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I recently just purchased the XE284 cam kit from Comp. I was wondering who else has this cam with a set of Vortec heads? What type of work did u have done to ur heads and what type of times have u ran? I have the XE274 cam in the car with stock Vortecs at the moment. Best time in 1/4 is 13.6. Im hopeing that with the cam change and head work to possibly get in the low 12's.
The setup that Ive got at the moment is 350SB, 10-2-1 compression, vortec heads, air gap intake, holley 750, beefed up 700R with 3000 stall, and 342 posi rear. Need anymore mods done to the motor to help give answers just ask. Thought the big ones would b enough.
I plan on keeping everything the same but the cam and getting some head work with 1.6 rockers and MSD box. Any suggestions on the head work would b great. THANKS
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I wouldn't waste my time switching cams... you have all the right parts to be running at least a full second faster as is. My car ran 12.52 @ 108mph first pass with almost the exact same combination as you only difference is that I had 3.92 gears.
Are you running sticky tires? What are your 60ft's like? In my opinion the XE284 would slow you down even more.
__________________
350 with out of the box Canfield 195 heads & Cam Motion solid flat tappet.
11.50 @ 120mph N/A in street trim through the single 3" catback and CRAAAAZY fast on spray.
No Im not running sticky tires. The 60 ft is consistently 1.9. My tire size is 245/50/16. I figured with the cam and some head work and the rockers there would be a big diff in power which would be quicker times too.
I think the XE274 still has alot left in it, there are quite a few people on this board with similar setups running into the the 12's with that cam. Perhaps its a tuning issue? What do you have for exhaust?
All you need is a set of slicks to get the times you want to run. Your 60ft's should be in the 1.70's... Don't waste your time and money on a that cam. Your gear and stall are already on a low side for the XE274 so by going bigger you're just going to bring your powerband up and further throw off your combo.
Slap a 27x10.5 Hoosier QTP on the car and watch how quick it jumps deep into the 12's
The Comp Cams XE284H will be to big for your set up and slow your car down . Also your Vortec heads may not be set up for that 510 lift cam ? Keep the XE274H Camshaft . But change the rear gear to a 410 . You may get that car to run high 12s . COOL
My exhaust is Headman elite headers into a custom y pipe with 3in exhaust that runs into a 80 series flowmaster. With a cut out when I fill like takeing it off!!
I've seen many 12 second cars with the same setup as you. I was surprised to see the 13.6 pass after reading what you were packing. Seems suspension is next on the chopping block. Tires would also be good as these guys have mentioned. Good luck.
__________________ 1995 Chevrolet Camaro Z28 - "Venom" - Current 1988 Chevrolet Camaro IROC - "Reaper" - Sold 1987 Pontiac Trans Am GTA - "Demon" - Sold 1986 Pontiac Trans Am - "Beast" - Sold My CarDomain - My FQuick
I cant stress enough how simple it will be to run the numbers you want with the parts you already have... I also had single 3" exhaust but no cutout. I set the timing at 34* and left my 750 Speed Demon with the factory jetting... absolutely no tuning netted me mid 12's. I'm sure if I played with the carb it would have run 12.20's without trouble. Another guy who used to post on here had a similar combo ran 11.90's with lightly ported Vortecs and around 10.8:1 ...I saw it with my own eyes at Atco Raceway
What pistons are in it? Was the block zero-decked to them? What head gaskets?
With typical stock replacement type pistons such as L2256F, hypreeutectics, cast, etc, you have the stock .025" or so of deck clearance, PLUS an extra .020" made into the pistons; for a grand total of .045" "down in the hole" at TDC.
Given that, .039" gaskets (FelPro 1004 or similar), 6cc valve reliefs, and 64cc chambers, your CR might be as low as 9.3:1. Not 10.2 at all. Meaning, you don't REALLY have enough compression for the cam you've got now; it'll just get worse with a bigger one.
Vortec heads are known not to respond well to lots of lift. I'd suggest skipping the 1.6 rockers, in any case. Likewise on the MSD box; if you aren't having ignition problems, there's nothing for it to fix. Not money well spent.
What valve springs do you have? How are they set up?
What does the car do now, besides leaving MUCH softer than it should? Does it lay down at the big end? Wheel hop? What is a run like?
__________________ Numquam ponenda est pluralitas sine necessitate. — William of Ockham, from Quaestiones et decisiones in quattuor libros Sententiarum Petri Lombardi
Roughly paraphrased into modern English, and applied to figuring out what's wrong with your car:
The simplest explanation that fits all the facts is probably the right one.
