index...V2hpcGxhc2ggTXVzY2xlIENhciBDYW1z&partid=30172
BSB67
Well-Known Member
There are several things you can do to boost power to your desired power level without pulling the short block, and keeping it reliable.
But without knowing your budget, it’s simply not worth the discussion.
But without knowing your budget, it’s simply not worth the discussion.
my 400 in my 63 SF is a 78, i looked up the compression: 8.25 (sad face). So...I have started buying 85 octane!! It has a mild cam upgrade and is more than sprightly! 3.23 rear. I probably won't upgrade it further, as it is fierce as it is!
Curiousyellow71
Well-Known Member
Iron head test starting on '78 440.
Look for threads from IQ52. He did some great dyno threads with low compression 440s. A 400 is a bit different beast with less stroke but some of the same bolt ons will give similiar gains. Your just starting off at a lower power level to begin with on a 400 vs a 440.
We have run several low compression 400s through the years. Probably the biggest tip I can give you is make sure it has a good updated timing chain. Every original 400 i have seen has compression even lower then the advertised numbers. With a worn timing chain ( 85k) and low compression the cam gets retarded from chain wear and they barely get out of the way of themselves. Buying a small chambered aluminum head is a good plan if you can swing it. Certainly change the gears unless you plan to run it at the salt flats. Honestly, this car sounds like a 440 would drop right in and would be more fun if you can find a good one!
Look for threads from IQ52. He did some great dyno threads with low compression 440s. A 400 is a bit different beast with less stroke but some of the same bolt ons will give similiar gains. Your just starting off at a lower power level to begin with on a 400 vs a 440.
We have run several low compression 400s through the years. Probably the biggest tip I can give you is make sure it has a good updated timing chain. Every original 400 i have seen has compression even lower then the advertised numbers. With a worn timing chain ( 85k) and low compression the cam gets retarded from chain wear and they barely get out of the way of themselves. Buying a small chambered aluminum head is a good plan if you can swing it. Certainly change the gears unless you plan to run it at the salt flats. Honestly, this car sounds like a 440 would drop right in and would be more fun if you can find a good one!
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Geoff 2
Well-Known Member
Wietse,
Hughes can say whatever they like, doesn't mean it is true. I ran a 232 @ 050 custom ground cam in my 10:1 440. Single pattern, 108 lsa. It had a very rough idle & I removed it a week later.
The Hughes cam has a tighter 107 LSA, & 232/245 @ 050. In a 400 with low compression with all that overlap, it will idle like crap & have poor low speed tq.
Here is a similar cam from Crane 232/242 @ 050 but on a wider 112 LSA, so it has less overlap. The description: ' Good mid range to upper rpm tq & hp, rough idle, 10.0 to 11.5 CR advised'.
Hughes can say whatever they like, doesn't mean it is true. I ran a 232 @ 050 custom ground cam in my 10:1 440. Single pattern, 108 lsa. It had a very rough idle & I removed it a week later.
The Hughes cam has a tighter 107 LSA, & 232/245 @ 050. In a 400 with low compression with all that overlap, it will idle like crap & have poor low speed tq.
Here is a similar cam from Crane 232/242 @ 050 but on a wider 112 LSA, so it has less overlap. The description: ' Good mid range to upper rpm tq & hp, rough idle, 10.0 to 11.5 CR advised'.
Wietse
Well-Known Member
Geoff,
I am quite sure to say that Hughes knows what they are doing with their cams.
You had used this cam in a 10.0:1 CR engine, the Crane cam you suggest is recommended with a 10.0 - 11.5 CR.
OP has 8.0 - 8.5 CR engine and is looking how to increase the power a bit, which is the intended purpose of this cam as mentioned.
Your use of this type cam was on the wrong application.
From Hughes website:
Our Whiplash cam is designed for basically stock, low compression engines. This cam will run on pump gas in a 383/400 with 8.5:1 or less compression and iron heads. If your compression is higher than this you may need to use a higher octane race fuel. Your vacuum should be in the 9"-11" range using this cam.
(Figures calculated using stock stroke & compression at 750' altitude.)
These SMC cams have bad-to-the-bone idle, very quick stop light to stoplight acceleration! Idles like a funny car but smooths out above 1600-1800 RPM.
These cams are designed to drive better than the sound would imply. These are killer cruising cams made for low compression engines and are designed so the cylinder pressure will not be reduced (Torque Killer!) like other cams of this size or type.
I am quite sure to say that Hughes knows what they are doing with their cams.
You had used this cam in a 10.0:1 CR engine, the Crane cam you suggest is recommended with a 10.0 - 11.5 CR.
OP has 8.0 - 8.5 CR engine and is looking how to increase the power a bit, which is the intended purpose of this cam as mentioned.
Your use of this type cam was on the wrong application.
From Hughes website:
Our Whiplash cam is designed for basically stock, low compression engines. This cam will run on pump gas in a 383/400 with 8.5:1 or less compression and iron heads. If your compression is higher than this you may need to use a higher octane race fuel. Your vacuum should be in the 9"-11" range using this cam.
(Figures calculated using stock stroke & compression at 750' altitude.)
These SMC cams have bad-to-the-bone idle, very quick stop light to stoplight acceleration! Idles like a funny car but smooths out above 1600-1800 RPM.
These cams are designed to drive better than the sound would imply. These are killer cruising cams made for low compression engines and are designed so the cylinder pressure will not be reduced (Torque Killer!) like other cams of this size or type.
Lefty71
Well-Known Member
I'm going to have to agree with this one. My limited experience is with their smallest solid lifter BBM cam. Not the Whiplash, but also a higher lift, shorter duration cam.. I know, I know, it's in a race car. But let's look at the similarities to the OP's situation. My car is all steel (except scoop and front bumper), all factory glass, roll bar added, so still heavy. Motor is iron headed 383 (factory 915's), no port work at all. No power adders or any voo-doo whatsoever. You'd be hard pressed to convince me that this car would not be an absolute blast to drive on the street if it was running 3.90's and street tires. BTW, it matches the advice I gave in post #3, and along those lines.... if you read post #4, I'll give you three guesses who put the performance curve in the distributor for me.
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I need the haha icon that's not available. Couldn't agree more. If you're going cross country and the car runs well now, don't mess with it just before the trip. Going to higher gears now, especially when you're not used to it, will only give you a headache on a long highway drive like that, not to mention the fuel costs. Keep what you've got for now, get the maintenance in shape with fluids, filters and plugs, throw some tools and spare parts in the trunk and enjoy.
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Truer words were never spoken.....see my #6 response.....everybody wants to change cams, heads, engine mods, steeper rear gears (3.55 and higher).....for what purpose.....to "MAKE A LITTLE MORE POWER"...which will result in higher fuel costs and reduced reliability.....where is the person going to get a replacement "whiplash" cam or equilivant, in Bumfuck Iowa or the middle of nowhere Montana, or Death Valley Arizona with 120 degree temp, when your car overheats and craps out, beside listening to the drone of the engine at 3000 RPM for 500 miles getting 12-15 MPG all day......personally, spend the $$ on first class plane tickets, first class hotel accommodations, enjoy great restraints.....go in style.....save the car mods for your "local buddies" at the car shows......but to each his own volition......
BOB RENTON
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