ok....my engine builder has ordered everything to put my 74 454 motor back together and is going to do a nice hydraulic roller lifter and grind a custom cam for the car...the heads are original - oval port...

the compression will be 10:1 with the domed pistons i have...

i ask him "around what horsepower can i expect with this combination"...and he says - "expect about 350" - im like WHAAT?

according to him...and he is a reputable engine builder in southwest florida...my original intake manifold is the worst ever made and basically is a "restrictor plate"...

problem is...id like to keep the car looking stock...and the original intake manifold is extremely low - which allows the cowl hood to rest on top of the air cleaner...any other intake manifold ive seen rises much higher...and would never allow my cowl induction to work....

so....is there anybody out there that has dealt with this problem - and is there a remedy for it?

my engine builder says that with a simple edelbrock air gap...my engine makes 500 h.p. easy....

can that intake be that bad?

 

I went through the same thing with my 74 454. I wanted to keep it under the stock hood but I also wanted to change manifolds to aluminum (stock is iron) and carbs to a Holley or Demon for horsepower. Unfortunately this meant disabling the cowl induction that seals to the underside of the hood. After much research, I determined that only 2 manifolds would work: (1) Edelbrock Torker II or (2) Factory GM 1970-72 LS-6 manifold. Both of these are square bore and will not work with the stock Quadrajet. I don't like the Torker II because it is not a good manifold, has small intake runners and an open plenum, but it does have oval ports. The LS-6 manifold is better, has a divided plenum and larger runners, but is made for rectangle-port heads. My solution was to buy an LS-6 manifold on Ebay for $600 (like new) and have the ports epoxyed and port matched to my GMPP aluminum heads by a local engine builder, another $350. But now I have a stock-appearing manifold that works with my 750 Street Demon and fits under the stock hood. My engine is fairly radical for the street and I estimate it to make 450-475 hp.

 

so there is hope!

any chance you could send me a pic of that with and without the air cleaner....?

i think as the 73 and 74 454's catch on in the years to come...this will be a thread that is referenced many times...

thanks!
RR

 

150 HP difference with a simple intake swap? Please. Maybe 15. I'm already questioning your builder's smarts.

Your other option is the L36 intake used in 1968 and 1969 which is the only factory aluminum big block q-jet intake made by Chevy. It was used on 390 HP 427's which had a mild hydraulic cam, O-port heads, and about 10.5:1 compression. By default, you're adding 30 HP to the 390 with the addtional cubes. Of course, you're adding a roller and probably some headers so your HP will be a little more than 350. You can have the L36 intake ported a bit and gasket-matched for a few ponies if you want a little more on top of the RPM range.

Yes, the Torquer II is a square bore intake and it will fit if you want to switch to a square bore carb,..Holley, for instance. The T-II is a fine intake that Edelbrock still sells today and has an RPM band of 2000 to 6500. Thousands have been sold.

I'm pretty sure the LS-6 intake won't work. It positions the carb quite a bit higher than the stock intake used on LS-4's.

Also, the Performer, RPM Performer, Air Gap, etc, won't fit under your stock hood with the stock air cleaner and cowl hood set-up (which is one of the things that makes 73's and 74's so unique). The Edelbrock site confirms this.

But don't despair. If the build is solid and the parts are compatable, you can easily reach 450-500 HP with a 454 with a stock intake.

What heads are you running?

 

I agree.

My '70 rebuilt 454 bored .030 with a roller hyd cam makes 532 torque and 462HP with the original heads, intake manifold, original qjet and original exhaust manifold. Cam is .569/.569 with 10.7 CR.
Stock was 390hp 500tq.

It can be done.

 

the heads are the original 781 heads (i think thats the casting number)...

and i will be running the original exhaust manifolds because i want to "place" the (empty) smog equipment back in the car (internals removed) to keep an original look.....

in defense of my engine builder...i think he was telling me 350 hp so that anything over that when all was said and done - made him look like a genius...

but he did say that my original intake was probably good for about a 100 hp loss as a neared the 500 hp level with a better intake...(once again - bid low sell high)....

so..maybe now ill just put the aluminum intake on ...forget the smog and put headers on it....

id like the ar to have around 500 h.p. when all is said and done..maybe thats the only way im going to get there...

thanks for your insight guys....

im going to bring these ideas to him in the morning

RR

 

I am going to do about the same thing I will be using ls6 heads iron, ls6 intake alum, ls6 cam with solid lifters, hooker side pipes and headers. I am going to try a proform carb 750 cfm. I am going to use the stock pistons. My engine is very strong, When I got it the block had been decked I don't know what has been done to it. after summer I guess I will do the change over.

Is there any one else that has done this?
What was your results.

 

I replaced my low rise LS6 manifold with an old oval port Holley Street Dominator. I also extended the runners and opened them up especially the top of the runner as it starts in the phlenum.

I experienced a big gain in power. I was using a Holley 950 (750) in both cases

 

If the engine is together and operable, just break it in and take it to a dyno for check-out and tuning it in. That will tell you how much HP you are getting to the rear wheels. Increase that number by about 20% to estimate "engine" output. THEN decide if it's worth all the trouble to search, buy and replace the intake components. My guess is that you will be satisfied with what you have. You can always remain 'on the lookout' for that special intake manifold you would like to do it up right {for a reasonable amount of $$$$}. [I think your engine builder is just stringing you along for some more ca$h.]