[vertigto]

Originally Posted by OCMDGTO

Very nice build, greatly exceeded my expectations. You taking it to the track?

It will essentially be a cruiser, but may take it to the track for giggles when completed.

[roger1]

Wow! I am super impressed with the numbers you achieved.
I don't know if mine will come close to yours but our engine specs are very similar. I'm expecting it to test on the dyno this week.

[scott70]

Goes to show that a factory RA4 engine was underestimated at 370 hp. Better heads and a bigger cam made 370 wheres yours made 400? Congrats on your output,,,,pretty good for a mild setup. I believe there was about a 15-17hp difference between 1 3/4" hookers VS RA manifolds and 2.5" mandrel bent headpipes when I dynoed mine back to back.

[vertigto]

Originally Posted by roger1

Wow! I am super impressed with the numbers you achieved.
I don't know if mine will come close to yours but our engine specs are very similar. I'm expecting it to test on the dyno this week.

Yes...I'm pretty happy. We started the process with a 400hp goal. Other big part for me is durability/reliability.

I think the cam selection (Tim Goolsby at Bullet/Ultradyne - great guy/knowledge) is a factor along with whatever head work was done. I was told by the builder that it was just a little bowl blending and cleanup, but not sure exactly what that means. For the labor cost billed, I don't imagine that it involved very much. He mainly builds race engines, so perhaps there is a little voodoo involved.

The carb was rebuilt by a friend's father (a long-time GM tech and alleged Quadrajet guru) just prior to the rebuild and the engine builder said he barely touched it, so maybe a factor. Forged pistons and rods are really the only other difference from stock for the .30 over (aside from a valve job/hardened seats).

[pastry_chef]

Originally Posted by vertigto

I think the cam selection (Tim Goolsby at Bullet/Ultradyne - great guy/knowledge) is a factor

Agree a good cam. It is right out of the old Ultradyne catalog. I gave the same suggestion to another a few weeks back.

[vertigto]

Yep...276/286. Most appreciative of the referral...paid off for me.

[400 4spd.]

Let me throw this tid-bit in. The numbers were achieved using a set of 3 tube headers.

[vertigto]

Originally Posted by 400 4spd.

Let me throw this tid-bit in. The numbers were achieved using a set of 3 tube headers.

Good to know Steve...I was not aware.

So maybe the difference between the 3 tube headers and oversized RARE manifolds may not be all the much?

I remember reading the following excerpt from Jim Hand's book on another forum:


Building a Strong Street Machine

By Jim Hand

Three tube vs. Four tube headers

The most significant advantage of tube headers (with a common collector) is their ability to lower the atmospheric pressure within the collector. This provides scavenging of the combustion chamber, which more effectively removes the exhaust gases and tends to "suck" the intake charge into the chamber during overlap. The effectiveness of the scavenging is dependent on proper matching (tuning) of the header pipe sizes to the engine RPM and application. All street Pontiacs run best with 1 5/8 or 1 ¾ inch primary ????? into a 3 inch collector. The primary ????? length should average 30 inches or longer. A race engine that never sees a load under 4500 RPM may run slightly better with larger diameter primary and secondary sizes. The "tuning" ability of 4 tube headers make them slightly more effective than 3 tube units. The 2 inch center tube simply will not "tune" in the operating range of the engine. Most three tube units have very short primary ?????, which again tune above the normal operating RPM of our Pontiacs.

How much difference in performance is there? We recently substituted a set of "Blackjack" aluminized three tube headers in place of "Hooker" four tube 1 ¾ inch primaries, 9 inch secondaries, on our 11 second ’67 Le Mans, and it lost .2 seconds and 2 MPH in the ¼. The three tube units were tried on our 12.5 second ’71 Le Mans in the place of four tube "Hookers", and it lost. 1 second and 1 MPH. Although there is a small, measurable difference in performance at the dragstrip, it is unlikely that this difference could be detected on the street. Accordingly, use the headers that fit best, are easiest to install, and are the most reasonably priced commensurate with their quality.

We have performed a similar test with the Pontiac GTO cast headers (Ram Air series) on the 12.5 second car, and they performed identically to the three tube units. The cast units are easier to install and maintain in comparison to the tube type headers, and are an excellent choice for street and street/strip applications.

[400 4spd.]

That's why I wanted to mention it, I don't see the manifolds hurting your performance in comparison to the dyno runs with the 3 tubes. In fact, he got the headers from me. I used them 20 years ago on a 442 that I was running a Pontiac engine in.

[roger1]

Interesting. Plus the RARE manifolds are larger then the stock RA manifolds. Might pick up just a touch there.

My '69 400 engine will have the RARE manifolds on it when they test it soon. I was really thinking the machine shop would be doing earlier this week so it should be any day. It's running but the machine shop is having trouble with the electric fuel pump they have on their dyno.
Very, very similar engine to Vertigto's. Lunati 702 cam and Edelbrock Pro Flo4 on top are the 2 major differences. Stock heads with no porting, stock rods are a couple of minor differences. Compression ratio should be the same with the new .040 over KB dished pistons I've got.

[vertigto]

The EFI should help. If the cam specs and compression are similar, I don't see why you wouldn't do at least as good as mine.

Post up the results, when you get them (if you don't mind).

[roger1]

Originally Posted by vertigto

The EFI should help. If the cam specs and compression are similar, I don't see why you wouldn't do at least as good as mine.
Post up the results, when you get them (if you don't mind).

Will do.
One thing the machine shop owner told me is sometimes with EFI it won't do quite as well on the dyno as in the car with an exhaust system because the O2 sensor doesn't read as accurately since there is only a short pipe in back of where the sensor mounts.
Anyway if I don't do as well as you, I'll blame it on that.

[RH68]

Those are nice dyno numbers vertigto. I am doing a very similar build right now. Also #13 heads but I had them ported and the cam is slightly bigger (228I/235E). I am using RARE long branch manifolds. I doubt I’ll dyno mine. Nice to see some other 400 builds in the works right now.

[roger1]

Just got back from the machine shop. My results are in:
425 HP at 5,000 RPM and 480 TQ at 4,100.

It appears my Lunati 702 cam has a little higher power band than your cam. My TQ at your peak of 3,600 is 443.
My power band should be great for my gearing. I'm going to be running 3.55 gears and an Art Carr 200-4R transmission.

He will have my engine ready for me to pick up later this afternoon.

[RH68]

What heads are you running? Great numbers.

Originally Posted by roger1

Just got back from the machine shop. My results are in:
425 HP at 5,000 RPM and 480 TQ at 4,100.

It appears my Lunati 702 cam has a little higher power band than your cam. My TQ at your peak of 3,600 is 443.
My power band should be great for my gearing. I'm going to be running 3.55 gears and an Art Carr 200-4R transmission.

He will have my engine ready for me to pick up later this afternoon.

[roger1]

Block is a .040 over YS block that is the factory original to the car. The heads are stock 62 castings. New valves and the Lunati springs that came in the cam kit. Roller tip rocker arms.

[vertigto]

Excellent numbers Roger...congrats!

What are the specs on your cam? Compression? Specs/valve sizes on the 62 heads (not sure the difference between my 13s)?

I'm thinking there is a little more in mine with some tuning. BTW...mine was .030 over and 3.23 gears.

[roger1]

Thanks. I was expecting less and would have been happy with less too.
Not sure what the differences are between 13 and 62 but stock valve size is the same. The factory listed 10.75 to 1 compression and with my dished KB pistons, the estimate was 9.5 to 1. Here are the Lunati 702 cam specs:
https://butlerperformance.com/i-2445...-10510702.html

Subsequent pulls on mine were getting better each time. When he called me to come on down, he said best HP was 418 but he'd do another pull after I got there. That's the one that did 425. He said that's normal on a brand new buiild and my Edelbrock was learning and tuning. That's the one that did 425.
Hear the shock in my voice at the end. I really was quite surprised. Also note that this doesn't have the choppy idle that Lunati states it does.
https://www.youtube.com/watch?v=opyoQKBO7aM

[roger1]

Took a photo of the print-out.

[RH68]

Interesting that he stopped the pull at only 5000rpm. It was still pulling.

Originally Posted by roger1

Took a photo of the print-out.