350 - 270 Combo Horsepower
 

My brother and I have been tossing around the idea of going from the BBC 402-300 combo we currently have in our car to a 350-270 combo. My question is, can anyone who has run this combination in the past, give me a ballpark horsepower and torque numbers this combination has the potential to make?

We currently run the BBC 402-300 combo.

Re: 350 - 270 Combo Horsepower
 

Needs to make north of 400 hp put you .06 to 07 under.

Re: 350 - 270 Combo Horsepower
 

I would agree with your comment but, I need some advice from someone who has ran or has built the 350-270 combo to get an idea in regard to horsepower/torque numbers to help us decide whether or not it is going to be a worthwhile combination to build. We will be starting from scratch if we choose to go the 350-270 route.

Re: 350 - 270 Combo Horsepower
 

Contact Ron Matson and Bruce Noland. They have had good success with this combo and I think they both have some real good parts for sale after moving to another class and engine combo.

Re: 350 - 270 Combo Horsepower
 

I have worked on several in my 15 plus years , But go ahead .

Re: 350 - 270 Combo Horsepower
 

How fast have you gone with the the 402 this time around?.Has it been on a dyno?. gsa612

Re: 350 - 270 Combo Horsepower
 

I hate to get into a pi%%ing contest on which engine is better . that being said anyone who thinks a 402/315 is better than a 350/270 is mistaken. If I am wrong someone needs to notify Demarzo,Johnny Gray and Sepanek so they will quit wasting their money and time running them. This is just one guys opinion ,I can say that the 402/315 is way to high. 280 to 285 would be a lot closer in stock. SuperStock is a different story. Oh by the way I run the 350/270 @278 not 270. Rick.

Re: 350 - 270 Combo Horsepower
 

Rick & Jim are dead on. The 350/270 rated 278 is a better combo. I had a 402 big block in my nova and researched a number of combo's and Johnny Gray gave me the best insights. What is nice is that a lot of racers run the combo (HP avg) and we share information on what works and doesn't. Rick I think you should move to D-1 (lol) and we can learn from each other. . It is not all about HP but torg, converter, carb, and suspension. Good luck with your choice njk53.

By the by Gray, Sepanek and I all have different engine builders.

Re: 350 - 270 Combo Horsepower
 

Joe, I would love to come east and race someday,but from what I hear about the taxes up there I could not afford to live anywhere near the east coast. As for sharing info I really don't think you want to slow down ?lol. Hope to meet you someday,maybe at the nationals.If you are ever near Cincinnati look me up. Take care. Rick. ps You are right ,Johnny knows his stuff and the Sepaneks are damn fast when it counts.

Re: 350 - 270 Combo Horsepower
 

Rick, when you say the 402-315 is way too high do you mean the NRHA factored horsepower as being way too high? If so I agree. We have asked the NHRA for a HP reduction for our combo but no dice. I hate to admit it I raced another K/SA car heads up at Norwalk a few weeks ago and he just walked all over me, it was that bad. I have had a couple of engine builders that stated the 402-300-315 engine combo wouldn't be their first choice. If you guys out there knows of anyone successfully running the 402-300-315 combination, I would sure like to speak to them for advise. Maybe we are doing something wrong, I don't know. I feel our car is just too heavy for the power it makes.

Re: 350 - 270 Combo Horsepower
 

Yes that's what I mean. If I remember right Cal Method ran that engine in a 71 Camaro years ago.He is one of best out here at making one run and changed for a reason. If you look at the class guide you can run 0/sa with a 350/270 @40 lbs lighter than you have to weigh in K/sa with a 402/300/315. I am not cutting your combo because anyone that can run under the index impresses me and that's not easy with anything. If you want to stay in K/sa you can make your car a Nomad 2 seat wagon @585 lbs.lighter than the 402. Its not going to be easy with any engine,but I know I would rather have the 350. Good luck. Rick.

Re: 350 - 270 Combo Horsepower
 

I think the main problem with the 402 in our 71 wagon is the intake manifold. Our current engine builder said the manifold is the limiting factor for making good power with that engine. I would love to stay in K/SA (because I have 2 engines and parts to boot) but, I also want to be somewhat competetive within my own class. Currently I am not anywhere near what other K stockers are running. The car itself is a good car hooks good, drives straight, and is an easy car to drive. I'd would like to keep it even if I have to go to a different engine combo.

Re: 350 - 270 Combo Horsepower
 

(1970) 350, 2bbl, R/SA Not much more weight .
Not many heads up runs that you couldn't handle in Div 3

K/SA is a bad place to be if you can't run at least 11.80.

Re: 350 - 270 Combo Horsepower
 

I ran the 402 combo in my 72. Sent several cams through it but it was never really steller. Granted, there is much better camshaft technology today that may make it worth while if you really don't want to change combos. If memeory serves me correct, my best et was 11:27 @ 117.01 in H weight, in great air. The intake is restrictive and very low. The ports actually turn up to the intake ports.

Tim

Re: 350 - 270 Combo Horsepower
 

I ran a 396/325 combo and will be running the same motor in my 65 Impala. I thought it ran pretty good pushing my 4100 lbs 68 Impala to 11.70's . Checking out the specs compared to the 402/315 they are pretty close except I run 290 heads which have a little more intake port volume. Cam intake lift same at .398 but more for 402 on exhaust at .430 Then I did notice the intake manifold for the 402 really a "low riser" compared to the 396/325 which is a more of a "high riser" design. Makes sense than that manifold is the problem. Just wanted to throw my thoughts in.

