Chevy guy trying to setup a mopar. Uh oh!

[whiskey]

Hello all, I hope that you all will not have to much fun at my expense but, I am a Big Block chevy guy and have been doing this for a long time. I have been asked by a close friend that is a Mopar guy to help him out. Not being familiar with these engines, I have a few questions to ask you experts. The car is a 1970 Cuda. It weighs in at about 3800 lbs. Has a 4 speed transmission and a 3:54 rear gear. It has a 440 6 pack that has been stroked to 493 cid. Bore is 4.35, stroke is 4.150. Compression is 9.75 to 1. The heads are stock 906 heads with stock sized valves. He is, in my opinion severely under cammed. The cam is a Comp cams extreme energy with 477/480 lift, and 224/230 duration @.050. This engine currently makes way more torque than he can put to the ground and lays down way too early. I have suggested that he go with a solid roller tappet cam. To get more area under the curve and push the rpm band up to shift at 6200 to 6400. This will sacrifice some low end torque that is just going up in tire smoke anyways. So I would like to know what you guys think or recommend as far as Camshaft specs, Brand of Lifters and a roller rocker setup. As I said, I am a chevy guy so I don’t know what kind of lift I can get away with before piston to valve problems. Also what kind of machine work would need to be done to convert to a roller setup. The target is to run 11’s on pump gas. I would also like to know what kind of ignition curve these engines will tolerate or like. Thank you in advance for any help you can give.
Thx
Bill

 

[Burntorange70]

Hay Bill Welcome to FABO! You have come to the right place. Sorry I don't know the answers to wour questions but some one on here will. Good luck with your build.

bump.

 

[3404spdvaliant]

A roller would sure milk those stock heads dry.
Hughes roller rockers or and go 1.6 I've also had ggod luck with ohio crankshafts full roller rockers and rocker arm specialties shafts & adjtrs
The timing is gonna depend on that specific engine combo,
but generally 35*-38* total and try and get the most initial timing your starter can handle[or raise it till the starter has trouble then back it off 2*] then find a way to limit the full advance to what ever the engine likes[runs best with].
I like the MSD pro billet cause you can make your own bushings to limit advance instead of welding up slots in the stock unit.
comp XR286R solid roller
comp solid flat tappet XS282S
Good luck

 

[whiskey]

Thank you for the recommendation. I had already picked the XR286r as a possible choice. I have been told about a MP 577 also but have no info on that one yet. I also think the heads are deficient but I dont know. I assume that I would have to go aftermarket to do better or port the heck outa these.
Thx
BILL

 

[moper]

It's the same physics...lol. Brand doesnt matter. You are right, the engine is way undercammed. But, a roller cam in a CHevy is easy. In a Mopar it takes a littel more, and if corners are cut can have some bad stuff happen. This is a street car, and a 3.54 gear so really, it doesnt need to make power over 6. I'm guessing the cam lays down about 5300 in that thing and the torque "peak" is probably from 2200- 3800...lol. The Mopar oils thru the lifter galley unlike the Chevy. This means little until you spit a lifter and the oil pressure to the lower end is cut off. The way to fix it is to bush the lifter bores, which has the added side benefit of fixing the terrible alignment work the factory did. You need the bushings, a thrust button if you dont go gear or belt drive, and the bronze gear oil pump drive, in addition to the cam and lifters. It gets pricey. but, there are alternatives. The GM lifter is the narrowest made. Mopars are the widests at the base. So the profiles in a GM that have to be roller, dont always have to be in a mopar. That existing cam uses single sprigns with dampners. Any larger modern grind will need dual springs, which means cutting spring seats and the guide tops for small seals. I would spec a flat tappet, either an older Crane number I use a lot (and will make 450hp in anything, close to 480 w/500 tq under 3000rpm) is the H302-2 hydraulic. It's not as fast rate of lift, but it works great. A modern grind might be the Comp XE275HL. These are both drop ins that need springs, and are hydraulic to keep the "street" part in place. Solids can go bigger. Generally on an iron head mopar, anything solid flat tappet from 250-260°@.050 is a good midrange cam. You can go bigger, but I wouldnt go roller if the engine is together. His cruise rpm will make things feel soft in 4th if you go much bigger than these.

