need more power for my '74 454

[dsbjc4]

i would like to add a little more power to my 1974 454 with out getting to radical. i was thinking maybe a cam and porting the heads. any suggestions?

 

[Mac]

i would like to add a little more power to my 1974 454 with out getting to radical. i was thinking maybe a cam and porting the heads. any suggestions?

Welcome to the Corvette Action Centre! I'm sure you'll enjoy the Forums!!

If it's alright, I'm going to have your enquiries moved over to the C3 Mods area where the 'experts' will provide any and all details you want.

Personally, I would say unless the heads have problems, I wouldn't port them. The 454 has tons of potential which can be unleashed with a well matched cam, set of headers, intake & carb combo. Opinions vary on which manufacturer makes the best setup but you're better off to buy a combo which works together rather than changing things piecemeal.

Good luck!!

-Mac

 

[JBsC5]

Lets see photos of your car if you can..

A 454 is an awesome vette!

Congrats on you're mod choices!

More power than a 454 ...

Wow! I never thought I'd hear that!

Awesome!

 

[Mac]

More power than a 454 ...

Wow! I never thought I'd hear that!

Awesome!

If it is the stock 454 from 1974 (last year for a big block if memory serves) then it's an LS4 only rated at 270 hp. The L82 at 250 hp with lighter weight was a better bang for the buck and had better performance stats. Last year before cat converters became mandatory as well.

c5d, as I understand, the bottom end of these engines is sturdy up to about 400 hp before one would have to consider changing any of the rotating stock or worrying about 2 bolt vs. 4 bolt mains. With the combo I suggested, at best one would realize about 350 hp or so with decent driveability.

Hmmm, I guess none of the admins are around... I don't have mod powers here on Intro, just on the Off Road Lounge, so we'll have to wait.

 

[JBsC5]

I remember as a teenager just beginning to drive in 74...or 75...that the 454 Corvette was a beast....

Sure the early emission controls took its toll (270hp stock) ....I just assumed that had been rectified over the years of ownership..

454 is now a classic too...


Great car...!!!!

 

[74bigblock]

Nice car! :dance Is yours a 4speed or the 400 auto?

I highly recommend the Edlebrock 750 performer with Elec, choke. You can confer with Edelbrock on your intake manifold choice based on the other mods you want/have already done. They will help you make the best decision for your build. You should expext at least 70HP gain just from the carb and intake. Be aware that most intakes will not fit under the stock 454 hood... you may need to consider a high rise style to gain the clearance you need.

You can also gain mucho HP from headers etc... I decided on Hooker sidemount with side pipes and glass packs, but there are other choices.

You will get quite far with just bolt on parts... there is no need to build if you are just looking to get up to the 350-400HP mark. I'm shooting for the 500 mark.

Dave

 

[dsbjc4]

more power for my 454

thanks for all the input, yes this is a #s matching car. that is why i did'nt know if i should change intake,carb, exhaust. this is my first vette. i have redone a '70 camaro and a ,84 monte both with small blocks and no matching #s. this is my first b/b, will changing bolt ons affect the value of the car that much or is the extra power worth it?

 

[74bigblock]

Mine is #'s match too... but there was already a lot done before I bought it. You need to make a decision now, and stick to it... Keep it bone stock and restore it to factory using all GM, or anything else you migght as well build her the way you want.. cause going back to stock GM with a frame off is the only way you would have a gain from keeping stock (both emotionally and economically).

Whatchya gonna do????

 

[dsbjc4]

more power

this car has never been touched except for the alt, i am all about more power. but i still don't know what i should do. it realy needs alot of work done to it. so i am leaning to more power. i don't think i want to change the hood so high rise intake is probally out. what to do, what to do????
it is a nice problem to have though

dsbjc4

 

[74bigblock]

Indeed... a good prob to have. I'm running the stock intake right now.. cause like you, I'm not sure if I want to run a high rise hood. In the mean time I'm looking for something that will fit. I can tell you now... get rid of that rochester carb. They are a PITA, and rob tons pf HP(keep all your old parts though). Also... if she is in bad shape... check your tank for rust. If clean.. you are good. If not.. get a new tank and sending unit. I didn't. OOOPS. What a mess.

 

[dsbjc4]

good idea,didn't think about the tank. will probally do the tank and the lines just to be safe. frame and body are in good shape it only has 47k on it. i got the engine and trans out last weekend, now comes the cleaning. new bushings all around,sand blast the a-frames, brackets,any other small parts.i am not going to do frame off, but i do want to clean it up good. paint hood bay, redo interior,paint body,add more power???

dsbjc4

 

[jfb4548]

I suspect the '74 is a 3999289 casting, 2 bolt main.

A 2 bolt block with splayed caps (angles the bolts outward 18 degrees to utilize the inherent rigidity in the cylinder walls resulting in an arrangement that is stronger than the straight bolt cap arrangement) will certainly handle up to 400hp, with a max at 500hp. If the caps are straight, then 400 is a good limit.

The 2/4 bolt determination is important for a couple reasons. Not knowing which HP figure dsbjc4 is looking for (although I did dismiss the LS7/465hp as too radical), if he chooses the 450hp, the 4 bolt mains are probably necessary.

And since LS6 (& LS7) HD engines used a 7/16" rod bolt, and presumably other HD components, these parts, if selected, may require 4 bolt main clearances.

If selecting the 390/365 versions, there probably is no need for concern with a two bolt main.

C'ya & Merry Christmas
D

Just my 2 cents....but unless you add a super charger / blower or large N20 system your two bolt block and 3/8" rod bolts are plenty strong. Two bolt blocks are fine till you get high compression and hi RPM applacations. Cylinder wall thickness is more of an issue but even so +.60 over is safe in most cases.
We have drag raced two bolt blocks and 3/8" rods for years with out failure of rod or bearings. These motors all made way more HP then Chevy ever intendend for them! I've even seen the cast cranks run in race motors. Rumor has it their forgiving nature makes more HP but for sure they don't last as long as a good forged or billet crank.

 

[74bigblock]

All good points here. Just depends on what you are going to do with her....

Lets ask this... what are you going to use your vette for? Racing? Daily? Weekender?

(Mine is for cruising the lanes in Chi town picking up women).

 

[dsbjc4]

I am thinking about a comp cam set up I have had good luck with them before. do you think i should leave the heads alone or do a little pocket porting? what size cam would work good? edelbrock,holley, or stay with the Q-jet? i don't know much about a B/B.

dsbjc4

 

[dsbjc4]

this will be a weekend driver no trailers here.driving the streets of northern ILL.

 

[74bigblock]

Northern IL??? What town?

 

[jfb4548]

I am thinking about a comp cam set up I have had good luck with them before. do you think i should leave the heads alone or do a little pocket porting? what size cam would work good? edelbrock,holley, or stay with the Q-jet? i don't know much about a B/B.

dsbjc4

Anything more then a good valve job and valve seals and maybe replacemnt valve guides if needed is a waste on a street motor.
Spend your money on a good intake and carb, cam, lifters and valvesprings. Call any of the cam company and they will give you the correct parts for your applaciation...They are the experts, no need to reinvent the wheel!

 

[74bigblock]

Anything more then a good valve job and valve seals and maybe replacemnt valve guides if needed is a waste on a street motor.
Spend your money on a good intake and carb, cam, lifters and valvesprings. Call any of the cam company and they will give you the correct parts for your applaciation...They are the experts, no need to reinvent the wheel!

Well said.

 

[jfb4548]

One last idea.....The exhaust system is a great way to find hidden HP....Pitch the factory mufflers at a very least!

 

[74bigblock]

Got a picture of her?? Here's mine: