[80TA]

Ok guys got my new 274H cam working in my car and it seems to work pretty good.I can idle it down to 800 or so,its lopey but in a good way don't stall out.The bottom end seems not bad still can spin the tires off the lights without braketorquing it and it seems to pull good thru the midrange.Haven't took it right to top yet since want to give the new crower springs a few heat cycles first.
So was I suspose to get a superdog car since my compression is like 7.5 to 1?
I would guess my stall and gears help a bit.I am sure it would be better with some 3.73 and maybe a 3000 stall and sure more compression will help too but the car seems very driveable and seems to be pretty strong.Is it stronger than before with my unknown cam.Guess have to make some new tazzo runs or try to get it to track before season ends.
The butt meter feels its faster and would think a mid thirteen on street tires now but butt meters can be wrong.
I just wish good aluminum heads for our cars were more like 1000 US not 2000 US.Maybe get lucky and find a nice used set next year.

Anyway just wanted to say that I don't think the cam is that bad in my 400.

[80TA]

Ok guys got my new 274H cam working in my car and it seems to work pretty good.I can idle it down to 800 or so,its lopey but in a good way don't stall out.The bottom end seems not bad still can spin the tires off the lights without braketorquing it and it seems to pull good thru the midrange.Haven't took it right to top yet since want to give the new crower springs a few heat cycles first.
So was I suspose to get a superdog car since my compression is like 7.5 to 1?
I would guess my stall and gears help a bit.I am sure it would be better with some 3.73 and maybe a 3000 stall and sure more compression will help too but the car seems very driveable and seems to be pretty strong.Is it stronger than before with my unknown cam.Guess have to make some new tazzo runs or try to get it to track before season ends.
The butt meter feels its faster and would think a mid thirteen on street tires now but butt meters can be wrong.
I just wish good aluminum heads for our cars were more like 1000 US not 2000 US.Maybe get lucky and find a nice used set next year.

Anyway just wanted to say that I don't think the cam is that bad in my 400.

[Z Code 400]

What are the specs on that 274 @ .050" Lift??? Isn't that a 110 LSA???...Robert

[80TA]

at .50 its 230 intake,236 exhaust
Its 110 lsa.Its got .488 lift intake and .491 lift exhaust gross valve lift.

At .006 tappet lift is 274 intake and 286 exhaust.

[Z Code 400]

Wow!! I thought my Custom Designed Hydraulic with .462"/.462" - 220°/226° @ .050" 111.5° LSA in a 413 with 8.88:1 compression was too much camshaft.

Guess I was wrong!!!...Robert

P.S. Great job!!! Sounds like you did everything right.

[80TA]

Well I still have to mess with timing and tune the carb and install my 800 thunder carb again tried it before the cam /intake stuff and it was too much ,wish they made them in the recommended 750 size rather than only 650 and 800 sizes.I may go up to 3.73 gears and like I said will think about some new heads possibly next year.
I was seriously considering a BBC crate motor in my car but trying to see what this 400 is capable of in the meantime and the meantime might be a long time depending on how it holds together.

[trigger]

That's simply too much cam and carb for the compression ratio. Either swap the heads for some with smaller chambers or use milder parts. You're in the position where a smaller carb and a milder cam would make for a quicker, more efficient car.

[Fox]

He is using an XE cam guys. Those cams do REALLY well on low CR engines but I'm sure his CR is probably better than 7.5:1 His gears and stall probably help a good deal as well. I can imagine that it's not running optimally with the low CR but like he says its not a dog.

[Cliff R]

I tested an XE cam here a few years ago and was remarkably impressed by how well it idled for the generous .050" specs. The XE274 cam has around 65 degrees of overlap nearly as I can remember. The short seat timing and less overlap of the XE cam would still salvage some low speed power. As you noticed it is tolerable in the low compression 400 engine. Get some track numbers on the combo, maybe you didn't hurt overall power as much as expected?.....Cliff

[jamaca85]

i just put one in my 455, interesting to see how it runs compared to my 280 i had in it.

[80TA]

Car craft has that build up on a 455 not 400 mind you.They did use same cam,similar rocker ratio not 1.65 and same intake and smogger same heads not touched and it did make 350 hp in that one and pretty good torque even down low.They had shortie headers on there and 2.5 inch exhaust.That was engine hp not rear wheel.So figured with my 400 maybe getting 275 since don't have headers or 2.5 inch exhaust just 2 and 1/4 exhaust.
And like was said the gears and stall help too.But I really likely only do have 7.5 to 1 since have 6 x 8 heads untouched as far as I know.
I can get hold of some 4x 73 4 barrel heads for cheap but think likely just wait till next year and get some e heads or kre or find some used ones.I gather with my 400 can use the smaller chamber e heads if find some since with 400 compression will not go as high as in a 455 with same heads right?

[ra3goat]

Is anyone running a XE284H in a 400", or any motor for that matter. My 400 has low vacuum at idle, around 6" in drive. untouched 62 heads, dished KB pistons for around 9.2-9.5 compression, and RPM intake. It idles on it's own, pretty rough. I have very light springs in the distributer, so the advance starts to comes in at idle, which helped vacuum, with total timing at about 34. I'm in the midst of installing KRE d-ports, milled to get 10.5 compression, I figure this is possible with the aluminum, chamber design, and plenty of cam overlap. Should this cam be making more vacuum at idle?? would advancing the cam be worth anything? this is in a '67 GTO, 3.55 rear, 2800 stall, 2004r trans. Thanks all.

