I have built a 1969 400 with a .030 over bore, used a 068 cam #16 heads midly pocket ported with an edelbrock perfromer RPM manifold. It also has headers with a flow master 40's 2.5" inch exhast It seems to go "ok" i just would have expected more seat of the pants feeling from it.
And its an 200r4 automatic with a 2000rpm converter turning a set of posi 3:55 rear gears.
I was thinking about dropping to a set of 2:72 or somthing as 5200 redline comes up fast in each gear! Seems like i should be pulling harder. I'll verify the shift points tonight if it stops raining!
So my questions are what would a good starting point for the jets and what would be a good starting point for timing . WHat should be total advance in by 3300 RPM?


Any help would apriated, my gf says it sounds like its going fast, but its not. Sounds nice idling though nice low rummble from the 40's! lol

Wrong intake manifold would be my guess.

The "regular" E-brock Performer is supposed to be an aluminum equivilent of the Ram Air IV manifold, It's power band is idle to 5500 RPM.

The RPM manifold is good from 1500 - 6500 RPM. So it does not match the real operating band of your motor. You have lost the off the line bottom end and it provides top end range you cannot use.

I tryed when building my 428 to keep it streetable. The problem you are facing we all faced. Are you getting any wheel spin? Are you getting any bog when you launch your car? What size tires you running with your gear? I am with everyone here pontiacs like 12-14 degreees initial timing and 36-38 total timing. Old pontiac guy said he always used the ear because you can hear when the car has the timing it wants.

oh i thougght it may have been too big for my engine. so i can put the raII intake on and it will be as good as the performer intake ? my 16 heads are midly pocked ported it feels like the engine does want to contiue climbing in RPM's though.

Agree with Sal38. Get a stock intake.
What carb ya use'n?
2000 rpm at what speed? With that cam, need to 3000 minimun on highway.

I thought about your setup a bit more. You have conflicting parts.

You have a bit higher than stock converter and an intake manifold set up to work best at RPM's shifted up 1500 from what the factory built the car for.

Then you put in a stock cam grind.

You either need to stick with stock level parts to compliment the cam you chose, or replace the cam.

You failed to mention the carb type and distributor...If not tuned properly, will cause performance issues. Timing should be all in by 3000 or so but it's a personal preference. The gears are fine with that trans...IMO

As well, what compression are you running?

its a quadrajet 800 cfm model , so what cam should i shoot for. i just wanted it to be more powqerful , but not horrble to drive.
so i can get the edel brock performer, and a new cam . any suggestions?
oh and CR i had dropped to 9.5 to 1

oh i forgot it realy feels like i could go over 5200 RPM and there is still some power up there i just get offf the gas when i see the 5200 coming up, it comes up fast too

No, I suggested going with either a change in manifold OR and change in cam. What you have was not set up to work together.

The issue with your upper end RPM is structural, not power related. Stock rods are OK to about 5500 RPM. Strongly suggest you pick up a copy of Jim Hands book, "How to Build High Performance Pontiac Engines"

What timing do you have your car set at? Do you know what your timing is at when rpm is above 3000rpm? You say your car runs hot 225? WHat did you set your initial timing at?

initial is around 8 to 10 BTDC i think its around 34% at 3000 rpm.

I was thinking the heat was a pump issue, as the thermostat opens at 165. rad temp is around 167 blaock at thermostat is 213 or so.
So if everything is OK for a more aggressive cam what is recommended. and yes i have a slight just off idle bog.it feels like its still pulling strong at 5500 rpm. I did pur arp bolts in he caps and the asembly is balanced. i also have springs that are good up to 6500.

Are you sure of the compression ratio? A 30 over 400 and 16 heads would need a good bit of mods to drop compression. I bet you have 10.5 ratio unless a lot of material had been removed from heads and pistons. You probably are getting detenaton but with the timing at 8-10 degrees it is not as noticable.

I Have that book its very good reading and i like the recipe section at the rear of the book. But my basic build is a
1969 xx block bored .030 over pistons matched to bore. He would not bore without the pistons present.

Fully balance rotating assembly using arp rod bolls and TRW forged pistons compression reduced to around 9.5 to 1 CR
A 068 clone cam from summit racing, with matching lifter (anti-pumpup)

1969 #16 heads full head job with SS valves and a higher pressure set of springs. And big block chevy rocker studs.
(I don’t know of the top of my head what they are )The shop that did the work accidently pocket ported the heads because they thought I had asked them too, but I didn’t. So I met him half way on the porting cost. And he does know Pontiacs.Also using ARP head bolts.
Edelbrock performer RPM manifold with an 1969 Qjet 800 cfm Carb

Stock distributor with an electronic conversion kit from MSD I think , again I’d have to go look at my receipt’s / orders. . Initial timing is either 8 or 10 % BTD And its 34% all in by 3300 RPM..( I have a spring kit haven’t played with it yet. )

This is connected to a 200-4r transmission from 200raptor.com the level3 Reptoid transmission good to 500HP . via a 2000 RPM stall converter

Rear is a 1969 positrac rear end (Pontiac) totally rebuilt running 3:55 ratio.

I’d rather NOT change the intake , id rather do the cam instead , took me a while to get all the hoses and linkage the way I wanted them so they would work correctly with the transmission. So what would be a good cam for this engine ?

i had a dish 2 mmm deep if i remeber correctly machined into the pistons. i checked with TRW and they said there is enough to safely do that. And that dropped me a whole point, stock .math it was around 10.5 to 1

Pontiacs are torque producers and need a fair bit of work and $$ put into them to spin them up to where the sbc can go easily..

It's your choice, but a suggestion before going down that road, try a stock intake or ebrock performer, you may be happy with outcome and you can usually pick up a used performer for $75.00. If you aren't happy you will get your money back less your time..

