FullSendRacing

Currently I'm running a comp cams hydraulic flat tappet cam with 1.5 aluminum roller rockers. duration at .050 is 228 / 236. this cam really is too much for my car, and undriveable with the MAF connected... way too much lope. I'm trying to decide what roller setup I want. I'm looking to lose probably about 10-15 degrees on intake and exhaust. My 355 is a '74 block.

What I'm really aiming for here is driveability with the TPI system fully functional (I will be able to reprogram the chip if needed), and still making good power. The lt4 hot cam and TPIS' zz9 cam are what I been looking at, any opinions on these ?

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'84 Recaro Trans Am WS6, Jegs SFC's
355 w/ '89 TPI system, holly AFPR
SLP 1 3/4 headers, custom free flowing exhaust
(I've done all work on this car myself, so if you have TPI retrofitting questions...)

GregWestphal

iTrader: (1)

The LT4 HOT cam makes very good power in modded TPI engines, 280-300 rear-wheel hp with aftermarket manifold and runners on top of good heads (AFR or TF). I have mine idling at 750 rpm in Drive, but it can even go as low at 700 rpm or even lower. The key to how it idles is increasing the spark advance a lot; I'm running 30 degrees at idle, which also gave more a couple more inches of vacuum compared to 20 degrees timing. The ZZ9 cam isn't as good at the LT4 HOT cam IMO, and costs $200 more. It'll still make good power, but the smaller intake duration will limit it more with a good-flowing intake setup. CompCams also makes some great cams, like the 218/224 on either a 112 or 114 LSA, or even the 218/230/114 blower/nitrous cam.

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Greg Westphal
'87 IROC 355TPI/A4

Matt87GTA

I agree. The LT4 HC is a pretty good one for the price. It is a lot cheaper than all of the other options out there and makes as good, or better power than comperable ones such as the ZZ-9 cam.

I actually had my car successfully idle at 550 rpm for a while with the LT4 HC... It was pretty smooth (lopy as all he11...) but would tend to stall out if I blipped the throttle pulling into a parking lot real slowly or somthing like that (the stall didn't help that...). But I would say that even where I have it now, 650 rpm, is plenty good, it never stalls out and it idles pretty smooth. I only have 20* of timing in at idle too...... hmmmm... might have to throw some more timing at it and see how that works...

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

Matt87GTA

One other thing. The LT4 HC is a roller hydraulic cam so you will need retrofit roller hydraulic lifters for it in that older block. They have little arms that connect each pair of lifters that are next to each other to keep them rolling straight on the cam lobe. You will also need the proper thrust plate for the cam.

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

FullSendRacing

Thanks for the help Greg. I took a look at Comp Cams' online catalog. The 218/224 at 110 separation is the closest I saw. I noticed that all recomended TPI cams are 112 separation though. I gave them a call and the guy directed me to the marine section. The marine version of the 218/224 cam has a 112 separation, so I think that's what I'll go with.
(When I told the guy what I was running, he laughed at me "that project was dead before it started")... the TPI will never work with the amount of overlap I have.

So the next dilemna is whether to go roller or stick with flat... to go roller, It'll cost me about $650 between lifters, cam, and pushrods. If I get the flat cam and flat tappets, it'll cost me 4170. I'll be losing 0.025 lift, but if Y need it it the future, I can always get 1.6 rockers.

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'84 Recaro Trans Am WS6, Jegs SFC's
355/'89 TPI, Holley pump and AFPR
SLP 1 3/4 headers, custom free flowing exhaust
(I've done all work on this car myself, so if you have TPI retrofitting questions...)

FullSendRacing

whoops, that '4' should be a '$' 170 for the non-roller setup.

NufNuffZ28

iTrader: (10)

Comp cams also recomended me the one up from the one you were looking at which I got(08-503-8) with 224/230 duration. Lift is 503''/510'' and I am using 1.6 rr. With ported everything, AFR heads, long tubes, 3.73's, 3000 stall, it should work good. Whatcha think?

Chris
One day my car will run again!!!

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1986 Iroc 355 TPI coming soon

1985 Z28/5-speed Daily Driver

lexussc94

iTrader: (2)

Whats the largest cam that will work on a 350 TPI?
What do you guys also think would be the largest cam for a 400 TPI?

JAY87GTA

What's your LSA on the cam your running now. Sometimes that is more important because excessive overlap will cause you to lose vacuum at idle. You might could stick with the same size cam but with 112-114 overlap and be alright. Just a thought.

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'87GTA w/ SLP Cold Air, MSD Coil, Airfoil, Gutted MAF, AFPR, TES Headers, HI-FLOW CAT, Flowmaster Catback, Energy Suspension Master Bushing Kit

FullSendRacing

yeah, the cam I'm using has a 110 LSA. it was great with a carb, but the car shakes like a Fing jackhammer with the TPI if I'm not careful with the gas. (and it only runs decently w/o the MAF). I'm pretty sure the 218/224 cam is the one for me. I still have stock intake... and that ain't gonna change anytime soon. Being a college student at an engineering school... I have no money to dump into my car. Just another 19 months...

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'84 Recaro Trans Am WS6, Jegs SFC's
355/'89 TPI, Holley pump and AFPR
SLP 1 3/4 headers, custom free flowing exhaust
(I've done all work on this car myself, so if you have TPI retrofitting questions...)