When you ran the 13.6, what was your best MPH at the track?
A good indication of how much actual horsepower your motor is making.
To see the benefit of going to a larger cam like the XE284H-10 you need 4.10's and at least a 3500stall. 10:1 compression ++ ( actual measured compression ratio, not "I got 10:1 pistons")
its quite probabile that your real measured cr is not near as high as you think.
You have the basic parts there to run high 12's now. You will need to bring the motor up to spec and get some sticky tires.
Most of the cheapy restalled stock diameter converters for the TH200r4 and th700 leave a lot to be desired. (efficientcy) You want to invest in a quality 245MM (small diameter case) custom converter (YANK or Precision or ATI)
You want a converter that will give you a real 3500 to 4000 stall with sticky drag tires (ET streets or slicks) and actually transmit the engines power to the ground over the quarter mile.
The stock vortecs heads will make enough power to run 12's . They do respond to general ,full porting and larger valves.
Like I said you should be running high 12's @106MPH now (with traction)
if you're not getting 106MPH now (reguardless of the ET) your motor is down on power from what the parts you have should support.
With the right tune (10-10.5:1 measured cr, ported big valve ported vortecs, XE284H cam, a real (3500-4000stall) custom built torque converter,4.10or 4.56:1 gears and ET streets and some rear suspension traction upgrades), you should be running high 11's @110-112MPH. You need to be in the 1.65-1.70 60ft zone. You need to swap to a long tube header exhaust.
The shortie headers are not a good match for either the cams you want to run.
F-BIRD'88 Is right when he says with the XE284H ported Vortecs and a 3500 to 4000 stall / 456 gear / Long tube headers may get you to the high 11s . But your car will be a strip car with lic-plates . Just the way I like them . COOL
My MPH is 106 and sometimes 107. So from speed I should be running faster times with that setup. As for going down the track it launches really good, it hooks 1/2 the time, which is from street tires. It seems really fast and shifts really smooth as to how it runs down the track. I run it at Bristol Dragway in TN. With how Im wanting to bulid this next setup it would be faster than the old one somewhat. As of lift n rockers I was thinking of going 1/2 1.5 n 1.6"s on the rockers, any opinions that?
As of springs it the stock springs until I get the head work done and I have the Beehive springs to go along with new locks n reatainers, bigger valves, and etc. Not sure on how much I will port r shave yet.
The gear size with new setup I figured that I would need at least a 373 r 410 So u think that long tube headers would be a better choice than the shortys? What difference would they make over what I have? The MSD Box is to help it start better and for the rev limiter.Thanks for all the help and info given so far.
Long tubes will bring the peak torque RPM down to where the car is on the convertor. That's the benefit of tuned secondary/ collectors and open exhaust (cut outs in the right place).
These guys are right. You should be making enough power to get 12's.
The racers in this group run steep gears and lots of convertor to get quick 60' times with out having to make tons of power.
I'm happy I found this thread. I've been doing a motor build this winter and I currently have a 1992 350 4 bolt main .060 over with flat top pistons, #906 vortec heads, stock rods, new federal crankshaft, and i have money now to invest in a cam, intake, and a carb. Whats the best cam for my heads? I heard vortec heads like alot of duration and thats why ive been considering a thumper cam such as this one (http://store.summitracing.com/egnsea...DS=1&N=700+115) So with a 9.5:1 compression should i stick with the vortec performer and a 600 cfm carb? any information would help, i want the best bang for my buck! and what et's should i be expecting with 245/55/R16? I am building my 700r and getting 3.73s and slicks
I've found that Northern Auto Parts have the best pricing around along with great technical support
I would go with a bigger carb. I had a Holley 600 n when i switched to a 750 there was a big difference. With the 600 it was almost like the car was starven for gas. The xe274 from comp is what alot of these guys like with Vortec heads as u seen from this form. Its really a toss up n what u want n my opinion, the Vortecs cant handle alot of lift with out some head work, which is what Im fixing to be getting done.
Im going with comp Beehive springs. My lift should be around 550 r so. Im either going to use 1.5's on the intake n 1.6's on the exhaust. If I dont do that it will be 1.5's all the way on the rockers. Im going with bigger valves on the exhaust side. They say bigger valves on the intake side really dont help any.
vortecs don't need over .520 lift on non-ported ones at all. I wouldn't be swapping to bigger valves if you're running low compression already. 1.6s typically won't do anything at the track either. I run vortecs and have gotten excellent numbers out of them definitely would be working on suspension since you're leaving a bunch on the table running 1.6 seconds slower than you possibly could be already with a 13.6 ET instead of 12.0
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