[KEN CROCIE]

80ta--go out and take one spring from your distributor.Report back with progress.

[buwalda]

RA3Goat,
I would think you should be able to get more than 6" of vacuum. Most CC cams have 4 degrees of advance ground in already. Advancing it another 2-4 degrees may help a little bit. Rhoads lifters will probably do more good. Sounds like the cam is a tad too much for your 400. As you found, giving it more initial timing helps idle quality & vacuum. If you stick with the cam, use vacuum advance hooked to FULL manifold vacuum to improve the idle & vacuum. With that cam, you will need an adjustable unit, such as a Crane to work, because the stock one won't. Good luck.

[80TA]

Update..The cam seems to be working not bad but seem to have a problem up top car seems slow to rev or something.I am wondering if the stock fuel pump can keep up to this new combo.I will do some pressure testing shortly and for short term may install and mechanical carter street pump as looks like edelbrock don't make one for our pontiacs unless big or small block chevy one fits.I plan on better electric and new lines later.
Also car has shut off several times lately in corners and stuff..suspect float is not right in my 800 will check that.

I ran a new time the other day on tazzo not track and car ran a 14.48 at 95mph with a 2.17 60ft think it was .So car is for sure slower right now.But again before giving in to the "its that big cam " theory also think having my pro magnum lifters set at 1/4 turn past zero is choking the top end too.They are supposed to be set to near zero lash hot.Will do that next week think also.
Timing is in that 34 to 38 range.Car is also a bit slow to start up.

[80TA]

Just installed new carter mechanical street pump.Also found out it appears floats were not set right from factory on my 800 thunder it was flooding out a lot.
Now car seems much faster.I seem to have all the bottom end I can handle on my current street tires the cam does not seem week down low at all to me.I do have 3.42 gears and 2400 stall.The cam pulls real hard in the midrange and pretty good up top.Have shifted it around 5500 and it seems to still be pulling up there.
I don't think shifting at 6000 is good idea though on my stock bottomed 400.

I still have some tuning to do but the cam seems streetable and powerful to me.Run some new times soon hopefully at track.

[Dean P]

Pontiac enthusiast did a 455 engine build-up with the XE274 cam and some SD Performance 4X 240 cfm heads in their July/August issue.
9.25:1 comp.
Made 459hp @ 5150 / 527 tq @ 4250.
From 4200 to 5500 the engine was making over 425hp.
From 2900 to 4700 over 500 ft. lbs. of tq.
Pretty impressive.

[bobzdar]

6000rpm should be ok, but I wouldn't go any higher than that. I had the same problem with fuel delivery when I went from an edelbrock performer cam to pontiac 744, but my car would just run completely out of fuel on the top end. I installed a high flow needle and seat, reset the float and installed a carter mech. pump and it seems to have solved the problem.

[80TA]

Ok guys..Haven't done any real tuning with jets or needles or any of that stuff just set secondaires to open a bit slower.
Ran three runs today with nearly full tank of fuel.
These are tazzo runs but tazzo was accurate within a tenth at track and 2.5 mph higher than track when took it there last year.

1st run..14.52 at 93.6 mph 2.11 60ft.Mild brake torque,thinkg shifted at 5500.

2nd run..14.39 at 96 mph 2.25 60ft also mild brake torque shifted at 5000.

3 rd run.13.78 at 99.7 with a 2.08 60ft.
Braked it up against converter as high as it would go and shifted not sure but think 5500 almost sure not higher.should keep better records.

Would have tried a few more runs but no time this morning.

So car has now gone faster than it ever went before.It does not appear that the new cam is hurting times although hard to say I guess if a bit milder one might have helped.Rather than go milder still think will put in some different heads and then think the 274 h will start to really shine.

The car seems good in daily driving..lumpy idle for sure buy don't stall.It pulls strong from around 2500 maybe a bit lower and pulls to 6000 without much problem..not planning on going past 6000.

I have to set my pro magnum rockers to close to zero lash they are still at 1/4 turn and have some tweaking to do with tuning but 13.5 look within reach.Keep in mind this is at 1900 feet altitude should have recorded my temp,humidity or dew and bar so you guys could correct if you want for density altitude.So does this data look about right for cars with similar mods?

Only real unknowns now is how much if any motor was bored when rebuilt and what if anything was done to 6 x 8 heads..suspect nothing.

So again it appears the xe 274 can work with lower compression and like I said in car craft they got like 350 hp and forget but good torque on 455 with 7.5 to 1 stock heads.

[80TA]

Further updates.After a week or so of playing with my 800 thunder and having some bogging issues I decided to buy an new edelbrock 750 electric choke carb.It seems to be snappier and after playing with the carb and my timing..think running around 38 total now not sure how quick it comes in think have one heavy and one medium spring or something in there speed shop did it.
Anyway we also set my pro magnum lifters to about 1/16 turn running.Anyway car seems much faster now and stronger and anyone that says this is too much cam well I don't think so.I do have low compression but with my 2400 stall comp recommended a 2000 up I think and my 3.42 gears I can shred street tires no problem.
Still even if get you guys some track times I guess some will still argue mellower cam and even smaller carb might have went faster.
All I can say is you guys are invited to go for a ride..the thing pulls off idle to redline.It pulls hard now.Timing is likely key too.You need maybe more advance with this setup and low compression but it can work.