Will Lamprecht

Re: 350 - 270 Combo Horsepower
 

The 402 isn't even in the same zip code as the 350/270
Approx .25 to .30 slower apples to apples!!!

Re: 350 - 270 Combo Horsepower
 

I agree with you on your statement that if I can't run 11.80 I am in a bad place. Unfortunately, I am almost .4 off of that. That's why we are looking at the 350-270. The 350-270 combo would put us in M/N/O. That is why I am trying to get information as to how much power the 350-270 combo can potentially make to sand help us make a decision if that would be a good combo for our car. As I said, the car itself is not a bad car, it is just the HP - Weight ratio that is lacking merit.

Re: 350 - 270 Combo Horsepower
 

NJK53, I think Jim said it earlier (I agree) that you would need to get 400 plus out of the 350/270 to be competitive. Probably put you in the upper/middle of the pack if everything else is right.

Re: 350 - 270 Combo Horsepower
 

Joe, all I need is someone who has built and/or run the 350-270 combo say the 350-270 combo can make 400 HP plus with this engine.

Re: 350 - 270 Combo Horsepower
 

I managed to make 360 horsepower at the flywheel(mathematically derived, not actually dyno horsepower), with a 68 327/250 horse engine. That one has only 8.5 to 1 compression,has small valve heads, and has a shorter stroke. The 350 should make a lot more torque, has way better ports and valve sizes, and it should be good for over 400 horsepower if it's a good one. The size and weight of a wagon is the biggest thing that has to overcome. It's been done. If the big block is really your preference, Herman Chapman had a 402 Chevelle wagon in Super Stock(no manifold restriction,open season on camshaft selection), maybe that would be an option.

Re: 350 - 270 Combo Horsepower
 

K/SA is a great class! Had a 1.45 last time out so we are inching closer to the 6.99 goal :)

Re: 350 - 270 Combo Horsepower
 

Please don't rub salt into the wound. LOL

Re: 350 - 270 Combo Horsepower
 

400 hp is no problem 425/435 for a killer!!

Re: 350 - 270 Combo Horsepower
 

400 hp is only 1.15 hp/in3 for a 350, so it should easily make 400 hp.

A good one should make north of 450 hp.

Re: 350 - 270 Combo Horsepower
 

Jim Hughes runs that engine with a stick, and runs pretty good, I think the 402 is a bit harder than the 350 . If you get the right engine builder it should be a fair engine and yes I have worked on a couple. They make about 480 or so.

Re: 350 - 270 Combo Horsepower
 

"They make about 480 or so"

Thats pretty accurate, with a peak of 6400 RPM.
488 HP
497 TQ

Re: 350 - 270 Combo Horsepower
 

Jim Hughes runs a 70 Nova with a 350 hp 402. Different animal than the '71

Re: 350 - 270 Combo Horsepower
 

Yes the 1970 402 is a way better motor. It also has an intake manifold that has a higher rise which produces better air/fuel flow than the 71 manifold. The 71 intake is flat as a pancake. The 70 engine is also 10.25-1 compression ratio. The 71 engine has a 9:28-1 CR.

Re: 350 - 270 Combo Horsepower
 

According to the tech. specs the 70/350 and 71/300 402 both run the same intake (flat #287).In order to get the 300/402 to be competitive you need a custom grind camshaft,if you have one of the "off the shelf" cams your leaving 2 tenths on the table,There basically a 325/396 cam with more ex. lift,but don't compliment the semi-open head (105cc) on the 300/402 which produces low torque #'s.With the right combo,cam/converter/gear,carb,light trans,good ring seal,right tune-up ( jetting,timing etc.) it should run with the majority of the cars in K. JMO gsa612

Re: 350 - 270 Combo Horsepower
 

Here's a picture of a 287 manifold. Doesn't look flat to me. The differences between the '70 and '71 engines are the heads (290 heads flow well and have a good combustion chamber design, 820 heads flow okay but the combustion chamber is sucky; not sure about the other '71 heads), camshaft, and 1.7 points of blueprinted compression (11.3 for the '70 and 9.6 for the '71). See www.classracerinfo.com for the actual calculated compression ratios.
http://i39.photobucket.com/albums/e2...psp5afhpdu.jpg

Re: 350 - 270 Combo Horsepower
 

The 287 manifold would be considered "flat"compared to a 68-69 396/325 (shown).There not as restrictive as you may think,as the 71' 454/365 Chevelles and Corvettes use it,with 50+ more ci.and the same cyl. head (#820). gsa612

Re: 350 - 270 Combo Horsepower
 

This is flat : '72 up manifold.
http://i39.photobucket.com/albums/e2...ps9dsm1rpb.jpg

Re: 350 - 270 Combo Horsepower
 

In '72 it gets screwed up,you have to run that ^^ flat intake (#753),and head #'s 241 or 292. In '71 you have to run the 287 manifold (semi-flat lol..) with a choice of head #'s 820,241,292, with the 820 being the best.Both years are factored at 315 hp. I can't see why the '72 can't also run the 820 casting along with the other two. If anything the 72 combo should allow the 820 head and drop 10 hp to 305 in rating because of the lower more restrictive intake.Then you might have something,as all other components (cam lift,pistons etc.) are the same. gsa612

Re: 350 - 270 Combo Horsepower
 

Big blocks as a whole are rated way to high as far as hp is concerned