Thoughts on engine combo
 

I recently bought a 77 Can Am with the original W72 engine. The car has been in storage for about 20 years. The owner was very meticulous and rebuilt the engine and added some aftermarket parts during the rebuild. I have cranked the car and it sounds very strong and feels very powerful. I can’t drive it right now due to the front sheet metal being off the car. All machine work was done by Race Engine Design in Chattanooga TN. It has TRW forged pistons, a Comp 280 Magnum cam, Comp roller tip rockers, Hooker Headers, Edelbrock Performer manifold, original Quadrajet rebuilt by the Carb Shop, DUI distributor, TCI 3500 stall converter, and 3.73 posi rear end.. What are your thoughts on this combo? I know a lot of people here don’t like single pattern cams and stall converters this big. It will be strictly for fun and no daily driving. Thanks!

The Comp roller tip rockers can be failure prone. Some have good luck with them and others burn them up at the ball pivot.

I’d replace them with some proven Harland Sharp aluminum full roller rockers.

Replace the Performer with an iron factory intake for a performance boost.

Other than that drive on!

Also, the heads were cut .060. The Performer intake is a bottleneck on 455s and also 400s?

The Performer is a toss up on 400 engines, but with that fairly aggressive cam and headers I think it’s wrong for your setup.

I see the Performer as a good performance street 326 or moderate street 350 intake, that’s about it.

Thanks Bman

I agree ditch the cast Comp roller tip rockers. Perf0rmer OK for a 400 like B man said , but with that cam a massaged factory intake might work a hair better -but will add 20 lbs!

Does a weight savings of 20 pounds on a 3800 pound car really make any measurable difference?

Not really.

Other than being easier to lift into place during assembly i can’t see any real advantage.

I’d go with the better performing cast iron factory intake over a lackluster aftermarket aluminum intake every time.

The performer on a 400 cid motor with stock 1977 heads is good to 5400 rpm which is fine since it seems like the motor still has factory rods in it.

And if this is the case and since it sounds by your intended usage of the car that you will be heavy on the gas pedal I would get those factory rods the heck out of that motor if you have the budget for it.

Not to hijack, but can the standard speed Pro/trw forged pistons be safely pressed off a stock rods without damage and re-pressed onto say the budget 5140 rods? And then obviously have the whole thing rebalanced.

Stated - " but with that cam a massaged factory intake might work a hair better "

They key word here... massaged.

SD Performance CNC machined & ported OEM Q-jet intake:

Patterned after Q-jet guru Cliff Ruggles personal modified OEM iron intake, a back to back dyno test showed a 12 hp gain over a stock plenum OEM intake

http://www.sdperformance.com/viewPro...productID=1727


Will 12 HP* on a 3800 pound car really make any measurable difference?

* Combination specific



.

Phil, piston wise yes.
If worst comes to worst and the shop screws up you get a set of new wrist pins if they can’t be reused.

The time when most rods get screwed up is when they are overheated in the rod oven before the pin gets pushed thru the rod.

New pins actually are not a bad idea since the pins that come in most street type non 455 pistons are 250 grams, and using far lighter 200 gram pins helps them motor to spin up faster and lessen’s the load on the rods and crank by a bunch!

i had that same combo/cam on a 6x-4 head 455 back in the 90's but using a holley mech secondary double pumper, car ran great as a daily driver & daily/nightly abused car. never had or noticed any of the "choking" or running like a "turd" related to the performer intake, im sure it would have ran better with a factory intake but aside from dyno or track testing to show a difference, it ran very good in all conditions, no cutting out, bogging, over heating or other issues.

the factory rods did fine in these mild builds for the most part for decades, even in some higher HP race situations... we didnt have forged rods readily available back then. i spun that 455 to 6000+ countless times over 10+ years & 100k+ miles with that build & they lived for ~80k miles in the 74 firebird the 455 engine came out of. i think the stock rods are stronger than some give them credit for, they should be fine on a mild build if kept to a reasonable rpm.

I have had Harland Sharp Full Rockers for years and have never had one issue.
The rocker ratio might be a bit higher than advertised when you have less than roller cam spring pressures working against the rocker/pushrod/lifter.

Tom V.

Yep. Most would cringe on what I, and we did to factory rods back in the day.
6000 on cast rods in a 455 and 7200 with rubber rods in a 428 are 2 examples.;)