The RPM manifold is not giving you the full advantage of the low grunt you motor has in it...

Cast rods were standard in most Poncho engines including the 455 H.O. (with a 5,600rpm redline), so a little cleanup and some new hardware will more than do the trick.

Read more: http://www.hotrod.com/techarticles/engin...l#ixzz1XkpcRxld

So with ARP rod bolts and the shot peening i should be ok to 5600 RPM.

That jives with what Jim Hand says in his book.

I am swapping out a RPM for a Performer hopefully this weekend. Will report back with results.

I completely agree. Just saying the rpm manifold is suited for 1500-6500 the stock / performer is suited for 0-5500. Which one is better suited for a mill built to spin to 5600?

From my testing the RPM starts make'n power closer to 2500.

Ya i would agree with that. Although i dont seem to have a "dog" below 2500 rpm by any means. i guess its hard to explain. car seems to go OK. but i am comparing it to my 07 impala SS. My ss would definitly beat the bird . car has a very slight off idle stumble which i would assume is the carb. Once its past that (matted) ;-) 5200 RPM comes up fast , shifts a little late for me so i manually shift it for now.2nd gear same thing revs right back up to 5200 aftter RPM drop, then 3rd again 5200 comes up pretty fast. speedo not working just going by feel . seat of the pants feel says it SOUNDS like im going fast but im not. i'll use my gps today and see just how fast i am going in 3rd..

Thanks
Bob

It almost seems like it revs too freely. like the 3:55 is too much and it would be better at 3:08 or 2:73

i contacted raptor transmissions and they gave me something to try as my shifts are kinda soft and lazy. i'll try it today.if this is it then im golden.

Someone here will be able to tell you the magic number when you combine the 1st gear ratio in your trans with your rear end ratio, memory has 9:1 sticking in my head as the target to aim for...

There is a post on it here..

That should help you to focus your energy on the likely culprit!

im close im at 8:76 for first and 2:37 for final drive

Bob

If you have any stumble in your carb you need to fix that first. A problem with your carb can cause all your problems/complaints. Whats the history on the carb? Nothing in your combo sounds too out of place to me. But again, a carb that is not set up right will make any combo seem off.

its a rebuild 1969 Quadra jet. it has just a minor off idle stumble . i have many of these so im bead blasting another to rebuild it my self. I bought the one currently in the car off ebay , and to be honest he didnt do the rebuild correctly. he forgot to put the hot idle compensator in which left a big vacuum leak to deal with.


I think i may be dealing with some trans slippage.
Bob

no forward movement on this yet , busy with work. But going out now to finish installing flex fan and shroud.

Ok tried the experiments on my trans.They had me pull the TV cable all the way out and vise grip it to see if it was a valvebody issue or pressure. it turned out to be the TV cable adjustment. Everything seems to work great now, shifts not quite as solid as id like so i will play with cable more tomorrow. Neighbors not to happy about a screaming 400 going sideways through 1st,2nd and 3rd... lol but atleast i have one issue ironed out. I forgot convertibles have a traction problem.

Thanks guys

Ahhh, neighbors. Aren't they great?!

MOST of them are , actually within 1/4 mile there are atleast 5 or 6 guys who have classic cars. Dennes has an awesome white 62 impala ss 409 4 speed its beautiful.Anda a nice aquamarine 63 split window vette.

What's a hot idle compensator?

Its a thermostatic vent at he rear of some qjets that opens to add some air during hot retsarts after a few minuets of sitting. Some qjets boiled over gas when real hot. It helped add air so as to not let the car flood during hot starts.

http://www.highperformancepontiac.com/tech/hppp_0311_rochester_quadrajet_carburetor/photo_04.html

Ok, so where is the bi-metal strip, on the inside?

its inside the rectangular opening in the picture. his one doesnt have the fuctionality. So its not drilled out for it>>
caused by excessive fuel vapors during hot engine operation.

The compensator consists of a thermostaticallycontrolled valve, a heat sensitive bi-metal strip, and a valve holder and bracket. The compensator valve assembly is held in place by a dust cover over the valve chamber. A seal is used between the compensator valve and the float bowl casting. The valve closes off an air channel leading from a hole in the top of the air horn, just beneath the air cleaner, to a point below the secondary throttle valves.

Normally, the compensator valve is held closed by tension of the bi-metal strip. During extreme hot engine operation, excessive fuel vapors entering the engine manifold cause richer than normally required mixtures, resulting in rough engine idle and stalling. At a predetermined temperature, when extra air is needed to offset the enriching effects of these fuel vapors, the bi-metal strip bends and unseats the compensator valve. This uncovers the air channel leading from the valve chamber to the point below the throttle valves. This allows enough air to be drawn into the engine manifold to offset the richer mixtures and maintain a smooth engine idle. When the engine cools and the extra air is not needed, the bi-metal strip relaxes, closes the valve, and operation returns to normal mixtures.

For proper idle adjustment when the engine is hot, the compensator valve must be closed. To check this, a finger may be held over the compensator air inlet channel located on top of the air horn. If no drop in engine RPM is noted on a tachometer, the valve is closed. If the valve is open, plug the hole or cool engine down to a point where the valve automatically closes for proper idle adjustment.

I did the swap today from the RPM to the Performer and I would say it was a improvement on the low end side. The Performer is more suited for my setup for sure.

i think im going to "tune" the setup i have , do a dyno run. and see what i have. if i need better rods , i'll buy them . But from what i have now performance wise i'm pretty happy and realy haven't touched much. my problem is/ was the tv adjustment on the tranny.
Tomorrow i'll check and adjust the advance curve and move the shift points .