 

[3404spdvaliant]

Bill, there are better heads out there, then again you can port these heads to 260-275cfm easily. 290cfm is about the max.
The stealth heads from 440 source sound like a good choice if heads are in the equation.
If it was 500+ci maybe the victor eddys have the port volume needed.I
I am not familiar with MP roller cams, or are you talking about the
MP solid .557 296* 110cl?
Glad to help.

 

[wedgie]

Thank you for the recommendation. I had already picked the XR286r as a possible choice. I have been told about a MP 577 also but have no info on that one yet. I also think the heads are deficient but I dont know. I assume that I would have to go aftermarket to do better or port the heck outa these.
Thx
BILL

Sounds similar to my stroker setup in my '65 coronet. 496 sixpack. 906 heads prepped by Koffel. Car weighs 3700# and has a 3800 convertor. I called Racer Brown and had him grind a hydraulic flat tappet cam for me. This is a street car and is absolutely awesome (scary fast). Remember that strokers don't like or need a lot of RPM.

 

[3404spdvaliant]

I think the the XE275 would be weak suck in this motor.
I mean 231*????
You would be better off throwing a MP.528 solid w1.6 rocker and only have to
'drop in' springs/rockers like the other guy said.
While yes the gear isn't all that great but would suit the fore mentioned and could be changed in the future.
Wedgie , your right they don't need a lot of rpm.

 

[demon seed]

Hey Bill, what Moper said, and I might add that for those RPM's roller rockers for sure and what kind of headers you running. If you're going to stick with the 906 heads, good heads for moderate street/strip in stock form, you really going have to open them up with at the very least a pocket port job and bowl blend. If the pistons are true flat tops with no valve reliefs a high lift cam (over .510") could be tricky so ultimately you're going have to do some measureing to make sure that the minimum clearance between the piston and valves is no less than .080", that's the number I use. You didn't mention the rear end (could be a Dana 9 3/4") but probably an 8 3/4" in which case the pinion gear snubber is all you need and of course sticky tires. Yea and carb. minimum 850DP'r.
\
Terry

 

[crackedback]

I'd work on getting the car to hook before throwing money at getting the engine hopped up even more. You may be surprised what it runs with the current set up. What does the car currently MPH?

 

[3404spdvaliant]

TRY 950 annular carb!!!!!!

 

[3404spdvaliant]

BTW when some one says 354 gear you can bet it's a dana.

 

[demon seed]

BTW when some one says 354 gear you can bet it's a dana.

He may have meant 3:55, ya never know

Terry

 

[3404spdvaliant]

He may have meant 3:55, ya never know

Terry

Fair enough, thanks for not taking offense.
[It's hard for others but thats what happens on the internet with no facial expressions and tone of voice to go by]

 

[demon seed]

Fair enough, thanks for not taking offense.
[It's hard for others but thats what happens on the internet with no facial expressions and tone of voice to go by]

:violent1: Like this, LOL. Not to worry

 

[whiskey]

Moper, Thanks for the advice. I just talked to him and told him about the spring seat issue. He still wants to go roller and is willing to spend the money. He is not willing to replace the heads. You can lead a horse to water…LOL… So with this stroke you are saying that 250 to 260 should fit the 6 grand bill or no? 3404spdvaliant, the MP 577 is a solid FT cam. Demon seed, The rear is a Dana. The one thing that I don’t know is the piston dome volume or p/n. So I am not sure yet what valve clearance I will have. Wedgie I agree that he doesn’t have to spin it much above 6 grand so maybe 6200. He tells me he spins it higher than that now. But I am sure that VE is in the dirt by then and it is all done in vain. Does anyone have a proven combo similar to this that I can use as a benchmark?
Thx again boys
Bill

 

[whiskey]

ttt

 

[3404spdvaliant]

???????